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8509A/B User`s Guide

1. pq7115_c Figure 2 40 The Measurement Summary The Measurement Summary Bar displays the PMD results obtained up to the current wavelength All of the displays have the same units which are user selectable but default to picoseconds The bar displays the PMD derived from each of the measured Stokes parameters as well as their average Making Measurements 2 37 PMD Measurement Wavelength Scanning Method The Measurement Annotation Area pcia 0 1525 PE E 0 2238 MEW 0 098 ES 0 1307 Start AA 1 gt 0 005 0 82 Fiber Length 1 0 km Stop 5 k Source level 100 0 Watt Delta Source atten 0 dB Points Continue Measurement Annotation Area pq7116_c Figure 2 41 The Measurement Annotation Area When the measurement ends the control panel at the bottom of the Graphs window is replaced by the Measurement Annotation Area This area lists the date and time of the start of the measurement the fiber length in kilometers the tunable laser power and attenuator settings the start and stop wavelengths and the step wavelength It also lists the number of points that is the number of wavelengths at which optical measurements were taken A table lists the number of peaks identified in each of the curves At the right hand edge of the annotation area is an icon which indicates
2. Rotate 2pt Ref 3pt Ref Apply He Home pq725b_c Figure 5 11 Power Display in Watts Mode The Display Menu 5 7 Marking the Current Point File Edit Measurement DMEJJEVA System Help HP8509B Lightwave Polarization Analyzer Show gt Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq729b_c Figure 5 12 The Mark Current Point Menu Often when data is being displayed on the Poincare sphere it is desirable to know where the current data point is You can turn on a feature that puts a flashing dot at the current data point by selecting Display and Mark Current Point When this feature is activated a check mark appears next to the menu selection The dot will be red if the data is on the front of the sphere and blue if it is on the back side of the sphere The following figure shows what the display looks like with the mark current point feature turned on File Edit Measurement Display System Hel HP8509B Lightwave Polarization Analyzer 90 aBm Markers On Clear Markers s2 s3 0 08 0 98 Clear Trace 1550 0 nm Current Point
3. Jones values Pol Dep values Done pq776b_c orientation relative to the first reference polarizer setting m Set the external polarizer angle to 0 degrees and then select Meas at 0 0 from the Jones Matrix window m Set the external polarizer angle to 60 degrees and then select Meas at 60 0 from the Jones Matrix window m Set the external polarizer angle to 120 degrees and then select Meas at 120 0 from the Jones Matrix window 2 64 Making Measurements CT gt External O Internal O Delta Max Min Delta No reference frame applied Measurement at 0 0 done Measurement at 60 0 done Measurement at 120 0 done Measat0 0 Meas at60 0 Clear Restart Meas at120 0 Jones Matrix 1 00 0 00 0 00 1 00 0 00 1 00 1 00 0 00 x iy O radians degrees Jones values Pol Dep values Done pq776b_c Figure 2 72 Measurement Results Jones Matrix Measurement Your measurement is complete The screen on your computer should look similar to the previous illustration Notice that the Jones matrix measurement data can be shown in three formats x jy and magnitude and phase in radians and degrees Polarization dependent values can be viewed by selecting Pol Dep values from the Jones Matrix window
4. Y Scale Autoscale Tabular Data y Autoscale Zero Based PMD Statistics Fixed Scale pq7108_c Figure 2 20 Changing the Graph s Y Scale To change the vertical axis on the measurement graph select Display and then Y Scale from the Graphs main window menu The submenu provides three selections The default selection Autoscale Zero Based autoscales the maximum Y axis value but uses zero as the minimum value The Autoscale selection optimizes both the minimum and maximum Y axis values to expand the measurement curve to fill the graph area The Fixed Scale selection allows specification of the maximum Y axis value and uses zero as the minimum value Displaying and Printing Data in Tabular Format HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 via File Edit Measure Format MEJENA Window Y Annotation F9 y Cursor Data Symbols Y Grid Y Scale Tabular Data PMD Statistics pq7109_c Figure 2 21 Displaying Data in Tabular Format Display the tabular measurement data by selecting Display and then Tabular Data from the Graphs main window menu A text box fills the Graphs window overlaying the measurement graph The text box lists information from the measurement annotation area the values in the measurement summary and a list of wavelengths at which optical measurements were performed along with the DGD values derived from e
5. pq7149_c Figure 3 1 Measurement Troubleshooting Matrix 3 2 Accuracy Enhancement and Troubleshooting Symptoms The measurement symptoms listed in Figure 3 1 describe conditions that can often be corrected or improved by addressing the appropriate areas described in the Solutions section of the measurement troubleshooting matrix Appearance of these conditions does not necessarily indicate a need for service nor does it confirm a system failure to perform within specified performance specifications If a system failure is suspected however refer to the Operation Verification section of the Installation and Quick Start Guide included with this manual Solutions The following is a list of various ways to address the symptoms listed in the measurement troubleshooting matrix In all cases it is assumed that the HP 8509A B system has passed the Operation Verification procedure discussed in the Installation and Quick Start Guide and is operating properly Connector Connector insertion loss and return loss of the test system and the test Care Reflections device can affect polarization measurements in a number of ways Refer to the Connector Care chapter of this manual for further information about procedures for avoiding connector related problems Following is an explanation of why reflections from dirty or damaged connectors may cause measurement uncertainty If a set of large optical reflections are present
6. The Polarization Ellipse is almost circular Markers gt On Clear Markers so si s2 s3 9 090 0 02 0 08 0 98 Rotate 2pt Ref 3 Apply Bed Home s3 is greater than 0 90 pq791b_c Figure 2 8 Circular Polarization Adjust the External Source Polarization knobs on the front panel of the HP 8509B until the active point on the Poincare sphere approaches a pole and the absolute value of the s3 marker is greater than 0 90 The active point is easier to see by marking the current point select Display and then Mark Current Point Also notice that the polarization ellipse will become more circular as s3 approaches 0 90 Un apply the 3pt reference reselect Apply 3pt before going on to do the JME PMD measurements Do not move the cable or the external source polarization knobs FOR MORE INFORMATION More information on State of Polarization SOP and Degree of Polarization DOP may be found in the glossary and in this chapter Making Measurements 2 7 PMD Measurement Jones Matrix Eigenanalysis Method Making the Measurement At this point your measurement system is ready to make your first measurement For our purposes we are going to measure a 10 kilometer spool of optical fiber Remove the fiber cable connecting
7. pq734b_c Figure 5 17 The Hold Function 5 10 The Display Menu Clearing the Trace From the Sphere HP8509B Lightwave Polarization Analyzer File Edit Measurement IMEJJEYA System Help Show gt Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq735b_c Figure 5 18 The Clear Trace Menu To clear data from the Poincare sphere via the Display menu select Display Clear Trace After the sphere is cleared data taking will continue You can also activate the Clear Trace function by pressing F7 on your keyboard or by selecting on the basic measurement screen Setting the Display to Refresh Automatically HP8509B Lightwave Polarization Analyzer File Edit Measurement DEIJEYA System Help Show gt Power Display Display Update Hold F6 Clear Trace F7 Auto Refresh pq7160_c Figure 5 19 The Auto Refresh Menu Usually Auto Refresh should not be selected Use it only if there are many tasks running in windows and the screen is not being repainted properly If this feature is needed select Display and then Auto Refresh The Display Menu 5 11 The System Menu This chapter contains information on the following subjects a Optical Source m Zero a Calibration Polarizers Shutter m Averaging Range m Analog Outputs m Reference Frame Info m Operation Verification
8. Sphere Display Exit Po gnes Metre Wf PDL Power Max Min W Jones Matrix Window Calibration Window pq7134_c Figure 4 1 The File Menu Printing measurement results allows you to print the results of measurements you make Saving measurement results allows you to save the results of measurements you make Recalling measurement results allows you to recall load previously saved measurements Loading the preset configuration allows you to recall the PRESET instrument configuration Saving an instrument configuration allows you to save an instrument configuration for use Loading an instrument configuration allows you to recall a previously saved instrument configuration Printing Saving and Recalling 4 1 Measurement Results and Instrument Configurations Conventions In this document HP 8509 menu items appear in shaded boxes Like This HP 8509 main window items appear in unshaded boxes Like This Illustrations and examples in this chapter show operation of an HP 8509B There are minor differences for an HP 8509A the most significant is that the Jones matrix eigenanalysis polarization mode dispersion measurement is not available with the HP 8509A For Additional Information For step by step instructions on making measurements and for more detailed information about a particular measurement refer to the Making Measurements chapter of this manual For information regarding
9. Measurement in hold Vary polarization at input of test device Select Reset to begin Max amp Min recording Max Min Power Sz dBm s1 s2 s3 Max 7 661 0 42 0 74 0 50 o Min 8 161 0 29 0 85 0 42 Reset Clear Trace Max Min Power Delta 0 500 dB Angle between Max amp Min states Done pq7122 c Figure 2 65 Measurement Results Your measurement is complete The screen on your computer should look similar to the previous illustration If an automatic polarization controller is used the scanning speed of the polarization controller and the display averaging factor of the HP 8509A B should be adjusted so that the HP 8509A B can follow the polarization state changes Making Measurements 2 57 PDL Measurement Power Max Min Method For the HP11896A polarization controller automatic polarization scan rates of 4 to 5 are recommended depending on the PDL of the test device Saving the Measurement Results Saving data capability is not available for this measurement 2 58 Making Measurements Jones Matrix Measurement Jones Matrix Measurement A Jones matrix is a complex two by two matrix that is measured by the analyzer and mathematically describes the polarization transfer function of an optical component at a specific optical wavelength
10. No reference frame applied Measurement at 0 0 done Measurement at 60 8 done Measurement at 120 4 done Measure Clear Restart Polarization Dependence Delta 0 15 dB O Jones values Pol Dep values Done Rotate Home pq774b_c Figure 2 58 Measurement Results Your measurement is complete The screen on your computer should look similar to the previous illustration Saving the Measurement Results When your measurement is complete you may save your results for future use by selecting File from the main window menu then Save and then Jones Matrix amp PDL Jones Matrix Also see chapter 4 in this manual Making Measurements 2 51 PDL Measurement Power Max Min Method PDL Measurement Power Max Min Method Polarization dependent loss PDL describes the insertion loss variation gain variation or coupling variation of an optical component given all possible input signal polarization states It is found in all lightwave components to some degree It can be desirable in a linear polarizer or undesirable in a telecommunication or cable TV system depending upon the application This measurement section explains how to measure the polarization dependent loss or gain of a test device using the power max min method PDL PMM A data display example is shown in the following figure
11. ACCURACY ENHANCEMENT NOTE The fiber leading from the second lens to the HP 8509A B optical input must be taped down to prevent movement during or following the creation of the reference frame Source Assembly Polarization Adjuster Fiber Interface Laser Source Figure 2 83 Measurement Setup External Source Preparation Test System l i HP 8509A B l External l l Source Optical Optical l l O Input Output Input o O Q I 1 I Rotatable f Lens for Reference Fiber l Polarizer l Launch i l t i l Fiber I l Polarization Reference Frame Location pq773b_c Before performing the measurement you must select an optical source The following procedure will guide you through the process Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs Reference Frame Info Operation Verification Figure 2 84 System Menu pq780b_c Making Measurements 2 75 Polarization Reference Frame Select System from the main menu and then select Optical Source Optical Source Setup rOpticalSourceSelection r Power HP8168A HP IB HP IB Address 724 On O Off Level Watt y Wavelength cw 1551 0 Cancel pq71b_c Figure 2 85 Optical Source Setup Select the external laser sour
12. HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Help 7 0084Bm Clear Trace PDL Power Max Mi Measurement in Hold Vary polarization at input of test device Select Reset to begin Max amp Min recording r Max Min Power 2227 dBm s1 s2 s3 Max 7 661 0 42 0 74 0 50 e Min 8 161 at 0 29 0 85 0 42 is Reset ClearTrace lX Hold r Max Min Power Delta 10 500 p Angle between Max amp Min states 169 36 Done pq775b_c Figure 2 59 Example of a PDL measurement data display Typical test devices for this method include linear polarizers EDFAs couplers isolators optical connectors and medium to long fiber cables Consider the following aspects of PMM PDL when deciding whether to use this method or the Jones matrix PDL method m Measurements are typically completed in 10 seconds to three minutes m Measurement uncertainty is typically 0 06 dB m Measurement range is 30 0 dB m Operation is completely automatic when an automatic polarization controller is used 2 52 Making Measurements PDL Measurement Power Max Min Method Basic Measurement The following measure
13. 2 Connect external laser and device 3 Select Start Measurement Start Measurement Optical Source Setup Done pq7i14ic Figure 2 38 PMD WS Measurement Start Select Start Measurement from the HP 8509A B Graphs screen The WS graphs are derived from a series of optical measurements performed across the selected wavelength range As the measurement progresses the Measurement Summary display bar directly below the graph lists the PMD results obtained up to the current wavelength ACCURACY ENHANCEMENT NOTE If your wavelength range was not sufficient to provide at least two peaks in one or more of the measurement curves you will get the message One or more of the wavelength scanning traces has an insufficient number of peaks If you choose OK and continue with the measurement the measurement will ignore these curves and derive PMD from the curves which do show at least two peaks HP8509 Graphs lt 2 gt PMD WS 1460 0 1560 0 5 0 File Edit Measure Format Display Window Fc 0 0934 A 0 0623 BPE 0 0934 BES 0 1246 Start 1460 0 nm Fiber Length km Stop 1560 0 nm Source level Watt Delta 5 0 nm Source atten dB Points 21 HAL T gt k 0 01 0 82 Continue
14. 10 25 Changes from Version 1 2 Software eee 10 26 O 2 a 10 26 Cal Calibrate 10 26 Disper Close Co e 10 26 Source Source External Source Internal Coe ee ee ee 10 26 Common Commands a ee ee a a 10 27 IDN 2 a 10 27 OPC 7 2 Ce a 10 27 Device Specific Commands Ce 10 27 Analog 1 6 1 ww ee 10 27 Analog Done e 10 27 Analog Off Raw i Stokes gt T o a 10 27 Angles AB AC BC aoaaa a a o 10 28 Angles Degrees Radians ooa a a a a a a e 10 28 Angles Done e 10 28 Angles Off On y o o 10 28 Average Display Off On y o 10 28 Average Display lt NumPoints gt 202 10 28 Average Done e 10 28 Average Measurel I lt NumPoints gt 0 0202202024 10 29 Cal a 10 29 Cal Calibrate o 10 29 Cal Done Save a a a 10 29 Cal Delete lt Wavelengthnm gt 10 29 Cal ie 10 29 Cal Off On 2 10 29 ClearParams 2 1 1 we ee a e 10 30 DOBase llosa 10 30 DBase Compact 2 a a a a 10 30 Contents 8 DBase Filename 2 2 0 0 a 2 2 ee 10 30 DBase Open lt filename gt 2 2 e 10 30 DBase Repair o 10 30 Disper 2 e 10 30 Disper e 10 31 Disper ActiveWindow Lone Co e 10 31 Disper Atten lt dBm value gt y AN 10 31 Disper Calibrate o 10 31 Disper Cascade Single ER o a L 10 32 Disper C
15. Opens the database interface dialog box allowing user to view database items and load saved measurement results and setup conditions into the graphs window 7 18 User Interface Reference Table 7 7 PMD Wavelength Scanning continued Control or Data Path Description Delay Delay L Delay sqrt L Graphs window Format menu Formats the differential group delay measurement results as simple delay in units of time for component measurements as ratio to fiber length or as ratio to square root of fiber length for measurement of highly mode coupled devices such as long fibers Extrema first to last Graphs window Format menu Analysis gt Counts the number of peaks and valleys which occur in the full measurement wavelength scan Subtracts one from the total divides by two and uses the result as N in the wavelength scanning formula Uses the wavelengths of the first and last peak or valley as the start and stop wavelengths in the wavelength scanning formula Extrema full scan Graphs window Format menu Analysis gt Counts the number of peaks and valleys which occur in the full measurement wavelength scan Divides total by two and uses result as N in the wavelength scanning formula Uses wavelength extremes of the scan as the start and stop wavelengths in the wavelength scanning formula Fiber length Graphs window Format menu Allows entry of the length of a fiber under
16. pq716b_c Figure 2 90 SOP and DOP Measurement Example Signal polarization parameters are presented on the basic HP 8509A B measurement screen shown in the previous figure Your measurement is complete The screen on your computer should look similar to the previous illustration 2 84 Making Measurements State of Polarization Measurements Specialized Measurement Techniques Measuring effective degree of polarization The degree of polarization DOP of a lightwave signal is defined as the ratio of the power of the polarized component of the signal to the total power The HP8509 calculates DOP from the square root of the sum of the squares of the normalized Stokes parameters which in turn are calculated from the ratios of the measured Stokes parameters to the total power The HP8509 can be used to measure the effective DOP of a polarization modulated signal by taking advantage of the display averaging feature When display averaging is used every normalized Stokes parameter produced by the measurement system represents the average of the most recent N measurement samples where N is the number of display averages selected by the user Because DOP is calculated from these averaged normalized Stokes parameters the DOP value represents the average of the most recent N measurement samples As an example suppose that a fully polarized signal is polarization modulated to random points on the Poincare sphere If the number of states produc
17. Main window System menu Operation Verification Starts the operation verification process Install a short Jumper between Optical Output and Optical Input before starting the verification process User Interface Reference 7 11 PMD Jones Matrix Eigenanalysis All PMD measurements take place within the Graphs window a parent window in Windows terminology The individual measurements are child windows within it Each new measurement configuration produces a new child window Select among the measurement setups using the Windows menu Change between PMD setups and open new PMD measurement setups from the Windows menu rather than returning to the Main window Table 7 5 PMD Jones Matrix Eigenanalysis Control or Data Path Description Analyzer window Graphs window Window menu Selects the main analyzer window Graphs window drops to the background but remains open Display menu Y scale gt Annotation Graphs window Places documentation of the most recent Display menu measurement at the bottom of the graphs window Autoscale Graphs window Automatically adjusts minimum and maximum values of the graph s vertical axis to accommodate measurement results Autoscale zero based Graphs window Display menu Y scale gt Automatically adjusts the maximum value of the graph s vertical axis to accommodate measurement results The minimum value is held at zero Cascaded devi
18. gt The date code of the device under test for this measurement being saved used for a Save operation with the HP 8509 database This field is optional If it is not provided this entry in the database is left blank A maximum of 16 characters can be used for the date code use only printable characters in the range of ASCII 32 space and ASCII 126 7 tilde Trailing spaces are ignored leading spaces are not ignored The date code must be enclosed in double quotes if it includes any colons otherwise the double quotes are optional 10 24 Programming Abbreviations Definitions analyzer window DDE DGD frame JME LPA Not Recommended OSS PDL PMD string TLS VTUNE WS The first window to open when the HP 8509A B lightwave polarization analyzer software starts Dynamic Data Exchange A mechanism Microsoft Windows uses for applications to communicate with each other HP 8509A B supports DDE links as documented in the HP 8509A B manual Differential Group Delay Differential propagation time of polarization modes Usually expressed in units of time A boxed in region within a window usually with a title that contains user interface elements such as option buttons command buttons text boxes etc Jones Matrix Eigenanalysis Mathematical technique used to calculate optical parameters such as DGD Lightwave Polarization Analyzer The HP 8509A B is an LPA The particular com
19. wavelength in nanometers 2 12 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method HP8509 Graphs lt 1 gt PMD JME 1460 0 1560 0 5 0 File Edit Measure Format Display Window 0 01 e 1460 Wavelength nm 1560 aci 0 08415 FEO 0 10086 MES 0 11546 VIT 0 06091 fem 0 01823 Start 1460 0 nm Fiber Length km Stop 1560 0 nm Source level Watt Delta 5 0 nm Source atten dB Points 21 Continue pq779b_c Figure 2 15 Measurement Results Your measurement is complete The screen on your computer should look similar to the previous illustration Making Measurements 2 13 PMD Measurement Jones Matrix Eigenanalysis Method Manipulating the Measurement Results When your measurement is complete you may Review the results in the Measurement Summary bar Review the measurement setup conditions in the Measurement Annotation area Examine the differential group delay at a particular wavelength by using the cursor bar Display edit and print the data in tabular form Print the graph with or without measurement annotation and data listing Save your measurement and annotation information to a database for future use or to reload the measurement back into the HP 8509A B Save your measurement data as a text file for use with spreadsheets Perform other PMD measurements without lea
20. 3 Select Calibrate Calibrate Calibrated Fixed Wavelengths 1311 0 nm Internal 1555 0 nm Internal Delete selection Done pq77b_c Figure 6 11 Deleting a Calibration 2 A window appears to confirm that you want to delete the calibration or cancel the delete calibration Select OK to proceed with the deletion or Cancel to abort the delete calibration process The System Menu 6 15 HP 85098 Calibration Q Delete calibration at 1561 0 nm OK Cancel pq7135 c Figure 6 12 Confirm or Abort the Deletion Process 3 When calibration data is deleted it is deleted from memory and from the disk file 6 16 The System Menu Polarizers Polarizers Internal External m o gt 0 No Polarizer o pq79b_c Figure 6 13 The Polarizers Window Opening the Polarizers Window You can open the Polarizers window on your HP 8509 in one of two ways 1 Select System Polarizers 2 Press F12 on your keyboard HP 8509A onlyhe illustration above shows the Polarizers window for an HP 8509B The HP 8509A is not equipped with internal polarizers Please disregard all references to internal polarizers if you are using an HP 8509A Selecting a Polarizer Selecting an Internal Polarizer HP 8509B Only The internal polarizer angles are fixed and t
21. Displays the ratio of power in orthogonal polarization modes corresponding to the diameter of the circle on the Poincare sphere Move circle Main window Sets the instrument to allow movement of the circle PM Fiber Launch selection Measurement menu on the Poincare sphere Move the circle by placing PM Fiber Launch the cursor anywhere on the sphere need not be within the circle and dragging in the desired direction New circle Main window Erases any existing circle and sets the instrument to selection Measurement menu allow creation of a new circle A new circle is formed after the user clicks in three places on the Poincare sphere Resize circle selection Main window Measurement menu PM Fiber Launch Sets the instrument to allow changing of the diameter of the circle on the Poincare sphere Resize the circle by clicking with the mouse either within the circle to make it smaller or outside the circle to make it bigger Size can also be changed by clicking or click dragging anywhere on the sphere 7 28 User Interface Reference Marker Angles The MARKER ANGLES feature allows the user to determine the relative angle between pairs of markers on the Poincare sphere The angle is defined between rays originating at the center of the sphere Table 7 12 Marker Angles Control Path Description or Data AB BC AC Main window Identifies the pair of markers represented in the disp
22. Lists characteristics of the optical input in the form of the Stokes vector Power level always dBm Stokes parameters normalized Three point reference button Main window Marker area Defines a polarization reference frame Requires three measurements with a linear polarizer inserted in the beam at each of three known relative angles The first polarizer orientation defines horizontal linear polarization Removes birefringence and polarization dependent loss PDL from the path following the polarizer Apply the reference frame by checking Apply 3pt Timed measurement Main window Measurement menu Enables the user to measure a desired number of points on a single timed or free running basis Points may be saved to the database or a text file Points on the Poincare sphere rotate with the sphere in this mode Two point reference button Main window Marker area Defines a polarization reference frame Requires two measurements with a linear polarizer inserted in the beam at roughly 45 60 degree relative angles The first polarizer orientation defines horizontal linear polarization Removes birefringence from the path following the polarizer Apply the reference frame by checking Apply 2pt User Configuration Load or Save Main window Filemenu Use the User Configuration features to save and recall instrument setup conditions Wavelength display amp button Main window
23. Making Connections Proper connection technique require attention to connector compatibility insertion technique and torque requirements Connectors must be the same connector type in order to ensure mechanical and optical compatibility Attempting to connect incompatible connector types may prevent the connection from functioning properly and even cause damage to the fiber surfaces A visual inspection of the mechanical interfaces may not be enough because some connector types have the same mechanical interface but have different optical fiber interfaces for example angled no contact angled contact or straight contact fiber interfaces Refer to the manufacturer s data sheet to confirm connector type compatibility before connecting When you insert the ferrule into a connector or adapter make sure that the fiber end does not touch the outside of the mating connector or adapter In this way you will not rub the fiber end against any undesirable surface Many connectors have a keyed slot provided for optimum measurement repeatability that also helps to align and seat the two connectors After the ferrule is properly seated inside the other connector use one hand to keep it straight rotate it to align the key and tighten it with the other hand Most connectors using springs to push fiber ends together exert one to two pounds of force Over tightening or under tightening these connectors can result in misalignment and nonrepeatable measurement
24. Note The value returned set by Disper WLen Points is one more than the value returned set by Disper WLen Steps Steps are transitions between the Points HP 8509B only Display Angles Off On Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Angles Off On Display Angles Degrees Radians Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Angles Degrees Radians Sets the displayed angles to degrees or radians see DISPLAY ANGLES 4 ON OFF Display Power Linear Log The lightwave power measurement can be displayed either in log format dBm or linear format uW The setting can be changed through this command Programming 10 39 Display Update lt NumPoints gt The number of points plotted to the Poincare sphere between updates of the other displays power DOP and Stokes A large number of points plotted to the Poincare sphere will slow down updates of the other displays A small number of points plotted to the Poincare sphere will slow down the plotting on the Poincare sphere This number may be set using lt NumPoints gt or queried using Drive Returns the letter of the drive currently set up for HP IB initiated data storage Drive lt MS DOS Drive Spec gt Sets the specified drive for HP IB initiated data transfers
25. Select the Source to be Calibrated 1 Open the Optical Source window by selecting A 2 Select either an internal or an external source If you select an external source be sure to input the wavelength Refer to Optical Source bj in this chapter of the manual for more information on selecting a source Optical Source Setup r OpticalSourceSelection Internal y Internal Laser Selection O 1311nm O 1539nm e Turn Laser Off Cancel pq73b_c Figure 6 4 The Optical Source Window The System Menu 6 7 Calibrate at the Selected Wavelength 1 Open the Calibration window by using the mouse to select System Calibration or by pressing F11 on your keyboard See Figure 6 5 Select the Fixed A source type Be sure that your source is turned on and tuned to the desired wavelength if it is an external source The calibration works best if the optical signal is polarized before it is applied to the HP 8509A B Optical Input Insert an external polarizer or pass the signal through one of the internal polarizers of the HP 8509B Select the polarizer using System Polarizers Select any of the three polarizers Remember to remove the polarizer when the calibration is complete Move the fiber ahead of the polarizer or adjust the front panel knobs of the HP 8509B if nece
26. The Stokes parameters are un normalized For path information on filename see Command Syntax at the beginning of this chapter SerialNum Returns the serial number of the HP 8509A B lightwave polarization analyzer SetMarker lt S0 gt lt s1 gt lt s2 gt lt s3 gt A B C Sets the specified marker to a polarization state given by the normalized Stokes parameters 81 82 83 and So the power in milliwatts The placed marker can be observed on the Poincare sphere coordinates pertaining to So 81 82 3 Single Places the Timed measurement frame on the analyzer window Single Done Using Done closes the Timed measurement frame in the analyzer window Single DBase Load lt title gt Loads a measurement from the current database with the specified title Single DBase Save lt title gt lt date code gt lt serial number gt Saves a measurement to the current database with the specified title 10 52 Programming Single Freq lt Hertz gt Sets the timed measurement sampling frequency to be used The frequency must correspond to a period with a resolution of 1 millisecond The query returns the frequency Single Mode Single Timed FreeRun Sets the timed measurement mode The query returns the mode Single Period lt Seconds gt Sets the timed measurement period The query returns the period Single Points lt NumPoin
27. in the Markers On box see Figure 1 5 When the markers are turned on and you set a marker the Stokes parameters appear in the marker table and the marker appears on the Poincare sphere When the markers are turned off the Stokes parameters still appear in the marker table but the marker will not appear on the Poincare sphere Clearing the Markers Click here to Clear Markers Clear Markers si s2 s3 pq749b_c Figure 1 6 Clear Markers Select Clear Markers to remove the markers from the sphere and clear the Stokes data in the marker table associated with markers A B and C 1 8 Getting Started Centering the Sphere on a Marker or Current Point Clear Markers si s2 s3 Click here to Rotate the Current Point or a Marker to Front Center on the Poincare Sphere 2pt Ref 3ptRef pq750b_c Figure 1 7 Center Sphere on Marker The buttons along the right side of the marker box correspond to the current data point and the three markers These buttons can be used to rotate the sphere so that the selected point or marker is front and center Two or Three Point Polarization Reference For information on setting a two or three point polarization reference frame refer to the M
28. 0 not VTUNE 1 VTUNE second The type of optical source setup source Source VTune Start Stop H lt Voltage gt The VTUNE start or stop voltage The query returns the voltage value the parameter lt Voltage gt sets the value The settings for the analyzer window is affected if not a query The query returns settings for the analyzer window Status This command waits until all previous commands have executed and then returns the status of the last command In this way it is similar to 0PC Append the Status command to the command whose status is requested separate the commands with a semicolon If Status returns either FAIL or PROBLEMS then a description of the problem may follow the return value Return values are PASS Command successful FAIL lt Optional Description gt Command failed PROBLEMS lt Optional Description gt Errors occurred during execution UNKNOWN Command not recognized Stokes lt NumPoints gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Stokes lt NumPoints gt Stokes lt NumPoints gt Measures the input signal and returns degree of polarization DOP and Stokes parameter test data in the form of So s1 82 83 DOP The measurement is made by averaging over npnts points So is linear power milliwatts s1 s2 s3 are the normalized Stokes parameters ran
29. 0 98 Rotate 2pt Ref 3pt Ref Apply Ref Home pq716b_c Figure 5 1 The PRESET Configuration 5 2 The Display Menu Displaying the Marker Table HP8509B Lightwave Polarization Analyzer File Edit Measurement BBIREWE System Help Markers Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh Sphere lt gt Ellipse pq718b_c Figure 5 2 The Show Markers Menu The marker table is displayed in the PRESET configuration but it may be turned off or hidden by selecting Display Show yMarkers This menu selection toggles the marker table on and off When the marker table is displayed a check mark appears next to the menu selection The following figure shows what the display looks like with the marker window hidden HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel 90 dBm Clear Trace Rotate Home pq717b_c Figure 5 3 Marker Window Hidden The Display Menu 5 3 Displaying the Poincare Sphere HP8509B Lightwave Polarization Analyzer File Edit Measurement EJEA System Help Power Display Mark Curr
30. 1560 0 Source level O uWatt Delta 5 0 Source atten dB Points 21 Continue pq779b_c Figure 2 1 Example of data display for a PMD JME measurement Typical applications of the JME method include measurement of EDFA s couplers isolators fibers and optical connectors Cables and systems consisting of any number of amplifiers and fiber spans can also be tested Consider the following aspects of the JME method when deciding which PMD measurement method to use a Differential group delay DGD is measured as a function of wavelength m Measurement of low PMD components can be accomplished with a narrow wavelength range m The measurement is independent of pigtail position and polarization launch condition Optical fiber DGD data can be shown in a histogram and compared with the expected distribution to assess the statistical confidence of the measurement 2 2 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509B Lightwave Polarization Analyzer to make a PMD JME measurement Other specialized measurement applications and techniques are included later on in this section Setting up the System Connect your measurement system as outlined in the following illustration Install the thru cable for the one time adjustme
31. 4 Rotate the reference polarizer another 60 degrees for a total of 120 degrees from the initial orientation Select marker C 5 From the Markers area select pt Ref and then Apply 3pt CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual Making the Measurement HP8509B Lightwave Polarization Analyzer File Edit AUESEMICIUENS Display System Help PMD Jones Matrix Eigenanalysis F2 PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 PM Eiber Launch F5 Marker Angles Timed Measurement pq796b_c Figure 2 70 Jones Matrix Measurement Selection Select Measurement from the main menu and then select Jones Matrix F4 Making Measurements 2 63 Jones Matrix Measurement Figure 2 71 Jones Matrix Measurement Window m Select External Polarizers and Delta Transmission Measurement m Insert the test device into the polarization reference frame location with the desired angular CT gt External O Internal Delta O Delta Max Min No reference frame applied Measurement at 0 0 done Measurement at 60 0 done Measurement at 120 0 done Measat0 0 Meas at60 0 Meas at120 0 Clear Restart Jones Matrix 1 00 0 00 0 00 1 00 0 00 1 00 1 00 0 00 x iy O radians degrees
32. 6 26 6 26 6 27 9 4 10 2 10 6 10 11 Tables 4 1 6 1 6 2 7 1 7 2 7 3 7 4 7 5 7 6 1 7 7 8 7 9 7 10 7 11 7 12 10 1 11 1 11 2 11 3 11 4 11 5 11 6 11 7 11 8 11 9 11 10 11 11 Summary of HP 8509 Measurement Results Save Recall Features Analog Outputs for DOP and Normalized Stokes Parameters Mode Analog Outputs for Raw Diode Currents Mode Main Window Optical Source Setup Calibration Operation Verification PMD Jones Matrix Figenanalysis PMD Statistics 0 PMD Wavelength Scanning Timed Measurements PDL Jones Matrix amp Jones Matrix PDL Power Max Min PDL Power Max Min Marker Angles Conventions Maximum Measurable DGD Using JME Delay HP 8509B PMD Measurement Uncertainty Using the JME Method HP 8509B Only Repeatability of JME PMD Measurement with Fixed Pigtail positions Repeatability of JME PMD Measurement with Randomized Pigtail Positions Minimum Measurable PMD Using the Wavelength Scanning Method Receiver Characteristics Lo Source Characteristics External Source Input Port Characteristics Measurement of Polarization Dependence HP 8509B Only Jones Matrix Method Measurement of Polarization Dependence HP 8509B Only Power Max Min Method e Other Characteristics 4 6 6 23 6 24 7 2 1 7 1 9 7 11 7 12 7 15 7 18 7 22 7 24 7 26 7 28 7 29 10 23 11 1 11 2 11 2 11 3 11 3 11 5 11 6
33. Address lt HP IB Address gt 4 Issue the command WaveScan HPIB The query returns an ASCII 1 if the PMD WS next measurement process will be in HP IB mode and a 0 if it will not be in this mode Also returns the name of the current laser source DDE Only WaveScan Manual Places the PMD WS measurement in manual control mode When the instrument is under manual control set the tunable laser source to the appropriate wavelength for each wavelength point between the start and stop wavelengths The query returns two parameters In manual control mode send the command WaveScan Measure once to begin the measurement process and once for each wavelength point as returned by the command WaveScan WLen Points The query returns an ASCII 1 if the PMD WS next measurement process will be in MANUAL mode and a 0 if it will not be in this mode Also returns the name of the current laser source WaveScan Measure Initiates a PMD WS measurement If the tunable laser source is Manually Tuned then send this command for each point in the wavelength range WaveScan Mode lt Mode Constant gt The Mode Calculation Constant k is set or queried 10 60 Programming WaveScan PmdResult Avg Max Median The PMD WS total is calculated in one of three different ways using the average maximum or median value of the polarization mode display PMD values calculated for the s1
34. An magnitude of Ex and Ey fields 6 tan 1 Ay Ay pq757b_c Figure 2 93 Mathematical description of an elliptical display of polarization Making Measurements 2 87 m Poincare Sphere The Poincare sphere is an excellent display format for monitoring signal polarization changes because all possible states of polarization presented at the same time This is accomplished by assigning each state of polarization its own specific point on the Poincare sphere Points on the equator represent states of linear polarization the poles represent right hand and left hand circular polarization and other points on the sphere represent elliptical polarization Each point on the HP 8509A B Poincare sphere has a unique set of coordinates defined by the sphere s three dimensional axes s1 s2 and s3 These coordinates are called normalized Stokes parameters 0 0 1 Right hand 1 Circular Polarization 1 0 0 Vertical 0 Linear Polarization 45 degree 0 1 0 Linear N Polarization Horizontal 1 0 0 Linear 2 Polarization 45 degree inear Polarization Left hand Circula Polarization pq758b_c Figure 2 94 Polarization states on a Poincare Sphere m Stokes Parameters A Stokes vector is a 4 x 1 real matrix of Stokes parameters So S1 S2 and s3 that completely describes the SOP of a lightwave Each element of the matrix is based upon measured power levels Sy is the average power of the enti
35. Displays currently selected wavelength in all measurement modes including PMD measurements Button provides access to the optical source setup window for selection and control of internal or external optical source especially setting of wavelength If wavelength numerals are grey the source is turned off User Interface Reference 7 5 Table 7 1 Main Window continued Control Path Description or Data Zero Main window Removes offsets due to internal analog circuitry System menu During zero process internal sources are automatically turned off and a shutter is inserted between External source input and Optical output Signals applied directly to the Optical input must be blocked by the user prior to zeroing Zoom Main window Changes magnification of Poincare sphere display to allow detailed examination of a small area Center button toggles between normal and zoomed conditions Points on sphere are erased by this operation unless they were collected by a timed measurement See Timed measurements under Measurement menu 7 6 User Interface Reference Optical Source Setup The Optical Source Setup window presents the source control features appropriate to the selected measurement in PMD or main window applications In PMD measurements once Measurement has been selected the source control parameters are associated with that measurement If multiple PMD measurement setups
36. Level 100 0 Watt y Start 2000 perPoint 100 Find Minimum of Points Done Cancel pq7100_c Figure 2 10 JME Source Setup Verify that the source and start and stop wavelengths are correct for your measurement and that the optical power is turned on If the screen on your computer looks like the previous illustration select Find Minimum of Points ADDITIONAL INFORMATION m The Jones matrix eigenanalysis method computes differential group delay DGD from pairs of optical measurements so the number of DGD values obtained in a completed measurement is actually one less than the number of measurement wavelength points a If you wish the source to remain leveled during the measurement enter into the power level display of the optical source setup window a value no greater than the minimum power shown in the lasers display of available laser power Making Measurements 2 9 PMD Measurement Jones Matrix Eigenanalysis Method Find Minimum of Points Sample measurements OK will be performed to determine the minimum number of measurement points required for the selected wavelength Cancel range Enter Number of Samples pqri01_c Figure 2 11 Segment Selection The window is called Find Minimum of Points Sample measurements will be performed to identify the maximum DGD of the DUT
37. Main Window Table 7 1 Main Window Control or Data Path Description Analog outputs Main window System menu Selects analog output signals at the rear panel connectors A B C D Apply 2pt Main window Applies an existing polarization reference frame Apply 3pt Main window Applies an existing polarization reference frame Auto Refresh Main window Display menu When enabled this forces the operating system to redraw the main window whenever it receives the focus Use only when System Resources are severely limited Check System Resources using Program Manager Help About Program Manager Averaging Main window System menu Provides control of display and measurement averaging Display average specifies the number of successive samples which are averaged to produce each point on the Poincare sphere display Measurement average specifies the number of successive samples which are averaged during PMD PDL Jones matrix and marker measurements Calibration Main window System menu Provides an automated calibration of the polarization receiver to optimize performance at a particular wavelength Not necessary for PMD measurements but may be helpful for Jones matrix PDL measurements and optimal DOP measurements in some cases Clear trace Main window button or F7 or Main window Display menu Clears all displayed points from the Poincare sphere display C
38. Please note the changes below and change your existing programs to accommodate the changes if necessary OPC On some fast controllers the windows operating system may not release system resources fast enough to acknowledge an 0PC that is sent in a separate bus transaction In general it is a good idea to limit the number of HP IB bus transactions by grouping the HP 8509 commands together separated by a semicolon Four thousand 4 000 characters may be sent in one HP IB bus transaction to the HP 8509 It is recommended to send 0PC to the HP 8509 as part of the same HP IB bus transaction as the command that is being 0PC d Cal Calibrate This command will always return PASS when used with DDE After this command is issued either from HP IB or DDE the HP 8509 system will be occupied performing the calibration No other activity on the HP 8509 Vectra PC will take place until the calibration completes The command 0PC has no effect since the HP 8509 system will not respond to any commands while a calibration is in progress The Cal Calibrate command takes about 25 seconds on a Vectra 486 66 The programmer should hard code a delay in the program which controls the HP 8509 after issuing this command After the delay issue the Status command to determine if the Cal Calibrate command was successful Disper Close In version 1 2 this command caused the PMD window to close In version 2 0 there can be many PMD child window
39. The System menu on the HP 8509 allows you to make changes to the system that are necessary to perform measurements The receiver can be zeroed and calibrated for specific wavelengths the optical source can be selected the polarizers can be selected and so on Conventions In this document HP 8509 menu items appear in shaded boxes Like This HP 8509 main window items appear in unshaded boxes Like This Illustrations and examples in this chapter show operation of an HP 8509B There are minor differences for an HP 8509A the most significant is that the HP 8509A does not have an internal source or internal polarizers The System Menu 6 1 Optical Source Opening the Optical Source Setup Window You can open the Optical Source setup window on your HP 8509 in one of three ways m Select System Optical Source m Select A located in the upper right corner of the HP 8509 basic measurement screen or m Press FS on your keyboard If the source you select within the Optical Source Setup window is an HP8167 8168 Tunable Laser Source connected to the HP8509A B system via HP IB source wavelength power and attenuation control can be done through this Optical Source Setup window After selecting the HP8167 or HP8168 you will be able to enter the HP IB address of the laser Internal lasers and the HP8167 and HP8168 sources if connected via HP IB are automatically turned on and off as you select the sources Other types of external sour
40. is in the form of wavelength 1 nm wavelength_2 nm dispersion wavelength 2 nm wavelength_3 nm dispersion wavelength_n 1 nm wavelength_n nm dispersion The above is for the dispersion measurement at n user defined wavelengths The units for the dispersion measurement are selected using the Disper Units command The default units are ps For path information on filename see Command Syntax at the beginning of this chapter HP 8509B only Disper Settle Point Start lt Delay msec gt The settling time to wait either initially Start or per point Point after setting a tunable laser source to the desired wavelength in the sweep range during a PMD JME measurement The query returns the current value See also WaveScan Settle Point Start H lt Millisec s gt HP 8509B only Disper Start Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Measure HP 8509B only 10 36 Programming Disper Trace lt filename gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Save lt filename gt HP 8509B only Disper Units ps ps L ps sqrtL fs fs L fs sqrtL Sets the units to use in PMD JME measurements The query returns the units of measure for PMD JME HP 8509B only Disper
41. pq Figure 2 39 Measurement Results Your measurement is complete The screen on your computer should look similar to the previous illustration 2 36 Making Measurements 777b_c PMD Measurement Wavelength Scanning Method The three graphs have fixed Y axes of 1 to 1 and show the measured values of the normalized Stokes parameters sl s2 and s3 PMD is determined from analysis of these graphs Manipulating the Measurement Results When your measurement is complete you may m Select one of the measurement curves to enlarge vertically m Review the results in the Measurement Summary bar m Review the measurement setup conditions in the Measurement Annotation area Examine a curve at a particular wavelength by using the cursor bar Display edit and print the data in tabular form Print the graph with or without measurement annotation and data listing Save your measurement and annotation information to a database for future use or to reload the measurement back into the HP 8509A B Perform other measurements without leaving the Graphs window Display all of your measurements in one window using either tile or cascade mode The Measurement Summary Bar Measurement Summary Bar ci 0 1525 PE Pam 0 2288 MEA 0 098 E 0 1307 Start 1460 0 nm AAG WA T gt 0 005 Fiber Length 0 km Stop _1555 0 nm k 0 82 Source level o uWatt Delta 0 5 nm Source atten 0 dB Points 194 Continue
42. system including some frequently used commands HP IB cables provide the physical link between devices on the bus There are eight data lines on each cable that are used to send data from one device to another Devices that send data over these lines are called Talkers Listeners are devices that receive data over the same lines There are also five control lines on each cable that are used to manage traffic on the data lines and control other interface operations Controllers are devices that use these control lines to specify the talker and listener in a data exchange When an HP IB system contains more than one device with controller capabilities only one of the devices is allowed to control data exchanges at any given time The device currently controlling data exchanges is called the Active Controller Also only one of the controller capable devices can be designated as the system controller The HP 8509 can function as a talker a listener or a controller at different times HP IB addresses provide a way to identify devices on the bus The active controller uses HP IB addresses to specify which device talks and which device listens during a data exchange This means that each device s address must be unique A device s address is set on the device itself using either a front panel key sequence or a rear panel switch The factory default address for the HP 8509 is 29 Bus Structure Data Bus The data bus consists of eight lines th
43. 0 72 Done Clear Markers si s2 s3 0 55 0 51 0 63 Rotate apt Ref a 5f Home pq763b_c Figure 2 75 Example of a Polarization Maintaining Fiber Alignment data display 2 68 Making Measurements Polarization Maintaining Fiber Launch Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509A B Lightwave Polarization Analyzer operating system software to make a PM Fiber Launch measurement Setting up the System Connect your measurement system as outlined in the following illustration HP 8509A B External Source Optical Optical D Input Output Input a O Q Q Lens for Fiber Launch Pull gt Linearly PM Fiber Polarized a LN Light Rotatable Fiber Chuck pq764b_c Figure 2 76 Measurement Setup Making Measurements 2 69 Polarization Maintaining Fiber Launch External Source Preparation Before performing the measurement you must select an optical source The following procedure will guide you through the process HP8508B Lightwave Polarization Analyzer File Edit Measurement Display FEE Help Optical Source Zero F9 Calibrations F11 Polarizers F12 Shutter A
44. 1 Word Processor Spreadsheet File Contents 1 Refer to the Microsoft 7410 Windows User s Guide for information regarding Notepad and Write the word processors provided with Microsoft Windows 4 6 Printing Saving and Recalling Measurement Results and Instrument Configurations Saving and Recalling Measurements PMD PDL Jones matrix and Timed polarization measurements can be saved for future use The HP 8509A B provides two ways to save data for PMD JME PMD WS and Timed measurements Microsoft Access database and text files The data stored in HP 8509 text files is very limited and is primarily useful for importing data into a spreadsheet Database files are much more versatile You can move the database file to another computer to do sophisticated analysis of the measurements and continue using the HP 8509 instrument For example you may wish to examine the PMD measurements for a particular device type during the month of May Since the HP 8509 database is a relational database it allows you to filter out all the unwanted data and view only those measurements that are of interest In addition Microsoft access also has many mathematical functions built in so that the measurements can be analyzed statistically This is helpful in a production environment where Statistical Process Control SPC can spot production trends early and lead to improved processes You can extend the Microsoft Access database fi
45. 2 Jones Matrix Eigenanalysis 10 25 Jones matrix eigenanalysis PMD measurement 2 2 Jones matrix measurement 2 59 PDL 2 45 L A button 1 1 1 12 level 7 7 licensing 9 1 Lightwave Polarization Analyzer 10 25 Load Config amp lt filename gt 10 43 Load Config Preset 10 43 load JME from database 7 12 Load Single amp lt filename gt 10 43 load ws from database 7 18 LPA 10 25 M main menu 1 1 1 4 display menu 1 4 edit menu 1 4 file menu 1 4 help menu 1 4 measurement menu 1 4 system menu 1 4 Mandatory Selection 10 23 mark current point 7 2 marker center the sphere on a 1 6 1 9 marker angles 7 2 marker box 1 1 marker functions 1 1 1 6 markers 7 2 clear 1 6 1 8 current point 1 6 off 1 6 1 8 on 1 6 1 8 point to center 1 6 rotate 1 6 set 1 6 stokes parameters 1 6 markers on 7 2 measurement annotation area 2 15 measurement data 4 1 measurement format 2 16 measurement menu 1 4 measurement summary bar 2 14 minimum feature size 7 18 mode 7 22 mode coupling factor k 7 18 N new JME window 7 12 new WS window 7 12 noise emission 9 1 no polarizer 7 18 number of samples 7 22 O OBSOLETE 10 25 OPC 10 27 operation verification 7 2 OperVer 10 44 OperVer Start Cancel Done 10 44 optical setup 7 12 optical source 7 2 optical source display See A button optical source information op
46. 2 1 ee 10 46 PolDep Done e 10 47 PolDep Internal External 12 Co a 10 47 PolDep JonesData PolDepData 22 10 47 PolDep JonesMode PolDepMode F o 10 47 PolDep MagRadians MagDegrees Reatimag JE o L 10 48 PolDep Measure A B C o L 10 48 PolDep NewThruCal oa 10 48 PolDep ReStart o 10 48 PolMarker A B C y o 10 48 PolMarker A IB IC 0 0 0 0 0 0 00000 00002004 10 49 Range Auto 0ff On 2 o 10 49 Range f Done Down Up 2 2 o o 10 49 Rangel lt GainValue gt a e 10 49 RawDat A 10 50 RefFrame a 10 50 RefFrame Off 1 On 17 o 10 50 RefFrame 2pt 3pt 7 en 10 51 Save Config lt filename gt 2 2 10 51 Save Disper lt filename gt 10 51 Save Jones lt filename gt 2 ee ee 10 51 Save PolDep lt filename gt 2 2 10 51 Save Single lt filename gt 2 2 2 10 52 SerialNum a 10 52 SetMarker lt S0 gt lt s1 gt lt s2 gt lt s3 gt LA 1 B a 10 52 Single 2 2 10 52 Contents 10 Single Done Ce ee eee 10 52 Single DBase Load lt title gt Lo 10 52 Single DBase Save lt title gt lt date code gt lt serial number gt 10 52 Single Freq lt Hertz gt aoaaa aa aaa a 10 53 Single Mode Single Timed FreeRun
47. 85 2 86 2 87 2 88 2 89 2 90 2 91 2 92 2 93 2 94 3 1 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 4 12 4 13 5 1 5 2 5 3 5 4 5 5 5 6 5 7 5 8 5 9 5 10 5 11 5 12 5 13 5 14 5 15 5 16 5 17 5 18 5 19 6 1 6 2 6 3 6 4 6 5 6 6 Measurement Setup System Menu Optical Source Setup Example of a SOP measurement data display Measurement Setup System Menu Optical Source Setup SOP and DOP Measurement Example Polarization changes with Ex t and Ey t Elliptical displays of polarization Mathematical description of an elliptical display of polarization Polarization states on a Poincare Sphere Measurement Troubleshooting Matrix The File Menu The Print Menu Customized Printing Example The Save Menu The Save As Window The Load Menu Viewing a Stored Trace on 1 the Poincare Sphere The Load PRESET Configuration Menu The Preset Confirmation Window The Save Menu The File Save As Configure File Window The Load Menu 0 The Load Window The PRESET Configuration The Show Markers Menu Marker Window Hidden The Show Sphere Menu Poincare Sphere Turned Off The Show Ellipse Menu Polarization Ellipse Turned Of o The Show Sphere lt gt Ellipse Menu Sphere and Ellipse Exchanged The Power Display Menu Power Display in Watts Mode The Mark Current Point Menu Mark Current Point Activated The Display Update
48. Bar Changing the Measurement Format Changing the Graph s Y Scale Displaying Data in Tabular Format Displaying Data in a Statistical Format Displaying Data in a Statistical Format PMD Statistics File Menu Printing the PMD JME Graph Save as Text Saving in Database Format Measurement Setup Measurement Start Thru Calibration The Measurement 1 4 1 6 1 7 1 7 1 8 1 8 1 9 1 10 1 11 1 12 2 2 2 3 2 4 2 4 2 5 2 6 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 12 2 13 2 14 2 15 2 16 2 16 2 17 2 17 2 18 2 19 2 20 2 23 2 23 2 24 2 25 2 26 2 26 2 27 2 27 Contents 13 2 33 2 34 2 35 2 36 2 37 2 38 2 39 2 40 2 41 2 42 2 43 2 44 2 45 2 46 2 47 2 48 2 49 2 50 2 51 2 52 2 53 2 54 2 55 2 56 2 57 2 58 2 59 2 60 2 61 2 62 2 63 2 64 2 65 2 66 2 67 2 68 2 69 2 70 2 71 2 72 2 73 2 74 2 75 2 76 2 77 2 78 2 79 2 80 2 81 2 82 The Results Example of data display for a wavelength scanning PMD measurement Wavelength Scanning System Setup Wavelength Scanning Measurement Selection Optical Source Setup for PMD Wavelength Scanning PMD WS Measurement Start Measurement Results The Measurement Summary The Measurement Annotation Area The Cursor Bar Changing the Measurement Format Displaying Data in Tabular Format Printing your Graph Save as Text Saving in Database Format Example of a Jones matrix
49. Compact 10 30 DBase Filename 10 30 DBase Open amp lt filename gt 10 30 DDE 10 25 declaration of conformity 9 2 default rotation 1 10 degree of polarization 1 5 See also DOP DOP display delay delay L delay sqrt 1 7 12 7 18 delta wavelength 7 7 Described parameter 10 23 DGD 10 25 Differential Group Delay 10 25 Disper 10 30 Disper 10 31 Disper ActiveWindow 10 31 Disper Atten amp lt dBm value gt 10 31 Disper Calibrate 10 31 Disper Cascade Single P 10 32 Disper Chain 10 32 Disper Clear 10 32 Disper Close 10 32 Disper DBase Load amp lt title gt 10 32 Disper DBase Save amp lt title gt 10 33 Disper FiberLen amp lt km gt 10 33 Disper FindMinPoints amp lt Num Samples gt 10 33 Disper HPIB 10 34 Disper Manual 10 34 Disper Manual 10 34 Disper Measure 10 34 Disper NewThruCal 10 35 Disper Power 10 35 Disper Power dBm uWatt amp lt value gt 10 35 Disper Restart 10 35 Disper Save amp lt filename gt 10 36 Disper Settle Point Start H amp lt Delay msec gt 10 36 Disper Start 10 36 Disper Trace amp lt filename gt 10 37 Disper Units ps ps L ps sqrtL fs fs L fs sqrtL y 10 37 Disper VTune 10 37 Disper VTune Start Stop H amp lt Voltage gt 10 37 Disper WLen 10 37 Disper WLen Points amp lt NumPoints gt 10 38 Index 2 Disper WLen S
50. IB Address 724 Level _ 100 0 Wavelength cw 1551 0 Cancel pq71b_c Figure 2 62 Optical Source Setup Select the external laser source and set the wavelength Use the default power level or set as desired If the screen on your computer looks similar to the previous illustration select Done Making the Measurement At this point your measurement system is ready to make your first measurement For our purposes we are going to measure an optical isolator Connect your test device between the polarization controller and the optical input 2 54 Making Measurements PDL Measurement Power Max Min Method ACCURACY ENHANCEMENT NOTE Accuracy is affected by the PDL of the optical connectors the phys ical stability of the fibers during the test procedure the DOP of the source and the test signal power level Accuracy is also degraded when the DUT depolarizes the test signal This can occur when the differential group delay between Ex and Ey caused by the DUT is greater than the coherence time 1 line width of the source in Hz of the test signal CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual HP8509B Lightwave Polarization Analyzer File Edit MESES Display System Help PMD Jones Matrix Ei
51. Lines Control Lines Sending Commands HP IB For the HP 8509 HP IB to DDE Interface Command Line Setup Options Errors Only HP8509 lt Name of executable gt HP8509TimeOut lt Number of Minutes gt HP 8509 Control Frame Loe HP IB Frame Data Separator 8 1 8 3 8 3 8 3 8 3 8 3 8 3 8 4 8 4 8 4 8 4 8 4 8 5 8 5 8 5 8 6 8 6 8 7 8 7 8 7 8 7 8 8 8 8 9 1 9 3 9 3 9 3 9 3 9 3 9 4 10 2 10 3 10 3 10 3 10 3 10 3 10 4 10 5 10 6 10 7 10 7 10 7 10 7 10 7 10 9 10 9 Contents 7 Cr Lf 2 10 9 Comma Ce 10 9 HP IB Exit State A 10 9 Controller 10 10 Non Controller a 10 10 Dynamic Data Exchange DDE Frame Co ee ee ee ee ee 10 10 Basic Instrument Control 2 2 a a a 10 13 Data Requesting Commands 10 14 Operation Complete o 10 155 Preparing For HP IB Control o a 10 166 Interacting with the HP 8509A B Through the DDE Soe ee ee ee ee 10 17 Establishing DDE Links o ee 10 17 Sending HP 8509 Commands via DDE Soe ee a ee ee eee 10 20 Retrieving HP 8509 Data via DDE 2 en 10 21 Measurement Programming 0 2 2222020004 10 21 Calibrate the Instrument 2 2 2 1 ee a a 10 22 Set Up the Instrument 2 a a ee ee ee 10 22 Connect the Device 2 2 1 we a a a a a 10 22 Take Data 2 2 2 a a a 10 22 Transfer Data o 10 22 Remote Command Reference a 10 23 Abbreviations Definitions e
52. Load PRESET Configuration 2 Select File Save User Configuration 3 Name the file The application default file name is HP8509 CFG Give the file this name if you wish to restore the default configuration to the preset factory default configuration ADDITIONAL INFORMATION Some instrument conditions are saved automatically to the database when you use the Save to Database features Examples include the wavelength start stop and delta parameters for PMD measurements However these parameters alone are not sufficient to configure the instrument Printing Saving and Recalling 4 15 Measurement Results and Instrument Configurations Recalling the Preset Configuration The default or preset configuration puts the lightwave polarization analyzer in the default state This is the configuration the lightwave polarization analyzer is in at power on HP8509B Lightwave Polarization Analyzer MIES Edit Measurement Display System Help User Configuration PRESET Configuration Save Print Database Exit Timed Measurement from Database Timed Measurement as Text pq7165_c Figure 4 8 The Load PRESET Configuration Menu Procedure l Load the preset condition by selecting File Load PRESET Configuration 2 A window appears asking you to confirm the load preset command See the following figure Select OK to load the preset configuration or select Cancel to ca
53. Making Measurements 2 65 Jones Matrix Measurement Concepts The Relative Jones Matrix The HP8509A B determines the Jones matrix to within a complex constant which relates to the absolute delay of the signal through the device under test In other words the Jones matrix only describes the differences between input and output light not the time delay When the Jones matrix is measured in the fashion described in the basic measurement example above the results are normalized before they are displayed In general the four elements of the matrix are normalized to the value in the lower right hand corner Both amplitude and angle are normalized Therefore the lower right element may be displayed as 1 j0 in the case of real and imaginary format or 1 0 at an angle of 0 0 in the case of polar format If the amplitude of the lower right element is very small and therefore vulnerable to noise the instrument normalizes to one of the other elements of the matrix This will be apparent from inspection of the results Jones matrix measurements should not be performed using the Delta Max Min mode as selected in the Jones Matrix window This mode does not use a reference frame and the values of the Jones matrix returned from this measurement mode are influenced by birefringence and PDL in the path between reference polarizer and the HP8509A B The sign of s3 Different reference texts use different conventions for the sign of normalized Stokes
54. Manager 9 2 Safety and Regulatory Information Safety Information Environmental Conditions The HP 8509 may be operated safely if the following environmental conditions are met m Indoor use a Altitude up to 2000 m m Temperature 5 C to 40 C m Maximum relative humidity 80 for temperatures up to 31 C decreasing linearly to 50 RH at 40 C m Mains supply voltage fluctuations not to exceed 10 of the nominal voltage m Pollution degree 2 a Installation category II Ventilation Requirements When installing the instrument in a cabinet the convection into and out of the instrument must not be restricted The ambient temperature outside the cabinet must be less than the maximum operating temperature of the instrument by 4 C for every 100 Watts dissipated in the cabinet If the total power dissipated in the cabinet is greater than 800 Watts then forced convection must be used Cleaning Instructions The connectors on the HP 8509 should be cleaned in accordance with the instructions provided in the Connector Care chapter in this manual The cabinet should only be cleaned using a damp cloth Instrument Conforms The 8509B complies with the following product specifications LASER SOURCE 21 CFR 1040 10 and 1040 11 Safety and Regulatory Information 9 3 Laser Aperture Location External Source Polarization ay Tunable Lightwave Source HP 8509A B 00 External Source Optical Optical Inp
55. N in the wavelength scanning formula Uses the wavelengths of the first and last peak as the start and stop wavelengths in the wavelength scanning formula Peaks full scan Graphs window Format menu Analysis gt Counts the number of peaks which occur in the full measurement wavelength scan and uses result as N in the wavelength scanning formula Uses wavelength extremes of the scan as the start and stop wavelengths in the wavelength scanning formula Polarizer A or B or C Graphs window Format menu Specifies which of the internal polarizers will be inserted in the source path during the WS PMD measurement The three linear polarizers differ in rotational angle by approximately 60 degrees Note that a polarized source such as the HP 8167 68A may be connected directly to the device under test HP 8509B only Print tabular data selection Graphs window Display menu Tabular data Prints the selected portion of or entire text box Print PMD gt Graphs window File menu Accesses print controls Print graphs amp annotation Graphs window File menu Print gt Prints graphs of the three normalized Stokes parameters and the annotation information which appears in the top portion of the text box found under Display Tabular data Print graphs annotation amp data Graphs window File menu Print PMD gt Prints the three normalized Stokes parameter graphs and the annotation inform
56. Out The Zoom Factor Function Rotate To Rotate the Sphere The Home Button Clear Trace and Hold Clear Trace soe Hold A and Cal Source Wavelength Cal 1 1 1 1 1 2 1 2 1 3 1 4 1 5 1 5 1 5 1 5 1 5 1 6 1 6 1 7 1 7 1 8 1 8 1 9 1 9 1 10 1 10 1 10 1 10 1 10 1 11 1 11 1 11 1 11 1 11 1 11 1 12 1 12 1 12 1 12 Contents 1 2 Making Measurements Conventions PMD Measurement Jones Matrix Eigenanalysis Method Basic Measurement Setting up the System External Source Preparation Making the Measurement Manipulating the Measurement Results The Measurement Summary Bar The Measurement Annotation Area Using The Cursor Changing The Measurement Format Changing The Graph s Y Scale Displaying and Printing Data in Tabular Format Displaying Data in a Statistical Format The File menu Add from Selected JME Window F2 Add from Database F3 Add from Text File F4 Load Statistics F5 Save Statistics F6 Print Bitmap Print Data Exit The Edit menu The Format Menu The Help menu The Annotation Area Printing the PMD JME Graph Saving your Measurement as Text Saving in Database Format Specialized Measurement Methods Performing a Cascade Measurement Setting up the System Making the Measurement Using a Voltage Tuned Source Using a Manually Tuned source PMD JME Concepts Polarization Mode Dispersion Polarization modes General effects Mo
57. PDL measurement data display Measurement Setup System Menu Optical Source Setup Polarizer Selection Polarizer Setup 3pt Reference Applied Circular Polarization Jones Matrix Measurement Selection Jones Matrix Measurement Window Measurement Results Example of a PDL measurement data display Measurement Setup System Menu Optical Source Setup PDL Measurement Selection PDL Power Max Min Measurement Window Measurement Results Example of data display for a Jones matrix measurement Measurement Setup System Menu Optical Source Setup Jones Matrix Measurement Selection Jones Matrix Measurement Window Measurement Results Comparing the output Jones Vectors to 3 known input Jones Vectors Jones Matrix Application Example of a Polarization Maintaining Fiber Alignment data display Measurement Setup System Menu Optical Source Setup PM Fiber Launch Measurement Selection PM Fiber Launch Alignment Window How PMF cable launch extension ratio is calculated Example of the results that can be achieved with and without a polarization reference frame Contents 14 2 28 2 33 2 34 2 35 2 35 2 36 2 36 2 37 2 38 2 38 2 39 2 40 2 41 2 41 2 42 2 45 2 46 2 47 2 47 2 47 2 48 2 48 2 49 2 50 2 50 2 51 2 52 2 53 2 54 2 54 2 55 2 56 2 57 2 59 2 60 2 61 2 61 2 63 2 64 2 65 2 67 2 67 2 68 2 69 2 70 2 70 2 71 2 72 2 73 2 74 2 83 2 84 2
58. PU indicate the required nature of the line module input power m The ON symbols are used to mark the posi tions of the instrument power line switch o O The OFF symbols are used to mark the posi ions of the instrument power line switch The CE mark is a regis ered trademark of the European Community CE The CSA mark is a regis ered trademark of the Canadian Standards Association The C Tick mark is a reg istered trademark of the Australian Spectrum Management Agency This text denotes the instrument is an Indus trial Scientific and Medi cal Group 1 Class A product ISM1 A 8509A B General Safety Considerations WARNING WARNING CAUTION General Safety Considerations This is a Safety Class 1 Product provided with a protective earthing ground incorporated in the power cord The mains plug shall only be inserted in a socket outlet provided with a protective earth contact Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous Intentional interruption is prohibited No operator serviceable parts inside Refer servicing to qualified personnel To prevent electrical shock do not remove covers Before switching o this instrument make sure that the line voltage selector switch is set to the voltage of the power supply and the correct fuse is installed 8509A B General Safety Considerations He
59. Reference Frame Info Operation Verification Figure 2 88 System Menu pq780b_c Select System from the Main menu and then select Optical Source Optical Source Setup r OpticalSourceSelection HP8168A HP IB HP IB Address 724 Wavelength cw 1551 0 r Power On Off Level 100 0 Cancel Figure 2 89 Optical Source Setup Select the external laser source and set the desired wavelength pq71b_c Making Measurements 2 83 State of Polarization Measurements Making the Measurement At this point your measurement system is ready to make your first measurement For our purposes we are going to measure the 1550 nm signal from a tunable laser source CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual Measurement Results HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 dBm Clear Trace Markers Clear Markers s2 s3 0 08 0 98 Rotate 2pt Ref 3pt Ref Apply Ref Home
60. Some of the HP 8509 HP IB commands deal with data storage and retrieval using the HP 8509 system Vectra PC memory For example execute OUTPUT 729 DRIVE C END This sets drive C in the HP 8509 system Vectra PC as the location for all data storage Some commands directly store information into the designated drive For example execute OUTPUT 729 SAVE CONFIG SYSTEM CFG END This causes the current system state or configuration to be saved into the file SYSTEM CFG The file is created in the HP8509 directory of the drive usually drive C known as the working directory This directory is specified by the program manager in the File Properties menu The default working directory is the directory where HP 8509 software is installed The file can be saved in another directory if an appropriate DOS format directory path is specified A saved system state can later be recalled by executing OUTPUT 729 LOAD CONFIG HP8509 SYSTEM CFG END Through this command a user determined instrument state can be achieved Note that the appropriate path to the configuration file must be specified Refer to the Command Reference section of this document for command specific information Data Requesting Commands Some of the HP IB commands request data from the HP 8509 This data is returned as an ASCII string or as a series of ASCII strings separated by commas It can be accessed by following the data request command with an ENTER remote com
61. The Jones matrix of a lightwave component or device can be used to predict the SOP of an optical output signal given a specific SOP input signal It is also used by the analyzer to calculate PDL and PMD and a polarization reference frame This measurement section explains how to measure the Jones matrix of a test device A sample data display is shown in the following figure CT gt O Internal External Delta O Delta Max Min No reference frame applied Measurement at 0 0 done Measurement at 60 0 done Measurement at 120 0 done Measat0 0 Meas at60 0 Meas at120 0 Clear Restart Jones Matrix 1 00 0 00 0 00 1 00 0 00 1 00 1 00 0 00 x iy O radians degrees Jones values Pol Dep values Done pq776b_c Figure 2 66 Example of data display for a Jones matrix measurement Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509A B Lightwave Polarization Analyzer operating system software to make a Jones Matrix measurement Making Measurements 2 59 Jones Matrix Measurement Setting up the System Connect your measurement system as outlined in the following illustration The HP 11896A polarization controller is recommended as the polarization adjuster for this application AC
62. When it is found incoming commands process normally Characters between the syntax error and the next terminator are lost The OUTPUT 729 statement will transmit one item at a time when a terminating END is used It will transmit literal information enclosed in quotes numeric variables and string variables Without the END a carriage return line feed is transmitted after each item This is suppressed by terminating the command with an END statement Setting a display state is just one form of command the HP 8509 will accept It will also accept commands that require specific user defined operands For example execute Programming 10 13 OUTPUT 729 SETMARKER 1 0 1 0 A END In response the HP 8509 will place marker A at the Poincare sphere location corresponding to the Stokes parameters Sg 1 s 0 s2 1 and s3 0 This corresponds to full 45 degree linear polarization The HP 8509 will also accept commands that turn various functions on and off Execute OUTPUT 729 POINCARE HOLD 0N END This causes the HP 8509 to freeze the Poincare sphere display at the current measurement trace To initiate continuous measurement execute OUTPUT 729 POINCARE HOLD OFF END As can be noted the command is POINCARE The accompanying parameters are the HOLD function and the function indicator of ON or OFF The HP 8509 does not distinguish between upper and lower case letters For example execute OUTPUT 729 poincare hold on END
63. a component intensity Brightness emitting or reflecting light luminosity optical power interface cable A multi wire cable connecting two instruments Can include the HP IB cable or a multi wire cable of the type that connects the computer to the HP 8509 hardware interpolate To determine the value of a signal between two known points by a procedure or algorithm Jones calculus An analytic method for describing fully polarized light and the effects of a two port optical device or network on the polarization state of fully polarized light Determination of the Jones matrix is the basis for the Jones matrix eigenanalysis method of PMD measurement and the Jones matrix method of PDL measurement Jones matrix A description of the polarization transforming effect of a two port optical device or network The two by two complex matrix relates the input and output Jones vectors The HP8509A B determines the Jones matrix to within a complex constant which relates to the absolute delay of the signal through the device under test In other words the Jones matrix only describes the differences between input and output light not the time delay When the Jones matrix is measured in the fashion described in the basic measurement example above the results are normalized before they are displayed In general the four elements of the matrix are normalized to the value in the lower right hand corner Both amplitude and angle are normalized Therefore t
64. a horizontal surface and warmed up for at least one hour Polarization Mode Dispersion PMD Specifications Jones Matrix Eigenanalysis JME Method HP 8509B only The JME method measures the differential group delay DGD of the test device as a function of wavelength Average DGD or PMD is taken as the average of the DGD values across the wavelength range The measurement requires a tunable wavelength single line laser source such as the HP 8168A Tunable Laser Source The JME measurement is operational over the ranges of 1280 to 1340 nm and 1470 to 1580 nm however the DGD uncertainty specification is warranted over the wavelength range of 1540 to 1560 nm Table 11 1 Maximum Measurable DGD Using JME Delay HP 8509B Maximum Measurable DGD Using JME Method Wavelength Step 1310 nm 1550 nm 0 01 nm 280 ps 400 ps 0 10 nm 28 ps 40 ps 1 0 nm 2 8 ps 4 ps 10 0 nm 0 28 ps 0 4 ps 1 Maximum measurable PMD delay 7 radian optical frequency interval Specifications and Characteristics Table 11 2 PMD Measurement Uncertainty Using the JME Method HP 8509B Only PMD Measurement Uncertainty 2 34 Wavelength Step Uncertainty 0 10 nm 310 fs 1 0 nm 90 fs 10 0 nm 60 fs 1 Receiver input level 20 to 40 dBm 2 Does not include external laser tuning accuracy 3 Measurement averaging set to 500 points 4 PMD is the average value of DGD across the measurement wavelength r
65. a saved instrument calibration performed at the current source wavelength If a calibration is not present then calibration corrections cannot be enabled Programming 10 29 ClearParams Used to clear the DDE parameters in the LPA after data is retrieved A DDE LinkPoke can also be used to clear the parameter boxes DDE Parameters should always be cleared after data is retrieved so that another query isn t confused by residual data that was previously left behind The HP IB gateway automatically sends this DDE command after retrieving data DDE only DBase Close Closes the currently opened database file DBase Compact Compacts the currently opened database file DBase Filename Returns the name of the currently opened database file DBase Open lt filename gt Opens the database file specified in lt filename gt DBase Repair Repairs the currently opened database file Disper Displays the PMD JM window on the HP 8509B instrument display Be sure to send Disper before sending any other Disper commands HP 8509B only 10 30 Programming Disper Upon command execution the analyzer returns the current wavelength the measured dispersion at the current wavelength and the average of the measured dispersion up to and including the current wavelength The command can be used under manual mode to check the status of a running measurement process The data is r
66. an HP 8703 lightwave component analyzer an HP 8702 analyzer with the appropriate source receiver and lightwave coupler an HP 8504 precision reflectometer and an HP 8153 lightwave multimeter with a source and power sensor module in conjunction with a lightwave coupler Many other possibilities exist The basic requirements are an appropriate lightwave source a compatible lightwave receiver and a compatible lightwave coupler Refer to the manuals provided with your lightwave test equipment for information on how to perform a return loss test As mentioned earlier in this handbook typical return loss is better than 20 to 30 dB and can be better than 40 dB For actual specifications on your particular cable or accessory refer to the manufacturer 8 8 Lightwave Connector Care Safety and Regulatory Information This chapter includes required regulatory and safety information that is not included elsewhere in the manual The first part of this chapter includes regulations and licensing information including the Manufacturer s Declaration of Conformity The second part of the chapter contains required safety information that is not included elsewhere in the manual Regulations and Licensing United States FDA Class 1 The HP 8509 Lightwave Polarization Analyzer is rated USFDA United States Food and Drug Administration Class 1 Laser Product according to Part 1040 Performance Standards for Light Emitting Products from the Center fo
67. are configured each is associated with a unique Optical Source Setup window Table 7 2 Optical Source Setup Control Path Description or Data Attenuation Optical source Sets the attenuation of compatible external HP IB entry box setup window optical sources Cancel button Optical source setup window Closes the dialog box with its original settings Delta wavelength entry box Optical source setup window The wavelength interval for a PMD measurement Find minimum of points button Optical source setup window In PMD Jones matrix eigenanalysis measurement mode automatically determines the minimum number of measurement wavelengths required for the device under test Additional points may be required to resolve the change in differential group delay with wavelength HP IB address entry box Optical source setup window Allows specification of HP IB select code and the address of the HP IB programmable optical source The default source is the HP 8168A and the default address is 24 If the address must be changed it can be saved for future use by saving user configuration before the end of the session The HP IB address function is accessible only when the HP 8167A or HP 8168A are selected HP 8167A source selection Optical source setup window Selects the HP 8167A Tunable Laser Source If the HP IB source address is incorrect wait 5 seconds for timeout then change the add
68. are included with the HP 8509 User s Reference Guide The programs on these disks demonstrate the exact executable syntax of the code One disk is in DOS format and the other is in LIF format The DOS formatted disk is for system operation with Windows There are example programs on the DOS disk for controlling the HP 8509 One example illustrates remote operation of the HP 8509 over the HP IB bus This program is written using HP Basic for Windows and runs on a PC configured as an HP IB controller and connected to the HP 8509 via the HP IB bus Another example illustrates remote operation of the HP 8509 using Windows DDE on the HP 8509 Vectra PC This program is written using VisualBasic for Windows and runs simultaneously with the HP 8509 software on the HP 8509 Vectra PC The LIF formatted disk is for system operation under HP BASIC running in an HP 9000 series 200 300 external controller 10 64 Programming 11 Specifications and Characteristics Specifications are the warranted performance standards or limits against which the HP 8509 can be tested Characteristics are not specifications but are typical parameters provided for use in applying the instrument Characteristics are representative of most though not necessarily all HP 8509 lightwave polarization analyzers Warranted Specifications The warranted specifications on the HP 8509 are valid over the temperature range of 23 C 5 C with the instrument oriented upright on
69. assurance that your lightwave connection is performing properly Optical Performance Testing Introduction Consistent measurements with your lightwave equipment are a good indication that you have good connections However you may wish to know the insertion loss and or return loss of your lightwave cables or accessories If you test your cables and accessories for insertion loss and return loss upon receipt and retain the measured data for comparison you will be able to tell in the future if any degradation has occurred Lightwave Connector Care 8 7 Insertion Loss Insertion loss can be tested using a number of different test equipment configurations Some of these are an HP 8702 or HP 8703 lightwave component analyzer system an HP 83420 lightwave test set with an HP 8510 network analyzer an HP 8153 lightwave multimeter with a source and power sensor module Many other possibilities exist The basic requirements are an appropriate lightwave source and a compatible lightwave receiver Refer to the manuals provided with your lightwave test equipment for information on how to perform an insertion loss test As mentioned earlier in this handbook typical insertion loss for cables is less than 1 dB and can be as little as 0 1 dB For actual specifications on your particular cable or accessory refer to the manufacturer Return Loss Return loss can be tested using a number of different test equipment configurations Some of these are
70. be averaged at each measurement point when conducting any measurement This number may be set using lt NumPoints gt or queried using Cal Returns the status of the Calibration apply option buttons 0 means Calibration is Off 1 means Calibration is On Cal Calibrate Performs an instrument calibration which optimizes the measurement performance of the analyzer The calibration is performed at the current user defined source wavelength Refer to the HP 8509A B User s Reference Guide for more in depth information on the instrument calibration capabilities of the HP 8509A B Cal Done Save The Done parameter terminates the instrument calibration sequence The calibration window is removed from the screen The Save parameter saves in memory an instrument calibration performed at a given source wavelength The source wavelength is specified through the source command All saved calibrations can be accessed when the Cal On command is sent Cal Delete lt Wavelength nm gt Deletes from memory the instrument calibration performed at the specified source wavelength Cal List Returns a list in the form of a comma separated string of the wavelengths for which calibrations have been performed The wavelengths are given in nanometers Cal Off On The Off and On parameters enable or disable the instrument calibration corrections When enabling a calibration the instrument will search for
71. behavior of the device Making Measurements 2 11 PMD Measurement Jones Matrix Eigenanalysis Method Optical Source Setup for PMD Jones Matrix Eigenanalysis rOpticalSourceS election HP8168A HP 1B y r Wavelength r Power On HP IB Address 724 Lz Start perPoint r Settling Time ms 2000 100 Start 1460 0 Off Stop 1560 0 Level 100 0 Watt y Delta 5 0 Points 21 Find Minimum of Points Done pq7100_ Figure 2 13 Optical Source Setup for PMD Jones Matrix Eigenanalysis Select Done on this window Avg DGD EE o Current i Max i Vir A Start Measurement 1 Connect external laser and device 2 Set conditions with Optical Source Setup Optical Source Setup 3 Select Start Measurement Start Measurement oz pq7103_c Figure 2 14 PMD JME Measurement Start Select Start Measurement from the HP 8509B Graphs screen The JME graph is derived from a series of optical measurements performed across the selected wavelength range As the measurement progresses the Measurement Summary display bar directly below the graph lists the PMD results obtained up to the current wavelength The axes of the PMD graph are annotated as differential group delay in picoseconds and
72. cleared clear them before sending a command Do While 1blStatus Caption BUSY DoEvents Loop gt Use to be sure that HP 8509 data buffers are clear 1lb1Status LinkExecute ClearParams 1b1Status LinkExecute Poincare Center A DoEvents Free Windows to allow it to do the LinkExecute 10 20 Programming Retrieving HP 8509 Data via DDE To retrieve HP 8509 data use the VB LinkRequest method The HP 8509 places data in the Param x labels Use LinkRequest with the controls which are linked to the Param x labels in the HP 8509 Be sure that there are no pending DDE conversations before attempting to get the data otherwise all the data may not be present Also clear the data buffers Param x labels in the HP 8509 after getting the data The following VB code fragment illustrates how to get data from the HP 8509 via DDE Do While 1b1lS5tatus Caption BUSY DoEvents Loop For if 0 ToT lblParam i LinkRequest DoEvents Free Windows to allow it to do the Link gt Since data is sequential once there is an gt empty label we re done If l1blParam i Caption Then Exit For Next 1 gt Required to do after getting the HP8509 data frmHpib lblStatus LinkExecute ClearParams Measurement Programming Earlier sections of this document outlined how to get commands into the HP 8509 The next step is to organize the commands into a measurement sequence A typical measurement sequence consists of the following s
73. detector optical detector A transducer that generates an electrical signal that is a function of irradiance optoelectronic Pertaining to a device that responds to optical power emits or modifies optical radiation or utilizes optical radiation for its internal operation Any device that functions as an electrical to optical or optical to electrical transducer optical path length In a medium of constant refractive index n the product of the geometrical distance and the refractive index If n is a function of position then optical path length fnds where ds is an element of length along the path This expression simplifies to n if the medium has a constant refractive index optical waveguide Any structure generally a fiber designed to transmit optical signals capable of guiding optical power PDL See polarization dependent loss phase velocity Velocity of the signal modulating a propagating electromagnetic wave It is given by c n where c is the velocity of light in vacuum and n is the refractive index phase The angular relationship between two lightwaves of nominally identical wavelength In the context of polarization it sometimes refers to the angular relationship between orthogonal electric field components of a lightwave as defined within a physical frame of reference photodetector A light detector PMD See polarization mode dispersion Poincare sphere A spherical representation of polarization states E
74. easily damaged Therefore these connectors should NEVER have cleaning solutions or any other substance applied to them unless it is specifically recommended by the manufacturer You may wish to use clean compressed air to rid them of dust from time to time Storage All of Hewlett Packard s lightwave instruments are shipped with either laser shutter caps or dust caps on the lightwave adapters that come with the instrument Also all of the cables that are shipped have covers to protect the cable ends from damage or contamination These dust caps and protective covers should be kept on the equipment at all times except when in use The adapters that were shipped on your instrument can be removed from the connectors on the instrument If you remove these adapters you should keep the exposed connector of your instrument covered until the next use Protective covers for these exposed connectors are not provided with the instruments so it is best to keep the adapters on the instrument with the dust covers on The list below provides the HP part numbers for the laser shutter cap and dust caps that are provided with lightwave instruments and accessories Item HP Part No Connector Option Laser shutter cap 08145 64521 All options FC PC dust cap 08154 44102 Opt O12 Biconic dust cap 08154 44105 Opt 015 DIN dust cap 5040 9364 Opt 013 HMS 10 HP dust cap 5040 9361 Opt 011 ST dust cap 3040 9366 Opt 014 Lightwave Connector Care 8 5
75. ee 10 59 WaveScan DBase Load lt title gt Lo 10 59 WaveScan DBase Save lt title gt lt date code gt lt serial number gt 11 10 59 WaveScan Feature lt Min Feature Size gt 10 59 WaveScan FiberLen lt km gt FF o 10 59 WaveScan Hpib 7 2 2 a e 10 60 WaveScan Manual a a a L 10 60 WaveScan Measure oaoa a a a a a a 10 60 WaveScan Mode lt Mode Constant gt aoa a a a a a a a a a a 10 60 WaveScan PmdResult Avg Max Median 2 10 61 WaveScan Polarizer A B C None 10 61 WaveScan Power ON 10 61 WaveScan Power dBm uWatt E lt value gt N 10 61 WaveScan Save lt filename gt 2 a a k k ee ee a 10 61 Contents 11 WaveScan WaveScan WaveScan WaveScan WaveScan WaveScan WaveScan Zero Settle Point Start 1 lt Delay msec gt Units 7 ps ps L ipsisqrth VTune o VTune Start 1 Stop H f Voltage WLen WLen Start Stop f Delta H f lt Wavelength nm gt WLen Points lt NumPoints gt N Example Programs 11 Specifications and Characteristics Warranted Specifications Polarization Mode Dispersion PMD Specifications Jones Matrix Figenanalysis JME Method HP 8509B only Characteristics o Jones Matrix Figenanalysis PMD Measurement Wavelength Scanning PMD Measurement Comparison Between Jones Matrix Figenanalysis and W
76. follows an elliptical spiral path it is elliptically polarized Polarized light may contain more than a single frequency However light of non zero spectral width may depolarize as it passes through dispersive devices polarization state See State of Polarization polarization controller A device used to adjust the relative phase of orthogonal electric field components of a lightwave A polarization controller may consist of loops of fiber cascaded optical retarders or a material of adjustable birefringence such as liquid crystal polarization dependent loss Abbreviated PDL polarization dependent loss refers to the maximum variation of optical insertion loss of a fiber or component as a function of polarization state The term is also loosely used in connection with the same principle in amplifier gain although the more specific polarization dependent gain PDG may be used polarization ellipse The elliptical representation of lightwave polarization in which the locus of the propagating electric field vector is traced in a plane normal to propagation The polarization ellipse is typically described within a physical reference frame reference directions for orthogonal electric field components in terms of ellipticity and azimuthal angle Circular and linear polarized light represent the extremes of ellipticity polarization mode dispersion PMD PMD is a fundamental property of optical devices by which an optical signal is split into t
77. highlighting the HP8509 icon and selecting File Properties If the current drive is changed using the Drive lt Drive Spec gt command then the default directory is the default directory of the current drive The filename must be enclosed in double quotes if it includes any colons otherwise the double quotes are optional Programming 10 23 Table 10 1 Conventions continued lt title gt The title to use for a Save Load operation with the HP8509 database A maximum of 80 characters can be used for the lt title gt Use only printable characters in the range of ASCII 32 space and ASCII 126 7 tilde for titles Trailing spaces are ignored leading spaces are not ignored The title must be enclosed in double quotes if it includes any colons otherwise the double quotes are optional lt serial number gt The serial number of the device under test for the measurement being saved Used for a Save operation with the HP 8509 database This field is optional If it is not provided this entry in the database is left blank A maximum of 25 characters can be used for the serial number Use only printable characters in the range of ASCII 32 space and ASCII 126 tilde Trailing spaces are ignored leading spaces are not ignored The serial number must be enclosed in double quotes if it includes any colons otherwise the double quotes are optional lt date code
78. in the test system or the test device some optical energy will re reflect travel three times the length between the two reflection points triple travel signal finally emerge and combine with that portion of the signal that traveled straight through straight through signal This triple travel signal has a different amount of phase shift because it has passed through a different birefringence path than the path used by the straight through signal The polarization state of the combined output signal can be modeled as two polarization components One component represents the straight through signal The second component represents the energy from the triple travel signal that is orthogonal to the straight through signal As the wavelength changes the phase relationships change and an arc is drawn on the Poincare sphere The radius of the arc increases with the magnitude of the reflections The radius of the arc represents measurement uncertainty and should be at least 30 to 40 dB for normal measurements Check this value using the PMF Launch tool provided under the Measurement menu of the HP 8509 main window The arc required for this PMF Launch tool can be created by manually changing the input wavelength The dB ratio related to the radius of the are will be automatically calculated and displayed Connectors should be properly mating physical contacting types with a reflection level better than 40 dB Accuracy Enhancement and Troubleshooting
79. is valid only if the optical source is set to Manual WaveScan Close Closes the PMD WS measurement window The PMD WS measurement process is ended WaveScan DBase Load lt title gt Loads a measurement from the current database using the specified title WaveScan DBase Save lt title gt lt date code gt lt serial number gt Saves a measurement to the current database using the specified title WaveScan Feature lt Min Feature Size gt The query returns the minimum size of features maxima and minima that are considered for the analysis type selected The query returns the value for the minimum size of features WaveScan FiberLen lt km gt The query returns the length of optical fiber used to normalize PMD WS measurements Using lt km gt sets the length of optical fiber Programming 10 59 WaveScan HpibL Sets the tunable laser source for a PMD WS measurement to an HP IB tunable laser source The HP 8509A B looks for a tunable laser source at the address specified with TLS Address and uses it if it is either an HP 8167 or HP 8168 tunable laser source Be sure that the wavelength range is set correctly for the connected HP IB tunable laser source before issuing this command To change tunable laser source selections between HP 8167 and HP 8168 1 Issue the command WaveScan Manual 2 Change the wavelength range using WaveScan WLen 3 Change the HP IB address using TLS
80. laser operating in a single transverse mode typically does not operate in a single longitudinal mode single frequency laser A laser that emits a range of wavelengths small enough to be considered a single frequency SOP See State of Polarization source A device which supplies signal power Used in this document 1 To refer to sweep oscillators or synthesized sweepers and 2 To refer to the signal source integrated in the analyzer splice A permanent junction between two fiber ends standard deviation The root sum of the squares of the deviation of individual data points from the mean or average value State of Polarization As a description of a lightwave signal the term State of Polarization is an overall label that includes several pieces of information total optical power degree of polarization and a description of the polarized portion of the light within some polarization reference frame All of these parameters are measured by the HP8509A B Sometimes the term SOP is used informally to denote the polarization state displayed on the Poincare sphere Stokes parameters The Stokes parameters are the four fundamental measurements produced by an optical polarimeter The first parameter S0 describes the total average optical power including polarized and unpolarized elements The second parameter 51 describes the difference in power between the horizontal and vertical linearly polarized components of the signal T
81. last TLS selected The LPA will automatically select the Manual TLS as the default unless another TLS HP IB controlled HP 8167 8 or Voltage Tuned has previously been selected Source External lt Wavelength nm gt Specifies the external source wavelength The wavelength should be specified in nm The settings for all open windows are affected See Note in Source External Off On for information on TLS Source HPIB Sets the tunable laser source for the analyzer window to an HP IB TLS The HP 8509A B looks for a tunable laser source at the address specified with TLS Address and uses it if it is either an HP 8167 or HP 8168 tunable laser source The query returns two parameters first 0 not HP IB TLS 1 HP IB TLS second The name of tunable laser source DDE only Source Hpib Off On lt Wavelength nm gt Specifies the state Off On or the wavelength setting of the HP IB source When turned on or set using lt Wavelength nm gt the HP 8509A B system automatically determines which tunable laser source HP 8167 or HP 8168 is connected to the HP IB bus at the address set using TLS lt HP IB address gt DDE only 10 54 Programming Source Internal Returns the wavelength in nm of the currently activated internal source in the analyzer window HP 8509B only Source Internal Off 1310 1550 Specifies the internal source in the analyzer window If the parameters 1310 or 1550 a
82. manufacturer for specific information about recommended solvents and cleaning procedures Lightwave Connector Care 8 3 Cleaning Non Lensed Lightwave Connectors Equipment The following is a list of the items that should be used to clean non lensed lightwave connectors Isopropyl alcohol 0 0 c cence eee eee eee eeeas HP part number 8500 5344 Cotton swabs 2 6 ccc cece eee cece nee e teen eens HP part number 8520 0023 Compressed air 0 i cece ocn rr HP part number 8500 5262 CAUTION Hewlett Packard recommends that you do not use any type of foam swab to clean optical fiber ends Foam swabs can leave filmy deposits on fiber ends that can degrade performance Process Before cleaning the fiber end clean the females and other parts of the connector Use isopropyl alcohol clean cotton swabs and clean compressed air Then use alcohol to clean the fiber end Some amount of wiping or mild scrubbing of the fiber end can help remove particles when application of alcohol alone will not remove them This can be done by applying the alcohol to a cotton swab and moving it back and forth across the fiber end several times This technique can help remove or displace particles smaller than one micron Allow the connector to dry about a minute or dry it immediately with clean compressed air Compressed air lessens the chance of deposits remaining on the fiber end after the alcohol evaporates It should be blown horizont
83. of fiber length for measurement of highly mode coupled devices such as long fibers Fiber length Graphs window Format menu Allows entry of the length of a fiber under test in kilometers Fixed scale Graphs window Display menu Y scale gt Allows the user to select the maximum value of the graph s vertical axis The minimum value is fixed at Zero Grid Graphs window Display menu Enables grid lines for the graph of measured results Load JME from database Graphs window File menu Sets up a new JME child window and loads stored JME measurement data and selected setup parameters from the database New JME window Graphs window Window menu Creates a new child window for a JME measurement New WS window Graphs window Window menu Creates a new child window for a WS measurement Optical Setup Graphs window Measurement menu Provides access to the optical source setup window Picoseconds femtoseconds Graphs window Format menu Selects units of differential group delay One picosecond is 10712 seconds one femtosecond is 1071 seconds PMD Statistics Graphs window Display menu Opens the PMD Statistics software application for the purpose of displaying one or more PMD measurements in statistical form Print graph amp annotation Graphs window File menu Print gt Prints the currently selected graph and the annotation information which
84. of individual sections may be measured using these taps without disturbing the through path connections The output pigtail of the polarization analyzer is connected to the input of the system and left there throughout the measurement A cascade reference measurement is taken with the optical input of the polarization analyzer connected to the tap just prior to the section of interest Then the section of interest is added and the second step of the measurement is performed The resulting measurement characterizes only the selected section If the goal of the PMD measurement is to relate the PMD of individual sections to the PMD of the whole system the cascade measurement may be repeated on each of the sections to characterize the sections At each stage the composite PMD of all preceding sections is given by the cascade reference measurement With individual and composite PMD values one may compare the addition of PMD with the expected root sum of squares expected value 2 32 Making Measurements PMD Measurement Wavelength Scanning Method PMD Measurement Wavelength Scanning Method Polarization mode dispersion PMD is a fundamental physical property of optical fiber and components in which a lightwave is split into two waves of slightly different speed on the basis of polarization state The two polarization modes experience a difference in propagation time known as differential group delay DGD The DGD of long optical fibers var
85. only as supplemental information and is not part of the measurement result Clear Trace Main window Clears the Poincare sphere display This may be selection Measurement menu useful when performing the measurement with a PDL Power manual polarization adjuster Max Min Delta Max Min Main window Displays the variation in the detected level of optical Power display Measurement menu signal since the Reset button was pressed PDL Power Max Min Hold box Main window Interrupts the measurement process Measurement menu PDL Power Max Min Max Power Main window Displays the maximum power which has been display Measurement menu detected since the Reset button was pressed PDL Power Max Min Min Power Main window Displays the minimum power which has been display Measurement menu detected since the Reset button was pressed PDL Power Max Min Reset selection Main window Clears the stored values of maximum and minimum Measurement menu power and resets both to the current power This is PDL Power used before a new measurement Max Min 7 26 User Interface Reference Table 7 10 PDL Power Max Min continued Control Path Description or Data sl s2 s3 Main window Displays the normalized Stokes parameters displays Measurement menu corresponding to the maximum and minimum power PDL Power Max Min that have been detected since the Reset button was pressed The normalized Stokes vector is extended to
86. parameter s3 The convention used in the HP8509A B is shown in the appendix to this manual Description of the Jones Matrix Measurement Algorithm The HP 8509B automatically calculates the Jones matrix of a component using three different known linear states of polarization typically at 0 60 and 120 degrees These are created using either the internal polarizer plates of the HP 8509B or an external rotatable linear polarizer as shown in the following figure Each state of polarization individually stimulates the DUT while the output polarization is measured and recorded It has been shown by R C Jones that this polarization information is sufficient for the HP 8509 to calculate a Jones matrix The simple case where the known polarized inputs are 0 45 and 90 degrees in shown in the following figure 2 66 Making Measurements Measured Output SOP Timed Measurements where Xn and Yn are the X and Y electric field components and C is a constant ky Y Xg kg 5 Y3 Jones _ Matrix o kika ko Ka i pq770b_c Figure 2 73 Comparing the output Jones Vectors to 3 known input Jones Vectors Application of the Jones Matrix A Jones matrix for a specific device can be used to project the output state of polarization given that the Jones vector of the input signal is known For example Jones matrix calculations predict that a quarter wave retarder oriented 45 degrees to horizontal
87. print graphs annotation amp data 7 18 print graphs sl s2 s3 7 18 print PMD gt 7 18 print tabular data 7 12 7 18 Q Query 10 23 question mark 10 23 R range 7 2 rate 7 22 recalling data 4 1 receiver characteristics 11 2 Index 4 reference frame apply 1 6 1 9 define 1 6 1 9 three point 1 6 1 9 two point 1 6 1 9 reference frame info 7 2 regulations 9 1 return to graph 7 12 7 18 rotate 7 2 rotate functions 1 1 1 10 default rotation 1 10 home button 1 10 rotate sphere 1 10 rotate markers 1 6 rotate sphere 1 10 S safety information 9 3 same JME data 7 12 sample period 7 22 samples taken 7 22 save database format 2 24 text file 2 23 save as window 4 13 save JME as text 7 12 save Jones matrix 4 13 save polarization dependence 4 13 save polarization mode dispersion 4 13 save single sweep trace 4 13 save WS as text 7 18 save WS data to database 7 18 saving data 4 1 f Selection Separator 10 23 set markers 1 6 at current data point 1 6 at user specified point 1 6 settling time 7 7 shutter 7 2 single 7 22 single device 7 12 single sweep trace 4 13 SOP measurements 2 81 source wavelength 1 1 1 12 specifications 11 1 start sample sequence 7 22 start wavelength 7 7 state of polarization measurements 2 81 statistical display 2 18 stokes parameters markers 1 6 Stokes vector 7 2 stop wavelength 7 7 string 10 25 system menu 1 4 T tabul
88. pulses In addition light from a spectrally wide source may become partly depolarized under the influence of large values of differential group delay Finally transmitter laser frequency chirp in combination with PMD in a transmission path can cause a transmitted signal to vary in polarization state as a function of time and signal intensity If polarization dependent loss is present in the system the polarization variation is converted to amplitude variation This effect causes composite second order distortion in cable television systems Mode coupling Mode coupling is the term given to the coupling of optical energy between polarization modes along the transmission path Two port optical devices including optical fiber fall into two categories according to the degree of mode coupling Non mode coupled devices include most components hi bi polarization maintaining fiber and short lengths of ordinary single mode fiber For these devices energy launched into each polarization mode remains in that mode as it propagates The differential group delay of non mode coupled devices is generally independent of wavelength The other extreme strong mode coupling is exhibited by long lengths of single mode fiber For long fibers energy couples between modes due to physical variations internal to the fiber and optical effects induced by the fiber s environment The differential group delay of highly mode coupled devices is a strong function of waveleng
89. remote control of the HP 8509 When beginning remote operation of the HP 8509 be sure to quit then restart the application if there has been any manual operation of the HP 8509 during the current session of the HP 8509 application Programming 10 5 HP IB to DDE Interface The HP 8509B Lightwave Polarization Analyzer uses Dynamic Data Exchange DDE for remote operation The HPIB2DDE EXE application connects the DDE system to the HP IB bus Therefore it is required to run this application before attempting remote operation of the HP 8509B using HP IB To start the HPIB2DDE EXE application select the HPIB TO DDE GATEWAY icon in the HP 8509 Group There are three basic parts to this window the HP 8509 Control frame the HP IB frame and the Dynamic Data Exchange DDE frame The HPIB2DDE EXE application window appears as below when the application starts The HP IB to DDE Gateway is a floating window when the program starts This means that the window will always appear on top of any other window To defeat this feature minimize the window by clicking once on the down arrow in the top right corner When the application is restored by double clicking on its icon the window will no longer float HP IBtoDDE Gateway A HP IBisACTIVE Do not operate HP 8509 using mouse or keyboard l HP8509 Control HP8509 Status PASS List IDN Command IDN L
90. the Analog Outputs Window Co 6 23 DOP and Normalized Stokes Parameters Mode Co 6 23 Raw Photodiode Currents 2 a a a a o 6 24 Reference Frame Info re 6 25 Opening the Reference Frame Information Window Co 6 25 Operation Verification 2 2 a ee a a 6 27 7 User Interface Reference Main Window ee a 7 2 Optical Source Setup 2 2 a 7 7 Calibration s a a e a 7 9 Operation Verification Loe Co 7 11 PMD Jones Matrix Figenanalysis So 7 12 PMD Statistics e 7 15 PMD Wavelength Scanning o 7 18 Timed Measurements e 7 22 PDL Jones Matrix amp Jones Matrix e 7 24 PDL Power Max Min 7 26 PM Fiber Launch 2 a a 7 28 Marker Angles 7 29 Contents 6 10 Lightwave Connector Care Introduction Cleaning and Handling Definition of Terms Connector Adapter Handling Cleaning Cleaning Non Lensed Lightwave Connectors Equipment Process Cleaning Lightwave Adapters Equipment o Process Cleaning Lensed Connections Storage Making Connections Summary Inspection Visual Inspection Optical Performance Testing Introduction Insertion Loss Return Loss Safety and Regulatory Information Regulations and Licensing Safety Information Environmental Conditions Ventilation Requirements Cleaning Instructions Instrument Conforms Laser Aperture Location Programming Starting Up the System For HP IB Control HP IB Overview a Bus Structure Data Bus Handshake
91. the HP 8509 system DDE is a standard communication technique which is provided by a majority of Windows applications In effect in order to remotely communicate via HP IB with the HP 8509 system HP IB messages must be translated to DDE messages Under these conditions the HP IB interface is seen as a Windows application directly communicating with the HP 8509 system software A second Windows application called HPIB2DDE provides the translation between HP IB commands and the DDE messages for the HP 8509 software The HPIB2DDE program is accessible within the HP 8509 system window In order to run HPIB2DDE an HP IB interface board must be installed on the HP 8509 system Vectra PC and configured for running under Microsoft Windows The external PC controller running Windows IBASIC must also have an HP IB interface board configured for running under Microsoft Windows The controller PC can send HP IB messages directly to the HP 8509 system and to other HP IB controllable instruments The current version of HPIB2DDE assumes as a default that the HP IB select code of the HP 8509 system is 7 and that the HP IB board address is set to 29 Figure 10 3 demonstrates a typical system configuration Warning When receiving HP IB commands the HP 8509 does not lock out manual operation Take care not to disrupt remote control through manual command execution Furthermore HP IB commands which lock out manual operations are not currently available for
92. the analyzer for the use of internal or external polarizers When using internal polarizers the specified polarizer is automatically inserted When set to external polarizers the appropriate polarizer must be inserted by the user when so required HP 8509B only PolDep Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep JonesData PolDepData PolDep Absolute Relative Specifies the type of polarization dependent loss PDL measurement An absolute measurement requires a thrupath calibration prior to the PDL measurement A relative measurement does not require a thrupath calibration The query returns 1 if the condition is true 0 otherwise PolDep Absolute is HP 8509B only PolDep Calibrate A B c The command is used for an absolute polarization dependent loss PDL measurement Triggers a measurement thrupath calibration If a PDL calibration was previously performed execute PolDep NewThruCal before PolDep Calibrate Otherwise the calibration constants will NOT be updated When optional selections A B or C are used external polarizers are assumed to be used The user must insert the appropriate polarizer and send a command for each polarizer The polarizer angles pertaining to each of the three markers a b and c must be specified using the polarizer command See Polarizer Angle A B C lt Degree value gt The PolD
93. the equivalent PDL of the path between the reference polarizer and the HP8509A B polarization receiver expressed in linear terms The equivalent PDL is found by multiplying the log to base ten of the displayed number by ten An excellent reference frame shows a transmission ratio of 1 0 equivalent to a PDL of 0 dB The equivalent PDL specified by the transmission ratio does not necessarily describe real PDL in the measurement both between reference polarizer and HP8509A B The quality of the reference frame can be degraded by not only weak or strong polarizing elements but also by low signal level incorrect setting of the reference polarizer angles or movement of fibers between polarizer rotations 2 80 Making Measurements State of Polarization Measurements State of Polarization Measurements The state of polarization of a lightwave signal is described by the parameters of total optical power degree of polarization and a description of the polarized portion of the light within a polarization reference frame All of these parameters are measured by the HP 8509A B and are discussed in this section A typical measurement window is shown in the following figure Unless a polarization reference frame is specifically created by the user see Polarization Reference Frame the HP 8509A B uses the reference frame of the polarimeter receiver inside the instrument HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System
94. the surface of the sphere and markers are placed at these points A solid circle marks the maximum power location and an open circle marks the minimum These polarization states are relative because they are measured at the polarimeter receiver separated from the output of the device under test by some length of optical fiber The two buttons located to the right of these controls allow rotating the Poincare sphere to bring the maximum or minimum points to the center of view allowing more detailed operator scrutiny in the case of manual polarization controller operation center selection Main window Measurement menu PDL Power Max Min Rotates the Poincare sphere to bring the maximum or minimum power point to the center of view User Interface Reference 7 27 PM Fiber Launch The PM FIBER LAUNCH feature provides a very sensitive measurement of the extinction ratio of light in polarization maintaining fiber providing feedback for launching light into a principal axis Table 7 11 PDL Power Max Min Control or Data Path Description Cone half angle display Main window Measurement menu PM Fiber Launch Displays the half angle of the cone represented by the circle on the Poincare sphere This is the angle subtended at the center of the sphere by the center of the circle and a point on its circumference Extinction ratio display Main window Measurement menu PM Fiber Launch
95. to Optical Input 3 Select Calibrate Calibrate Calibrated Fixed Wavelengths Done pq7126_c Figure 6 8 The Calibration Window The System Menu 6 11 Saving Wavelength Calibrations When all desired wavelengths have been calibrated save the calibrations according to the following procedure 1 To save all the calibrations in the list with the New designation select Save new calibrations as shown below Calibrated Tunable Wavelengths 1302 1nm External New Save new calibrations Delete selection pq7127_c Figure 6 9 The Calibration List 6 12 The System Menu Applying A Calibration In the Calibration Off condition the analyzer uses the factory calibration constants In the Calibration On condition the analyzer uses the calibration you have performed to modify the internal cal constants for the current wavelength Applying a Calibration a lf you are still working within the Calibration window and wish to apply your calibration use the mouse to select Apply Calibration On m To apply another calibration select the item in the calibration list Select apply on if necessary ADDITIONAL INFORMATION If you have calibration turned on and enter a wavelength for which there is no calibration calibration is automatically turned o
96. two bold triangular marks indicate whether the analysis is using the full scan or first and last feature wavelengths in the wavelength scanning formula The smaller vertical marks indicate whether the analysis is counting peaks or peaks and valleys Making Measurements 2 43 PMD Measurement Wavelength Scanning Method Depending upon the analysis mode selected the wavelength scanning algorithm counts peaks or extrema peaks and valleys When the number of peaks occurring in the selected wavelength range is small accuracy is improved by choosing one of the extrema based analysis modes extrema full scan or extrema first to last When measuring single mode fiber analysis should be applied to the full wavelength scan When measuring components and polarization maintaining fiber cases in which the wavelength scanning responses are sinusoidal analysis should be started and ended on the first and last peak or extrema This avoids error caused by the arbitrary relationship of the endpoints of the wavelength scan and the first and last peaks or extrema of the wavelength scanning response In summary use the analysis modes as follows Single mode fiber peaks or extrema full scan Components PMF peaks or extrema first to last Always analyze extrema if the number of peaks is small Minimum feature size Once a wavelength scanning response has been measured it must be analyzed to identify and count the peaks or peaks and valleys ext
97. updates of the firmware you should provide a mechanism for the HP 8509 application to change without requiring the program to be re compiled Following is a VB code fragment that allows you to specify the HP 8509 application name as a command line parameter to his program The command line parameter may be specified in the Windows Program Manager properties dialog accessed in the menu File Properties Place the parameter after the name of the program in the Command entry Use this code fragment to get the name of the HP8509 gt application at run time The command line parameter that this code fragment looks for is gt HP8509 lt Name of HP8509 Program gt gt If parameter not present use the default name Use the variable Hp8509DdeName when establishing DDE links Programming 10 17 Const HP8509_DDE_DEFNAME HP8509_2 Get the name of the HP8509 Application UCaseCmd Trim UCase Command if InStr UCaseCmd HP8509 If if 0 Then Hp8509DdeName HP8509_DDE_DEFNAME Else if 1 8 j InStr i UCaseCmd If j 0 Then j Len UCaseCmd 1 Hp8509DdeName Mid UCaseCmd if j ih End If The HP8509 uses nine link items One item is used to convey DDE status information The name of this DDE link item is Status Eight items are used to send data to the application via DDE The name of these DDE link items are Param 0 Param 1 Param 2 Param 3 Param 4 Param 5 Param 6 Pa
98. using external Main Window System menu under Polarizers These polarizers angles are editable by the user but the same angles must be used for both calibration and measurement Calibrate Main window Starts the calibration measurement of a thru path in Measurement menu preparation for a Delta Max Min measurement PDL Jones Matrix using internal polarizers Clear Restart Main window Clears the measurement displays and sets up for a new measurement Degrees control Main window Measurement menu PDL Jones Matrix Jones matrix mode Selects the polar format for the elements of the Jones matrix with angles given in degrees Jones Values control Main window Measurement menu PDL Jones Matrix Selects display of the measured Jones matrix Meas at angle selection Main window Measurement menu PDL Jones Matrix using external polarizers These three controls appear when using external polarizers The angles given are those which appear in the Polarizers control frame to be found under the Main Window System menu under Polarizers These angles are editable by the user No reference frame applied message Main window Measurement menu PDL Jones Matrix This message indicates that no polarization reference frame has been applied Pol Dep Values control Main window Measurement menu PDL Jones Matrix Selects display of the polarization dependence value s derived from th
99. will create a right hand circular polarized output when excited by a horizontal linear polarized lightwave signal lt gt Horizontal Linear Polarized Input Signal DUT Linear Retarder oriented 45 to 0 Input Jones Vector DUT Jones Matrix e horizontal 1x1 Oxj 2 1xj 0x1 2 Right hand Circular Polarized Output Signal Calculated Output Jones Vector pq759b_c Figure 2 74 Jones Matrix Application Making Measurements 2 67 Polarization Maintaining Fiber Launch Timed Measurements Timed measurement documentation is in an online document Select the Read Me icon in the Windows Program Group for more information about timed measurements Polarization Maintaining Fiber Launch This measurement section explains how to align an input signal relative to a principal polarization state of a PMF cable An HP 8509A B Poincare sphere PMF alignment method is used and 0 to 60 dB extinction ratios may be achieved depending on the polarization maintaining fiber A sample data display is shown in the following figure HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel P 9 48 dBm Clear Irace id Sal 2 1303 nm PM Fiber Launch Greate arc on sphere 2 Select 3 points to define circle 8 Move Circle Resize Circle Extinction ratio Cone half angle dB
100. window by using the mouse to select System Calibration or by pressing F11 on your keyboard Select a tunable wavelength source as shown in Figure 6 8 Be sure your source is turned on and tuned to the desired wavelength The calibration works best if the optical signal is polarized before it is applied to the HP 8509A B Optical Input Insert an external polarizer or pass the signal through one of the internal polarizers of the HP 8509B Select the polarizer using System Polarizers Select any of the three polarizers Remember to remove the polarizer when the calibration is complete Move the fiber ahead of the polarizer or adjust the front panel knobs of the HP 8509B if necessary to assure a good signal level through the polarizer Select Calibrate You will hear clicking from inside the HP 8509 as the calibration is being performed The calibration takes about 60 seconds The HP 8509 automatically averages 250 measurements at each state Calibrating subsequent wavelengths a Enter the new wavelength in the wavelength box in the Calibration window by selecting the existing entry then writing over it You may also input the new wavelength using the Optical Source window b Select Calibrate Source Type i J O Fixed A Tunable 4 Optical Source A HP8168A 1510 0 nm 1 Set external source to 1510 0nm or select new Wavelength 2 Connect source
101. 10 53 Single Period lt Seconds gt 10 53 Single Points lt NumPoints gt 4 2 10 53 Single Start 2 2 ee 10 58 Source o 10 53 Source External o o 10 54 Source External Off On y o 10 54 Source External lt Wavelengthnm gt 0 10 54 Source HPIB a 10 54 Source Hpib 1 Off On lt Wavelength r nm gt a 10 54 Source Internal A 10 55 Source Internal f Off I 1310 f 1550 y o 10 55 Source Manual 2 a 10 55 Source Shutter a 10 55 Source Shutter Off On y o 10 55 Source VTune Ce a 10 56 Source VTune Start Stop E lt Voltage gt o 10 56 Status o 10 56 Stokes lt NumPoints gt Ce 10 56 Stokes lt NumPoints gt 2 ee 10 56 TLS 2 a 10 57 TLS Address 1 lt HP 1B Address gt 10 57 TLS Isc lt HP IB card ISC gt 10 57 TLS Power lt Power gt o 10 57 TLS f SettlePoint SettleStart ve lt Millisec s gt 02 2 10 57 TLS Power Unit dBm Watt nn 10 58 Trace Points lt NumPoints gt 10 58 Version 2 a a a 10 58 WaveScan a a a a a a L 10 58 WaveScan Analysis 10 58 WaveScan Analysis Extrema Peaks y FullScan FirstToLast y 10 59 WaveScan Atten lt dBmvalue gt 020200202202424 10 59 WaveScan Clear oaoa a a a a a 10 59 WaveScan Close Ce
102. 11 6 11 7 11 7 Contents 17 Getting Started This chapter contains the following sections m Description of the Instrument a Installation m About This Manual Set m The Main Menu a The Data Displays Power DOP Ellipse and Poincare Sphere m The Marker Functions a Zoom and Rotate a Clear Trace and Hold m A and Cal Description of the Instrument The HP 8509A B Lightwave Polarization Analyzer offers high speed calibrated polarization measurements of optical signals and components Installation The lightwave polarization analyzer is preconfigured at the factory All that is required to install the system is to unpack the pieces correctly connect them and turn them on Refer to the Installation chapter of the HP 8509A B Installation and Quick Start Guide for complete instructions The Installation chapter also provides instructions for unpacking the system and returning the system to the factory for service Getting Started 1 1 About This Manual Set The HP 8509A B manual set is made up of three documents HP 8509A B Lightwave Polarization contains an installation procedure Installation Quick Reference Card Installation and Quick Start Guide contains an installation procedure and an operation verification procedure to ensure that your analyzer is operating properly User s Reference Guide this manual this is the main manual for the lightwave polarization analyzer This manual is d
103. 2271 ps Minimum 0 21484 ps 1 Test device is a pigtailed quartz PMD standard under development 2 Measurement wavelength range of 1500 to 1560 nm 3 Measurement wavelength interval of 10 nm 4 Reposition pigtails randomly before each measurement 5 The 0 010 ps tolerance is provided to allow for the effects of pigtails and packaging Wavelength Scanning PMD Measurement Table 11 5 shows the minimum measurable PMD for the wavelength scanning method for two types of devices Non mode coupled devices include most components Highly mode coupled devices include most long single mode optical fibers Table 11 5 Minimum Measurable PMD Using the Wavelength Scanning Method Minimum Measurable PMD Type of test device Minimum measurable PMD value non mode coupled devices most components 0 040 ps highly mode coupled devices long fibers 0 195 ps 1 Assumes 100 nm wavelength tuning range 2 Assumes a single peak and a single valley 3 Assumes an average of 3 cycles of polarization change 4 peaks Specifications and Characteristics 11 3 Comparison Between Jones Matrix Eigenanalysis and Wavelength Scanning Methods Figure 11 1 is a comparison between the Jones matrix eigenanalysis and wavelength scanning measurement methods HP 8509B JME and WS measurements agree to within approximately 15 for this test device 10 1 1 10 DGD from wavel
104. 3 Disper HPIB Sets the tunable laser source for a PMD JME measurement to an HP IB tunable laser source The HP 8509B looks for a tunable laser source at the address specified with TLS Address and uses it if it is either an HP 8167 or HP 8168 tunable laser source Be sure that the wavelength range is set correctly for the connected HP IB tunable laser source before issuing this command To change tunable laser source selections between HP 8167 and HP 8168 1 Issue the command Disper Manual 2 Change the wavelength range using Disper WLen 3 Change the HP IB address using TLS Address lt HP IB Address gt 4 Issue the command Disper HPIB The query returns an ASCII 1 if the PMD JME next measurement process will be in HP IB mode and a 0 if it will not be in this mode Also returns the name of the current laser source HP 8509B only DDE only Disper Manual Places the polarization mode dispersion measurement in manual control mode When the instrument is under manual control the user must set the external source to the appropriate wavelength for each wavelength step between the start and stop wavelengths In manual control mode you must send the command Disper Measure once to begin the measurement process and once for each wavelength point as returned by the command Disper WLen Points HP 8509B only Disper Manual Returns an ASCII 1 if the PMD JME next measurement process will be in manu
105. 3 3 2 3 4 Fiber Cable Layout Movement Zeroing Wavelength amp Wavelength Calibration Fiber cables used in the instrument setup of an HP 8509 polarization measurement should be laid out and secured in a relaxed and flowing manner free from sharp kinks and tight radius curves lt 2 inch Secure the fiber using tape or some other technique to prevent the fiber from moving and to reduce the waiting time for fiber relaxation A few minute relaxation time is recommended in any case to allow the stress pattern within the fiber to stabilize Changing stress patterns alter the birefringence within a fiber changing the polarization of a signal being transmitted through the fiber Unstable polarization from an improperly deployed fiber cable increases measurement uncertainty After caring for the fiber layout random vibration may still cause unstable polarization Display averaging may be used to minimize the effect of these vibrations on the Poincare sphere display Measurement averaging will reduce the effect of vibration on PMD and PDL measurements and any measurements using the markers As in all measurements with the polarization analyzer effective zeroing of analog circuit offsets is required for measurement accuracy Refer to the Zeroing section of this manual for information about this procedure and feature Although zeroing is automatically performed at power on zero the instrument again after a one hour warmup per
106. 4 10 Printing Saving and Recalling Measurement Results and Instrument Configurations 4 To resume normal operation of the lightwave polarization analyzer toggle the Hold function by selecting Hold See the following figure HP 8509 File Recall Results HP 5096 Lightwave Polarization Analyzer File Edit Measurement Display System Help Power 7 55 dBm DOP 99 6 Figure 4 7 Viewing a Stored Trace on the Poincare Sphere Word Processor Spreadsheet and Database Numeric File Format The comma delimited ASCII format for each measurement is shown below This format is useful for spreadsheet users and database analysis programs The following symbols are used in the format descriptions of this section A wavelength Sx Stokes parameter So average optical power Sx normalized Stokes parameter Sx So DGD differential group delay DOP degree of polarization units Printing Saving and Recalling 4 11 Measurement Results and Instrument Configurations Refer to the appropriate user information outside of this manual if measurement results are being recalled using a separate word processor spreadsheet or database program 4 12 Printing Saving and Recalling Measurement Results and Instrument Configurations PMD Jones Matrix Eigenanalysis Save Format Format Ay An41 DGD units are unspecified Example 1500 1501 2310215 PMD Wavelength Scanning Save Format Format A nm So dBm s1 82 3 D
107. 9B It exercises the polarimeter the internal polarizer assembly and the polarization adjuster assembly which precedes the polarimeter for use in calibration The instrument measures polarization with each of the three polarizers inserted for each of 32 polarization adjuster settings The results are analyzed and compared with expected values A pass fail message appears No save feature is available If you need a hard copy of the results use Print Screen on the keyboard and the Paintbrush program see the Printing Saving and Recalling chapter Table 7 4 Operation Verification Control or Data Path Description Cancel selection Main window System menu Operation Verification Cancels the operation verification process without closing the window Done Main window Exits the operation verification window System menu Operation Verification DOP Max Main window Displays the statistical results of the DOP Mean Min System menu measurement portion of the operation verification displays Operation Verification The target value is 100 See the Specifications chapter for tolerances Polarizer Angles AB AC displays Main window System menu Operation Verification Displays the mean value of the polarizer angles as measured by the polarimeter These values are compared with values stored in instrument ROM The stored values can be inspected by selecting System menu and Polarizers Start selection
108. Agilent 8509A B Lightwave Polarization Analyzer User s Guide ae Agilent Technologies Copyright Agilent Technologies 1992 1994 2001 All Rights Reserved Reproduc tion adaptation or translation without prior written permission is prohibited except as allowed under copyright laws Agilent Part No 08509 90016 Printed in USA December 2001 Agilent Technologies Lightwave Division 3910 Brickway BoulevardSanta Rosa CA 95403 USA Windows is a U S registered rademarks of Microsoft Corpora ion Microsoft is a U S registered rademark of Microsoft Corpora ion MS DOS is a U S registered rademark of Microsoft Corpora ion Notice The information contained in this document is subject to change without notice Companies names and data used in exam ples herein are fictitious unless otherwise noted Agilent Tech nologies makes no warranty of any kind with regard to this material including but not lim ited to the implied warranties of merchantability and fitness for a particular purpose Agilent Tech nologies shall not be liable for errors contained herein or for incidental or consequential dam ages in connection with the fur nishing performance or use of his material Restricted Rights Legend Use duplication or disclosure by he U S Government is subject to restrictions as set forth in sub paragraph c 1 ii of the Rights in Technical Data and Computer Software clause a
109. CURACY ENHANCEMENT NOTE All fiber cables must be taped down to prevent any movement Movement of cables may jeopardize measurement accuracy Test System HP 8509A B l l External l Source Optical Optical l O Input Output Input o O Q Source Assembly Rotatable l l Lens for o Reference Fiber i Polarization Adjuster Polarizer l Launch l t l i PA i Fiber Interface l Fiber i Laser Source I Polarization Reference Frame pq773b_c Figure 2 67 Measurement Setup 2 60 Making Measurements Jones Matrix Measurement External Source Preparation Before performing the measurement you must select an optical source The following procedure will guide you through the process Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs Reference Frame Info Operation Verification pq780b_c Figure 2 68 System Menu Select System from the main menu and then select Optical Source Optical Source Setup rOpticalSourceSelection r Power HP8168A HP IB y On Ooff HP IB Address 724 y Level _100 0 Watt Wavelength cw 1551 0 Cancel pq71b_c Figure 2 69 Optical Source Setup Select the external laser source and set the CW wavelength for your measurement Use the def
110. D JME measurement Changing any of these values causes the number of points in the Optical Source Setup window to change according to WlenPoints WlenStop WlenStart WlenDelta 1 The query returns the value of the setting in nanometers Using the lt Wavelength nm gt parameter sets the value Note The Start and Stop values can never have the same value For example when segmenting a wavelength range over several measurements and sweeping from low to high always issue the command Disper WLen Stop before the command Disper WLen Start when specifying the next wavelength segment This will prevent the Start and Stop values from being equal when switching from one segment to the next HP 8509B only 10 38 Programming Disper WLen Steps lt NumPoints gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper WLen Points lt NumPoints gt Sets the number of steps between the start and stop wavelengths for the polarization mode dispersion PMD measurement Each step corresponds to two adjacent wavelengths for PMD measurements If the number of steps does not correlate with the delta value and the start and stop wavelengths the delta value is reset to accommodate the number of steps according to WlenDelta WlenStop WlenStart WlenSteps The query returns the number of steps specified in the current PMD WS measurement settings
111. D Statistics continued Control Path Description or Data Save Statistics File Saves a histogram as text May be retrieved to the PMD Statistics application with the Load Statistics feature Total size Shows the total number of data points contained in display the histogram including undisplayed wavelengths Undo Last Add Edit The curve last added to the DGD versus wavelength display is shown in red Undo Last Add removes the red trace from the display and removes the corresponding points from the cumulative DGD histogram data set Wavelength Range gt Format Allows selection of range mode for the DGD vs wavelength display Selections are Autorange or Fixed Range Autorange sets the minimum and maximum displayed wavelengths to accommodate the minimum and maximum value of wavelength of the measurement data Fixed Range allows the user to define the wavelength range The cumulative DGD histogram is composed only of points which fall within the displayed wavelength range User Interface Reference 7 17 PMD Wavelength Scanning All PMD measurements take place within the Graphs window a parent window in Windows terminology The individual measurements are child windows within it Each new measurement configuration produces a new child window Select among the measurement setups using the Windows menu Change between PMD setups and open new PMD measurement setups from the Windows menu
112. Drive C is the HP 8509A B system default drive If using drive C all saved data files using HP IB will be placed in the HP 8509A B directory unless a specific directory path is specified for the file If another drive such as A or B is designated all files will be saved to the root directory unless an alternate path is specified GetFile lt filename gt This command will via HP IB transfer an ASCII data file from the HP 8509A B system Vectra PC to the external controller The file is transferred as an ASCII string An ENTER HP IB command must be used to access the file from the HP 8509A B Vectra PC The file must be placed into a large enough string variable Otherwise data will be lost In the HPIB2DDE window the user can specify whether the string separator is a comma or a carriage return linefeed The user should specify the format which coincides with the string variable specified in the ENTER HP IB command statement For path information on filename see Command Syntax at the beginning of this chapter HP IB Operation only GetMarker A BIC Not Recommended See GetMarker A BIC GetMarker A BIC Places the specified marker at the current state of polarization and returns the results So s1 82 83 So is the power in milliwatts and s1 s2 83 are the normalized Stokes parameters which serve as coordinates on the Poincare sphere 10 40 Programming Jones Not Recommended Command may no
113. H Hae AAE 15429 BIAS CAR SUSU 43849 Hewlett Packard AJF A JRE AAAS 2979 BO A AFB Agilent Technologies EPER AQeuc Hewlett Packard7 gt Agilent Technologies 4247 COMES CAAT Hewlett Packard O PEA CH fa SMEAR AAA CS LO PURA LEE Agilent Technologies CERINTOET lla BERE ANI CU CTA 4OMHOARARSNELE COMENT Ii Hewlett Packard Eh TFT ARTE E TRENTO ETA aid Technologies 1411 2M TOET RF EEA A ERA ECR TEE JE SCRAPS AT EH Hewlett Packard TRAMA ih AA BL LEAN RH A Agilent Technologies PYAR AKA AED FLETE REET AR SOMERS Be m AE E ih ZK BAN ZERAT SA ALEA ADE AUS a Hewlett Packard SA gt MAREA ASTRAL Agilent Technologies gt ER REA gt EZART SS A E Pee SOS Contents 1 Getting Started Description of the Instrument Installation About This Manual Set This guide uses the following conventions HP 8509A B User s Reference Guide Table of Contents this manual The Main Menu The Data Displays Power 1 DOP Ellipse and Poincare Sphere Power Display DOP Display Poincare Sphere Polarization Ellipse The Marker Functions Setting a Marker Setting a Marker at the Current Data Point Setting a Marker at a User Specified Point Turning the Markers On and Off Clearing the Markers Centering the Sphere on a Marker or Current Point Two or Three Point Polarization Reference Zoom and Rotate Zoom To Zoom In To Zoom
114. Hel Clear Trace ld Lal 1550 0 nm Markers W _ On Clear Markers s2 s3 0 08 0 98 Rotate 3pt Ref Apoy Bet Home pq716b_c Figure 2 86 Example of a SOP measurement data display Making Measurements 2 81 State of Polarization Measurements Basic Measurement The following measurement procedure illustrates how to use the HP 8509A B Lightwave Polarization Analyzer operating system software to measure the polarization parameters of a signal Setting up the System Connect your measurement system as outlined in the following illustration HP 8509A B External Source Polarization External Source Optical Optical O Input Output Input O O Q ay Tunable Lightwave Source pq7166_c Figure 2 87 Measurement Setup 2 82 Making Measurements External Source Preparation State of Polarization Measurements Before performing the measurement you must select an optical source The following procedure will guide you through the process HP8508B Lightwave Polarization Analyzer File Edit Measurement Display FEE Help Optical Source Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs
115. M VECTRA PC HP8509 LIGHTWAVE POLARIZATION ANALYZER DEDICATED INTERFACE CABLE OO oooooooooo oo ooo a A a a LI IOC rrr Coo OTHER HP IB CONTROLLABLE cop oooooooeess ao cao DEVICES PRINTER PC CONTROLLER Figure 10 3 HP IB Connections In a Typical Setup Programming 10 11 Given the translation mode under which HP IB control is achieved for the HP 8509 system certain constraints exist dictated by the HPIB2DDE application The constraints are relative to the full set of capabilities provided by the HP IB interface see references The constraints are listed below a Data is transmitted and received as ASCII strings In other words only formatted data transfers are possible m EOI is used to indicate the completion of data transmission The EOI can be set by using an HP IB END statement to terminate the sending of a command a EOL default lt cr gt lt lf gt is NOT used by default This can be toggled from the HPIB2DDE application window and will stay at the last setting EOL should be toggled on for HP IB control through an external PC controller running IBASIC for Windows EOL stands for End Of Line and refers to a string which defines the end of a command line when an OUTPUT statement is sent The HP IB END statement serves as the line terminator a Use only ENTER OUTPUT formatted da
116. Marker 2pt Ref 3pt Ref 5 8 The Display Menu Rotate Home pq730b_c Figure 5 13 Mark Current Point Activated Changing the Display Update Frequency HP8509B Lightwave Polarization Analyzer File Edit Measurement IDIEJJEPA System Help Show gt Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq73ib_c Figure 5 14 The Display Update Menu The power measurement DOP measurement polarization ellipse and Stokes displays are updated after the display of a user selected number of points on the Poincare sphere The default display update rate is once every 400 sphere points The acceptable range of values for the display update number is 1 to 2000 The following figure shows the Display Update window that appears when you select Display Display Update To change the display update number select the existing number and enter your new value Enter Display Update Display Update Number 400 Sphere points update of Here Power DOP Ellipse Stokes vector marker Exit Done pq732b_c Figure 5 15 The Display Update Box To maximize the update rate of the Poincare sphere display set the Display Update value at the maximum 2000 CAUTION The display update frequency cannot be smaller than the display averaging factor Disp
117. Menu The Display Update Box The Hold Menu The Hold Function The Clear Trace Menu The Auto Refresh Menu The HP 8509A Optical Source Window The HP 8509B Optical Source Window The Calibration Window Loe The Optical Source Window The Calibration Window The Calibration List 2 75 2 75 2 76 2 81 2 82 2 83 2 83 2 84 2 86 2 87 2 87 2 88 3 2 4 1 4 3 4 4 4 8 4 9 4 10 4 11 4 16 4 16 4 17 4 17 4 18 4 18 5 2 5 3 5 3 5 4 5 4 5 5 5 5 5 6 5 6 5 7 5 7 5 8 5 8 5 9 5 9 5 10 5 10 5 11 5 11 6 2 6 3 6 5 6 7 6 8 6 9 Contents 15 6 7 6 8 6 9 6 10 6 11 6 12 6 13 6 14 6 15 6 16 6 17 6 18 6 19 6 20 6 21 9 1 10 1 10 2 10 3 11 1 The Optical Source Window The Calibration Window The Calibration List Calibration Applied Deleting a Calibration Confirm or Abort the Deletion Process The Polarizers Window The Shutter Menu The Averaging Window The Range Window The Analog Outputs Window No Reference Frame Defined Window Two Point Reference Frame Information Window Three Point Reference Frame Information Window The Operation Verification Window for the HP 8509A Laser Aperture Location HP IB Setup HP IB to DDE Gateway HP IB Connections In a Typical Setup Comparison of JME and WS Measurement Methods for Long Optical Fiber Test Contents 16 6 10 6 11 6 12 6 14 6 15 6 16 6 17 6 19 6 20 6 22 6 23 6 25
118. O or its input pigtail Connect the device to be measured DUT between the output pigtail of the DCO and the Optical Input of the polarization analyzer 8 Select Start Measurement When the measurement is complete the PMD effects of the first DCO are removed and the displayed DGD represents the newly inserted device Refer to the following figure Making Measurements 2 27 PMD Measurement Jones Matrix Eigenanalysis Method HP8509 Graphs lt 2 gt PMD JME 1500 0 1550 0 2 0 Edit Measure Format Display Window Fiber Length 0 km Source level OJuWatt Delta Source atten dB Wavelength nm Stop Points Figure 2 33 The Results 1550 paco PONa O VEYA 0 60022 VI 0 24687 fom 0 11257 Continye pq7158_c CAUTION In general the PMD values of cascaded devices do not simply add Single Device measurements of two devices cannot be added to produce the expected DGD of the same devices in cascade ADDITIONAL INFORMATION The effectiveness of this method can be verified in two ways 1 Perform a cascade thru calibration on a device and then measure the same device without moving any fibers The result should be a very small value of DGD typically under 0 010ps indicating that the device itself has been removed from the measurement path The device must be stable in tempe
119. OP Example 1525 2 704419 9104293 3429706 2233345 99 81926 PDL Jones Matrix and Jones Matrix Save Format Format Absolute Measurement Flag PDL Delta PLD Max PDL Min JOO real j00 imag JO1 real j01 imag J10 real j10 imag J11 real j11 imag where Absolute Measurement Flag is 1 1f the Jones matrix PDL measurement is absolute and 0 if it is relative In the case of a relative measurement PDL Max and PDL Min are both 0 Example 1 3 017851E 02 0171138 1 306471E 02 296185061242171 746302479489197 137726371786746 58206929707534 488929498642804 3450943751558 800210126957622 0 Timed Measurement As Text Save Format Format An nm So mW S1 52 53 DOP Example 1537 1844145 8 568172E 02 1516657 5 691557E 02 99 37248 ADDITIONAL INFORMATION The Save format for Timed Measurements to database uses normalized Stokes parameters Printing Saving and Recalling 4 13 Measurement Results and Instrument Configurations Saving and Recalling Instrument Configurations The HP 8509A B always starts up with a set of default conditions These sets of conditions are called configurations and the necessary parameters are stored in configuration files which are loaded at startup You can change conditions via the HP 8509A B pull down menus If you want to save particular sets of conditions to use later without having to reset all the conditions manually you can s
120. The equivalent PDL specified by the transmission ratio does not necessarily describe real PDL in the measurement bath between reference polarizer and HP8509A B The quality of the reference frame can be degraded by not only weak or strong polarizing elements but also by low signal level incorrect setting of the reference polarizer angles or movement of fibers between polarizer rotations variable A symbol the numeric value of which changes from one iteration of a program to the next or within each iteration of a program vector A quantity that has both magnitude and phase vertical Resolution The degree to which an instrument can differentiate between two closely spaced signal amplitudes waveguide A structure that guides electromagnetic waves along its length An optical fiber is an optical waveguide wavelength The distance an electromagnetic wave travels in the time it takes to oscillate through a complete cycle Wavelengths of light are measured in nanometers 10 m or micrometers 10 m wavelength calibration The HP8509A B provides a wavelength calibration process that allows the operator to improve upon the built in calibration for a particular source even if the wavelength of the source is not accurately known The HP8509A B contains in memory a set of factory calibration coefficients that optimize the accuracy of the polarimeter at a series of discrete wavelengths Between these wavelengths the instrument interpolates spec
121. The number of points will be set to accommodate this value Sample measurements are evenly spaced across the wavelength range For this measurement use the default setting by selecting Ok FOR MORE INFORMATION More information on selecting the appropriate number of points may be found in the Concepts section later on in this chapter Choosing Delta Wavelength and Fiber PMD Statistics Enlarging the Sample Size 2 10 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Find Minimum of Points At least 2 points are required for the selected wavelength range Additional points may be required for optimum resolution of wavelength dependent differential group delay To use fewer points reduce the wavelength range pq7102 c Figure 2 12 Find Minimum of Points When the automatic routine is finished you will be advised what minimum number of measurement points is required for your wavelength range The minimum number of points is automatically entered in the optical source setup window when this message box is closed Select OK to continue with the measurement ACCURACY ENHANCEMENT NOTE When measuring components polarization maintaining fiber or short lengths of single mode fiber use the indicated minimum number of points When measuring long fiber or any device that is expected to exhibit wavelength dependent PMD increase the number of points to measure the wavelength dependent
122. UT extends the amplitude range of the measurement to allow measurement of higher loss devices If the source is not polarized an external polarizer must be used Making the Measurement At this point your measurement system is ready to make your first measurement For our purposes we are going to measure a ten kilometer length of fiber Connect your test device between the optical output of the laser source and the optical input of the analyzer ACCURACY ENHANCEMENT NOTE The fiber path leading from the tunable laser source to the DUT and from the DUT to the 8509 optical input must not move during the measurement process Unsupported fiber particularly unjacketed fiber should be taped down or placed against stationary objects Movement of the fiber may jeopardize PMD measurement accuracy 2 34 Making Measurements PMD Measurement Wavelength Scanning Method CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual HP8509B Lightwave Polarization Analyzer File Edit AUESEMICIUNENS Display System Help PMD Jones Matrix Eigenanalysis PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 Jones Matrix F4 PM Fiber Launch F5 Marker Angles Timed Measurement pq793b_c Figure 2 36 Wavelength Scanning Measurement Selection Select Measurement from the main menu and then select PMD Wa
123. VTune Sets the Optical Source Setup source selection to VTune in order to control a VTUNE tunable laser source The query returns an ASCII 1 if the PMD JME next measurement process will be in VTUNE mode and a 0 if it will not be in this mode Also returns the name of the current laser source HP 8509B only Disper VTune Start Stop 1 lt Voltage gt The VTUNE start or stop voltage The query returns the voltage value the parameter lt Voltage gt sets the value HP 8509B only Disper WLen Returns the next wavelength in nm at which the PMD JME measurement will be conducted This command is typically used only when the tunable laser source is Manually Tuned HP 8509B only Programming 10 37 Disper WLen Points lt NumPoints gt Sets the number of points between the start and stop wavelengths for the polarization mode dispersion PMD measurement Each point corresponds to a wavelength for PMD measurement If the number of points does not correlate with the delta value and the start and stop wavelengths the delta value is reset to accommodate the number of points according to WlenDelta WlenStop WlenStart WlenPoints 1 The query returns the number of points specified in the current PMD WS measurement settings HP 8509B only Disper WLen Start Stop Delta lt Wavelength nm gt Specifies the Start Stop or Delta wavelengths for the PM
124. ach pair The Start Measurement button is disabled when the text box is open ADDITIONAL INFORMATION You can add your own notes to the text All of the standard key board and mouse editing features are available Use the mouse to place a text insertion point anywhere in the document and then type the desired text Text may be selected using the drag features of the mouse Selected text may Making Measurements 2 17 PMD Measurement Jones Matrix Eigenanalysis Method be deleted or copied to the clipboard for use in a report or a spreadsheet by pushing the button The tabular data text box is limited to 60 000 characters All or a portion of the text box information may be printed Printing uses the default printer selected in the windows control panel To print all of the text box information just press the Print tabular data button at the top of the text box To print a portion of the text box information hi light the desired text with the mouse before pressing the Print tabular data button To return to the graphic display press the Return to graph button or re select Tabular Data under the Display menu Displaying Data in a Statistical Format Data from PMD JME measurements can be displayed in statistical format using the PMD Statistics feature See the Concepts section for a discussion of its application Fiber PMD Statistics HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 E
125. ach point on the sphere represents the same information as the more familiar polarization ellipse along with the handedness left or right of the polarization All linearly polarized states fall on the equator Right and left handed polarization fall at the north and south poles respectively All elliptical states are between the equator and the poles right handed elliptical in the northern hemisphere and left handed in the southern Orthogonal polarization states are diametrically opposite one another on the Poincare sphere For example rotation of a linear polarizer by 90 degrees in a light beam moves the point on the sphere along the equator by 180 degrees Phase shift between orthogonal electric field components of a lightwave is represented by a circular path on the Poincare sphere If the components are of equal magnitude the circle is a great circle having the diameter of the sphere itself Glossary 7 polarized light Fully polarized or simply polarized light can be represented by a pair of orthogonal electric field components of defined magnitude and relative phase Fully polarized light has no unpolarized component therefore the degree of polarization is 100 polarization Refers to the behavior of the electric field vector of an optical signal If the path of the instantaneous electric field vector of a lightwave falls in a plane it is linearly polarized It follows a circular spiral path it is circularly polarized If it
126. acteristics Polarization Dependence Jones Matrix Method Table 11 9 Measurement of Polarization Dependence HP 8509B Only Jones Matrix Method Measurement of Polarization Dependence Jones Matrix Method gt Polarization dependence wavelength operating range 1280 to 1340 nm 1470 to 1580 nm 3 4 5 0 1 dB Polarization dependence uncertainty 1 Polarization dependence is the peak to peak variation in transmission of the device under test over all polarization states 2 Specified with single line laser source 3 For measured values less than 3 dB receiver input level gt 20 dBm 4 Does not include the effect of optical connectors 5 Measurement averaging set to 500 points Polarization Dependence Power Max Min Method Table 11 10 Measurement of Polarization Dependence HP 8509B Only Power Max Min Method Measurement of Polarization Dependence Power Max Min Method gt Polarization dependence wavelength operating range 1280 to 1340 nm 1470 to 1580 nm 3 4 5 0 1 dB Polarization dependence uncertainty 1 Polarization dependence is the peak to peak variation in transmission of the device under test over all polarization states 2 Specified with single line laser source 3 For measured values less than 3 dB receiver input level gt 20 dBm 4 Does not include the effect of optical connectors 5 Measurement averaging set to 500 points Fiber Si
127. again Conditions are stable if the output polarization drifts less than one degree per minute on the Poincare sphere Test devices should be allowed to settle in temperature before measurements are started Re zero the HP 8509A B if the temperature has changed Typically one hour of test system warm up time within a thermally stable environment is required Re zero the HP 8509A B if the temperature changes Wavelength step size or Delta or wavelength interval is important to the two PMD measurement methods In each case error can result from a step size that is very large or very small In the JME method large step size can cause the measurement to produce alias results and can limit the ability to resolve or identify the wavelength dependence of the DUT In the WS method large step size can result in missing certain peaks or valleys in the counting process For both JME and WS methods very small steps may be unnecessary and can introduce error JME and increase measurement time See the JME and WS measurement application sections for more information Wavelength span affects both of the PMD measurement methods particularly in the measurement of fiber PMD For fiber PMD measurements use the full wavelength range of the optical source This will give the broadest possible exposure to the random polarization behavior of fiber PMD and provide the most statistically meaningful measurement In wavelength scanning measurements choice o
128. ails 2 Does not include the effects of optical connectors 3 Uncertainty introduced in defining an external reference frame in open beam applications is not included 4 500 point display averaging running average 5 Characteristic applies for 100 polarized light for the purpose of practical verification 6 Characterized in degrees on the Poincare sphere 7 For input light at least 98 percent polarized Uncertainty increases as degree of polarization decreases 8 For uncertainty in the angle between two displayed points multiply by two Specifications and Characteristics 11 5 Source Characteristics Table 11 7 Source Characteristics Source Characteristics A Min Typical Max Average Optical Power Output 1310 nm 180 uW 315 uW 600 uW 1550 nm 125 uW 220 uW 400 uW Wavelength Accuracy 1310 nm 20 nm 1550 nm 20 nm Spectral width RMS 1310 nm 5 nm 1550 nm 3 nm Return loss 17 dB Laser type Fabry Perot Table 11 8 External Source Input Port Characteristics External Source Input Port Characteristics Wavelength operating range 1200 to 1580 nm Insertion loss 6 dB Return loss 35 dB 1 Internal path loss between EXTERNAL SOURCE INPUT and OPTICAL OUTPUT connectors with no polarizer selected 2 Does not include the effects of optical connectors 3 When optical output is connected with return loss of 30 dB or better 11 6 Specifications and Char
129. aking Measurements chapter of this manual Getting Started 1 9 Zoom and Rotate Rotate Buttons zoom Rotate adaut 1 in gt aly Home Zoom In Buttons Zoom Factor Button Zoom Out Buttons pq75lb c Figure 1 8 Marker Zoom and Rotate Zoom To Zoom In To zoom in on data on the Poincare sphere select either inb or gt gt Use Ind to advance the zoom factor in increments of one Use P gt to advance the zoom factor more rapidly To Zoom Out To zoom out select either 40ut or lt 4 Use 40ut to decrease the zoom factor in increments of one Use 44 to decrease the zoom factor more rapidly The Zoom Factor Function You can use the zoom factor function in two ways Select this function in a zoomed condition to immediately bring the zoom factor back to 1 without having to use the Out buttons Select this function when the factor is 1 to set the zoom factor to the most recently visited zoom factor 1 10 Getting Started Rotate To Rotate the Sphere To rotate the sphere select any of the four arrows in the Rotate area see Figure 1 8 The sphere will rotate in the direction of the selected arrow The Home Button To bring the sphere back to the default orientation select Home CAUTION Any time you rotate the sphere the trace is cleared The only exception to this is when you are viewing a recalled data trace or a timed measuremen
130. al mode and a 0 if it will not be in this mode Also returns the name of the current laser source HP 8509B only Disper Measure Triggers a PMD JME measurement at the current source wavelength setting HP 8509B only 10 34 Programming Disper NewThruCal Not Recommended This command is ignored It is provided for compatibility with old code Command will not be available in future versions Plan your programming to use the alternate commands Disper Calibrate HP 8509B only Disper Power Returns the power and the power units for the tunable laser source HP 8509B only DDE Only Disper Power dBm uWatt lt value gt Sets the units for the tunable laser source If the lt value gt parameter is specified the power setting can also be changed If the power setting is not valid for the TLS the command fails Note When changing only the units the numerical value of the power does not change Be sure to change the value of the power to correspond to the new units HP 8509B only DDE Only Disper Restart Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Clear HP 8509B only Programming 10 35 Disper Save lt filename gt Saves a polarization mode dispersion measurement trace into the file lt filename gt The trace is saved as a series of ASCII strings separated by commas The saved trace information
131. ally across the fiber end Visually inspect the fiber end for stray cotton fibers As soon as the connector is dry the connection should be made CAUTION Inverting the compressed air canister while spraying will produce residue on the sprayed surface Refer to instructions provided on the compressed air canister Cleaning Lightwave Adapters Equipment All of the items listed above for leaning connectors may be used to clean lightwave adapters In addition small foam swabs may be used along with isopropyl alcohol and compressed air to clean the inside of lightwave connector adapters NOTE As noted in a previous caution statement the foam swabs can leave filmy deposits These deposits are very thin however and the risk of other 8 4 Lightwave Connector Care contamination buildup on the inside of adapters greatly outweighs the risk of contamination of foam swab deposits left from cleaning the inside of adapters Process Clean the adapter by applying isopropyl alcohol to the inside of the connector with a foam swab Allow the adapter to air dry or dry it immediately with clean compressed air Cleaning Lensed Connections Some instruments may have a connector that is lensed in other words the connection does not provide a physically contacting connection but the light is received into a lens rather than into a connecting fiber These receiving lenses usually have an anti reflective coating that is very
132. analysis F2 PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 Jones Matrix F4 PM Eiber Launch F5 Marker Angles Timed Measurement pq794b_c Figure 2 56 Jones Matrix Measurement Selection Select Measurement from the main menu and then select PDL Jones Matrix F3 6 PolarizationDependence Polarization Analyzer System Hel ar Trace ld Est 1539 0 nm 8 Internal O External Delta O Delta Max Min No reference frame applied Measurement at 0 0 done Measurement at 60 8 done Measurement at 120 4 done Measure Clear Restart Polarization Dependence _ Delta 0 15 dB O Jones values Pol Dep values Rotate Done Home pq774b_c Figure 2 57 Jones Matrix Measurement Window m Select Internal Polarizers and Delta Transmission Measurement m Connect the device you wish to measure 2 50 Making Measurements PDL Measurement Jones Matrix Method m Press the Measure button with your mouse pointer The results of the measurement will appear in the Polarization Dependence data window 6 PolarizationDependence Polarization Analyzer System Hel Internal External ar Trace Delta Delta Max Min
133. ange Characteristics Jones Matrix Eigenanalysis PMD Measurement Table 11 3 shows the repeatability of a measurement of a 0 218 ps quartz PMD standard in which the fibers do not move between measurements Table 11 3 Repeatability of JME PMD Measurement with Fixed Pigtail positions Repeatability of JME PMD Measurement 2 3 4 Number of measurements 20 measurements 0 218 0 010 ps Expected value of DGD 0 2173525 ps Mean Standard deviation 0 0000085 ps Maximum minimum 0 00003 ps Maximum 0 21737 ps Minimum 0 21734 ps 1 Test device is a pigtailed quartz PMD standard under development 2 Measurement wavelength range of 1500 to 1560 nm 3 Measurement wavelength interval of 10 nm 4 No movement of test device or pigtails between measurements 5 The 0 010 ps tolerance is provided to allow for the effects of pigtails and packaging 11 2 Specifications and Characteristics Table 11 4 Shows the repeatability of 20 measurements of a pigtailed quartz PMD standard in which Pigtail positions are randomized before each measurement Table 11 4 Repeatability of JME PMD Measurement with Randomized Pigtail Positions Repeatability of JME PMD Measurement 2 3 4 Number of measurements 20 measurements Expected value of DGD 0 218 0 010 ps Mean 0 21821 ps Standard deviation 0 00246 ps Maximum minimum 0 00787 ps Maximum 0 2
134. appears in the top portion of the text box found under Display Tabular Data Print tabular data selection Graphs window Display menu Tabular Data Prints the selected portion of or entire text box Print graph annotation amp data Graphs window File menu Print gt Prints the currently selected graph and the annotation information and data lists which appear in the text box found under Display Tabular Data User Interface Reference 7 13 Table 7 5 PMD Jones Matrix Eigenanalysis continued Control or Data Path Description Print graph Graphs window File menu Print gt Prints the currently selected graph Return to graph Graphs window Closes the Tabular Data text box and returns the selection Display menu display to the graph Tabular Data Save JME to Graphs window Saves the current JME measurement data and database File menu selected setup parameters to the database Save JME as text Graphs window File menu Saves JME measurement data as an ASCII text file Single device Graphs window Measure menu Selects the single device PMD measurement default case See Cascaded device for the alternative Tabular data Graphs window Display menu Places a text box in the graph area listing measurement conditions and actual measurement results Notes may be added by the user Text can be selected and copied or printed Capacity of t
135. ar data 7 12 7 18 take sample 7 22 text file save 2 23 text files Jones matrix 4 13 polarization dependence 4 13 polarization mode dispersion 4 13 single sweep trace 4 13 three point reference 7 2 timed 7 22 timed measurement 7 2 timed measurements 2 68 amp lt title gt 10 23 TLS 10 25 Tunable Laser Source 10 25 turn laser off 7 7 two point reference 7 2 U underrange message 1 5 V ventilation requirements 9 3 voltage tuned 7 7 vtune 7 7 VTUNE 10 25 Ww warranty 111 wavelength of the source 1 12 wavelength display amp button 7 2 Wavelength Scanning 10 25 wavelength scanning PMD measurement 2 33 window 7 12 WS 10 25 Y Y scale changing graphs 2 17 y scale gt 7 12 Z zero 7 2 zero message 1 5 zoom 7 2 zoom factor 1 10 zoom functions 1 1 1 10 zoom factor 1 10 zoom in 1 10 zoom out 1 10 zoom in 1 10 zoom out 1 10 Index 5
136. arization The Delta Max Min mode produces the maximum and minimum insertion loss or gain as well as the delta value The Delta Max Min mode requires a calibration measurement of a thru fiber x ly control Main window Measurement menu PDL Jones Matrix Main window Measurement menu PDL Jones Matrix Selects the real plus imaginary format for the elements of the Jones matrix User Interface Reference 7 25 PDL Power Max Min The PDL POWER MAX MIN feature determines the PDL of a two port device from measurement of the optical power as the input polarization state to the device under test DUT is changed over all possible states The resulting value corresponds to the variation of optical insertion loss or gain for all possible states of polarization The method is most convenient when the DUT input polarization is changed by an automatic motorized controller but the method also improves the convenience of measurements employing manual polarization controllers Table 7 10 PDL Power Max Min Control Path Description or Data Angle between Main window Displays the relative angle between the Poincare Max and Min states Measurement menu sphere markers of maximum and minimum power display PDL Power This angle approaches 180 degrees for most test Max Min devices having large PDL The angle will deviate greatly from 180 degrees for low values of PDL It is provided
137. at are used to transfer data from one device to another Programming commands and data sent on these lines is typically encoded in the ASCII format although binary encoding is often used to speed up the transfer of large arrays Only ASCII format is available to the HP 8509 In addition every byte transferred over HP IB undergoes a handshake to ensure valid data Handshake Lines A three line handshake scheme coordinates the transfer of data between talkers and listeners This technique forces data transfers to occur at the speed of the slowest device and ensures data integrity in multiple listener transfers With most computing controllers and instruments the handshake is performed automatically which makes it transparent to the programmer Control Lines The data bus also has five control lines that the controller uses both to send bus commands and to address devices The HP 8509 makes explicit use of the EOI line through the HP IB END statement used to terminate all command transmissions A brief description of the five HP IB control lines is provided below Programming 10 3 IFC Interface Clear Only the system controller uses this line When this line is true low all devices addressed or not unaddress and go to an idle state ATN Attention The active controller uses this line to define whether the information on the data bus is a command or is data When this line is true low the bus is in the command mode and the data lin
138. ation and data lists which appear in the text box found under Display Tabular data Print graphs sl s2 s3 Graphs window File menu Print PMD gt Prints graphs of the three normalized Stokes parameters Return to graph selection Graphs window Display menu Tabular data Closes the Tabular Data text box and returns the display to the graph 7 20 User interface Reference Table 7 7 PMD Wavelength Scanning continued Control Path Description or Data Save WS to Graphs window Saves the current WS PMD measurement data and database File menu setup parameters to the database Save WS as text Graphs window File menu Saves WS PMD measurement data as an ASCII text file Tabular data Graphs window Display Places a text box in the graph area listing measurement conditions and actual measurement results Notes may be added by the user Text can be selected and copied or printed User Interface Reference 7 21 Timed Measurements The Timed Measurements feature captures measurement points in computer memory This allows saving to a file or as a database record and allows rotation of the Poincare sphere without erasure of the displayed data Data may be taken in a free running timed or single mode Table 7 8 Timed Measurements Control Path Description or Data Back step Main window In the single mode removes the previous sample selection Measu
139. atistics window Add from Text File F4 Selecting this menu item will cause a window titled Load Text File to open You can then impose a previously stored text file to import into the PMD Statistics window Load Statistics F5 Selecting this menu item clears the PMD Statistics displays and opens a window titled Load Text File You can then load previously stored PMD statistics data into the PMD Statistics window Save Statistics F6 Selecting this menu item opens a window titled Save Text File You can then save the current statistical data in a text file for future retrieval to the PMD Statistics window or analysis with a spreadsheet All measurement points are saved including points beyond the displayed wavelength range Print Bitmap Selecting this menu will give you three choices To print the DGD versus Wavelength graph the Histogram or the entire window Print Data Selecting this menu will print the data Printing uses the default printer selected in the windows control panel Exit Selecting this menu will quit the PMD Statistics window The Edit menu Selecting Edit from the main PMD Statistics window will drop down a menu structure The following is a brief description of the elements of that Edit menu Undo Last Add Alt Bksp Selecting this menu item removes the most recently added measurement from the statistics displays and from the statistical data set This allows you to examine the DGD versu
140. ault power level or set as desired If the screen on your computer looks similar to the previous illustration select Done Next set the HP8509B to use external polarizers In the main window select the System menu and Polarizers When the Polarizers controls appear select External with the mouse and select Done The next step is to adjust the source polarization so that approximately circularly polarized light is applied to the polarizers To do this we create a temporary polarization reference frame Set the external reference polarizer to a starting angle say 0 degrees and select marker A on the main window Set the polarizer approximately 60 degrees from the original position and select marker B Carefully remove the rotatable reference polarizer Making Measurements 2 61 Jones Matrix Measurement Select 2pt Ref and Apply 2pt with the mouse Adjust the source assembly polarization adjuster until the active point on the Poincare sphere approaches a pole and the absolute value of the s3 marker is greater than 0 90 The active point is easier to see by marking the current point select Display and then Mark Current Point Un apply the 2 pt reference before proceeding Replace the reference polarizer in the light beam FOR MORE INFORMATION More information on State of Polarization SOP and Degree of Polarization DOP may be found in the glossary Measurement Procedure At this point your measurement syste
141. ave configurations in files and recall them later CAUTION At start up the default configuration file hp8509 cfg is used to initialize the lightwave polarization analyzer Any changes to the default configuration file will change the default power on conditions of the analyzer The HP 8509A B recalls the configuration file HP8509 CFG at startup The polarization analyzer searches in the following sequence m First in the windows working directory m Second in the application s directory a Finally in the Windows system directory The polarization analyzer uses the first file it finds If it can not find a file the polarization analyzer uses the preset configuration The preset configuration is set in the factory and never changes To start the HP 8509A B with other than the default HP 8509 CFG configuration file add this command line parameter to the icon s properties CFG filename where filename is the name of the configuration file you want to use A command line parameter follows the name of the program in the Windows Program Manager properties Command Line entry This window is accessed by highlighting the HP 8509 icon and selecting File Properties in the Windows Program Manager or pressing ALT ENTER on the keyboard 4 14 Printing Saving and Recalling Measurement Results and Instrument Configurations To create a configuration file with factory defaults 1 From the lightwave analyzer Windows menu select File
142. avelength Scanning Methods Receiver Characteristics Source Characteristics Polarization Dependence Jones Matrix Method Polarization Dependence Power Max Min Method Fiber Size and Analog Output Range 12 Coordinate System and Generation of Right Hand Circularly Polarized Light Glossary Index Contents 12 10 62 10 62 10 62 10 62 10 62 10 63 10 63 10 63 10 64 11 1 11 1 11 1 11 2 11 2 11 3 11 4 11 5 11 6 11 7 11 7 11 7 Figures 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 2 19 2 20 2 21 2 22 2 23 2 24 2 25 2 26 2 27 2 28 2 29 2 30 2 31 2 32 The HP 8509 Basic Measurement Screen The Marker Window Setting a Marker Close Set Marker Window Turn Markers On Off Clear Markers Center Sphere on Marker Marker Zoom and Rotate Clear Trace and Hold A and Cal Example of data display for a PMD JME measurement Measurement Setup So a System Menu Optical Source Setup Polarizer Selection Polarizer Setup 3pt Reference Applied Circular Polarization JME Measurement Selection JME Source Setup Segment Selection Find Minimum of Points Optical Source Setup for PMD Jones Matrix Figenanalysis PMD JME Measurement Start Measurement Results The Measurement Summary The Measurement Annotation Area The Cursor
143. aximum displayed DGD value to accommodate the maximum DGD value of the measurement data The minimum displayed DGD value is always zero Fixed Scale allows the user to define the maximum displayed DGD value in the cumulative DGD histogram Last file added Numeric display Shows number of data points contained in the last file added to the histogram Load as Text File Loads a histogram saved as text Maximum display Displays the actual maximum value of DGD from JME measurement results shown in the graphical displays Maxwell alpha parameter display Shows the value of the alpha parameter the single parameter which specifies the shape of the Maxwell curve automatically fitted to the cumulative DGD histogram Mean display Displays the actual mean value of DGD from JME measurement results shown in the graphical displays Minimum display Displays the actual minimum value of DGD from JME measurement results shown in the graphical displays Number of bins Editable numeric Allows the user to specify the number of equal sized entry box display bins in the cumulative DGD histogram Print Bitmap gt File Prints a bitmap of the selected item Selections are DGD vs wavelength the DGD histogram and the entire PMD Statistics window Print Data File Prints a listing of the data which makes up the cumulative DGD histogram 7 16 User Interface Reference Table 7 6 PM
144. ay by selecting the double carrot located in the upper right corner of the HP 8509 measurement window Press Print Screen on the upper right side of the HP 8509 system computer key board Select Hold Use the mouse to minimize the HP 8509 measurement window by selecting the down carrot in the upper right corner of the HP 8509 measurement window This will cause the HP 8509 window to become a small icon at the bottom of the screen and reveal the Windows Program Manager Locate the Accessories icon and select it using the mouse When the Accessories icon opens select the Paintbrush icon When the Paintbrush program is running select the View menu at the top of the screen Select Zoom Out Highlight the Edit menu and select Paste and Paste again From the View menu select Zoom In and begin customizing graphics and text 10 When the desired Paintbrush display is achieved save it to a file name using the appropriate format The appropriate format depends on the word processor or graphics program that will be used AmiPro and Freelance for example can easily import or receive pasted graphics using a bit map BMP or PCX format Printing Saving and Recalling 4 5 Measurement Results and Instrument Configurations Measurement data is saved and recalled according to the formats and viewing options listed in Table 4 1 Table 4 1 Summary of HP 8509 Measurement Results Save Recall Features Wavelength S
145. by clicking the right mouse button on the Log On check box HP8509 lt Name of executable gt The Windows DDE system uses the name of the executable file to establish a DDE link to the HP8509 program Future versions of the HP8509 may use a different name to establish this link This command line parameter is useful only if your HP8509 software is updated to a version greater than version 2 0 If this parameter is not used the lt Name of executable gt used is HP8509_2 HP8509TimeOut lt Number of Minutes gt This parameter specifies the number of minutes the HP IB to DDE Gateway program should wait for data from the HP8509 when the HP IB controller requests data sends a query If this parameter is not specified the default value used is 1 minute If the HP8509 takes longer than the specified time to return data to the HP IB controller the HP IB to DDE Gateway will reset the DDE channel in an attempt to clear the problem and record the attempt in the log file if open as a DDE timeout error The HP IB to DDE Gateway will reset itself in this manner ten times After ten attempts the HP IB to DDE Gateway program will issue a critical error and HP IB operation will stop until the user acknowledges the critical error issued by the HP IB to DDE Gateway Note This timeout occurs only when the HP IB controller requests data The HP IB to DDE Gateway queues all commands from the HP IB bus a synchrono
146. c gt The settling time to wait either initially Start or per point Point after setting a tunable laser source to the desired wavelength in the sweep range during a PMD WS measurement The query returns the current value See also Disper Settle Point Start lt Millisec s gt WaveScan Units ps ps L ps sqrtL The units to use in PMD WS measurements The query returns the selected units WaveScan VTune Sets the Optical Source Setup source selection to VTune in order to control a VTUNE tunable laser source The query returns an ASCII 1 if the PMD WS next measurement process will be in VTUNE mode and a 0 if it will not be in this mode Also returns the name of the current laser source WaveScan VTune Start Stop lt Voltage gt The VTUNE start or stop voltage The query returns the voltage value the parameter lt Voltage gt sets the value WaveScan WLen Returns the next wavelength in nm at which the PMD WS measurement will be conducted This command is typically used only when the tunable laser source is Manually Tuned 10 62 Programming WaveScan WLen Start Stop Delta lt Wavelength nm gt Specifies the Start Stop or Delta wavelengths for the PMD WS measurement Changing any of these values causes the number of points to change according to WLenPoints WLenStop WLenStart WLenDelta 1 The query returns
147. calibrations refer to The System Menu chapter of this manual 4 2 Printing Saving and Recalling Measurement Results and Instrument Configurations Printing Measurement Results The lightwave polarization analyzer print function uses the Microsoft Windows print drivers It is necessary that you use the proper Microsoft Windows print drivers to print your documents The printer used is the default printer in the Windows control panel Detailed instructions for installing serial RS 232 and parallel interfaced printers are provided in the Microsoft Windows User s Guide Standard Printing HP8508B Lightwave Polarization Analyzer MES Edit Measurement Display System Help Sphere Display Database Analyzer Window Exit oo e biati tA PDL Power Max Min Window Jones Matrix Window Calibration Window pq7134_c Figure 4 2 The Print Menu Procedure Once you make a measurement you can print the results 1 Select File Print 2 Select one of the following items a Sphere Display prints only the Poincare Sphere b Analyzer Window prints the entire main measurement window display C PDL Jones Matrix Window prints the Jones matrix PDL measurement window d PDL Power Max Min Window prints the power max min PDL measurement window Jones Matrix Window prints the entire Jones matrix measurement window Calibration Window prints the entire wavelenth calibration measurem
148. canning PMD WS to Text Database Format Comma Delimited ASCII Database Word Processor Spreadsheet MEASUREMENT SAVE FORMAT RECALL LOAD VIEWING DATA OPTIONS OPTIONS OPTIONS PMD Jones Matrix PMD JME to Database Microsoft Access PMD JME from Graph Eigenanalysis Database Format Database Tabular Data PMD JME to Text Comma Delimited Word Processor File Contents ASCII Spreadsheet PMD Statistics program DGD vs Wavelength and DGD Histogram PMD PMD WS to Database Microsoft Access Microsoft Access Graph Poincare Sphere Tabular Data File Contents PDL Jones Matrix Jones Matrix amp PDL Jones Matrix Comma Delimited ASCII 1 Word Processor Spreadsheet File Contents Jones Matrix Jones Matrix amp PDL Jones Matrix Comma Delimited ASCII 1 Word Processor Spreadsheet File Contents State of Polarization using timed measurement only Timed Measurement to Database Timed Measurement to Text Microsoft Access Database Format Comma Delimited ASCII Timed Measurement from Database Timed Measurement from Text Word Processor Spreadsheet Poincare Sphere Poincare Sphere File Contents via other software applications Degree of Polarization using timed measurement only Timed Measurement to Database Timed Measurement to Text Microsoft Access Database Format Comma Delimited ASCII Microsoft Access only
149. ce Graphs window Measure menu Selects the cascade method in which the PMD of an element in the measurement path can be removed prior to measuring the actual device under test Copy window Graphs window Edit menu Places bitmap of the graphs window on the clipboard Copy to clipboard selection Graphs window Display menu Tabular data Copies the selected text to the clipboard If no text is selected the entire text box is copied Capacity of the text box is 60 000 characters Display menu Copy graph Graphs window Places bitmap of the selected graph on the clipboard Edit menu Cursor Graphs window Places cursor controls and display directly below the graph area allowing detailed examination of the measurement graph Data symbols Graphs window Display menu Places measurement point markers on the graph Database Graphs window File menu Opens the database interface dialog box allowing user to view database items and load saved measurement results and setup conditions into the graphs window 7 12 User Interface Reference Table 7 5 PMD Jones Matrix Eigenanalysis continued Control or Data Path Description Delay Delay L Delay sqrt L Graphs window Format menu Formats the differential group delay measurement results as simple delay in units of time for fiber or component measurements as ratio to fiber length or as ratio to square root
150. ce and set the wavelength to the desired value Use the default power level or set as desired If the screen on your computer looks similar to the previous illustration select Done Choosing the Polarizers To set a reference frame in an open beam environment you must select the external polarizers option on the analyzer You may choose the external polarizers by first selecting System with your mouse pointer from the main window menu and then Polarizers When the Polarizers window appears select External with the mouse pointer then select Done Setting the Reference Frame The next step in this procedure is to establish a reference for the analyzer to use in computing the reference frame To do this you will rotate the reference polarizer and then set a marker using the Markers on the Main measurement window Polarizer angles must be set precisely to the angles listed in the Polarizer section of the System menu m Set the external polarizer to horizontal linear polarization and select the A Marker m Rotate the external polarizer 60 degrees from original position and select the B Marker m Rotate the external polarizer an additional 60 degrees to a position 120 from the original Select the C Marker m Select pt Ref with your mouse pointer ADDITIONAL INFORMATION The pt Ref Polarization Reference Frame PRF minimizes the uncertainty effects of the birefringence and PDL of the test system A 2pt Ref minimiz
151. ces must be turned on and off manually CAUTION External sources connected to the External Source Input of the HP8509B must be turned off when internal sources are turned on to prevent both source signals from coming out of the Optical Output of the HP8509B Selecting an Optical Source HP 8509A Only Optical Source Setup rOpticalSourceSelection Powe HP8168A HP IB y HP8167A HP IB m Manually tuned H Voltage tuned Wavelength cw 1551 0 Cancel pq7133_c Figure 6 1 The HP 8509A Optical Source Window The HP 8509A has no internal sources Opening the Optical Source window allows you to select the source you want to use with your HP 8509A and set the wavelength The default wavelength is 1550 nm To enter a different wavelength use the mouse to select the existing numbers in the wavelength box and then input the correct wavelength for your measurement 6 2 The System Menu Selecting an Optical Source HP 8509B Only Optical Source Setup OpticalSourceSelection InternalLaserSelection El Internal y O 1324nm HP8167A HP IB 7 HP8168A HP IB 1555nm Turn Laser Off Manually tuned 7 Voltage tuned Cancel pa7i25_c Figure 6 2 The HP 8509B Optical Source Window If your HP 8509B is standar
152. d it is equipped with two internal sources If you have one or both of the delete source options you will have either one internal source or no internal sources In any case when you open the Optical Source window the choices available to you will appear Use the mouse to select the desired source The source can be turned off by selecting Turn Laser Off NOTE The actual wavelength of your internal source is probably different from the nominal values of 1310 nm and 1550 nm used in this procedure The optical source setup window and the wavelength display in the basic measurement screen will reflect the factory measured value of your internal source to the nearest nm The System Menu 6 3 Zero The zeroing routine is performed automatically at instrument startup However it should be performed again after the instrument has warmed up for approximately one hour or after large ambient temperature changes Initiating the Receiver Zeroing Routine The zeroing routine can be initiated in one of two ways m Select System Zero m Press F9 on your keyboard Making Accurate Measurements For accurate measurements it is important that the receiver is not detecting any power while the zeroing routine is being performed 1 If you have an HP 8509A you will be prompted to Block the external laser To do this cover the OPTICAL INPUT connector with a connector cap or a piece of dark paper 2 If you have an HP 8509B y
153. d automatically When optional selections A B or C are used then external polarizers are assumed to be used The user must insert the appropriate polarizer and send a command for each polarizer The polarizer angles pertaining to each of the three markers A B and C must be specified using the polarizer command See Polarizer Angletf A B C lt Degree value gt PolDep Measure is HP 8509B only PolDep NewThruCal Clears any current thrupath calibration and begins a new calibration sequence A calibration must first be done using PolDep Calibrate A B C The PolDep NewThruCal and the PolDep Calibrate A B C commands are valid only for absolute measurements that is when the transmission measurement is either Delta Max or Min HP 8509B only PolDep ReStart Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Clear PolMarker A B C Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolMarker A B cCH 10 48 Programming PolMarker A B Cc When using the internal polarizers the parameters for this command are such that A refers jointly to polarizer A and marker A similarly for parameters B and C When the internal polarizers are used this command inserts the specified polarizer A for 0 B for 60 and C for 120 at the source output T
154. ddress 724 Level _ 100 0 Watt Wavelength cw 1551 0 Cancel pq71b_c Figure 2 51 Optical Source Setup Select the external laser source and set the CW wavelength for your measurement Use the default power level or set as desired If the screen on your computer looks similar to the previous illustration select Done HP8509B Lightwave Polarization Analyzer File Edit Measurement Display GGS Help Optical Source F8 Zero F9 Calibrations F11 Shutter Averaging Range Analog Outputs Reference Frame Info Operation Verification pq783b_c Figure 2 52 Polarizer Selection Making Measurements 2 47 PDL Measurement Jones Matrix Method Select System from the main menu and then select Polarizers Polarizers Internal External o gt 0 No o Polarizer pq79b_c Figure 2 53 Polarizer Setup Set the polarizers to and select No Polarizer If the screen on your computer looks like the previous illustration select Done Markers On Clear Markers SO st 2 s3 lt S 9 090 0 02 0 08 0 98 S A A B C 2pt Ref 3pt Ref Apply 3pt Select Select
155. de coupling PMD units Fiber PMD statistics Fitting the Maxwell curve to the distribution Enlarging the sample size Source spectral characteristics Should I use the reference frame Cascade measurements Contents 2 2 1 2 2 2 3 2 3 2 4 2 8 2 14 2 14 2 15 2 16 2 16 2 17 2 17 2 18 2 20 2 20 2 21 2 21 2 21 2 21 2 21 2 21 2 21 2 21 2 21 2 22 2 22 2 23 2 23 2 24 2 25 2 25 2 25 2 26 2 29 2 29 2 30 2 30 2 30 2 30 2 30 2 30 2 31 2 31 2 31 2 31 2 32 2 32 What is a cascade measurement Typical applications PMD Measurement Wavelength Scanning Method Basic Measurement eo eee o Setting up the System Making the Measurement Manipulating the Measurement Results The Measurement Summary Bar The Measurement Annotation Area Using The Cursor Changing The Measurement Format Displaying and Printing Data in Tabular Format Printing your Graph o Saving your Measurement as Text Saving in Database Format PMD WS Concepts Polarization Mode Dispersion Polarization modes General effects Mode coupling PMD units Optimizing the setup for fiber or component test Wavelength tuning range Analysis mode Minimum feature size Statistical characterization of fiber PMD PDL Measurement Jones Matrix Method Basic Measurement Setting up the System External Source Preparation Making the Measurement Saving the Measurement Results 0 PDL Measurement Power Max Min Method Basic M
156. deal differently with these two kinds of HP IB commands For example for most HP instrumentation HP BASIC can use a unique keyword to send each bus management command but always uses the keyword OUTPUT to send device commands It must be noted however that for the HP 8509 all commands must be sent using the OUTPUT statement The following example shows how to send a typical device command in IBASIC OUTPUT 729 POINCARE CLEAR END This sends the command within the quotes POINCARE CLEAR to the HP IB device at address 729 If the device is an HP 8509 the command instructs the analyzer to clear all measured traces from the Poincare sphere ADDITIONAL INFORMATION The HP IB card select code is 7 and the HP IB address is 29 The select code is set by adjusting switches on the HP IB card inside the computer 10 4 Programming HP IB For the HP 8509 The HP 8509 system can be described as a Windows application running on a Vectra PC which controls an external instrument containing the system hardware The system hardware consists of all devices required by the HP 8509 software to conduct polarization measurements Remote control of the HP 8509 system is achieved through direct communication with the system s Windows application software Use an external controller for remote control of the HP 8509 Given that the HP 8509 software is a Windows application Dynamic Data Exchange DDE can be used to communicate with and control
157. dit Measure Format MEJENA Window v Annotation F9 Y Cursor Data Symbols v Grid Y Scale Tabular Data PMD Statistics pq7145_c Figure 2 22 Displaying Data in a Statistical Format After making your PMD JME measurement and while still in the PMD J ME measurement window you may display the results in a statistical format by first selecting Display and then PMD Statistics A PMD Statistics window will open 2 18 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method PMD Statistics Edit Format Help Differential Group Delay versus Wavelength 0 13 O ps 1460 2 nm Cumulative Differential Group Delay Histogram O ps Mean 0 0899ps Last file added 11 Minimum 0 0679ps Total size 11 Maximum 0 1322ps Number of bins Chi square 816 Maxwell a param 0 0582ps pq7148 c Figure 2 23 Displaying Data in a Statistical Format The previous illustration is an example of the PMD statistics window A Maxwell curve is automatically fitted to the histogram Single or multiple PMD JME measurements can be displayed in the PMD Statistics window Use any combination of Add from Selected JME Window F2 Add from Database F3 and Add from Text File F4 to import data ADDITIONAL INFORMATION The PMD Statistics function can be selected in two ways from the PMD JME measure
158. dress 29 the HP 8509 POINCARE CLEAR END The HP 8509 mnemonic for clearing the Poincare sphere The mnemonic less the quotation marks is sent literally by the OUTPUT statement followed by the terminating END statement The POINCARE CLEAR command performs the same function as selecting the DISPLAY menu and within that menu selecting the CLEAR SPHERE option As can be noted the command mnemonic CLEAR is derived from the menu option for equivalent manual control Most of the HP 8509 HP IB commands where possible are derived from the equivalent menu option label Otherwise they are derived from the common name for the function As can be noted from the example above the HP 8509 command syntax is in the form of COMMAND P1 P2 P3 where P1 P2 P3 are the parameters pertaining to the command and the number of parameters depends on the function performed by the command If for example the function of the command is to perform a type of measurement the number of required parameters will vary with measurement process complexity Please refer to the HP 8509 Command Reference section of this document or to the Remote Access files in the HP 8509 instrument window for specific command information The END following the CLEAR terminates the command inside the HP 8509 EOI set true and prepares the HP 8509 for the next command If there is a syntax error in the command the HP 8509 will ignore the command and look for the next terminator
159. dure ooa a a a 4 5 Contents 4 Saving and Recalling Measurements Saving Measurements Procedure Recalling Measurements HP 8509 File Recall Procedure HP 8509 File Recall Results Word Processor Spreadsheet and Database Numeric File Format PMD Jones Matrix Figenanalysis Save Format PMD Wavelength Scanning Save Format PDL Jones Matrix and Jones Matrix Save Format Timed Measurement As Text Save Format Saving and Recalling Instrument Configurations Recalling the Preset Configuration Procedure Saving a User Configuration Procedure Recalling a User Configuration Procedure re The Display Menu For Additional Information The PRESET Configuration Displaying the Marker Table Displaying the Poincare Sphere Displaying the Polarization Ellipse Exchanging the Poincare Sphere and the Polarization Ellipse Changing the Power Display Units a Marking the Current Point Changing the Display Update Frequency Holding the Data Display Loe Clearing the Trace From the Sphere Setting the Display to Refresh Automatically The System Menu Conventions Optical Source Opening the Optical Source Setup Window Selecting an Optical Source HP 8509A Only Selecting an Optical Source HP 8509B Only Zero o Initiating the Receiver Zeroing Routine Making Accurate Measurements Calibration Calibrating For Use With a Fixed Wavelength Source Select the Source to be Calibrated o Calibrate at the Selected Wavelength Save and
160. e 1 1 The HP 8509 Basic Measurement Screen The main menu selections are File Most of the menu items under this selection are explained in the Printing Saving and Recalling Measurement Results and Instrument Configurations chapter of this manual Edit This selection allows you to copy the display or a measurement window to the Clipboard Measurement The measurement selections are discussed in the Measurement Applications chapter of this manual Display The items in the Display menu are discussed in The Display Menu chapter of this manual System The system functions are described in the The System Menu chapter of this manual Help The online help function is not available at this time 1 4 Getting Started The Data Displays Power DOP Ellipse and Poincare Sphere Refer to Figure 1 1 for the location of the displays on the basic measurement screen Power Display The power of the optical signal under test is displayed as both a horizontal bar and a digital readout When the receiver zeroing routine is being performed a green zero message appears in the power display Red Overrange and Underrange messages appear here also DOP Display The Degree of Polarization DOP is displayed as both a horizontal bar and a digital readout For the most reliable and accurate measurements use polarized light that approaches 100 DOP Poincare Sphere The HP 8509 Poincare sphere is a
161. e Jones matrix measurement 7 24 User Interface Reference Table 7 9 PDL Jones Matrix amp Jones Matrix continued Control Path Description or Data Polarization Main window Provides display of measurement result which may Dependence Measurement menu be Delta or Delta Max Min values of the displays PDL Jones Matrix polarization dependence Polarizer Controls Internal or External Main window Measurement menu PDL Jones Matrix Specifies whether internal or external polarizers will be used for the Jones matrix measurement Internal polarizers are automatically inserted as part of the measurement algorithm External polarizers must be inserted by the user External polarizers are typically used when it is necessary to measure only the PDL of a bulk optic assembly without the residual PDL of pigtails and connectors Radians control Main window Measurement menu PDL Jones Matrix Selects the polar format for the elements of the Jones matrix with angles given in radians Reference frame applied message Main window Measurement menu PDL Jones Matrix This message indicates that a polarization reference frame has been applied Transmission measurement Delta or Delta Max Min controls Main window Measurement menu PDL Jones Matrix Specifies the type of measurement Delta mode produces the variation in insertion loss or gain corresponding to all possible states of pol
162. e PMF cable launch extinction ratio by using a circle that you fit into an arc The location of the arc and circle on the Poincare sphere are not important since only the length of the radius of the circle is used to calculate the extinction ratio of the launch As the alignment is adjusted the axis of the PMF cable will approach the linearly polarized input signal Most of the optical power will be launched into one axis of the fiber and the arc on the Poincare sphere will approach a center point The ideal alignment is at the center point of the arc CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual HP8509B Lightwave Polarization Analyzer File Edit ALECEMICUEOA Display System Help PMD Jones Matrix Eigenanalysis F2 PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 Jones Matrix F4 Marker Angles Timed Measurement pq797b_c Figure 2 79 PM Fiber Launch Measurement Selection Select Measurement from the main menu and then select PM Fiber Launch F3 Making Measurements 2 71 Polarization Maintaining Fiber Launch HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 48 dBm Clear Trace ja Cal 2 1303 nm PM Fiber Launch Greate arc on sphere 2 Select 3 points to defi
163. e a variety of sizes core cladding combinations jackets and indexes of refraction In general different types of cables do not work well together cables must match each other and the system However regardless of the cable type the connectors have only one function to provide a direct and low loss optical signal transition from one fiber end to another When these connectors are used in a measurement system repeatability becomes an important factor Lightwave connectors differ from electrical or microwave system connectors In a fiber optic system light is transmitted through an extremely small fiber core Because fiber cores are often 9 microns 0 009 mm or less in diameter and dust particles range from tenths of a micron to several microns in diameter dust and very minute contamination on the end of the fiber core can degrade the performance of the connector interface where the two cores meet Therefore the connector must be precisely aligned and the connector interface free of trapped foreign material Connector or insertion loss is one important performance characteristic of a lightwave connector Typical values are less than 1 dB of loss and sometimes as little as 0 1 dB of loss with high performance connectors Return loss is another important factor It is a measure of reflection the less reflection the better the larger the return loss the smaller the reflection The best physically contacting connectors have return losse
164. e enabled or disabled using the Polarizer controls accessed under the System menu of the main software window Various measurement applications use different cases you must select the appropriate condition Signal level can drop if the polarization of the input signal to a polarizer is crossed with or blocked by the polarizer This can be an issue in any of the HP 8509A B applications in which the Jones matrix is measured with internal or external reference polarizers and in measurements of PMD and PDL by the Jones matrix method It can also affect power level in the wavelength scanning PMD measurement if the source light is passed through an internal or external polarizer prior to the DUT Adjust the source polarization for a circular state at the reference polarizer The process for doing this is discussed under the measurement types in the Making Measurements chapter Setting the input polarization relative to the test device can affect wavelength scanning PMD measurements by changing the relative illumination of the polarization modes of the device This can introduce measurement variability versus the position of the polarizer or the position of the input fiber to the DUT If variability is severe average the results of several measurements with the input fiber in different positions Optical source wavelength and output power level should be stable and within the operating range of each element of the test system For all measurements
165. easurement Setting up the System External Source Preparation Making the Measurement Saving the Measurement Results Jones Matrix Measurement Basic Measurement Setting up the System External Source Preparation Measurement Procedure Establish the Polarization Reference Frame Making the Measurement Concepts The Relative Jones Matrix The sign of s3 Description of the Jones Matrix Measurement Algorithm Application of the Jones Matrix Timed Measurements 2 32 2 32 2 33 2 34 2 34 2 34 2 37 2 37 2 38 2 38 2 39 2 40 2 41 2 41 2 42 2 42 2 42 2 42 2 42 2 43 2 43 2 43 2 43 2 43 2 44 2 44 2 45 2 46 2 46 2 47 2 49 2 51 2 52 2 53 2 53 2 54 2 54 2 58 2 59 2 59 2 60 2 61 2 62 2 62 2 63 2 66 2 66 2 66 2 66 2 67 2 68 Contents 3 Polarization Maintaining Fiber Launch 2 7 ee 2 68 Basic Measurement 2 a a 2 69 Setting up the System 2 69 External Source Preparation 2 we ee a 2 70 Making the Measurement 2 71 Concepts e 2 73 Explanation of Polarization Maintaining Fiber Launch Lo ee 2 73 Polarization Reference Frame 2 1 ee 2 74 Basic Measurement 2 2 a 2 74 Setting up the System 2 1 a 2 75 External Source Preparation 2 a a a ee 2 75 Choosing the Polarizers 2 o 2 76 Setting the Reference Frame a ee 2 76 Checking Reference Frame Quality 2 2 2 0 2 77 Setting a Circular State o
166. ecified title HP 8509B only 10 32 Programming Disper DBase Save lt title gt lt date code gt lt serial number gt Saves a measurement to the current database using the specified title HP 8509B only Disper Done Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Close Disper FiberLen lt km gt The length of optical fiber used to normalize PMD JME measurements The query returns the length of the fiber Using the parameter lt km gt sets the length of optical fiber HP 8509B only Disper FindMinPoints lt Num Samples gt Activates the PMD JME feature that automatically determines the minimum number of points required to prevent aliasing in the specified wavelength range PMD JME measurements are activated with this feature The only tunable laser sources supported with this feature are HP IB HP 8167 8 and VTune tunable laser sources HP 8509B control of the HP IB bus is available only using DDE Therefore this feature will not work for the HP 8167 8 tunable laser sources when using the HP IB bus for remote operation of the HP 8509B Only the VTune tunable laser source can be used with HP IB The lt Num Samples gt value specifies the number of sections of the Poincare sphere the test for aliasing The default value for lt Num Samples gt is 4 if no value is specified HP 8509B only Programming 10 3
167. ected on the computer screen Making Measurements 2 1 PMD Measurement Jones Matrix Eigenanalysis Method PMD Measurement Jones Matrix Eigenanalysis Method Polarization mode dispersion PMD is a fundamental physical property of optical fiber and components in which a lightwave is split into two waves of slightly different speed on the basis of polarization state At a given wavelength these two polarization modes experience a difference in propagation time known as differential group delay DGD The DGD of long optical fibers varies with wavelength The PMD of a test device also refers to the average value of the differential group delay PMD is fundamentally expressed in units of time typically picoseconds 1 ps 107 s In the case of long fibers it may be normalized to the square root of fiber length with the units of picoseconds per root kilometer This section explains how to measure the PMD of a test device using the Jones matrix eigenanalysis JME method available in the HP 8509B A typical measurement result showing the differential group delay as a function of wavelength is shown in the following figure HP8509 Graphs lt 1 gt PMD JME 1460 0 1560 0 5 0 File Edit Measure Format Display Window 0 14 0 01 e 1460 Wavelength nm 1560 aci 0 08415 FEO 0 10086 MES 0 11546 VIT 0 06091 fem 0 01823 Start 1460 0 Fiber Length 0 km Stop
168. ed two or three reference polarization states are provided from a polarization maintaining fiber in which all of the light is confined to a single mode high extinction ratio For accurate results some fixturing is required One of the connectors must be keyless to allow the pair to rotate relative to one another A graduated dial is required to measure rotational angle The scale may be indexed to the excited axis of the PMF See the Polarization Maintaining Fiber Launch section for details on launching light into a single polarization mode of PMF Making Measurements 2 79 Polarization Reference Frame Concepts Explanation of Polarization Reference Frame Mathematics The HP 8509A B produces a polarization reference frame using Jones Matrix calculus The HP 8509A B measures the Jones Matrix of the test system Figure 2 83 The inverse of this Jones Matrix is applied to any incoming SOP data in an attempt to remove the birefringence and PDL effects of the test system Refer to the Jones matrix concept section of this manual for further information about the Jones Matrix Transmission Ratio 3pt Reference Frame The quality of a 2pt or 3pt reference frame is checked by selecting Reference Frame Info from the System menu of the main screen For the 3pt reference frame the resulting dialog box provides both a qualitative description good very poor and a parameter called the transmission ratio Transmission ratio is a measure of
169. ed briefly at the end of this section HP 8509 File Recall Procedure The following procedure describes how to use the analyzer s FILE LOAD menus to recall measurement results The measurement FILE LOAD menus for the PMD measurements are explained within the PMD JME and PMD Wavelength Scanning measurement sections of this manual HP8509B Lightwave Polarization Analyzer MIES Edit Measurement Display System Help User Configuration Save PRESET Configuration Print Database Exit Timed Measurement from Database Timed Measurement as Text pq737b_c Figure 4 6 The Load Menu 1 Select FILE LOAD and then one of the Load sub menu selections shown in the figure above 2 For text files select the drive directory and file where the desired trace is stored and then select OK Measurement results will be recalled and displayed as summarized in Table 4 1 3 For database files select the desired measurement from the drop down list then select LOAD ADDITIONAL INFORMATION While a recalled trace is being viewed on the Poincare sphere the lightwave polarization analyzer data displays become inactive See the following figure Also note that the wavelength readout in the upper right corner is gray inactive This is to remind the user that the displayed wavelength is the wavelength with which the Single Sweep was taken but not necessarily the current wavelength
170. ed by passing horizontal linearly polarized light through a quarter wave plate whose fast axis is oriented at 45 degrees in the coordinate system described below Coordinate System Generation of Right hand Orientation Circularly Polarized Light Optical Source Tv Linear a Polarizer BC y ES Quarter pave Plate e R circ_c Coordinate System and Generation of 12 1 Right Hand Circularly Polarized Light Glossary address An identification as represented by a name label or number for a register location in storage or any other data source or destination such as the location of a station in a communications network or a device on the Hewlett Packard Interface Bus antireflection coating A thin dielectric or metallic film or several such films applied to an optical surface to reduce the reflectance and to increase the transmittance attenuation The diminution of signal amplitude or power In optical waveguides attenuation results from several mechanisms that may operate simultaneously absorption scattering and losses into radiation modes Attenuation is generally expressed in dB km for cables assuming approximate uniformity with length attosecond 10713 seconds calibration The process by which measurement accuracy is improved by removing systematic and repeatable errors Wavelength calibration optimizes accuracy at a chosen wavelength See wavelength calibration cladding The layer of glass surr
171. ed parameters are provided below polarization angle 90 pi Acos angle between 2pts In the above equation angle between 2pts refers to the angular separation as observed in the Poincare sphere between the two state of polarization points used to establish the two point reference frame transmission ratio The ratio of the highest polarization dependent loss to the lowest polarization dependent loss of the thrupath used to establish the three point reference frame A small transmission ratio is a desirable result The grading system for the applied reference frame is invalid 0 very poor 1 poor 2 fair 3 good 4 RefFrame Off On Applies or un applies a two or three point reference frame See RefFrame 2pt 3pt 7 If using internal polarizers the reference frame is set up and applied or not applied automatically With external polarizers the appropriate markers must first be placed and read using the PolMarker A B C command The query returns an ASCII 1 if the specified function Off On is active and a O is returned if it is not active 10 50 Programming RefFrame 2pt 3pt Specifies the type of reference frame to be applied The query returns an ASCII 1 if the specified function 2pt 3pt is active and a O if it is not active See RefFrame Off On 7 Save Config lt filename gt Saves the current instrument configuration i
172. ed the next time the HPIB2DDE application is started Programming 10 9 Controller Some applications may require that the HP IB card in the HP 8509 is set to Controller when the HP 8509 itself is not being controlled by the HP IB bus Other systems may require that the HP IB card never becomes a controller while on the HP IB bus Non Controller The HP IB card is Non Controller while the HPIB to DDE gateway application is running Dynamic Data Exchange DDE Frame This frame is used to display data that is being transmitted via DDE to the HPIB to DDE Gateway application The elements of this frame are described below Param x from HP 8509 Used to establish a DDE link for data from the HP 8509 and the HPIB2DDE EXE application Terminate DDE Link Initiate DDE Link Used to connect or disconnect the HP IB bus to the DDE When the DDE link is established selection shows Terminate DDE Link the HP IB card is opened and DDE transactions can take place When there is no DDE link selection shows Initiate DDE Link the HP 8509 Status selection show NO DDE LINK in yellow and the HP IB card is closed and the device address may be changed Clicking the right mouse button on this command button while in Terminate Link mode will cause only the HP IB bus to close and allow the HP IB gateway to be used for a DDE client without interference from the HP IB bus 10 10 Programming HP a509 HP 8509 SYSTEM SYSTE
173. ed within the averaging time is statistically large the average measured DOP for this signal will be nominally zero percent In another example the state of polarization may be modulated to follow a great circle on the Poincare sphere If the polarization states on this circle are occupied with equal frequency and a statistically large number of states is created during the averaging interval the average measured DOP will again be nominally zero percent When measuring the effective DOP of polarization modulated light the modulation rate should be kept below 1 MHz to avoid spurious coupling and rectification of the demodulated electrical signal within the analog circuitry of the polarization receiver The number of display averages should be large enough to provide a statistically significant average For best accuracy the instrument should be fully warmed up and zeroed following warmup Performing a wavelength calibration may improve accuracy Making Measurements 2 85 State of Polarization Measurements Concepts Degree of Polarization The DOP of the lightwave signal used in measuring your fiber optic cable is displayed as a percentage in the upper left hand corner of the main window display As a review the DOP is a measure of what percentage of the total average lightwave signal power is polarized Degree of polarization of lightwave signal is related to that signals Stokes parameters as shown below DOP 8S1 S2 37 S
174. elay values may be compared to a best fit Maxwell probability distribution function The Maxwell curve represents the expected shape for long fibers If the data closely resembles the Maxwell curve the average differential group delay taken from the measurement can be considered statistically accurate The HP 8509B software provides a statistical display of Jones matrix eigenanalysis measurement results for this purpose It uses the chi squared method to generate the best fit Maxwell curve Once the Maxwell curve fit has been performed the quality of the fit to the data must be determined This may be done qualitatively by visually assessing the fit or by use of the quality of fit parameter displayed in the statistics window Enlarging the sample size If the quality of fit is poor more data is required to fully represent the fiber This is most easily accomplished by expanding the wavelength range of the measurement Generally long fiber PMD measurements should be taken over as wide a wavelength range as possible with wavelength interval small enough to capture the features of the curve of differential group delay versus wavelength However for some fibers even the full wavelength range may not be sufficient to produce a distribution of Maxwellian shape In such cases the sample size can be increased by repeating the measurement at different temperatures based on the fact that the mode coupling characteristics of the fiber are strong funct
175. elected Ea Select this box if every HP IB bus action is to end with a line feed This setting is saved in the file C WINDOWS WIN INI under the heading HPIB2DDE and is restored to this setting the next time the HPIB2DDE application is started Address Put the address of the HP 8509 here To change the address select Terminate DDE Link to enable Address Change the HP 8509 device address then select Initiate DDE Link to re enable the HP IB bus and the DDE link This setting is saved in the file C WINDOWS WIN INI under the heading HPIB2DDE and is restored to this setting the next time the HPIB2DDE application is started ADDITIONAL INFORMATION Terminate DDE Link and Initiate DDE Link are toggle selections Allows you to set the HP IB timeout This setting is saved in the file C WINDOWS WIN INI under the heading HPIB2DDE and is restored to this setting the next time the HPIB2DDE application is started Data Separator This setting is saved in the file C WINDOWS WIN INI under the heading HPIB2DDE and is restored to this setting the next time the HPIB2DDE application is started Cr Lf Sets the data separator to carriage return line feed delimited Comma Sets the data separator to comma delimited HP IB Exit State Allows you to set the HP IB card to Controller or Non Controller when the program exits This setting is saved in the file C WINDOWS WIN INI under the heading HPIB2DDE and is restor
176. ence Frame Information Window 6 26 The System Menu Operation Verification The operation verification procedure is a fully automatic pass fail indicator of your system s performance Perform this procedure after you install your system to verify that your system is working properly 1 Allow the instrument to warm up for at least 1 hour and then zero the instrument 2 Make sure the optical cable connecting the polarizer to the lightwave polarization analyzer s OPTICAL INPUT is stable This can be accomplished by taping the cable to the work surface 3 Select System Operation Verification from the main window display Operation Verification 1 Connect Optical Output to Optical Input 2 Select Start Start pq7144_c Figure 6 21 The Operation Verification Window for the HP 8509A 4 Select Start When the verification procedure is finished the message Operation Verification passed is displayed in the message window and the Max Min and Mean DOP values are displayed For the HP 8509B the relative angles between internal polarizers is also displayed If the verification fails see the Degree of Polarization topic in Chapter 3 Accuracy Enhancement and Troubleshooting 5 The operation verification is complete Select Done to clear the window and begin your measurement The System Menu 6 27 User Interface Reference Th
177. ength scanning ps o 1 2 3 4 5 6 7 DGD from Jones matrix eigenanalysis ps pq7146_c Figure 11 1 Comparison of JME and WS Measurement Methods for Long Optical Fiber Test Comparison of JME and WS Measurement Methods for Long Optical Fiber Test 3 1 The test device was 14 km of loosely spooled dispersion shifted fiber Eleven measurements of each type were taken with random arrangements of the loose turns of the fiber 2 Wavelength scanning responses typically exhibited 16 extrema of extrema of peaks of valleys 3 Wavelength scanning measurements use mode coupling factor of 0 82 11 4 Specifications and Characteristics Receiver Characteristics Table 11 6 Receiver Characteristics Receiver Characteristics Wavelength operating range 1200 to 1600 nm Input power operating range 10 to 55 dBm Input average power damage level 16 dBm Average power measurement uncertainty 15 Degree of polarization measurement uncertainty gt 1200 to 1280 nm 5 0 1280 to 1340 nm 2 0 1470 to 1580 nm 2 0 1580 to 1600 nm 3 0 Poincare representation uncertainty 27 8 1200 to 1340 nm 1 5 1470 to 1600 nm 1 5 Measurement rate gt 2000 per second Display update rate gt 2000 per second 1 The HP 8509 performs polarization measurements over this range See individual measurement specifications or characteristics for det
178. ent Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq719b_c Figure 5 4 The Show Sphere Menu The Poincare sphere is displayed in the PRESET configuration but it may be turned off or hidden by selecting Display Show Sphere This menu selection toggles the Poincare sphere on and off When the sphere is displayed a check mark appears next to the menu selection The following figure shows what the HP 8509 display looks like with the sphere turned off HP8509B Lightwaviag File Edit Measurement Display System Help Power 7 638 dBm Markers On Clear Markers so s1 s2 s3 2pt Ref 3pt Ref pq720b_c Figure 5 5 Poincare Sphere Turned Off 5 4 The Display Menu Displaying the Polarization Ellipse HP8509B Lightwave Polarization Analyzer File Edit Measurement MEE System Help Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh Sphere lt gt Ellipse pq721b_c Figure 5 6 The Show Ellipse Menu The polarization ellipse is displayed in the PRESET configuration but it may be turned off or hidden by selecting Display Show yEllipse This menu selection toggles the polarization ellipse on and off When the ellipse is di
179. ent window Customized Printing An HP 8509A B measurement window can be customized and inserted into a text document or slide presentation for printing by using the following procedure An example is shown below This procedure uses the Clipboard and Paintbrush graphics program which are included with the HP 8509 system computer Printing Saving and Recalling 4 3 Measurement Results and Instrument Configurations Results Isolator PN 410A Run 2 PDL Test Data Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 2 70 dBm Clear Trace 1550 0 nm Power Max amp Min v Recording max and min power Vary polarization at input of test device Select Reset to begin Max Min recording r Max Min Power dBm s1 82 s3 Sz Max L 2 46 0 60 0 56 0 57 Min 2 82 0 59 0 56 0 56 o Reset ClearTrace Hold r Max Min Power Delta L_0 36 qB Angle between Max amp Min states 179 58 Done pq7124_c Figure 4 3 Customized Printing Example 4 4 Printing Saving and Recalling Measurement Results and Instrument Configurations Procedure 1 Create the desired HP 8509A B measurement display You may choose to maximize the displ
180. ep NewThruCal and the PolDep Calibrate A B C commands are valid only for absolute measurements that is when the transmission measurement is elther Delta Max or Min HP 8509B only PolDep Clear Aborts or re starts a polarization dependent loss measurement process Any current measurements are cleared The command does not erase the thrupath calibration corrections from memory 10 46 Programming PolDep Done Ends a polarization dependent loss PDL measurement process The PDL measurement controls are removed from the screen PolDep Internal External 7 Specifies whether internal or external polarizers will be utilized in a polarization dependent loss measurement Internal polarizers are those which are a part of the HP 8509B system The user must implement and specify external polarizers through the polarizer command The query returns the selected polarizers HP 8509B only PolDep JonesData PolDepData When the mandatory selection is PolDepData the instrument returns data in one of two ways depending on whether it is in absolute mode or relative mode For absolute measurements the analyzer returns the polarization dependent loss as either Delta Max Min delta_transmission max_transmission min_transmission For relative measurements it returns the polarization dependent loss as Delta delta_transmission When the mandatory selection is JonesData the analyzer returns the Jones matrix a
181. er Start Cancel Done Opens the Operation Verification window if not already open and activates the specified command button PdlMaxMin Shows the PDL Max Min window on the HP 8509A B screen The query returns the PDL Max Min data as follows Dbm Max si Max s2 Max s3 Max Dbm Min si Min s2 Min s3 Min PdlMaxMin Max Min Centers the Poincare Sphere on the Max or Min point PdlMaxMin Delta Returns the Max Min power in dBm PdlMaxMin f Reset Clear Done Activates the appropriate button on the PDL Max Min window Poincare Center f Stokes A B C If the parameters A B or C are sent upon command execution the Poincare sphere is rotated so that the specified marker is at the center of the Poincare sphere display The marker must first be set before the command is executed If the parameter Stokes is sent the Poincare sphere is rotated so that the current state of polarization is at the center of the Poincare sphere display 10 44 Programming Poincare Clear Clears all visible measurement traces on the Poincare sphere After clear measurement continues at the current state of polarization Poincare Hold Off On Toggles Hold on or off When toggled on the Poincare sphere display is held at the current measurement state When toggled off continuous measurement is initiated Poincare Marker A BIC Places the specified marker at the currently measured sta
182. er window Rangel lt GainValue gt The query returns the gain range and the state of the autorange check box in the Range frame 0 not checked 1 checked Using lt GainValue gt allows the range to be set and returns an error if autorange is on The valid values for lt GainValue gt are 0 to 6 where 0 is the highest gain and 6 is the lowest gain This corresponds to Range Done Down Up See Range Auto Off On Programming 10 49 RawDat Returns the raw ADC voltages with offsets subtracted associated with the four photodiode detectors within the HP 8509A B receiver The voltages are returned in terms of a scaled value in the range 0 to 65 535 Each value within that scale is proportionally related to a value from 10 to 10 volts The subtracted offsets correspond to the voltage values generated by the detectors under zero input conditions The resulting information can be converted to voltage through the following equation rawdat volts obtained rawdat 65536 20 10 RefFrame This command will return information regarding the quality of a currently applied reference frame If a two point reference frame has been established the command will return the polarization angle and a grade for the frame quality If a three point reference frame has been established the command will return the transmission ratio and a grade for the frame quality The definitions of the return
183. erification pq783b_c Figure 2 5 Polarizer Selection Select System from the main menu and then select Polarizers Making Measurements 2 5 PMD Measurement Jones Matrix Eigenanalysis Method Polarizers Internal External m o gt 0 No Polarizer pq79b_c Figure 2 6 Polarizer Setup Set the polarizers to and select No Polarizer If the screen on your computer looks like the previous illustration select Done Markers On Clear Markers so s1 s2 s3 9 090 0 02 0 08 0 98 S olojo 2pt Ref 3pt Ref Apply 3pt Select Select this this first second pq790b_c Figure 2 7 3pt Reference Applied Select 3pt Ref from the Markers Area on the Main Screen wait 5 seconds and then select Apply 3pt ADDITIONAL INFORMATION Creating and applying a 3pt reference frame allows measurement of polarization state within a physical frame of reference In this case the reference frame is located inside the internal polarizer assembly 2 6 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method The Active Point isneara Pole HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 Bm Clear Trace T call 42 1550 0 nm
184. es all data clearing both graphical displays This operation cannot be undone Copy Bitmap Edit Copies a bitmap of the selected item to the clipboard Selections are DGD versus wavelength the DGD histogram and the entire PMD Statistics window Cumulative differential group delay histogram Lower graphical display Displays a histogram of the DGD values corresponding to the individual wavelength intervals of one or more single JME PMD measurement sweeps Differential group delay vs wavelength display Upper graphical display Displays the DGD vs wavelength measurement result s from one or more JME PMD measurements Exit File Closes the PMD Statistics application without saving the results User Interface Reference 7 15 Table 7 6 PMD Statistics continued Control or Data Path Description Fixed range Format Wavelength Range gt Fixed Range allows the user to define the wavelength range The cumulative DGD histogram is composed only of points which fall within the displayed wavelength range Fixed Scale Format Histogram X Axis gt Fixed Scale allows the user to define the maximum value of DGD displayed in the cumulative DGD histogram The minimum displayed DGD value is always zero Histogram X Axis gt Format Allows selection of range mode for the cumulative DGD histogram display Selections are Autoscale or Fixed Scale Autoscale sets the m
185. es carry bus commands When this line is false high the bus is in the data mode and the data lines carry device dependent instructions or data SRO Service Request This line is set true low when a device requests service the active controller services the requesting device REN Remote enable Only the system controller uses this line When this line is set true low the bus is in the remote mode and devices are addressed either to listen or talk When the bus is in remote and a device is addressed it receives instructions from HP IB rather than from its front panel When this line is set false high the bus and all devices return to local operation EOI End or Identify This line is used by a talker to indicate the last data byte in a multiple byte transmission or by an active controller to initiate a parallel poll sequence The analyzer recognizes the EOI line as a terminator and it pulls the EOI line with the last byte of a message output data markers plots prints error messages Sending Commands Commands are sent over the HP IB via a controller s language system such as IBASIC QuickBasic or C The keywords used by a controller to send HP IB commands vary among systems When determining the correct keywords to use keep in mind that there are two different kinds of HP IB commands Bus management commands which control the HP IB interface m Device commands which control analyzer functions Language systems usually
186. es only the uncertainty effects of the test system s birefringence 2 76 Making Measurements Polarization Reference Frame Checking Reference Frame Quality To check the quality of the reference frame select System and then Reference Frame Info If the quality is poor then you must repeat the previous steps starting at Choosing the Polarizers If the quality is good select OK to continue then select Apply 3pt with your mouse pointer from the Markers window Setting a Circular State of Polarization This procedure works best when the source supplies a circular SOP With a circular SOP input signal there is no chance for a low power 45 dBm reference point caused by the rotatable polarizer being placed orthogonal to a linear SOP input signal To set a circular SOP perform the following steps m Remove the Rotatable Reference Polarizer m Use the mouse pointer to select the button m Adjust the polarization adjuster until the active data point approaches a pole on the Poincare sphere and s3 is greater than 0 9 m Reinsert the Rotatable Reference Polarizer into the test setup and repeat the Reference frame procedure once more Using the Reference Frame At this point a polarization reference has been established The reference polarizer and any part of the source assembly may be moved or replaced without affecting the Polarization Reference Frame The HP 8509A B measures within the polarization reference frame N
187. escribed in detail later in this chapter This guide uses the following conventions Button This represents a button that can be selected on the computer screen to perform an action Menu Item This indicates a menu item that can be selected on the computer screen 1 2 Getting Started HP 8509A B User s Reference Guide Table of Contents this manual This manual contains the following chapters 1 2 10 11 Getting Started Making Measurements Accuracy Enhancement and Troubleshooting Printing Saving and Recalling Measurement Results and Instrument Configurations The Display Menu The System Menu User Interface Reference Lightwave Connector Care Safety and Regulatory Information Programming Specifications and Characteristics Glossary Index Appendix describes the HP 8509A B manual set and provides a description of the Main Menu screen of the software provides step by step instructions for making the following measurements a Polarization Mode Dispersion Jones Matrix Eigenanalysis Method PMD JME a Polarization Mode Dispersion Wavelength Scanning Method PMD WS Polarization Dependent Loss Jones Matrix PDL JM Polarization Dependent Loss Power Max Min Method Jones Matrix Polarization Maintaining Fiber Alignment Polarization Reference Frame State of Polarization Degree of Polarization provides procedures for improving the accuracy of measurements and solving
188. ets the polarization mode dispersion measurement PMD process for measuring a single device under test or for the measuring of a device under test included in a chain of devices under test The Cascade parameter is used to de embed the effects of components inserted along the measurement path of the desired device under test If Cascade is set a thrupath calibration must first be conducted at each measurement wavelength Once the thru calibration process is completed the PMD measurement process can be executed The query returns an ASCII 1 if the specified setting single or cascade is being used in the PMD measurement and a 0 if it is not HP 8509B only Disper Chain Not Recommended Command may not be available in future versions Plan your programming to use the alternate commands Disper Cascade and Disper Cascade HP 8509B only Disper Clear Aborts a PMD JME measurement process This command is valid only if the optical source is set to manual The command does not erase the current thrupath calibration corrections HP 8509B only Disper Close Closes the PMD JME measurement window The PMD JME measurement process is ended The original version 1 0 command closed the PMD JME window In version 2 0 the PMD JME window is a child of the HP8509 Graphs window The HP 8509 Graphs window closes when the last graph is closed Disper DBase Load lt title gt Loads a measurement from the current database using the sp
189. eturned as a comma separated ASCII string in the following format lt Wavelength nm gt lt Current Dispersion gt lt Average Dispersion gt The units for the returned dispersion data are selected with Disper Units The default units are ps HP 8509B only Disper ActiveWindow Upon command execution the analyzer returns the comma separated data from the currently active PMD JME window The number of data points is returned in Param 0 The wavelengths are returned in Param 1 The polarization mode dispersion delay is returned in Param 2 The units for the returned dispersion data are selected with Disper Units The default units are ps HP 8509B only Disper Atten lt dBm value gt The attenuation for the HP IB tunable laser source The query returns the attenuation in dBm Using lt dBm value gt sets the attenuation for an HP IB tunable laser source HP 8509B only DDE Only Disper Calibrate Clears any current thrupath calibration and begins a new PMD JME calibration sequence at the current wavelength setting This command is used when the command Disper Cascade has been sent to specify that a thrupath calibration is required prior to the PMD JME measurement of a given device under test Once the PMD JME controls have been accessed the Disper Calibrate command must be sent before any Disper Measure commands can be sent HP 8509B only Programming 10 31 Disper Cascade Single 3L S
190. etween the instrument and DUT can also affect accuracy Isolate the DUT as much as possible from fan vibrations bumps and shocks Use averaging to reduce the effects of unavoidable vibrations The HP 8509A B is equipped with the ability to mathematically remove the birefringence and PDL of the path between a reference polarizer and the HP 8509A B polarization receiver using a 2pt birefringence compensation only or 3pt birefringence and PDL compensation polarization reference frame PREF Reference frames become invalid if this path moves during creation of the reference frame or during subsequent measurements A polarization reference frame should not be applied for PMD measurements Refer to the PREF section of this manual for further information about creating a PRF and deciding between a 2pt or 3pt PRF The wavelength scanning WS PMD measurement method uses the mode coupling factor in determining PMD from the measured curves The value used relates to the degree of mode coupling in the DUT For long fibers that are highly mode coupled use 0 82 For most components and non mode coupled devices use 1 0 Refer to the discussion on mode coupling in the PMD measurement sections for more detail Multimode fibers MMF and damaged single mode fibers and connectors SMF cause a number of polarization measurement problems and should be replaced with high quality single mode fibers and connectors MMF should not be used for polarization measu
191. f Analysis mode under the Format menu determines how the start and stop wavelengths for the wavelength scanning formula will be derived This can dramatically influence accuracy in measurements of components and short fibers See the discussion in the Wavelength Scanning PMD section of this manual Feature Size located in the Format menu affects the peak and valley count during an HP 8509A B wavelength scanning measurement The value of the feature size determines whether a variation in a trace is ignored or counted as a peak or valley This value can affect PMD results so much that it should be stated with measurement results in order to compare and repeat measurement data Increase feature size if vibration or movement are causing false peaks in the wavelength scanning response Refer to PMD Measurements Wavelength Scanning Method for further information 3 6 Accuracy Enhancement and Troubleshooting 12 Analysis Mode 13 Mechanical Vibration 14 Polarization Reference Frame 15 Mode Coupling Factor 16 Fiber amp Connector Type Wavelength scanning PMD measurement accuracy can be improved by using the analysis mode appropriate to the test device This is why the HP 8509A B offers four analysis modes Refer to PMD Measurements Wavelength Scanning Technique for further information about Analysis Mode Mechanical vibration picked up by the measurement instrument or the DUT can degrade measurement accuracy Differential motion b
192. f Polarization 2 2 o 2 77 Using the Reference Frame Co 2 77 Additional Measurement Applications Co 2 78 2pt and 3pt Polarization Reference Frames Loe 2 78 Measurement of the Retardance of an Optical Device Lo Lo 2 78 Measurement of Output Polarization of an Optical Integrated Circuit o 2 79 Measuring Polarization State at a Connector Surface 2 2 2 79 Concepts Loe ee 2 80 Explanation of Polarization Reference Frame Mathematics o 2 80 Transmission Ratio 3pt Reference Frame a a a 2 80 State of Polarization Measurements a a a 2 81 Basic Measurement 2 a a a 2 82 Setting up the System 2 a 2 82 External Source Preparation 2 a a a ee 2 83 Making the Measurement 2 84 Measurement Results o 2 84 Specialized Measurement Techniques o 2 85 Measuring effective degree of polarization 2 85 Concepts e 2 86 Degree of Polarization o e 2 86 Electric Fields and Polarization e 2 86 3 Accuracy Enhancement and Troubleshooting Before You Proceed 1 1 we a a a a 3 1 Symptoms 2 3 3 Solutions 2 ke e 3 3 4 Printing Saving and Recalling Measurement Results and Instrument Configurations o 4 1 Conventions o o 4 2 For Additional Information o 4 2 Printing Measurement Results 2 ee 4 3 Standard Printing 4 3 Procedure 2 2 fe a 4 3 Customized Printing 2 e 4 3 Results 2 a a a a a 4 4 Proce
193. f the measurement the fiber length in kilometers the tunable laser power and attenuator settings the start and stop wavelengths and the wavelength interval or delta It also lists the number of points that is the number of wavelengths at which optical measurements were taken The measurement annotation area can be toggled on and off by selecting Display from the main window menu and then Ann otation ADDITIONAL INFORMATION The Jones matrix eigenanalysis method computes differential group delay DGD from adjacent pairs of optical measurements so the number of DGD values obtained in a completed measurement is actually one less than the number of measurement wavelengths Making Measurements 2 15 PMD Measurement Jones Matrix Eigenanalysis Method Using The Cursor Cursor Bar Avg DGD 0 01055 Current 0 00772 Max 0 02576 Min 0 00403 g 0 00607 Mea e81550 05 iio 005509 PO TR TA E Td Start Fiber Length 0 km Stop Source level OJuWatt Delta Source atten dB Points Continue pq7106_c Figure 2 18 The Cursor Bar Maximize the PMD JME window within the HP 8509B graphs window Activate the Cursor Bar by selecting Display and then Cursor from the Graphs window menu The cursor bar appears between the Measurement Summary Bar and the Measurement Annotation area The cursor display shows the DGD value for a selec
194. ff The HP 8509 warns you that no calibration exists The HP 8509 does not interpolate between calibrations The System Menu 6 13 How to Tell If a Calibration is Applied When a user performed calibration is applied the word Cal in the box in the upper right corner of the measurement screen will be bold black letters on a white background Black Lettering indicates an Applied Calibration HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 dBm Clear Trace k 4 1550 0 nm Markers On Clear Markers s2 s3 0 08 0 98 Rotate 2pt Ref 3pt Ref Home Figure 6 10 Calibration Applied When a user performed calibration is not applied the word Cal in the box in the upper right corner of the measurement screen will be gray inactive 6 14 The System Menu Deleting a Calibration 1 A calibration can be deleted by selecting an entry in the Calibration List and then selecting Delete selection Calibration Source Type Fixed A Tunable A Optical Source A Internal 1510 0 nm 1 Set external source to 1510 0 nm or select new Wavelength 2 Connect source to Optical Input
195. figure Files CFG fl c ms dos_5 pq739b_c Figure 4 11 The File Save As Configure File Window Select directory Select drive Printing Saving and Recalling 4 17 Measurement Results and Instrument Configurations Recalling a User Configuration User configurations allow you to store instrument states you want to use again Use the procedure below to recall a user configuration HP8509B Lightwave Polarization Analyzer MIES Edit Measurement Display System Help User Configuration Save PRESET Configuration Print Timed Measurement from Database Database Timed Measurement as Text Exit pq737b_c Figure 4 12 The Load Menu Procedure To call up an instrument state that has been stored 1 Select File Load in the main HP 8509 menu 2 Select User Configuration 3 The Load Configure File window opens See the following figure 4 Choose a configuration to open by specifying the drive directory and filename by typing the complete path in the File Name box You can also use the mouse to select the drive path and file 5 Select OK when the file you want appears in the File Name box Load Configure File Select your configuration File Name Directories file oK ms espesos Cancel hp8509 cfg t Den hp8509b E hp Select directory List Files of Type Drives Selec
196. fy the current measurement point on the Poincare sphere Marker angles displays Main window Measurement menu Lists the angle between rays from the center of the Poincare sphere to any two of the markers A B amp C following a great circle arc Provides results in radians and degrees Also provides commonly used trigonometric functions of these angles Markers on Check box Main window Marker area Toggles display of the markers without clearing them Markers displays amp buttons Main window Capture up to three Stokes vectors triggered by pressing buttons A B C to the left of the marker display chart Parameters s1 s2 and sg are the normalized Stokes parameters So is the total power in dBm Operation verification Main window System menu Automatically verifies system operation including the programmable polarizer and the optical receiver polarimeter Requires user to install a thru patchcord Optical source Lambda button or Main window System menu Optical Source Provides access to the optical source setup window for selection and control of internal or external optical source especially setting of wavelength PDL Jones matrix Main window Measurement menu Enables user to set up and perform a PDL measurement in which PDL is derived from a Jones matrix measurement of the device under test User Interface Reference 7 3 Table 7 1 Main Wi
197. g creation and application of a reference frame rotation of the reference polarizer should cause the point on the Poincare sphere to move along the equator Measurement of the Retardance of an Optical Device Retardance measurements make use of the polarization reference frame feature For details see the Jones matrix measurement section of this chapter 2 78 Making Measurements Polarization Reference Frame Measurement of Output Polarization of an Optical Integrated Circuit Measurement of the output state of polarization of an optical IC may be achieved by creating a polarization reference frame at the end of a fiber which is in turn butt coupled to the IC This removes the effects of birefringence and polarization dependent loss in the path between fiber tip and the HP8509A B Creation of the reference frame requires a setup procedure in which light is coupled through a rotatable reference polarizer into the fiber tip Alternatively polarized light at three angles can be provided from a single mode of a polarization maintaining fiber by rotating the fiber to the necessary angles with a fiber chuck or holder This PMF can also be used to stimulate the input of the optical IC See the Polarization Maintaining Fiber Launch section for details on launching light into a single polarization mode of PMF Measuring Polarization State at a Connector Surface A polarization reference frame can be established at a connector interface The requir
198. ge 1 0 to 1 0 and DOP is the degree of polarization range 0 to 1 2 10 56 Programming TLS Returns the name of the current tunable laser source Valid return values are Voltage tuned HP8167A HP IB HP8168A HP IB Manually tuned Unknown TLS Address lt HP IB Address gt This setting is used for all windows The HP IB address of a tunable laser source on the HP IB bus DDE only TLS Isc lt HP IB card ISC gt This setting is used for all windows The ISC of the HP IB card installed in the HP 8509A B Vectra PC DDE only TLS Power lt Power gt This setting is used for the analyzer window only The power setting of the HP IB tunable laser source The units are set in TLS Unit lt units gt DDE only TLS SettlePoint SettleStart lt Millisec s gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Settle Point Start lt Millisec s gt DDE only Programming 10 57 TLS Power Unit dBm Watt The units of power for the HP IB tunable laser source power This setting is used for the analyzer window only See also Disper Power dBm uWatt lt value gt and WaveScan Power dBm uWatt lt value gt If the power setting is not valid for the TLS the command fails DDE only Trace Points lt NumPoints gt Not Recommended Although this co
199. ge data is lost Operation Complete Occasionally there is a need to find out when certain operations have completed inside the HP 8509 For instance a program should not have the operator connect the DUT while the HP 8509 is still measuring the measurement thrupath To provide such information the HP 8509 has an Operation Complete reporting mechanism that will indicate when certain key commands have completed operation The mechanism is activated by sending OPC immediately after an OPC able command The HP 8509 will output a 1 when the command completes execution The OPC command should occur in the same output statement as the command being OPC d As an example when ready for remote control type in the following program 10 OUTPUT 729 JONES ABSOLUTE END Set up for an absolute measurement 20 OUTPUT 729 Conduct the thrupath calibration and OPC the JONES CALIBRATE OPC END thrupath calibration measurement 40 DISP Measuring 50 ENTER 729 String The program will halt at this point until the HP 8509 completes the measurement and issues a 1 60 DISP DONE 70 END This program causes the controller PC to display the Measuring message for about 3 seconds while the instrument executes a thrupath calibration in preparation for an absolute Jones matrix measurement The controller PC will display DONE just as the instrument completes Programming 10 15 the measurement procedure When the DONE message appears the pro
200. genanalysis F2 PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 Jones Matrix F4 PM Fiber Launch F5 Marker Angles Timed Measurement pq795b_c Figure 2 63 PDL Measurement Selection Connect the device you wish to measure then select Measurement from the main menu and then select PDL Power Max Min Shift F3 Making Measurements 2 55 PDL Measurement Power Max Min Method PDL Power Max Min v Recording max and min power Vary polarization at input of test device Select Reset to begin Max amp Min recording Max Min Power S dBm s s2 7 661 0 80 0 26 Min 7 693 0 90 0 37 Reset Clear Trace Max Min Power Delta 9 032 dB Angle between Max amp Min states Done pq7151_c Figure 2 64 PDL Power Max Min Measurement Window 2 56 Making Measurements PDL Measurement Power Max Min Method m Select the Reset button with your mouse pointer m Vary the polarization at the input of your device under test preferably using an automatic like the HP 11896A polarization controller versus a manual controller polarization controller Continue adjustment until the Poincare sphere has been fully explored or the value of Delta has stabilized PDL Power Max Min
201. gives active control to the computer 20 CLEAR 729 This clears all HP IB errors resets the HP IB interface and clears syntax errors 30 OUTPUT 729 LOAD CONFIG PRESET Preset the instrument This resets all END instrument window menu settings 40 END 10 16 Programming Interacting with the HP 8509A B Through the DDE This chapter focuses on using Microsoft Visual BASIC for Windows VB to create a custom application for programmed control of the HP 8509 to directly and continuously exchange data with other Windows based applications that support the Dynamic Data Exchange DDE DDE data exchanges are called conversations DDE conversations are started by establishing DDE links Applications using DDE to converse with the HP 8509 for automatic control can be custom programs using a computer language such as C or Visual BASIC for Windows They can also be applications such as Microsoft Excel that allow users to interface to the DDE system Establishing DDE Links The HP8509 allows other applications to establish DDE links to text based controls called labels in the HP8509 firmware To establish a DDE link an application must know three things about the item it wants to link to m The name of the application it wants to talk to m The subject of the conversation called a topic m The name of the item with which the DDE conversation should take place Since the name of the HP 8509 application may change with future
202. gram could then continue on being assured that there is a valid thrupath calibration in memory ADDITIONAL INFORMATION Some operations on the HP 8509 may take more time than the HP IB bus provides for a timeout Therefore when you send OPC either execute a delay before ENTER or trap the HP IB timeout error using ON TIMEOUT in the IBASIC program to allow for this delay Preparing For HP IB Control At the beginning of a program the HP 8509 has to be taken from an unknown state and brought under computer control One way to do this is with an abort clear sequence ABORT 7 is used to halt bus activity and return control to the computer CLEAR 729 will then prepare the HP 8509 to receive commands by clearing syntax errors the input command buffer and any messages waiting to be output The abort clear sequence makes the HP 8509 ready to receive HP IB commands The next step is to put the HP 8509 into a known state The easiest way to do this is to send LOAD CONFIG PRESET which returns the instrument to the preset state The user can specify different configuration parameters and then save them by sending SEND CONFIG lt filename gt To load the user specified configuration parameters send LOAD CONFIG lt filename gt For syntax see Chapter 8 Remote Command Reference Running the following program brings the HP 8509 to a known state ready to respond to HP IB control 10 ABORT 7 This halts all bus action and
203. h HP BASIC syntax In effect the same syntax can be used to create both IBASIC and HP BASIC programs However the user should be aware that IBASIC and HP BASIC file formats differ IBASIC files are usually created in DOS text format while HP BASIC files are created in LIF format In effect a program created in IBASIC will not directly run under HP BASIC though the same syntax can be utilized under HP BASIC to create a program with identical functionality Utilities exist under the UNIX operating system to translate DOS formatted files to LIF format and vice versa 10 12 Programming Basic Instrument Control A computer controls the HP 8509 by sending it commands over HP IB The commands sent are specific to the HP 8509 Each command is executed automatically upon receipt During remote control the analyzer is receptive to manual control The user must take care not to disrupt remote operations Most commands are equivalent to front panel functions For example after preparing the system for HP IB control type OUTPUT 729 POINCARE CLEAR END on the alpha command line and execute by clicking the RUN button on the IBASIC control pad The Poincare sphere on the HP 8509 display is now cleared from all measurement traces and measurement continues at the current state of polarization The construction of the command is OUTPUT 729 The BASIC data output statement The data is directed to interface 7 HP IB and on out to the device ad
204. h the DGD range is divided for construction of the DGD Histogram Maxwell alpha parameter This display shows the value of the single parameter which specifies the Maxwell curve that is automatically fitted to the DGD histogram 2 22 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Printing the PMD JME Graph HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 Edit Measure Format Load JME from Database Save JME to Database Save JME as Text Display Window Graph amp Annotation Database Close All PMD Windows Graph Annotation amp Data pq7110_c Figure 2 25 Printing the PMD JME Graph Select File and then Print from the Graphs main window m Selecting Graph will print only the graph m Selecting Graph amp Annotation will print the graph and the annotation information discussed in The Measurement Annotation Area m Selecting Graph Annotation amp Data will print the graph annotation information and list the measurement wavelengths and the corresponding data points Saving your Measurement as Text HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 Edit Measure Format Display Window Load JME from Database Save JME to Database Print Database Close All PMD Windows pq7iiiic Figure 2 26 Save as Text Select File and then Save JME as Text from the G
205. hain a 10 32 Disper Clear 10 32 Disper Close e 10 32 Disper DBase Load lt title gt Loe 10 32 Disper DBase Save lt title gt date code gt T lt serial number gt 37 10 33 Disper Done e 10 33 Disper FiberLen mM lt km gt y o o 10 33 Disper FindMinPoints lt Num Samples gt Lo 10 33 Disper HPIB 7 2 e 10 34 Disper Manual 2 2 ee 10 34 Disper Manual 2 2 10 34 Disper Measure 1 10 34 Disper NewThruCal 2 2 10 35 Disper Power Co e 10 35 Disper Power dBm uWatt E lt value gt Coke ee L 10 35 Disper Restart e 10 35 Disper Save lt filename gt o e 10 36 Disper Settle Point Start ve i lt Delay msec gt 10 36 Disper Start e 10 36 Disper Trace lt filename gt e 10 37 Disper Units ps ps L ips sarth fs fs L fs sqrtL 10 37 Disper VTune 7 Ce a 10 37 Disper VTune Start Stop ve lt Voltage gt o 10 37 Disper WLen e 10 37 Disper WLen Pointst 7 lt NumPoints gt 10 38 Disper WLen Start Stop Delta lt Wavelengthnm gt 10 38 Disper WLen Steps lt NumPoints gt oa a a a a a e 10 39 Display Angles Off On o L 10 39 Display Angles Degrees Radians 3 o a 10 39 Display Power Linear Log oaoa a a a a e 10 39 Display Update lt NumPoints gt 10 40 Drive e 10 40 Drive l
206. he 52 parameter describes the difference in power between the 45 and 45 degree linearly polarized components The last parameter 3 describes the difference in power between the right and left hand circularly polarized components See also Normalized Stokes Parameters termination A load connected to a transmission line or other device thru An abbreviation for through which is used to refer to the calibration technique in which the measurement planes are connected together and the through path is measured timed The name given to the HP 8509 A B feature which captures the polarization characteristics of a signal at intervals of time Available modes include free run timed and single Glossary 10 toggle To switch states usually to change a function from on to off or off to on transfer function A complex function magnitude and phase equal to the ratio of output to input as a function of modulation frequency transmission The measurement of the insertion loss or gain of a network or device Transmission Ratio 3pt Reference Frame Transmission ratio is a measure of the equivalent PDL of the path between the reference polarizer and the HP8509A B polarization receiver expressed in linear terms for a 3pt polarization reference frame The equivalent PDL is found by multiplying the log to base ten of the displayed number by ten An excellent reference frame shows a transmission ratio of 1 0 equivalent to a PDL of 0 dB
207. he text box is 60 000 characters Window menu Graphs window Provides management of windows Y scale gt Graphs window Display menu Provides control of the vertical scale of the measurement graph 7 14 User Interface Reference PMD Statistics The PMD Statistics feature provides a statistical representation of fiber DGD data measured with the Jones matrix eigenanalysis method This is a separate software application which is accessed through a Display menu selection from the PMD measurement window Table 7 6 PMD Statistics Histogram X Axis gt Control Path Description or Data Add from Selected File Imports to the graphical displays the JME JME Window measurement result currently displayed in the HP8509 Graphs window Add from File Adds to the graphical displays a JME measurement Database result selected from the Database Add from File Adds to the graphical displays a JME measurement Text File result selected from a text file Auto Range Format Autorange sets the minimum and maximum Wavelength Range gt displayed wavelengths to accommodate the minimum and maximum value of wavelength of the measurement data Autoscale Format Autoscale sets the maximum value of DGD displayed in the cumulative DGD histogram to accommodate the maximum DGD value of the measurement data The minimum displayed DGD value is always zero to Clipboard gt Clear All Data Edit Remov
208. he alternate command PolDep Measure A B C HP 8509B only 10 42 Programming Jones NewThruCal Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep NewThruCal HP 8509B only Jones ReStart Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Clear HP 8509B only Load Config Preset Loads the factory default configuration for the LPA Load Config lt filename gt Loads the user created configuration file lt filename gt For compatibility with previous versions the search path for filename is 1 The windows working directory 2 The HP 8509A B application directory 3 The Windows directory usually CA WINDOWS For path information on filename see Command Syntax at the beginning of this chapter Load Single lt filename gt Loads a timed measurement from the file lt filename gt For path information on filename see Command Syntax at the beginning of this chapter Programming 10 43 OperVer 7 Opens the Operation Verification window The query returns the results of the operation verification procedure in the following format lt Result of OperVer gt lt Max DOPY gt lt Mean DOP gt lt Min DOPY gt lt Angle AB gt lt Angle AC gt where lt Result of OperVer gt is 1 if success 0 if fail OperV
209. he lower right element may be displayed as 1 j0 in the case of real and imaginary format or 1 0 at an angle of 0 0 in the case of polar format If the amplitude of the lower right element is very small and therefore vulnerable to noise the instrument normalizes to one of the other elements of the matrix This will be apparent from inspection of the results Glossary 4 Jones matrix eigenanalysis The extraction of information about the polarization behavior of a two port optical device from the Jones matrix including the analysis of pairs of Jones matrices measured at different optical frequencies Also the name given to a PMD measurement method Jones vector An analytical description of the state of polarization It specifies the amplitude and phase of two orthogonal electric field components within a physical frame of reference reference directions of orthogonal electric fields launch Typically the condition of coupling light into an optical fiber May refer to the effectiveness of coupling or the polarization condition of the coupled power LED Light Emitting diode local lock out A condition or command that prevents any analyzer front panel entries specifically TA local operation To operate manually from the front panel loss Attenuation of optical signal normally measured in decibels marker Typically an indicator placed by the user on a graphical display of measurement results Maxwell function The Maxwell fu
210. he marker pertaining to the specified polarizer A B or C is placed as observed on the Poincare sphere at the resulting state of polarization Command execution also returns the resulting state of polarization in the form of the normalized Stokes parameters So 81 S2 83 When external polarizers are used this command should be executed when the desired state of polarization has been set using an external polarizer The command execution places the specified marker as observed on the Poincare sphere at the resulting state of polarization The resulting state of polarization is returned as the normalized Stokes parameters So 1 82 83 The main purpose of this command is for use in placing and reading markers when external polarizers are utilized Specifically this is done when performing a Jones matrix measurement a polarization dependent loss measurement or when the application of a two or three point reference frame is required Range Auto Off On Through this command the range function auto mode is as specified by the user turned On or off The query returns an ASCH 1 if the range function is in auto mode and an ASCII o if it is not Range Done Down Up When the auto function is turned Off the user may through this command increase Up or decrease Down the power measurement range of the HP 8509A B See Range Auto 0ff On Using the Done parameter closes the Range frame in the analyz
211. he mouse Selected text may be deleted or copied to the clipboard by pushing the Copy to clipboard button The tabular data text box is limited to 60 000 characters All or a portion of the text box information may be printed Printing uses the default printer selected in the Windows Control Panel To print all of the text box information just press Print tabular data on the Graphs window area To print a portion of the text box information select the desired text with the mouse before pressing Print tabular data To return to the 2 40 Making Measurements PMD Measurement Wavelength Scanning Method graphic display select Return to Graph at the top of the window or re select Tabular Data under the Display menu Printing your Graph HP8509 Graphs lt 1 gt PMD WS 1460 0 1555 0 0 5 Edit Measure Format Display Window Load WS from Database Save WS to Database Save WS as Text Print PMD Graphs s1 s2 s3 Database Graph amp Annotation Close All PMD Windows Graph Annotation amp Data pq7i18_c Figure 2 45 Printing your Graph Select File and then Print PMD from the Graphs main window m Selecting Graphs S1 2 53 will print only the graph m Selecting Graph amp Annotation will print the graph and the annotation information discussed in The Measurement Annotation Area m Selecting Graph Annotation amp Data will print the graph annotat
212. heir angles are measured at the factory The nominal relative angles for internal polarizers A B and C are 0 60 and 120 degrees respectively The values shown on your screen for these polarizers will be the measured angle values unique to your instrument 1 To select an internal polarizer select Internal in the Polarizers window 2 Select polarizer A B or C 3 Select No Polarizer to remove an internal polarizer from the signal path The System Menu 6 17 About Internal Polarizers Internal polarizers are effective only when using an internal source or an external source that is routed through the HP 8509B via the EXTERNAL SOURCE INPUT Internal polarizers are inserted automatically during several types of measurements and may be inserted manually to polarize light from an external source Selecting an External Polarizer When using external polarizers to make certain measurements you must input the angles of your polarizers into the HP 8509 HP 8509A users should go directly to step 2 1 Select External polarizers from the Polarizers window NOTE The angles displayed are the default values for use with a rotatable external polarizer The buttons for polarizer selection are gray inactive and no longer apply however they continue to show the status inserted or not of the internal polarizers 2 Input your angle values in degrees for external polarizers A B and C select the numbers in the approp
213. ial calibration coefficients For accurate operation of the instrument the user must enter the operating wavelength to at least 1 nm accuracy It is suggested that the wavelength be entered to 0 1 nm accuracy if the source is a single line source and the wavelength is well known Errors in the entry of wavelength will affect all measurements The effect is quite apparent in Glossary 11 the DOP measurement When measuring fully polarized light from a fiber the DOP will fluctuate about 100 as the fiber is moved Larger wavelength error produces a greater DOP fluctuation wavelength scanning A method for measurement of PMD in which the source wavelength is changed over a broad range and the output polarization state is monitored The number of cycles of change in the output polarization state over the given wavelength range indicates the amount of PMD present in the test device Glossary 12 Index Special characters 10 23 amp lt gt 10 23 10 23 10 23 10 23 10 23 A acoustic noise emission 9 1 Analog 10 27 Analog Done 10 27 Analog Off Raw Stokes 10 27 analog outputs 7 2 analysis gt 7 18 analyzer window 7 12 10 25 angle brackets 10 23 Angles AB AC BC 10 28 Angles Degrees Radians 10 28 Angles Done 10 28 10 33 Angles Off On 10 28 annotation 7 12 7 18 apply 2pt 7 2 apply 3pt 7 2 attenuation 7 7 autoscale 7 12 auto
214. iber end most open at the end of a lightwave cable or on the front panel of an instrument or accessory Adapter Does not contain optical fiber Used to mate two optical connectors Handling Always handle lightwave connectors and cable ends with great care Fiber ends should never be allowed to touch anything except other mating surfaces or cleaning solutions and tools CAUTION Hewlett Packard strongly recommends that index matching compounds NOT be applied to their Instruments and accessories Some compounds such as gels may be difficult to remove and can contain damaging particulates If you think the use of such compounds is necessary refer to the compound manufacturer for information on application and cleaning procedures Always keep connectors and cable ends covered with a protective cap when they are not in use See Storage Cleaning Three cleaning processes are provided The first process describes how to clean non lensed lightwave connectors The second process describes how to clean lightwave adapters The third process describes how to care fa lensed lightwave connections CAUTION These cleaning processes apply only when dry connections are used no Index matching compounds Hewlett Packard strongly recommends against the use of index matching compounds particularly gels as they may be difficult to remove and can contain damaging particulates If an index matching compound is used contact the compound
215. ies with wavelength The PMD of a test device also refers to the average value of the differential group delay PMD is fundamentally expressed in units of time typically picoseconds 1 ps 1072 s although in the case of long fibers it may be normalized to the square root of fiber length with the units of picoseconds per root kilometer This section explains how to measure the PMD of a test device using the wavelength scanning WS method A typical measurement result is shown in the following figure File Edit Measure Format Display Window 1 1460 cla 0 0934 Fes A 0 0623 BPE 0 0934 BES 0 1246 Start 1460 0 nm WN T gt Fiber Length km Stop 1560 0 nm Oe k 0 Source level Watt Delta 5 0 nm Source atten dB Points 21 Continu pq777b_c Figure 2 34 Example of data display for a wavelength scanning PMD measurement Typical applications of the wavelength scanning method include measurement of medium to long optical fibers and cables It can also be applied to the measurement of some components and may be used to characterize amplified systems in which the level of PMD is large enough to produce a useable number of peaks and valleys in the response within the system passband Consider the following aspects of the wavelength scanning method when deciding which PMD meas
216. ilometers Optimizing the setup for fiber or component test Wavelength tuning range The wavelength scanning PMD measurement is based upon the detection of changes in output polarization as a function of wavelength These changes are manifested as peaks and valleys in the normalized Stokes parameter responses sl s2 and s3 Single mode fiber measurements are more accurate if the number of peaks is large wavelength range should be chosen to produce ten or more peaks However because the 8509 s implementation of wavelength scanning method analyzes three polarization axes or components accuracy is enhanced and useful measurements may be obtained from wavelength scanning responses having fewer peaks When measuring components and polarization maintaining fiber the wavelength scanning responses are sinusoidal In such cases a good measurement can be derived from a single pair of peaks or extrema although accuracy is somewhat improved for larger numbers of features The wavelength spacing of peaks is predictable for non mode coupled devices most components At 1550 nm the product of the DGD of the test device in ps and the wavelength interval between adjacent peaks in nm is approximately 7 4 ps nm A device with DGD of 1 0 ps produces a peak every 7 4 nm Analysis mode The analysis mode is represented at the right hand edge of the annotation area of the Graphs window by an icon showing a sine wave with two types of marks or tics The
217. involving a Jones matrix the spectral line width AA of the optical test signal should be narrow enough to guarantee that the coherence time approximately equal to A cAA of the test signal is less than 1 3 of the differential group delay DGD of the test device This will reduce any measurement uncertainty that may be introduced by depolarization of the test signal Best performance is achieved when the lightwave test signal DOP is near 100 Wavelength accuracy and stability are important because the calibration factors in the HP 8509 are based upon accurately knowing the wavelength of the test signal If the test signal s true wavelength differs from the wavelength expected by the HP 8509 then measurement uncertainties will result See item 4 Wavelength amp Wavelength Calibration for more detail or refer to the Calibration section of the System Menu chapter of this manual Accuracy Enhancement and Troubleshooting 3 5 7 Temperature Stability of DUT and Environment 8 Instrumentation Temperature Stability 9 Wavelength Step Size Delta 10 Wavelength Span Start Stop 11 Feature Size Accurate polarization measurements must be performed in a thermally stable environment Changes in room temperature during a measurement will cause the ambient temperature of the instrument and the test device to drift This will adversely affect measurement accuracy and repeatability until all temperature transients have stabilized once
218. iod Zeroing with optical power applied to the optical input creates offsets in the instrument which seriously degrade accuracy and can result in power overrange or underrange warnings The HP 8509A B contains in memory a set of factory calibration coefficients that optimize the accuracy of the polarimeter at a series of discrete wavelengths For accurate operation of the instrument enter the operating wavelength to at least 1 nm accuracy Wavelength errors affect all measurements The effect is apparent in the DOP measurement When measuring fully polarized light from a fiber the DOP fluctuates about 100 as the fiber is moved Larger wavelength error produces a greater DOP fluctuation The HP 8509A B provides a wavelength calibration process that allows the operator to augment the built in calibration for a particular source even if you don t know the wavelength of the source See the Calibration procedure in the System Menu chapter of this manual 3 4 Accuracy Enhancement and Troubleshooting 5 6 Polarizer Lightwave Source Performance Polarizers may include the polarizers internal to the HP 8509B an external reference polarizer used for an HP 8509A B application a polarizer in the signal path or the test device itself In general the last polarizer in the test signal path determines the polarization of the signal The HP 8509B contains an internal polarizer unit with three insertable linear polarizers These may b
219. ion by double clicking on the HPIB2DDE icon in the HP 8509 window The HP 8509 window is within the Program Manager window If the Program Manager window is obscured by the HP 8509 instrument window merely double click anywhere outside the existing windows This will bring up a window called the Task List Double click on the Program Manager entry to bring its window to the front of the screen The HP 8509 window should become visible The HPIB2DDE icon resides within the HP 8509 window Once the HPIB2DDE application has been started if desired the HPIB2DDE window can be minimized by clicking on the down arrow in the top right hand corner of this window Begin sending HP IB Commands from the controlling external PC up esas HP 8509 SYSTEM SYSTEM CONTROLLER PC VECTRA PC HP 8583 LIGHTWAVE 600000 900000 POLARIZATION ANALYZER HP IB CABLE DEDICATED INTERFACE CABLE Figure 10 1 HP IB Setup 10 2 Programming HP IB Overview HP IB the Hewlett Packard Interface Bus is a high performance bus that allows individual instruments and computers to be combined into integrated test systems The bus and its associated interface operations are defined by the IEEE 488 1 standard The IEEE 488 1 standard defines the interface capabilities of instruments and controllers in a measurement
220. ion can be automatically performed on the HP 8509 if desired This can be done remotely by sending the CAL CALIBRATE and CAL ON commands It should not be necessary to perform more than one instrument calibration per day or even one per week depending on room temperature changes and the accuracy required If in doubt a calibration should be performed For more information on instrument calibration please refer to the HP 8509 User s Reference Guide Set Up the Instrument All pertinent measurement parameters must be set Set the type of source internal external wavelength and set for internal or external polarizers The number of steps in the set up procedure depends on the type of measurement to be conducted Some of the measurements require a thrupath measurement calibration and or application of a two point or three point reference frame prior to the execution of the DUT measurement One of the measurements polarization mode dispersion requires setting parameters such as the start and stop wavelengths the number of steps and the step wavelength separation Connect the Device Have the operator connect and adjust the device under test DUT All adjustments take place at this stage so that there is no danger of taking data from the device while it is being adjusted Take Data With the device connected and adjusted conduct the desired measurement The process of taking data is different depending upon the type of measurement that
221. ion information and list the measurement wavelengths and the corresponding data points Saving your Measurement as Text HP8509 Graphs lt 1 gt PMD WS 1460 0 1555 0 0 5 IAS Edit Measure Format Display Window Load WS from Database Save WS to Database Save WS as Text Print PMD Database Close All PMD Windows pq7119_c Figure 2 46 Save as Text Select File and then Save WS as Text from the Graphs main window A standard window Save screen will be displayed At this point you can select a file name and a directory for the data to be stored Columns of wavelengths and measurement data points will be saved as text for later use in a spreadsheet The data saved as text cannot be recalled for future display by the instrument Making Measurements 2 41 PMD Measurement Wavelength Scanning Method Saving in Database Format HP8509 Graphs lt 1 gt PMD WS 1460 0 1555 0 0 5 Edit Measure Format Display Window Load WS from Database Save WS to Database Save WS as Text Print PMD Database Close All PMD Windows pq7120_c Figure 2 47 Saving in Database Format Select File and then Save WS to Database from the Graphs main window to save the entire measurement and annotation for future analysis using a database program or to reload the measurement and certain setup parameters into the analyzer A defau
222. ions of temperature All of the resulting data is combined in a single histogram for analysis If the fiber temperature is changing naturally due to changes in the ambient temperature the measurement may be repeated versus time to enlarge the sample size If the fiber is in cable form temperature change may be induced by passing a current through the metal members of the cable The sample size for spooled fiber can also be enlarged by rearranging the turns of fiber on the spool For example a spool of loosely coiled fiber can be turned end over end between measurements Source spectral characteristics The Jones matrix eigenanalysis method of PMD measurement involves measuring the output state of polarization of the device under test with various linear polarizers inserted in the path between optical source and the device This requires that the output of the test device always be at least partially polarized The output will depolarize if the coherence time of the source approaches the differential group delay of the test device Single line lasers of narrow spectral width such as the HP 8168A Tunable Laser Source are recommended for the Jones matrix eigenanalysis PMD measurement method Making Measurements 2 31 PMD Measurement Jones Matrix Eigenanalysis Method Should I use the reference frame The reference frame feature removes birefringence 2 point method or birefringence and polarization dependent loss 3 point method from the tes
223. is conducted For the majority of measurements the taking of data is automatically performed Certain measurements however such as PMD under manual mode require a high degree of operator interaction When taking data the operator must ensure proper synchronization This can be done by using the OPC command Transfer Data Lastly read the results out of the instrument The data output command is designed to ensure that the data transmitted reflects the current state of the instrument The data as previously discussed can be read from the instrument using the ENTER remote command All measured data is returned by the HP 8509 system as a sequence of comma separated strings The operator must take care to reformat or parse this data if so desired 10 22 Programming Remote Command Reference None of the commands are case dependent Commands may be sent in upper case lower case or mixed case Any item not enclosed in angle brackets lt gt must be considered a literal command Most of the commands in this chapter are available using Microsoft Windows DDE as well as HP IB Any restrictions to the use of a command are noted in the chapter for that command When receiving HP IB commands the HP 8509 does not lock out manual operation Do not disrupt remote control through manual command execution Furthermore HP IB commands which lock out manual operations are not currently available for remote control of the HP 8509 When yo
224. is not intended to teach programming or to discuss HP IB or DDE theory except at an introductory level Related information can be found in the following references m Information concerning HP Instrument BASIC for Windows is available in Installing and Using HP Instrument BASIC for Windows HP part no E2200 90000 m Information on HP Instrument BASIC is available in the HP Instrument BASIC User s Handbook HP part no E2083 90000 m Information on using the HP IB is available in the Tutorial Description of the Hewlett Packard Interface Bus HP literature no 5952 0156 m Microsoft documentation of DDE Additional information about the HP 8509 measurement procedures can be found in the following references a HP 8509 User s Reference Guide HP part no 08509 90010 Programming 10 1 Starting Up the System For HP IB Control The HP 8509 can be remotely controlled from HP IB according to the setup illustrated in Figure 10 1 and the procedures described below 1 Power up the HP 8509 system according to the instructions provided in the Installation and Quick Start Guide document HP part no 08509 90002 Connect an HP IB cable from the HP IB board of the system controller PC to the HP 8509 Vectra HP IB board connector The board connector is in the back of the HP 8509 Vectra Start up the HP 8509 application by double clicking on the HP 8509 icon in the HP 8509 instrument window Start the HPIB2DDE applicat
225. is section briefly describes all of the controls and displays you may encounter while manually operating the HP 8509A B It supplements the measurement applications section of the manual by providing quick access to the description of a particular control or display Remote control features of the instruments are discussed in the Programming chapter a Main window m Optical source setup m Calibration m Operation Verification PMD Jones Matrix Figenanalysis a PMD Statistics PMD Wavelength scanning m Timed Measurements a PDL Jones Matrix Jones Matrix a PDL Power Max Min a PM Fiber Launch m Marker Angles Information is presented in sections corresponding to the major windows such as Main Window PMD Jones matrix eigenanalysis PMD Wavelength scanning and so on Within the sections the descriptions are presented in chart format with the control or data display names arranged in the first column in alphabetical order The items in the first column are menu selections unless otherwise noted The next column gives the path by which the control or display is found For example in the Main Window section the Calibration feature is found in the System menu The last column describes the use of the control or display Additional information on the use of these features is found in the corresponding sections of Chapter 2 Measurement Applications Specialized terminology is defined in the Glossary User Interface Reference 7 1
226. kes parameters comprised of the average optical power S0 in dBm and the normalized Stokes parameters sl s2 and s3 Stokes parameters for the current data point are on the top line 5 of the marker table When marker A B or C is set the respective parameters will also be displayed adjacent to the respective marker button A B or C For information on Stokes parameters refer to the Making Measurements chapter of this manual The following marker functions are discussed in this section m Setting a marker a Turning the markers on and off a Clearing the markers m Centering the sphere on a marker or current point a Two and three point polarization reference frames Setting a Marker There are two ways to set markers on the Poincare sphere m set a marker at the current data point or m set a marker at a user specified point on the sphere regardless of where the current data point is In both of these cases when a marker is set the Stokes parameters for the particular marker A B or C always appears in the table in the Markers window However for the marker to appear on the Poincare sphere the Markers must be turned on 1 6 Getting Started Setting a Marker at the Current Data Point 1 Select A E or on the left side of the Marker window to set a marker on the Poincare sphere at the current data point See Figure 1 3 Once a marker has been set the Stokes parameters for the marke
227. larization modes along the transmission path Two port optical devices including optical fiber fall into two categories according to the degree of mode coupling Non mode coupled devices include most components hi bi polarization maintaining fiber and short lengths of ordinary single mode fiber For these devices energy launched into each polarization mode remains in that mode as it propagates The differential group delay of non mode coupled devices is generally independent of wavelength The other extreme strong mode coupling is exhibited by long lengths of single mode fiber For long fibers energy couples between modes due to physical variations internal to the fiber and optical effects induced by the fiber s environment The differential group delay of highly mode coupled devices is a strong function of wavelength An intermediate degree of mode coupling typical of short to medium lengths of optical fiber results in differential group delay which is a relatively weak function of wavelength PMD units Differential group delay is expressed in units of time generally either picoseconds 1 ps 1072 s or femtosecond 1 fs 107 s Short fiber PMD may be expressed in terms of time per meter or kilometer Due to the effects of mode coupling long fiber differential group delay increases as the square root of fiber length Therefore long fiber differential group delay is often expressed in terms of time per square root of fiber length in k
228. lay Measurement menu measurements displayed on the same row Marker Angles Cos x Main window Marks the column in which the cosine of the relative display Measurement menu angles are displayed Marker Angles Cos2 x 2 Main window Marks the column in which the square of the cosine display Measurement menu of half of the angle is displayed Marker Angles Degrees control Main window Measurement menu Marker Angles Expresses the measured angles in degrees Radians control Main window Measurement menu Marker Angles Expresses the measured angles in radians x display Main window Measurement menu Marker Angles Marks the column in which the angles between markers are displayed User Interface Reference 7 29 Lightwave Connector Care Introduction Lightwave cable interfaces can be damaged by improper cleaning and connection procedures Dirty or damaged lightwave interfaces can result in nonrepeatable or inaccurate measurements This chapter will suggest some best practices to clean care for connect and inspect lightwave connectors Lightwave connectors are used to connect two fiber ends together These connections may be used to join cables between optical ports on devices laser sources receivers patch panels terminals and many other types of systems or components Fiber optic cables are used at different wavelengths in single or multi mode and in different environments There ar
229. lay averaging factor is automatically reduced to avoid this condition The Display Menu 5 9 Holding the Data Display Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq733b_c Figure 5 16 The Hold Menu If you wish to hold the current data display and not see new data put up on the Poincare sphere you can activate the Hold function by selecting Display Hold This menu selection toggles the hold function on and off When the Hold function is activated a check mark appears next to the menu selection Also there will be an X in the Hold box on the HP 8509 basic measurement screen See the following figure The Hold function can also be toggled on and off with the F6 key on your keyboard or by selecting the Hold window on the basic measurement screen Putting the instrument in hold allows windows operations such as screen repaints and other software applications to run faster X Indicates Hold Activated HP850SB Lightwave Polarization Analyzer File Edit Measurement Display System Help 9 090 dBm Glear Trace Cal 1550 0 nm Markers Clear Markers si s2 s3 0 02 0 08 0 98 Rotate 2pt Ref 3pt Ref Apuly Be Home
230. le created by the HP 8509 to add fields and tables which are updated by other stages in the production process or by sales or shipping departments See the database read me file in the HP 8509A B program group for additional information and for a map of the HP 8509A B database Printing Saving and Recalling 4 7 Measurement Results and Instrument Configurations Saving Measurements After performing a measurement the results can be saved as summarized in Table 4 1 Use FILE SAVE menu selections shown in the figure below The measurement FILE menus for the PMD measurements are located within the PMD JME and PMD wavelength scanning measurement sections of this manual All other measurement FILE menus are located in the analyzer s main window as shown in the figure below HP8509B Lightwave Polarization Analyzer MIES Edit Measurement Display System Help Load gt User Configuration Print Timed Measurement to Database Database EEDEN Exit Jones Matrix amp PDL Jones Matrix pq744b_c Figure 4 4 The Save Menu ADDITIONAL INFORMATION Refer to Figure 4 4 You must make a measurement before the lightwave polarization analyzer allows you to save data Once you make a measurement the corresponding command in the Save menu appears in black lettering 4 8 Printing Saving and Recalling Measurement Results and Instrument Configurations Procedure 1 To save measurement resu
231. le only in the HP 8509B See the PMD WS Concepts section titled Polarizers for details Select the appropriate units for the measurement results If the fiber is long enough to exhibit strong polarization mode coupling you may wish to express the result in units of time per root length Format Delay sqrt L The new units are listed and all values are updated on the Y axis of the graph and in the measurement summary bar Displaying and Printing Data in Tabular Format HP8509 Graphs lt 1 gt PMD WS 1460 0 1560 0 0 5 Edit File Measure Format EJEA Window Annotation F9 Cursor Data Symbols Grid Mark Curve Features Tabular Data pq7162_c Figure 2 44 Displaying Data in Tabular Format Display the tabular measurement data by selecting Display and then Tabular Data from the Graphs main window menu A text box fills the Graphs window overlaying the measurement graph The text box lists information from the measurement annotation area the values in the measurement summary and a list of wavelengths at which optical measurements were performed along with the DGD values derived from each pair ADDITIONAL INFORMATION You can add your own notes to the text All of the standard key board and mouse editing features are available Use the mouse to place a text insertion point anywhere in the document and then type the desired text Text may be selected using the drag features of t
232. lign another PMF cable connect it to the analyzer and repeat the previous procedure 2 72 Making Measurements Polarization Maintaining Fiber Launch Concepts Explanation of Polarization Maintaining Fiber Launch Mathematics The dB extinction ratio of the PMF launch is calculated according to the radius R drawn on the Poincare sphere as shown in the following figure Poincare sphere Launch alignment Py Power in A principal 12 21 Y axis Px Power in principal X axis PMF Extinction Ration 10 Log 1 A 1 A where A 1 R2 1 2 a cos R A af2 physical angle between he axis of the PMF and the input linear light pq762b _c Figure 2 81 How PMF cable launch extension ratio is calculated Making Measurements 2 73 Polarization Reference Frame Polarization Reference Frame A polarization reference frame can increase the accuracy of polarization measurements by isolating the test device response and minimizing the effect of the test system including the optical cables used to connect the test system to the test device This is valuable for measurements where the response of the test device would otherwise be hidden by the response of the test system as illustrated in the following figure The following figure illustrates the response of a linear polarizer being rotated from 0 degrees to 90 degrees The expected response Calibrated Test trace along the equator of the Poincare
233. lt title for the measurement is provided The title is made up of the measurement type and the date and time It is a unique name but you may wish to edit it for your own purposes PMD WS Concepts Polarization Mode Dispersion Polarization modes PMD is a fundamental property of optical fiber and components by which any lightwave signal is split into two polarization modes that travel at different speeds In effect single mode fiber is bimodal with respect to polarization The difference in propagation time between the two polarization modes is called differential group delay General effects Because of PMD lightwave pulses launched partly into each of the polarization modes broaden as they propagate degrading the distinction between pulses In addition light from a spectrally wide source may become partly depolarized under the influence of large values of differential group delay Finally transmitter laser frequency chirp in combination with PMD in a transmission path can cause a transmitted signal to vary in polarization state as a function of time and signal intensity If polarization dependent loss is present in the system the polarization variation is converted to amplitude variation This effect causes composite second order distortion in cable television systems 2 42 Making Measurements PMD Measurement Wavelength Scanning Method Mode coupling Mode coupling is the term given to the coupling of optical energy between po
234. lts first make the desired measurement 2 Save the resulting data by selecting File Save 3 Select one of the following items a Timed Measurement to Database b Timed Measurement as Text C Jones Matrix amp PDL Jones Matrix 4 You will see either the Save As Text File window Figure 4 5 or a dialog box for adding the measurement to the database Save As Text File File Name Directories OK Bloons c hp8509b cn gt hp8509b Cancel List Files of Type Drives Text Files TXT y c ms dos_5 pq7129_c Figure 4 5 The Save As Window 5 Specify the drive path and filename by typing it in the File Name window or type the filename in the File Name window and use the mouse to select the drive and the directory The filename will have the default extension txt 6 Once you have named the file drive and directory select OK and the measurement data will be stored Printing Saving and Recalling 4 9 Measurement Results and Instrument Configurations Recalling Measurements After saving measurement results you can recall and view the results as summarized in Table 4 1 Recall the results using the HP 8509 system software and or separate word processor spreadsheet or database program as noted HP 8509 procedures are discussed in detail below Numeric word processor spreadsheet or database file formats are discuss
235. ly increases the accuracy of polarization mode dispersion PMD measurements of devices and components that can t be directly connected to the HP 8509B Optical Output without using additional optical interfacing PMD cascading techniques are used in bulk optical applications to separate the PMD response of the test device from the cloaking effects of the combined PMD response of the fixtures and adapters between the HP 8509B Optical Output and the input to the test device Fiber optical applications benefit as well because the response of optical source interfacing isolators connectors and cables of the test system represented by DCO in the figure shown below can be mathematically removed from the total PMD response leaving behind the response of the targeted test device DUT in the figure shown below This technique is most effective when the PMD response of the test device DUT and the undesired PMD of the optical source interfacing DCC are approximately the same and individually greater than 100 fs HP 8509B External Source Polarization External Source Optical Optical O Input Output Input z Y ay Tunable Lightwave Source o be calibrated out Connector DCO pq7159_c Figure 2 28 Setting up the System Attach the device to be calibrated out DCO between the Optical Output and the Optical Input of the HP 8509B as outlined in the following illustration Tape down the pigtails so that o
236. lyzer operating system software to make a PDL Jones Matrix measurement Setting up the System Connect your measurement system as outlined in the following illustration Begin by connecting the thru cable as shown in the following figure ACCURACY ENHANCEMENT NOTE The fiber cable leading from the external source to the HP 8509A B EXTERNAL SOURCE INPUT must be taped down to prevent any movement after source polarization has been adjusted Movement of this source cable may jeopardize measurement accuracy HP 8509B External Source Polarization External Source Optical Optical Input Output Input ES Lightwave Source l J DUT Q Q Tunable Thru Cable pq761b_ce Figure 2 49 Measurement Setup 2 46 Making Measurements PDL Measurement Jones Matrix Method External Source Preparation Before performing the measurement you must select an optical source The following procedure will guide you through the process HP8508B Lightwave Polarization Analyzer File Edit Measurement Display FEE Help Optical Source Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs Reference Frame Info Operation Verification pq780b_c Figure 2 50 System Menu Select System from the main menu and then select Optical Source Optical Source Setup rOpticalSourceSelection r Power HP8168A HP IB A On Off HP IB A
237. m is ready to make your first measurement For our purposes we are going to measure a quarter wave retarder oriented 45 to horizontal The measurement has two parts 1 A polarization reference frame is established in the open beam by mathematically removing the birefringence and residual PDL of the path from the reference polarizer to the polarization receiver inside the HP8509A B 2 The test device is inserted in the open beam Jones Matrix measurement window is opened and the device is measured at the same three reference polarizer angles used to create the reference frame Establish the Polarization Reference Frame The Jones matrix of the test device is measured and expressed within the context of the angular relationship of the test device to the first or horizontal reference polarizer position In some applications it may be able to align a particular axis of the test device with this polarizer orientation 1 Place the reference polarizer in the open beam allowing enough space following the polarizer to insert the test device 2 Rotate the polarizer to the position you wish to define as horizontal Select marker A 2 62 Making Measurements Jones Matrix Measurement ACCURACY ENHANCEMENT NOTE From this point on the fiber path and optics between the reference polarizer and the HP 8509A B must not move Movement will degrade measurement accuracy 3 Rotate the reference polarizer by 60 degrees Select marker B
238. mand An example is given below OUTPUT 729 JONES MEASURE END OUTPUT 729 JONES END ENTER 729 String The device command JONES MEASURE directs the HP 8509 to conduct a Jones matrix measurement of an inserted DUT The results are requested through the JONES command 10 14 Programming The data is transferred through the ENTER remote command and placed in a string variable named String There are two types of HP IB commands which request data from the HP 8509 system Some commands such as JONES MEASURE cause a measurement to be conducted by the HP 8509 while others request information regarding a particular instrument state As an example of the second type execute OUTPUT 729 DRIVE END ENTER 729 String The command DRIVE causes the HP 8509 system to return the letter of the drive which is currently set up for data transfers This letter is read from the HP 8509 into the string variable named String The IBASIC statement ENTER addresses the HP 8509 to talk This allows the HP 8509 to transmit information to the controller PC Specifically the ENTER statement takes the stream of binary data output by the HP 8509 and reformats it back into an ASCII string through the HPIB2DDE application The controller PC places the data transmitted by the HP 8509 into the string variable listed in the ENTER statement The string variable dimensions must match the data the HP 8509 has to transmit If the variable is not sufficiently lar
239. mand is supported in this version However it may not be supported in future versions of the HP 8509A B Optical Source Setup The window used to adjust the optical source laser parameters Polarization Dependent Loss The loss or gain variation of an optical signal due to polarization Polarization Mode Dispersion Average DGD over wavelength range A series of characters The codes for string characters range from 0 to 128 and are the same as those defined by the ASCII character set Only the printable characters codes 32 to 126 are used in HP IB bus communications for messages Codes 13 10 lt CR gt lt LF gt are often used for EOL end of line see HP IB configuration and setup information Tunable Laser Source HP 8167 8 are tunable laser sources Tunable Laser Source controlled by analog voltage output VOUT A of the HP 8509A B Using a VTUNE source prevents the use of the analog outputs for any other purpose Wavelength Scanning A method used to determine the polarization mode dispersion of an optical system by examining cyclical characteristics of the output polarization using the normalized Stokes parameters over a wavelength range Programming 10 25 Changes from Version 1 2 Software Every effort has been made to assure the compatibility of version 2 0 remote commands with version 1 2 remote commands In some instances this has not been possible due to fundamental changes in the design of the HP 8509 software
240. measurement problems provides information about the items in the File menu provides a description of the items in the Display menu provides a description of the items in the System menu shows each control and display the path to reach it and a description of what it does provides information on caring for the analyzer s connectors provides licensing safety regulatory cleaning and environmental information provides guidance for programming problems provides performance specifications and characteristics of the lightwave polarization analyzer provides an alphabetized list of terms and their definitions provides an alphabetized list of terms with page number references This is a subject index provides specialized background information Getting Started 1 3 The Main Menu This chapter describes the functions that are available from the basic measurement screen Subsequent chapters describe functions that are accessed through the main menu shown in this screen HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 dBm Clear Trace ld Gal 1550 0 nm Markers On Rotate 2pt Ref 3pt Ref Apply Ref Home pq716b_c Figur
241. ment be performed once a week or once at the beginning of a long series of tests Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs Reference Frame Info Operation Verification Figure 2 3 System Menu pq780b_c To set up the optical source select System from the main menu and then select Optical Source You may also set up the optical source by selecting the A button in the upper right hand corner of the main window Optical Source Setup rOpticalSourceSelection HP8168A HP IB HP IB Address 724 Wavelength cw r Power On Off Level uWatt y 1551 0 Cancel Figure 2 4 Optical Source Setup 2 4 Making Measurements pq71b_c PMD Measurement Jones Matrix Eigenanalysis Method Select the external tunable laser source and set the wavelength to the approximate center of the widest range you expect to use in your JME PMD measurements Use the default power level or set as desired If the screen on your computer looks similar to the previous illustration select Done HP8509B Lightwave Polarization Analyzer File Edit Measurement Display GGS Help Optical Source F8 Zero F9 Calibrations F11 Shutter Averaging Range Analog Outputs Reference Frame Info Operation V
242. ment procedure illustrates the simplest and most straightforward path in using the HP 8509A B Lightwave Polarization Analyzer operating system software to make a PDL Power Max Min measurement Setting up the System Connect your measurement system as outlined in the following illustration The HP 11896A Polarization Controller is recommended for this application ACCURACY ENHANCEMENT NOTE Avoid fiber movement to eliminate errors due to bending loss HP 8509B External Source Polarization External Source Optical Optical D Input Output Input Q Q Q Tunable Lightwave Source 0000 Automatic Polarization Controller HP 8509A Optical Input ES Automatic Tunable Polarization Controller Lightwave Source pq7152 c Figure 2 60 Measurement Setup Making Measurements 2 53 PDL Measurement Power Max Min Method External Source Preparation Before performing the measurement you must select an optical source The following procedure will guide you through the process Zero F9 Calibrations F11 Polarizers F12 Shutter Averaging Bange Analog Outputs Reference Frame Info Operation Verification pq780b_c Figure 2 61 System Menu Select System from the main menu and then select Optical Source Optical Source Setup rOpticalSourceSelection r Power HP8168A HP IB A On Off HP
243. ment window or by double clicking on the PMD Statistics Making Measurements 2 19 PMD Measurement Jones Matrix Eigenanalysis Method icon in the HP 8509 Program Group in the Program Manager The PMD Statistics function is actually provided by a separate software application PMD Statistics Edit Format Help Add from Selected JME Window Add from Database Add from Text File Load Statistics Print Bitmap Print Data Exit Mean Last file added Minimum Total size Maximum Number of bins Maxwell a param pq7123 c Figure 2 24 PMD Statistics File Menu The File menu Selecting File from the main PMD Statistics window will drop down a menu structure The following is a brief description of the elements of the File menu Add from Selected JME Window F2 The data from the current JME window will be shown in the Differential Group Delay versus the Wavelength graph The individual measurement points of this graph are used to build the Cumulative Differential Group Delay Histogram and to derive the other statistics listed in the PMD Statistics window 2 20 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Add from Database F3 Selecting this menu item will cause the PMD Statistics Database Interface window to open You can then load the measurement results from a previously stored measurement into the PMD St
244. mes called a polarization filter which passes light of a selected polarization state port An input or output point of a circuit or device power See irradiance radiant power preset 1 A predefined instrument state which also runs a self test in the analyzer 2 The action of pushing the PRESET key reference frame See polarization reference frame reference polarizer Creation of a polarization reference frame requires a reference polarizer Measurements of two or three angular rotations of the polarizer are required reflection The phenomenon in which a traveling wave that strikes a discontinuity is returned to me original medium refraction The bending of light as it passes between materials of a different refractive index remote A mode of operation where an instrument is controlled by another device or computer via the HP IB or from the HP 8509 s computer via DDE return loss The ratio in dB between power incident upon and power reflected from a device Represented by a p symbol self test A group of tests performed at power up or preset to verify proper instrument operation shutter A device which can block the optical beam upon command signal to noise ratio The ratio of signal to noise measured in decibels and indication of signal quality in analog systems Glossary 9 single mode Containing only one mode Beware of ambiguities because of the difference between transverse and longitudinal modes A
245. mmand was documented for Version 1 x code it was never implemented This command is NOT VALID Command will not be available in future versions Plan your programming to use the alternate command Single Points lt NumPoints gt Version Returns the current version number of the HP 8509A B software WaveScan Shows the PMD WS window on the display Be sure to send WaveScan before sending any other WaveScan commands The query returns the polarization mode display PMD values of the measurement as follows Current wavelength nm Total PMD PMD for sj PMD for s2 PMD for s3 Note The running totals are returned The measurement may not be complete WaveScan Analysis Returns the type of analysis used to calculate the polarization mode display PMD Valid values are Peaks FullScan Peaks FirstToLast Extrema FullScan Extrema FirstToLast 10 58 Programming WaveScan Analysis Extrema Peaks FullScan FirstToLast Sets the type of analysis to use in calculating the polarization mode dispersion PMD WaveScan Atten lt dBm value gt The attenuation for the HP IB tunable laser source The query returns the attenuation in dBm Using lt dBm value gt sets the attenuation for an HP IB tunable laser source If the attenuation setting is not valid for the TLS the command fails DDE Only WaveScan Clear Aborts a PMD WS measurement process This command
246. mode coupled devices long fibers modulation A controlled variation with time of any property of a wave for the purpose of transferring information multimode Transmits or emits multiple modes of light multiplexer A device that combines two or more signals into a single output NA Numerical aperture nanometer 107 meters nanosecond 107 seconds normalize To subtract one trace from another to eliminate calibration data errors or to obtain relative information Normalized Stokes Parameters The parameters displayed in the table at the lower left corner of the main window are the normalized Stokes parameters referred to as a group as the normalized Stokes vector The normalized Stokes parameters sl s2 and s3 are derived by dividing the Stokes parameters S1 52 and 3 respectively by the total optical power S0 numerical aperture NA the sine of half the angle over which a fiber can accept light This is multiplied by the refractive index of the medium containing the light but that equals 1 for air the normal medium in which NA is measured optical cable A fiber multiple fibers or a fiber bundle in a structure fabricated to meet optical mechanical and environmental specifications in an installed lightwave system Glossary 6 optical coupler 1 A device whose purpose is to distribute optical power among three or more ports 2 A device whose purpose is to couple optical power between a waveguide and a source or
247. n of a test device using the Jones matrix PDL JM method This method measures the absolute or relative PDL of a lightwave component and displays the results as shown in the following figure 6 PolarizationDependence Polarization Analyzer System Hel Internal External ar Trace 1 zal 1539 0 nm Delta Delta Max Min No reference frame applied Measurement at 0 0 done Measurement at 60 8 done Measurement at 120 4 done Measure Clear Restart Polarization Dependence Delta 0 15 dB Jones values Pol Dep values O py Rotate Done Home pq774b_c Figure 2 48 Example of a Jones matrix PDL measurement data display Typical test devices for this method include EDFAs couplers isolators optical connectors and long fiber cables Consider the following aspects of this method when deciding whether to use PDL JM or the PDL Power Max Min method m Measurements are typically completed in two to three seconds m Measurement uncertainty is typically 0 1 dB m Measurement range is 3 0 dB Operation is completely automatic Making Measurements 2 45 PDL Measurement Jones Matrix Method Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509B Lightwave Polarization Ana
248. n on the Optical Source window Source Wavelength The source wavelength is displayed next to the A function Cal The Cal function indicates whether or not a user performed calibration has been applied If a wavelength calibration has been applied the word Cal appears in bold black lettering If a calibration has not been applied the word Cal appears in gray lettering Refer to The System Menu chapter of this document for instructions on performing a wavelength specific calibration 1 12 Getting Started Making Measurements This chapter contains information on the following measurements Jones Matrix Figenanalysis Method PMD Measurement Wavelength Scanning Method PMD Measurement Jones Matrix Method PDL Measurement Power Max Min Method PDL Measurement Jones Matrix Measurement Polarization Maintaining Fiber Launch Polarization Reference Frame Measurement State of Polarization Measurements Conventions The measurements in this chapter tend to follow this outline m Description of the measurement and an example data display m Performing a basic measurement o Setting up the System o Source Preparation oO Making the Measurement a Manipulating the Measurement Results m Specialized Measurements m Measurement Specific Concept Information This represents a button that can be selected on the computer screen to perform an action Menu Item This indicates a menu item that can be sel
249. ncel the command CONFIRM Q Load PRESET configuration OK Cancel pq736b_c Figure 4 9 The Preset Confirmation Window 4 16 Printing Saving and Recalling Measurement Results and Instrument Configurations Saving a User Configuration You can save any instrument configuration to a file for later use This is useful for recalling the configuration of an instrument setup you use frequently MIES Edit Measurement Display System Help HP8509B Lightwave Polarization Analyzer User Configuration Print Database Exit pq738b_c Figure 4 10 The Save Menu Procedure To save a particular configuration first set the lightwave polarization analyzer to the configuration you want to save and then follow the steps below 1 Select File Save from the main HP 8509 menu 2 Select User Configuration 3 The Save As Configure File window opens See the following figure 4 Enter the drive path and filename by typing it in the File Name box or by typing the filename in the File Name box and using the mouse to select the drive and directory The filename will have the default extension cfg 5 Select OK and the file is stored Give your file File Name aname Save File as Type Directories c hp8509b Save As Configure File OK Den E hp8509b Cancel Drives Con
250. nction or curve is described by the formula f Ar 2 Apa TA a where delta tau is the independent variable corresponding to the value of DGD in this application Alpha is the single parameter which specifies the shape of the Maxwell curve The expected value of a Maxwellian probability function is given by alpha 8 pi 1 2 The peak or mode of the distribution occurs at alpha 2 1 2 micron 107 meters modal dispersion Dispersion arising from differences in the times that different modes take to travel through multimode fiber mode An electromagnetic field distribution that satisfies theoretical requirements for propagation in a waveguide or oscillation in a cavity e g a laser Light has modes in a fiber or laser Glossary 5 mode coupling The phenomenon which occurs when light travels through a device that consists of sections having different polarization modes As an example consider several lengths of PMF spliced randomly together Light in the principal modes of the first section does not exactly align with the second section and so on As a result each mode is continually split or coupled into new modes This phenomenon gives long fiber DGD its strong wavelength dependency mode coupling factor A parameter used in the wavelength scanning formula to account for the wavelength dependence of the principal states of polarization Use the value 1 0 for non mode coupled devices most components and 0 82 for highly
251. ndow continued Control or Data Path Description PDL Power max min Main window Measurement menu Enables user to set up and perform a PMD measurement based on the variation in output power of the test device as its input polarization state is changed May be performed with manual or automated polarization adjuster at input of the device Polarization adjustment may be random or systematic PM Fiber launch Main window Measurement menu Provides graphical tools for launching light onto a principal axis of polarization maintaining fiber Provides a measurement of the resulting extinction ratio PMD Wavelength scanning Main window Measurement menu Enables user to set up and perform a PMD measurement using the wavelength scanning method PMD Jones matrix eigenanalysis Main window Measurement menu Enables user to set up and perform a PMD measurement using Jones matrix eigenanalysis Poincare sphere display Main window Describes the state of polarization of the polarized portion of the optical signal Polarizers Main window System menu Provides access to the internal polarizers used in Jones matrix based measurements Also allows selection of internal or external polarizers and entry of the angles of external polarizers Power display Main window Displays the power level of the optical input See the Display menu for dBm versus Watts selection Pre
252. ndow v Delay Delay L Delay sqrt L Fiber Length Avg Median Max Delay gt Analysis Extrema Full Scan Minimum Feature Size Extrema First to Last Mode Coupling Factor k Peaks Full Scan y Polarizer A Peaks First to Last Polarizer B Polarizer C No Polarizer pq7163_c Figure 2 43 Changing the Measurement Format Select Format from the Graphs window menu to access the measurement formatting functions For a discussion of PMD units see the section by that title in PMD WS Concepts m Delay Causes the PMD values in the Measurement Summary Bar to be displayed in picoseconds Delay L Causes the PMD values in the Measurement Summary Bar to be displayed in picoseconds per kilometer of fiber length Delay sqrt L Causes the PMD values in the Measurement Summary Bar to be displayed in picoseconds per root kilometer of fiber length Fiber Length This menu selection lets you enter the length of the fiber you have just measured Avg Median Max Delay The PMD value displayed in the left most position of the Measurement Summary Bar may be chosen as the average median or maximum value of PMD derived from the three graphs sl s2 and s3 m Analysis This menu item allows selection of the method by which the wavelength scanning response curves are analyzed The instrument can be set to count peaks or extrema peaks plus valleys and to use the endpoints of the wavelength range or the
253. ne circle 8 Move Circle Resize Circle Extinction ratio Cone half angle dB 0 72 Done Clear Markers si s2 s3 0 55 0 51 0 63 Rotate 2pt Ref 3pt Ref af Home pq763b_c Figure 2 80 PM Fiber Launch Alignment Window m Slightly stress the PMF cable by pulling or heating it until an arc appears on the Poincare sphere Be sure that the arc is on the front of the sphere as indicated by a red line If the arc is on the back side of the sphere use the Rotate function on the lower right side of the main window m Place three points along this arc by using the mouse pointer and then clicking the left mouse button m Select the Center button to center the display m Rotate the fiber chuck until the active point on the Poincare sphere approaches the center of the circle m Use the Poincare display Zoom and PM Fiber Launch Center functions to optimize the view of the arc m Slightly stress the PMF cable by pulling or heating it until an arc appears again m Select the New Circle button place three points on the arc using the mouse pointer m Continue the previous steps until the value in the dB extinction ratio window is maximized m Select the Done button to finish this procedure a To a
254. ng a measurement point The wait may be increased for the starting wavelength to allow the source to reset from a previous measurement Start wavelength entry box Optical source setup window The first wavelength of a PMD measurement series Stop wavelength entry box Optical source setup window The last wavelength of a PMD measurement series Turn laser off Optical source setup window Turns both of the internal lasers off Voltage tuned source selection Optical source setup window Sets up the instrument for use of an external voltage tuned source Vtune entry boxes Optical source setup window In PMD measurement modes when an external voltage tuned source is used allows user to set up the tuning voltage profile Also displays the voltage change corresponding to a single wavelength delta 7 8 User Interface Reference Calibration Calibration is provided to optimize the accuracy of the HP 8509A B at the current wavelength and with the current source Calibration is optional The term calibration in the following chart refers only to the wavelength calibrations performed by the user and not to the calibration constants stored in instrument ROM at the factory Table 7 3 Calibration Control or Data Path Description Apply calibration on off Main window System menu Calibration When this control is in the On condition calibration is ap
255. ng the month of May Since the HP 8509 database is a relational database it allows a user to filter out all the unwanted data and view only those measurements that are of interest In addition Microsoft Access also has many mathematical functions built in so that the measurements can be analyzed statistically This is helpful in a production environment where Statistical Process Control SPC can spot production trends early and lead to improved processes The Microsoft Access database file created by the HP 8509 can be extended by the user to add fields and tables which are updated by other stages in the production process or by a sales or shipping departments dB An abbreviation for Decibel A relative unit of measure dBm Power in decibels referenced to 1 mW default A known set of conditions used by the analyzer in the absence of user defined conditions degree of polarization The degree of polarization DOP describes the percentage of the total power of an optical signal that is in polarized form that is the portion that can be described systematically in terms of components having determined phase DOP is given by the square root of the sum of the squares of the normalized Stokes parameters It is also given by the square root of the sum of the squares of the Stokes parameters all divided by the optical power detector A device that generates an electric signal when illuminated by light The most common in fiber optics are pho
256. nly the final portion of the output pigtail of the DCO will be allowed to move when the final test device DUT is inserted Movement of the DCO or movement of its input pigtail between the calibration and measurement causes measurement error Making Measurements 2 25 PMD Measurement Jones Matrix Eigenanalysis Method HP 8509B External Source Polarization External Source Optical Optical Input Output Input Y p Y Tunable Lightwave Source calibrated out DCO pq7154_c Figure 2 29 Measurement Setup Making the Measurement 1 Prepare the external source to provide a circular state of polarization by following the procedure described in the External Source Preparation portion of this JME PMD section 2 Select Measurement from the main window menu selections and then PMD Jones Matrix Eigenanalysis F2 3 Set up the optical source for the desired wavelength range and the number of points then select Done 4 Select Measurement from the graphs main window menu selections and then Gascaded Device Avg DGD ME ps Current i Max i Vio A 4 Connect external laser and thru path Start Measurement Cascade 2 Set conditions with Optical Source Setup Optical Source Setup Start Calibration 3 Select Start Calibration Done pq7156_c Figure 2 30 Measurement Start 5 Note that the measurement control area at the bottom
257. not required for HP 8509 operation The System Menu 6 5 The HP 8509A B Lightwave Polarization Analyzer has a built in calibration feature that allows you to calibrate your instrument for specific wavelengths The purpose of using the calibration feature is to Optimize performance when using a source whose wavelength is uncertain to greater than 1nm m Optimize performance when using a source with broad optical spectrum such as a Fabry Perot laser or an LED m Minimize any uncertainty caused by ambient temperature change or instrument aging The illustrations in this section show windows that appear on the HP 8509B interface Remember that the HP 8509A does not come equipped with an internal source ADDITIONAL INFORMATION The calibration must be performed with the source that will be used to make measurements Follow the Fixed Wavelength Source instructions when calibrating with sources which will not be tuned Follow the Tunable Wavelength Source instructions when you expect to use a single tunable source at a number of different wavelengths This avoids confusion with calibrations taken at the same wavelength s using sources that have other spectral characteristics 6 6 The System Menu Calibrating For Use With a Fixed Wavelength Source Make sure the instrument has warmed up for at least one hour and then zero the instrument Refer to Zero in this chapter for information on how to zero the instrument
258. nt of external source polarization ACCURACY ENHANCEMENT NOTE The fiber cable leading from the external source to the HP 8509B EXTERNAL SOURCE INPUT must be taped down to prevent any movement after source polarization has been adjusted Movement of this source cable may jeopardize PMD measurement accuracy HP 8509B External Source Polarization External Source Optical Optical Input Output Input Tunable e oy k Lightwave Source J DUT Q Q Q Thru Cable pq761b_ce Figure 2 2 Measurement Setup Making Measurements 2 3 PMD Measurement Jones Matrix Eigenanalysis Method External Source Preparation Before performing the PMD JME measurement external source polarization must be adjusted via the two knobs on the front panel of the HP 8509B The following procedure will guide you through the process ADDITIONAL INFORMATION The 8509B uses an internal three state switchable polarizer to condition the light before it is applied to the device under test Adjustment of external source polarization via the front panel knobs is done to provide a roughly circular state of polarization within the polarizer assembly so that all three polarizers will pass high levels of optical power This adjustment typically need not be repeated unless the front panel knobs or the fiber connecting the tunable optical source and the HP 8509B have moved However it is recommended that the adjust
259. nto the file lt filename gt For path information on filename see Command Syntax at the beginning of this chapter Save Disper lt filename gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Disper Save lt filename gt Save Jones lt filename gt Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Save PolDep lt filename gt Save PolDep lt filename gt Saves a Jones matrix measurement polarization dependent loss measurement to the file filename The file format is lt Absolute Measurement Flag gt lt PDL Delta gt lt PDL Max gt lt PDL Min gt lt JOO real gt lt j00 imag gt lt JO1 real gt lt jO1 imag gt lt J10 real gt lt j10 imag gt lt J11 real gt lt j11 imag gt Where lt Absolute Measurement Flag gt is 1 if the measurement is absolute and 0 if the measurement is relative In the case of a relative measurement lt PDL Max gt and lt PDL Min gt are both 0 For path information on filename see Command Syntax at the beginning of this chapter Programming 10 51 Save Single lt filename gt Saves a timed measurement to the filename The file format for the data is lt Wavelength of Source gt lt 50 milliWatts gt lt S1 gt lt S2 gt lt S3 gt lt DOP gt one line for each point
260. nu only provides information about the software revision of the PMD Statistics software which is a separate application The Annotation Area At the bottom of the PMD Statistics window are a group of numeric displays which are described below Mean This display shows the mean or average value of the data points which are displayed in the DGD vs Wavelength graph The mean is not affected by selection of the X axis scale of the histogram Minimum Maximum These displays show the minimum and maximum values of DGD of the data points which are displayed in the DGD vs Wavelength graph These values are not affected by selection of the X axis scale of the histogram Last file added This display shows the number of DGD measurement data points which were added with the last add operation The number indicates the size of the original measurement data set and is not affected by the choice of X axis limits of either of the graphical displays Total size This display shows the cumulative size of the statistical data set when the DGD versus Wavelength graph is in the Wavelength Range Auto Range mode Subset size This display replaces the Total size display when the DGD versus Wavelength graph is placed in the Fixed Range mode This parameter indicates the number of DGD measurement data points that fall within the displayed wavelength range Number of bins This is an editable display which shows the number of categories or buckets into whic
261. o s1 82 837 Sx is a standard Stokes parameter while sx 5x So is a normalized Stokes parameter Electric Fields and Polarization m The electric field of a lightwave can be resolved into two arbitrary orthogonal vector components Ex t and Ey t The relative magnitude and phase of these E field vector components determine the polarization of the signal Polarization changes with Ex t and Ey t Direction of lightwave propagation pa755b_c Figure 2 91 Polarization changes with Ex t and Ey t 2 86 Making Measurements State of Polarization Measurements a Elliptical Displays of Polarization Any state of polarization can be created by adjusting the magnitude and phase relationships of the Ex t and Ey t components of a lightwave signal All polarization states can be shown as unique elliptical displays Several classical examples are shown in the following figure Notice the E field magnitude and phase relationships for each case Horizontal Right hand Right hand Linear _ Circular Elliptical Polarization Polarization Polarization Ex 1 00 Ex 1 00 Ex 1 00 Ey 0 00 Fy Ey 1 00 Ey Ey 1 00 Fy Ag 45 00 Ag 90 00 A 0 00 Ex Ex pq756b_c Figure 2 92 Elliptical displays of polarization where a length of semi major axis b length of the semi minor axis w the elliptical angle a azimuth or tilt of the X Y axes
262. o part of the signal path after the reference polarizer can be moved without invalidating the Polarization Reference Frame ACCURACY ENHANCEMENT NOTE A polarization reference frame can be used with external reference polarizers to improve PDL and Jones matrix measurement accuracy The polarization reference frame however is ignored and has no effect on HP 8509B PMD measurements CAUTION Observe proper Laser Safety Refer to the Safety and Regulatory Information chapter in this manual Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual Making Measurements 2 77 Polarization Reference Frame Additional Measurement Applications 2pt and 3pt Polarization Reference Frames The 3pt frame of reference mathematically removes birefringence and polarization dependent loss from the path between the reference polarizer and the polarization analyzer receiver This method requires that the reference polarizer be set precisely to the angles listed in the polarizers display found by selecting the Polarizers from the System menu in the main window The 2pt frame of reference mathematically removes only birefringence from the path between the reference polarizer and the polarization analyzer receiver This method requires only two orientations of the polarizer The angle between the two reference orientations is not critical but an angle of 45 60 degrees is suggested Followin
263. o to full counts The connector assignments are listed in the following table Table 6 2 Analog Outputs for Raw Diode Currents Mode Stokes Channel Connector 0 A 1 B 2 C 3 D 6 24 The System Menu Reference Frame Info Opening the Reference Frame Information Window Open the Reference Frame Information window by selecting System Reference Frame Info If a reference frame has not been defined the following window appears Reference Frame Info No reference frame has been defined pq714b c Figure 6 18 No Reference Frame Defined Window If a reference frame has been defined a window will appear with the following information m The type of reference frame two or three point and whether or not it has been applied a The polarization angle two point reference only or the transmission ratio three point only a The quality of the reference frame one of the following good fair poor very poor The System Menu 6 25 Following are examples of the information given when a two or three point reference frame has been defined Reference Frame Info Two point frame currently not applied Polarization angle is 59 1 Frame quality is good pq7i5b_c Figure 6 19 Two Point Reference Frame Information Window Reference Frame Info Three point frame currently not applied Transmission ratio is 1 0 Frame quality is good pq7i3b_c Figure 6 20 Three Point Refer
264. of the graphs window a yellow Cascade banner appears Select Start Calibration or New Thru Cal whichever appears at the bottom right portion of the graph window 2 26 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method HP8509 Graphs lt 2 gt PMD JME 1500 0 1550 0 2 0 File Edit Measure Format Display Window 00 1500 Wavelength nm 1550 GUSE 0 2163 PESO 0 21702 VES 0 22023 Wiley 0 21421 98 0 00158 Measurement Complete 1 Insert New Device 2 Select Start Measurement Start Measurement Cascade Optical Source Setup New Thru Cal Clear Restart Done pq7157_c Figure 2 31 Thru Calibration 6 The resulting measurement characterizes PMD effects of the DCO When the thru calibration is complete select Continue The calibration may be redone by selecting New Thru Cal Perform this only if the fiber or the DCO has moved during the calibration HP 8509B External Source Polarization External Source Optical Optical D Input Output Input 2 ay Tunable Lightwave Source DUT AD oOo rl UN Device to be calibrated out Connector DCO pq7159_c Figure 2 32 The Measurement 7 Remove the output pigtail of the DCO from the optical input of the HP 8509B taking care to move only the output pigtail and not the DC
265. og On Pick File Execute Cmd Get Data Exit r HP IB To LPA To HP IB Status HP IB card OPEN Aug 04 94 9 18 51 am EOL Address Cr Lf Controller Comma e Non Controller Data Separator HP IB Exit State Timeout 2 r Dynamic Data Exchange DDE Terminate DDE Link Param x from HP8509 O 1 2 3 Copyright O 1994 Hewlett Packard Company pq7167_c Figure 10 2 HP IB to DDE Gateway 10 6 Programming Command Line Setup Options The HP IB gateway program may be configured using command line parameters at runtime Two command line parameters are available and may be added to the HP IB gateway icon s properties This selection can be found by highlighting the icon by clicking once on it then selecting File Properties in the Windows Program Manager Add the command line parameter after the name of the program in the Command Line text box Errors Only Add this command line parameter to configure the HP IB gateway to record only HP IB bus errors DDE link errors Windows critical errors and HP8509 commands which did not return a status of PASS when Log On is checked If this parameter is not specified all bus transactions including errors are recorded in the log file During program execution this feature may be turned on and off
266. okes parameters the DOP value represents the average of the most recent N measurement samples external modulation Modulation of a light source by an external device gt Extrema Peaks and valleys in a measurement response curve as in the wavelength scanning PMD application femtosecond 10715 seconds fresnel reflection The reflection of a portion of incident light at the normal interface between two media of different refractive index graticule An electronically drawn grid on the CRT great circle A circular path on the Poincare sphere which is of the same diameter as the sphere itself This is the locus of the state of polarization of a lightwave in which orthogonal components are shifting in phase relative to one another hold An instrument feature that allows the user to suspend or halt temporarily the processing and display of new data Glossary 3 horizontal resolution The spacing of the horizontal data points taken over the full sweep HP IB An abbreviation for Hewlett Packard Interface Bus index matching compound A fluid with refractive index close to glass that reduces the refractive index discontinuities caused by air gaps index of refraction The ratio of the speed of light in a vacuum to the speed of light in a material usually abbreviated n initialize The process in which information locations are assigned to a disk insertion loss The power loss in a transmission system caused by the insertion of
267. on ellipse will become more circular as s3 approaches 0 90 Then un apply the 3pt reference before going on to do the JME PMD measurements Do not move the cable or the external source polarization knobs FOR MORE INFORMATION More information on State of Polarization SOP and Degree of Polarization DOP may be found in the glossary Making the Measurement At this point your measurement system is ready to make your first measurement For our purposes we are going to measure a optical isolator Remove the fiber thru cable connecting the optical output to the optical input on the HP 8509B Connect your test device between the optical output and the optical input Making Measurements 2 49 PDL Measurement Jones Matrix Method ACCURACY ENHANCEMENT NOTE Accuracy is affected by the PDL of the optical connectors the phys ical stability of the fibers during the test procedure the DOP of the source and the test signal power level Accuracy is also degraded when the DUT depolarizes the test signal This can occur when the differential group delay between Ex and Ey caused by the DUT is greater than the coherence time 1 line width of the source in Hz of the test signal CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual HP8509B Lightwave Polarization Analyzer File Edit AUESEVICUENS Display System Help PMD Jones Matrix Eigen
268. opy sphere display Main window Edit menu Copy bitmap Copies only the Poincare sphere display to the Windows clipboard as a bitmap Copy analyzer window Main window Edit menu Copy bitmap Copies the entire main window to the Windows clipboard as a bitmap Display update Main window Display menu Sets the number of Poincare sphere points which are displayed between successive updates of the power DOP and Stokes parameter displays DOP display Main window Displays the degree of polarization of the optical input 7 2 User Interface Reference Table 7 1 Main Window continued Control or Data Path Description Ellipse display Main window Describes the state of polarization of the polarized portion of the optical signal in elliptical format Hold Main window box or Main window Display menu check Freezes displays in current condition and stops the internal measurement process Allows graphical operations and other computer tasks to run faster Jones matrix Main window Measurement menu Enables user to set up and perform a measurement of the Jones matrix of the device under test This is a relative measurement Load gt Main window File menu Provides access to stored Timed Measurements and Configurations see User and Preset Configuration Mark current point Main window Display menu Enables a blinking dot to identi
269. or Apply the Calibration Calibrating For Use With a Tuneable Wavelength Source Select External Source and Input Wavelength Calibrate at the Selected Wavelength 4 7 4 8 4 9 4 10 4 10 4 11 4 11 4 13 4 13 4 13 4 13 4 14 4 16 4 16 4 17 4 17 4 18 4 18 5 1 5 2 5 3 5 4 5 5 5 6 5 7 5 8 5 9 5 10 5 11 5 11 6 1 6 1 6 2 6 2 6 2 6 3 6 4 6 4 6 4 6 5 6 7 6 7 6 8 6 9 6 10 6 10 6 11 Contents 5 Saving Wavelength Calibrations 2 2 2 eee 6 12 Applying A Calibration 2 2 2 ee 6 13 Applying a Calibration Lo 6 13 How to Tell If a Calibration is Applied a 6 14 Deleting a Calibration 2 u a a a a 6 15 Polarizers e 6 17 Opening the Polarizers Window e 6 17 Selecting a Polarizer So 6 17 Selecting an Internal Polarizer HP 8509B Only re 6 17 About Internal Polarizers 2 ee 6 18 Selecting an External Polarizer 2 2 we ee 6 18 Polarizer Angles and the Poincare Display So 6 18 Using the Shutter HP 8509B only Co 6 19 Averaging Ce 6 20 Opening the Averaging Window Se 6 20 Selecting Display Averaging 2 en 6 20 About Display Averaging ee 6 20 Selecting Measurement Averaging 2 ee 6 21 About Measurement Averaging oaoa e a a ee ee eo 6 21 Range o 6 22 Opening the Range Window e 6 22 Selecting Autorange AN 6 22 Selecting a Specific Gain State AN 6 22 About Range 6 22 Analog Outputs a 6 23 Opening
270. ou will not be prompted to but you must either cover the OPTICAL INPUT connector as in step 1 above or turn off your external source If the external source is connected to the HP 8509B External Source input its power will be blocked automatically so that no power will emerge from the Optical Output connector during the zeroing operation While the zeroing routine is running a green zero message will appear inside the power display in the upper left corner of the HP 8509 basic measurement screen and the mouse pointer appears as an hourglass When the zero message disappears and the mouse pointer changes back to an arrow the zeroing routine is finished 6 4 The System Menu Calibration The following information is provided in this section m Fixed wavelength source calibration m Tunable wavelength source calibration a Applying and deleting calibrations Calibration Source Type a Fixed A Tunable A Optical Source 4 Internal 1510 0 nm 1 Set external source to 1510 0 nm or select new Wavelength 2 Connect source to Optical Input 3 Select Calibrate Calibrate Calibrated Fixed Wavelengths 1311 0 nm Internal 1555 0 nm Internal Delete selection Done pq77b_c Figure 6 3 The Calibration Window ACCURACY ENHANCEMENT NOTE Calibration is optional Calibration is
271. ounding the light carrying core of an optical fiber It has a lower refractive index than the core Coatings may be applied over the cladding controller 1 A device capable of specifying the talker and listeners for an information transfer 2 An external computer connected to an instrument to control its operation core The central part of an optical fiber in which the light propagates coupler A device that connects three or more waveguide ends dividing one input between two or more outputs or combining two or more inputs into one output coupling The transfer of light in or out of an optical fiber Note that coupling does not require a coupler Glossary 1 cursor An electronically generated pointer which moves across the trace to identify point values or interfaces to a windows application cut off wavelength The shortest wavelength at which a single mode fiber carries only one mode database The HP8509A B provides users with two ways to save data for PMD JME PMD WS and Timed measurements Microsoft Access database and text files The data stored in HP 8509 text files is very limited and is primarily useful for importing data into a spreadsheet Database files are much more versatile A user can move the database file to another computer to do sophisticated analysis of the measurements and continue using the HP 8509 instrument For example a user may wish to examine the PMD measurements for a particular device type duri
272. outputs for the lightwave polarization analyzer are four BNC connectors located on the rear panel of the lightwave polarization analyzer They are labeled A B C and D Opening the Analog Outputs Window Open the Analog Outputs window by selecting System Analog Outputs DOP and Normalized Stokes Parameters Mode In this mode the BNC outputs provide the modes listed in the following table Table 6 1 Analog Outputs for DOP and Normalized Stokes Parameters Mode Parameter Connector Output Voltage DOP 0 to 100 A DOP 100 10 sl 1 to 1 B 10 to 10 s2 1 to 1 C 10 to 10 s3 1 to 1 D 10 to 10 The System Menu 6 23 Raw Photodiode Currents In this mode the BNC connectors provide signals proportional to the channel levels in the polarization receiver These signals are corrected for front end analog offset but are not processed by the receiver calibration or ranging algorithms These signals are developed from the output of the system ADC which means that their values are linearly related to channel levels within any particular range see Range earlier in this chapter In other words as the input power is increased from very low levels to high levels the rear panel outputs will rise in each range and then drop and again start to rise as the next range is switched in The output voltage covers the range of 10 volts to 10 volts as the ADC goes from zer
273. p8509DdeName amp lpadde 1b1lParam i LinkItem Param amp Format 1 amp lblParam 1 LinkMode LINK_MANUAL DoEvents Free Windows to allow it to do the Link Next 1 1b1Status LinkMode LINK_NONE DoEvents Free Windows to allow it to do the Link 1b1Status LinkTopic Hp8509DdeName amp lpadde 1b1Status LinkItem Status 1b1Status LinkMode LINK_ AUTOMATIC DoEvents Free Windows to allow it to do the Link gt Use to be sure that HP8509 data buffers are clear 1b1Status LinkExecute ClearParams DoEvents Free Windows to allow it to do the Link Exit Sub Err_cmdLink_click Select Case Err Case 200 To 299 MsgBox Failed to Link to HP8509 0 DDE Link Error Case Else Other error handler here End Select Exit Sub Programming 10 19 Sending HP 8509 Commands via DDE To send commands to the HP 8509 using DDE use the LinkExecute method in VB Be sure that a previous DDE conversation is complete before sending the DDE command The following VB code fragment illustrates how to send the DDE command Poincare Center A once the DDE Links have been established The ClearParams command is sent as a precaution to clear out the HP 8509 data buffers Param x labels It is required that these buffers are empty before any commands are sent to the HP 8509 Generally the data buffer is empty unless a previous command prepared a response by the HP 8509 If you are not sure if the buffers were previously
274. plied to all measurements Apply calibration can only be turned on if a calibration exists for the current wavelength Calibrate selection Main window System menu Calibration Starts the calibration process The HP 8509A B takes 32 measurements with different settings of fiber coil polarization adjusters in the input path of the polarimeter receiver Calibrated tunable wavelengths display Main window System menu Calibration When the tunable wavelength source is selected this list shows the existing calibrations available for use with a tunable laser source Calibrations labeled as New have not yet been saved and will be lost if the instrument is turned off If you wish to recalibrate at a wavelength listed here double click on the desired wavelength It will appear in the wavelength display Calibrated fixed wavelengths display Main window System menu Calibration When the fixed wavelength source is selected this list shows the existing calibrations available for use with fixed wavelength non tunable sources Calibrations labeled as New have not yet been saved and will be lost if the instrument is turned off If you wish to recalibrate at a wavelength listed here double click on the desired wavelength It will appear in the wavelength display Delete selection Main window System menu Calibration Pressing Delete selection deletes the highlighted wavelength calibration Done Main window S
275. priate markers must be turned on in order to obtain the desired angle See Angles Off On Angles Degrees Radians 7 Sets the units of the displayed angles to either radians or degrees The query returns 1 if the condition is true 0 otherwise See Angles Off On Angles Done Not Recommended Command may not be available in future versions Plan your programming to use the alternate command Angles Off Closes the Marker Angles frame in the analyzer window Angles Off On Displays the angles between markers A and B markers A and C and markers B and C The measured angles are displayed in the Marker Angles frame in the analyzer window The angles are measured from the Poincare sphere coordinate location of the markers The markers must be turned on in order to obtain the measured angles Average Display Off On gt Turns on or off the moving average of a measurement trace on the Poincare sphere display Average Display lt NumPoints gt Specifies the number of points lt NumPoints gt to be used in the moving average of the Poincare sphere display The query returns the number of points set in the Averaging frame of the analyzer window and the state of the display averaging 0 if off 1 if on Average Done Closes the Averaging frame in the analyzer window 10 28 Programming Average Measure lt NumPoints gt The number of points NumPoints to
276. r Devices and Radiological Health International IEC Class 1 The HP 8509 is rated as an IEC International Electrotechnical Commission Class 1 Laser Product according to IEC 825 Hewlett Packard designs to the intent of IEC 348 Canada The HP 8509 is certified to the Canadian Electrical Code CAN CSA C22 2 No 231 Series M89 Notice for Germany Noise Declaration LpA lt 70 dB am Arbeitsplatz operator position normaler Betrieb normal position nach DIN 45635 T 19 per ISO 7779 Acoustic Noise Emission Geraeuschemission LpA lt 70 dB LpA lt 70 dB Operator position am Arbeitsplatz Normal operation normaler Betrieb per ISO 7779 nach DEN 45635 t 19 Safety and Regulatory Information 9 1 DECLARATION OF CONFORMITY according to ISO IEC Guide 22 and EN 45014 Manufacturer s Name Hewlett Packard Company Manufacturer s Address 1400 Fountaingrove Parkway Santa Rosa California 95403 U S A declares that the product Product Name Lightwave Polarization Analyzer Model Numbers HP 8509A HP 8509B Product Options This declaration covers all options of the above product conforms to the following Product Specifications Safety IEC 348 1978 TEC 1010 1990 EMC EN 55011 1991 CISPR 11 1990 Group 1 Class A EN 50082 1 1991 TEC 801 2 1991 4kV CD 8 kV AD TEC 801 3 1984 3V m 27 500 MHz IEC 801 4 1988 500 V signal 10000 V AC Santa Rosa O e location date John Lamy Quality
277. r point will be displayed in the marker table ADDITIONAL INFORMATION Once a marker has been set it is fixed on the sphere and cannot be adjusted to move along a trace Clear Markers si s2 s3 Click here to Set a Marker at the Current Data Point pq747b_c Figure 1 3 Setting a Marker Setting a Marker at a User Specified Point 1 Move the mouse pointer to the point on the front face of the sphere where you want to place a marker Double click the left button on the mouse The Set Marker window appears below the Poincare sphere see Figure 1 4 Use the mouse to select A B or C to set a marker at the place on the sphere where you double clicked the mouse Notice that the Stokes parameters for that point appear in the marker table in the marker window If you have decided not to set a marker and wish to close the Set marker window select None Set marker Oa Os Oc ONone pq7150_c Figure 1 4 Close Set Marker Window Getting Started 1 7 Turning the Markers On and Off X indicates Markers are On Clear Markers si s2 s3 2pt Ref 3pt Ref pq748b_c Figure 1 5 Turn Markers On Off When the markers are turned on there is an X
278. ram 7 The DDE link items are specified in VB with the LinkItem property The DDE Application and the DDE topic are combined in VB separated by the pipe character and is called the LinkTopic property The DDE link topic of the HP8509 is lpadde so combined with the application name the VB LinkTopic property is HP8509_2 lpadde Microsoft Windows uses 3 types of DDE links for DDE conversations Automatic The source supplies data to the application every time the data defined by the LinkItem changes This link is also commonly called a HOT Link Manual The source supplies data only when the destination requires it This link is also commonly called a COLD Link Notify The source notifies the destination when the data changes but supplies data only when the destination requests it 10 18 Programming For the HP 8509 use Automatic links for the DDE link item Status and Manual links for the DDE link items Param x A VB Code fragment that establishes a DDE link to the HP 8509 from a users application follows This code fragment establishes a DDE link to the HP 8509 application from the labels gt lblParam 0 to l1blParam 7 and 1blStatus gt in the user s application On Error GoTo Err_cmdLink_click gt Establish a new link with the HP 8509 For if 0 To T7 Remove any existing link first lblParam 1 LinkMode LINK_NONE DoEvents Free Windows to allow it to do the Link lblParam i LinkTopic H
279. raphs main window A standard window Save screen will be displayed At this point you can select a file name and a directory in which the data will be stored Columns of wavelengths and measurement data points will be saved as text for later use in a spreadsheet Data saved as text cannot be recalled for future display by the analyzer Making Measurements 2 23 PMD Measurement Jones Matrix Eigenanalysis Method Saving in Database Format HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 Edit Measure Forma Load JME from Database Save JME to Database Save JME as Text Print Database Close All PMD Windows Display Window pq71i12_c Figure 2 27 Saving in Database Format Select File and then Save JME to Database from the Graphs main window to save the entire measurement and annotation for future analysis using a database program or to reload the measurement and certain setup parameters back into the analyzer A default title for the measurement is provided The title is made up of the measurement type and the date and time It is a unique name but you may wish to edit it for your own purposes You may also enter a serial number and date code for the device under test 2 24 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Specialized Measurement Methods Performing a Cascade Measurement Cascading is a measurement procedure that mathematical
280. rather than returning to the Main window Table 7 7 PMD Wavelength Scanning Control Path Description or Data Analysis gt Graphs window Enables user to customize the wavelength scanning Format analysis performed on individual normalized Stokes parameter traces Annotation Graphs window Places documentation of the most recent Display measurement at the bottom of the graphs window Avg Median Graphs window Specifies how the final PMD result is derived from Max delay gt Format results of the three individual normalized Stokes parameter measurements Selects the average median central or maximum of the three results Copy graph sl or s2 or s3 Graphs window Edit menu Places bitmap of the normalized Stokes parameter sl or s2 or s3 measurement graph on the clipboard Copy window Graphs window Edit menu Places bitmap of the entire graphs window on the clipboard Copy to clipboard selection Graphs window Display menu Tabular data Copies the selected text to the clipboard If no text is selected the entire text box is copied Cursor Graphs window Display menu Enables the cursor function allowing detailed examination of the measurement graph Only accessible when a single normalized Stokes parameter graph is expanded vertically Data symbols Graphs window Display menu Places measurement point markers on the graph Database Graphs window File menu
281. rature for this verification to be meaningful 2 Measure the DGD of a device DUT in the Single Device mode without a cascade thru calibration Then perform a cascaded PMD measurement using this same device DUT connected to a second device DOC that has been cascaded out The PMD measurement result should be very close to the measurement obtained in the Single Device mode Again temperature stability is important 2 28 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Using a Voltage Tuned Source The JME PMD measurement may be performed using a voltage tuned optical source Operation is automatic once the measurement is started To perform a measurement with a voltage tuned source open a JME PMD window and select Optical Source Setup Use Optical Source Selection to choose the voltage tuned mode You will see a change in the information displayed in the Wavelength area of the window Enter the wavelength parameters and number of points as you would for an HP IB source Enter the tuning voltages corresponding to the start and stop wavelengths This calibrates your wavelength tuning and requires knowledge of the source tuning characteristic The tuning voltage is programmed in linear fashion between the entered limits Set the settling times as required for your source or use the default values Connect the tuning voltage from BNC connector A on the rear panel of the 8509 to the voltage tuned laser Clo
282. re light beam 51 is the difference in power between the horizontal and vertical linear polarization components of the beam S indicates the power difference between 45 degree and 45 degree linear polarization 53 is the power difference between the right hand and left hand circular polarization The Stokes vector has a magnitude equal to S1 82 83 1 and originates from the center of the Poincare sphere The HP 8509A B graphically projects the normalized Stokes vector termination point onto the surface of a unity radius sphere even when the magnitude of the normalized Stokes vector is not equal to one 2 88 Making Measurements Accuracy Enhancement and Troubleshooting This chapter contains reference information regarding measurement accuracy and measurement troubleshooting Before You Proceed Verify the following conditions before you proceed with this chapter m Connect the electrical power and turn the instrument on m Connect the interface cable between the computer and the HP 8509A B m Connect the HP IB cable to the external optical source if necessary m Allow the instrument to warm up for at least one hour and zero the instrument following warm up m Allow the tunable laser source to warm up completely if used m Clean all connector surfaces m Stabilize the optical fiber during some types of measurements For help with operating the keyboard or the mouse or with Windows conventions use the Windows Help menu in
283. re sent the specified internal source 1310 or 1550 nm is turned on If the off parameter is sent any currently active internal source is turned off HP 8509B only Source Manual Places the analyzer window in manual control mode When the instrument is under manual control the user must set the tunable laser source to the appropriate wavelength for each wavelength point The query returns two parameters first O not manually tuned 1 manually tuned second The type of optical source setup source Source Shutter Returns an ASCII 1 if the shutter is currently activated on and returns an ASCII 0 if the shutter is not activated off See Source Shutter Off On HP 8509B only Source Shutter Off On This command controls the shutter located in the path to the optical output port of the HP 8509A B The two HP 8509A B internal sources and any external source coupled into the external source port of the HP 8509A B share a common instrument internal path to the optical output port of the HP 8509A B By sending the parameter on a shutter in the path to the optical output port can be activated so that the source output is blocked The shutter can also be removed by sending the parameter off HP 8509B only Programming 10 55 Source VTune Sets the Optical Source Setup source selection to VTune in order to control a VTUNE tunable laser source The query returns two parameters first
284. rema The minimum feature size parameter specifies the magnitude change which differentiates a peak from an adjacent valley The default minimum feature size is 05 a dimensionless number The value is user selectable It may be increased in size in situations where fiber movement is causing the detection of false peaks and valleys Statistical characterization of fiber PMD The wavelength scanning method is less commonly used for accumulation of fiber PMD statistics than its counterpart the Jones matrix eigenanalysis method However statistics may be gathered from a series of wavelength scanning measurements performed at different temperatures or other physical configurations of the fiber Each wavelength scanning measurement contributes a single point to the distribution unlike the Jones matrix eigenanalysis method in which each wavelength interval produces a point 2 44 Making Measurements PDL Measurement Jones Matrix Method PDL Measurement Jones Matrix Method Polarization dependent loss PDL describes the insertion loss variation gain variation or coupling variation of an optical component given all possible input signal polarization states It is found in all lightwave components to some degree PDL can be desirable in a linear polarizer or undesirable in a telecommunication system or cable TV system depending on the application This measurement section explains how to measure the polarization dependent loss or gai
285. rement menu from memory and Poincare sphere display and sets Timed measurement up to replace it with the next single sample Single mode Free run Main window Sets instrument to collect data at its normal open mode selection Measurement menu Timed measurement mode loop rate which is about 1 kHz for the 486 33 computer and 2 kHz for the 486 66 computer Mode Main window Measurement Timed measurement Specifies the timing format Choices include free running timed or single measurements Number of samples Main window Specifies the number of samples that will be taken Timed measurement Timed mode entry box Measurement menu Samples may be free run or timed The maximum Timed measurement number of samples is 16 381 Timed or free run mode Rate Main window Specifies the sampling rate in the timed mode The entry box Measurement menu rate is the inverse of the sample period Sample period entry box Main window Measurement menu Timed measurement Timed mode Specifies the time in seconds between samples in the timed mode Minimum time is 0 002 maximum value is 7 209 070 000 in increments of 0 001 Samples taken Main window Records the number of samples taken in the current mode selection Measurement menu Timed measurement mode display Measurement menu series of single samples The number of samples is Timed measurement limited to 16 381 There is no
286. rements because it supports a variety of spacial modes each of which experiences a different delay and birefringence as it passes along the fiber These multiple paths can depolarize the test signal is some cases In MMF the output polarization is not well defined nor uniquely related to fiber birefringence This makes all polarization measurements extremely difficult in MMF Connectors may exhibit small values of PDL Damaged SMF and connectors attenuate optical power and may cause triple travel reflections See item 1 Connector Care Reflections for details Connectors should be properly mating physical contacting types with reflection level better than 40 dB Accuracy Enhancement and Troubleshooting 3 7 17 Circular State of For measurements involving the Jones matrix it is recommended that the Polarization reference polarizers be supplied with circular states of polarization This is in order to avoid low power points during linear polarizer adjustments Information about confirming a circular state of polarization can be found in the measurement application sections 3 8 Accuracy Enhancement and Troubleshooting Printing Saving and Recalling Measurement Results and Instrument Configurations 4 This chapter contains information about the File menu in the main window and the measurement windows Database Analyzer Window HP8508B Lightwave Polarization Analyzer MES Edit Measurement Display System Help
287. ress to correspond to the laser Alternatively change the address at the laser to 24 HP 8168A source selection Optical source setup window Selects the HP 8168A Tunable Laser Source If the HP IB source address is incorrect wait 5 seconds for timeout then change the address to correspond to the laser Alternatively change the address at the laser to 24 User Interface Reference 7 7 Table 7 2 Optical Source Setup continued Control or Data Path Description Internal laser source selection Optical source setup window Internal Allows user to select one of the internal lasers Only available if internal laser option is installed Level entry box Optical source setup window Sets the output power level of compatible external HP IB optical sources Optical source selection drop down list Optical source setup window Allows selection of an internal or external optical source Points entry box Optical source setup window In PMD measurement modes allows control of the number of measurement wavelengths Power on off controls Optical source setup window Turns optical power on and off at the source when used with internal or compatible external HP IB optical sources Settling time entry box Optical source setup window In PMD measurement modes provides time for the tunable external source to settle at each wavelength prior to taki
288. riate polarizer angle box and then input the value for your external polarizer angle Polarizer Angles and the Poincare Display There is a 1 2 relationship between rotation of a linear polarizer and the resultant angle swept out on the Poincare sphere For example a 180 rotation of a linear polarizer produces a 360 great circle on the Poincare sphere display 6 18 The System Menu Using the Shutter HP 8509B only Shutter Unblock Laser Light Block External Laser Light Done pq76b_c Figure 6 14 The Shutter Menu In the HP 8509B a shutter can be engaged to block light from internal sources and from external sources that are routed through the HP 8509B via the EXTERNAL SOURCE INPUT This shutter can be put into the signal path manually by selecting System Shutter The System Menu 6 19 Averaging Averaging Display 25_ Samples ch Measurement 250 Samples Done pq710b_c Figure 6 15 The Averaging Window Opening the Averaging Window Open the Averaging window by selecting System Averaging Selecting Display Averaging The default number N of display samples is 25 while the range is 0 to 1000 To enter a different number of samples select the existing number in the display samples box then enter your new selection for Display Averaging ADDITIONAL INFORMATION The Display Averaging entry must be less than the Display Upda
289. rn an ASCII 1 when all pending overlapped operations have been completed The command is used to ensure the completion of a particular function as requested by a prior command Append this command to the command being OPC d separated with a semicolon Device Specific Commands Analog Returns Off Raw or Stokes depending on the setting of the analog outputs see Analog Off Raw Stokes Analog Done Closes the Analog frame in the analyzer window Analog Off Raw Stokes 7 Selects and turns on or off the output of the four BNC connectors on the rear panel of the HP8509 If stokes is sent the output of the four BNC connectors will be four voltages proportional to the Stokes parameters 0 s1 s2 and s3 When raw is sent the four voltages will be proportional to the currents induced on the four photodiodes of the HP8509 receiver The voltages are always in the range of 10 to 10 volts When off is sent the four BNC outputs will be turned off Please refer to the HP 8509 User s Reference Guide for more in depth information The query returns 1 if the particular control is selected in the Analog frame of the analyzer window and 0 if not selected Programming 10 27 Angles AB AC BC Returns the angle between the specified markers its cosine and the cosine squared of half the angle The largest angle measurable is 180 degrees or PI radians The angles and appro
290. s jO00 real j00 imag j01 real j01 imag j11 imag or J00 magnitude j00 phase j01 magnitude j01 phase j11 phase Before sending this command using either selection be sure that a measurement has been taken To take a measurement If the analyzer is in absolute mode a calibration is performed first using PolDep Calibrate A B C The measurement is performed using PolDep Measure A B C Use optional selection A B or C when external polarizers are selected PolDep JonesMode PolDepMode 7 Selects the data format as polarization dependent loss values or Jones values This is similar to selecting the option button at the bottom of the window Use this command to open the Polarization Dependence window The query returns 1 if the condition is true 0 otherwise Programming 10 47 PolDep MagRadians MagDegrees RealImag Sets the format of the Jones matrix numerical results to a polar magnitude and phase or rectangular real imaginary format Through this command the angle of the polar numerical results can be presented either in radians degrees or as complex numbers The query returns 41 if the indicated format is selected 0 if not selected PolDep Measure A B Cl Calculates the polarization dependent loss of a given device under test The results can be read from the analyzer through the use of the poldep HP IB remote command With internal polarizers the measurement is performe
291. s Always finger tighten the connector in a consistent manner Refer to the manufacturer s data sheet for any torque recommendations Summary When making measurements with lightwave instruments or accessories the following precautions will help to insure good reliable repeatable measurements m confirm connector type compatibility m Use extreme care in handling all lightwave cables and connectors m Be sure the connector interfaces are clean before making any connections m Use the cleaning methods described in this handbook m Keep connectors and cable ends covered when not in use 8 6 Lightwave Connector Care Inspection Visual Inspection Although it is not necessary visual inspection of fiber ends can be helpful Contamination and or imperfections on the cable endface can be detected as well as cracks or chips in the fiber itself Several fiber inspection scopes are on the market but any microscope with an enlargement range of 100X to 200X can be used It is helpful to devise some method to hold the fiber in place while viewing in this range Inspect the entire endface for contamination raised metal or dents in the metal as well as any other imperfections Inspect the fiber core for cracks and chips Visible imperfections not touching the fiber core may not affect the performance of the lightwave connection unless the imperfections keep the fibers from contacting Consistent optical measurements are the best
292. s Wavelength data before committing it to the statistical data set Clear All Data Selecting this menu item removes all displayed data and purges the statistical data set Copy Bitmap to Clipboard This menu item provides three selections copying to the clipboard your choice of DGD versus Wavelength the Histogram or the entire PMD Statistics window The Format Menu Selecting Format from the main PMD Statistics window will drop down a menu structure The following is a brief description of the elements of that Format menu Wavelength Range This menu item provides two ways to select the wavelength range to be used in the DGD vs Wavelength graph Only data points displayed in this graph are included in the histogram Autorange adjusts the wavelength limits to include the lowest and highest Making Measurements 2 21 PMD Measurement Jones Matrix Eigenanalysis Method wavelengths of the added or loaded JME PMD data The Fixed Range selection opens a dialog box with which you can set the minimum and maximum displayed wavelengths Histogram X Axis This menu item provides two ways to select the range of DGD values to be displayed in the histogram When Autoscale is selected the X axis range automatically adjusts to include all DGD values in the statistical data set When Fixed Scale is selected a dialog box enables you to set the maximum value of DGD to be displayed The minimum value is always zero The Help menu The Help me
293. s better than 40 dB although 20 to 30 dB is more common Lightwave Connector Care 8 1 Causes of connector loss and reflections include core misalignment differences in the numerical aperture of two fibers spacing and air gaps reflections caused by damaged worn ot loose fiber ends and the improper use and removal of index matching compounds Achieving the best possible connection where the fiber end faces are flush no air gap and properly aligned is dependent upon two things 1 the type of connector and 2 using the proper cleaning and connecting techniques If the connection is lossy or reflective light will not make a smooth transition If the transition is not smooth or the connection is not repeatable measurement data will be less accurate For this reason lightwave connections can make a critical difference in optical measurement systems 8 2 Lightwave Connector Care Cleaning and Handling Proper cleaning and handling of lightwave connectors is imperative for achieving accurate and repeatable measurements with your Hewlett Packard lightwave equipment Lightwave interfaces should be cleaned before each measurement using the techniques described in this handbook Information on protecting and storing your connectors cables and tips on how to properly mate connectors are also included in this section Definition of Terms To avoid confusion the following definitions are used in this handbook Connector Houses the f
294. s open all within a main Multiple Document Interface MDI parent window This command will close only the first PMD J ME child window which was opened The MDI parent window which holds all of the PMD child windows will close automatically after the last PMD child window is closed Source Source External Source Internal Version 1 2 of the HP 8509 had only one set of settings to control a TLS so when querying the TLS the returned value was the setting of the TLS for the HP 8509 instrument This is not true for version 2 0 of the HP 8509 software In version 2 0 each PMD window and the analyzer window each have their own set of TLS settings When using the above Source commands be aware that the TLS settings returned are for the ANALYZER WINDOW ONLY Version 2 0 provides other commands to query the TLS settings for the PMD windows Note When setting the TLS parameters using the Source External lt Wavelength nm gt Source External 0ff On and Source Internal Off 1310 1550 commands all windows TLS settings are changed This conforms to version 1 2 operation 10 26 Programming Common Commands IDN Returns a string that uniquely identifies the analyzer The string is in the form lt Manufacturer gt lt Model Number gt lt Serial Number gt lt Firmware Version gt for example HEWLETT PACKARD HP 8509B 3206A00156 2 10 HP IB Operation Only OPC 7 Operation complete The query will retu
295. s2 and s3 traces This command selects the type of PMD total to calculate the query returns the type of PMD result WaveScan Polarizer A B C None The internal polarizer to insert before starting the PMD WS measurement The query returns the selected polarizer HP 8509B Only WaveScan Power Returns the power and the power units for the tunable laser source DDE Only WaveScan Power dBm uWatt lt value gt Sets the power units for the tunable laser source TLS If the lt value gt parameter is specified the power setting can also be changed If the power setting is not valid for the TLS the command fails Note When changing only the units the numerical value of the power does not change Be sure to change the value of the power to correspond to the new units DDE Only WaveScan Save lt filename gt Saves a PMD WS measurement trace into the file lt filename gt The trace is saved as a series of ASCU strings separated by commas The each line of the saved trace information is in the form of Wavelength_1 Power dBm s1 s2 83 DOP Wavelength_n Power dBm s1 82 83 DOP The above is for the dispersion measurement at n user defined wavelengths The Stokes parameters are normalized For path information on filename see Command Syntax at the beginning of this chapter Programming 10 61 WaveScan Settle Point Start lt Delay mse
296. scale zero based 7 12 Average Display amp lt NumPoints gt 10 28 Average Display Off On 10 28 Average Done 10 28 Average Measure amp lt NumPoints gt 10 29 averaging 7 2 avg median max delay 7 18 back step 7 22 basic measurement screen 1 1 braces 10 23 c Cal 10 29 cal box 1 1 Cal Calibrate 10 29 Cal Delete amp lt Wavelength nm gt 10 29 cal display See cal box Cal Done Save 10 29 calibration 7 2 Cal List 10 29 Cal Of On 10 29 cancel 7 7 cascaded device 7 12 center the sphere on a current point 1 6 1 9 on a marker 1 6 1 9 certification 111 characteristics 11 1 11 2 cleaning 9 3 clear markers 1 6 1 8 ClearParams 10 30 clear trace 1 11 7 2 clear trace functions 1 1 colon 10 23 Command Separator 10 23 copy analyzer display 7 2 copy graph 7 12 copy graph sl or s2 or s3 7 18 copy sphere display 7 2 copy to clipboard 7 12 7 18 copy window 7 12 7 18 amp lt CR gt amp lt LF gt 10 25 cumulative DGD 2 18 current point center the sphere on a 1 6 center the sphere on a 1 9 markers 1 6 cursor 7 18 cursor 7 12 cursor bar 2 16 D data measurement 4 1 recalling 4 1 saving 4 lff database 7 12 7 18 database format save 2 24 data displays degree of polarization 1 5 DOP 1 1 1 5 Index 1 ellipse 1 1 1 5 poincare sphere 1 1 1 5 power 1 1 1 5 data symbols 7 12 7 18 DBase Close 10 30 DBase
297. se the Optical Source Setup form and start the measurement Using a Manually Tuned source The JME PMD measurement may be performed using a manually tuned optical source This feature enables you to use tunable single line laser sources that lack hardware tuning interfaces To perform a measurement with a manual source open a JME PMD window and select Optical Source Setup Use Optical Source Selection to choose the manually tuned mode The settling time parameters are no longer relevant and are grayed out Enter the wavelength parameters and number of points as you would for an HP IB source Close the Optical Source Setup form and start the measurement The instruction window will prompt you to adjust the wavelength of the source and take the next point Repeat this until the measurement is complete Making Measurements 2 29 PMD Measurement Jones Matrix Eigenanalysis Method PMD JME Concepts Polarization Mode Dispersion Polarization modes PMD is a fundamental property of optical fiber and components by which any lightwave signal is split into two polarization modes that travel at different speeds In effect single mode fiber is bimodal with respect to polarization The difference in propagation time between the two polarization modes is called differential group delay General effects Because of PMD lightwave pulses launched partly into each of the polarization modes broaden as they propagate degrading the distinction between
298. set Configuration Load Main window File menu Loading the Preset Configuration loads the default conditions set at the factory See the Printing Saving and Recalling section of the manual for changing the default configuration Print gt Main window Provides for printing various measurement displays File menu or windows Range Main window Allows operation in autorange default or fixed gain System menu range Press up button to accommodate large level signals Reference frame info Main window System menu Provides feedback on the quality of the applied polarization reference frame Rotate buttons Main window Rotates the Poincare sphere in 22 5 degree 1 16 revolution increments The Home button returns the display to the default view Save gt Main window File menu Allows saving a Configuration of the instrument see User Configuration or various measurements 7 4 User interface Reference Table 7 1 Main Window continued Control Path Description or Data Show gt Main window Allows the user to customize the appearance of the Display menu main window by deleting or interchanging displays Shutter Main window Inserts shutter in the optical beam between internal System menu or external optical source and the device under test The shutter is situated in the switchable polarizer assembly Stokes vector display Main window Marker area top row
299. sphere is only achieved when the measurement is done in a polarization reference frame The analyzer automatically creates a polarization reference frame using open beam polarization standards and Jones calculus You can define the location of a polarization reference frame by following the instructions discussed in this measurement section HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 18 03 aBm Clear Trace Markers On Clear Markers so si s2 s3 18 03 0 99 0 00 0 00 LS 18 03 0 99 0 00 0 00 A 12 00 0 00 0 99 0 00 B 11 48 1 00 0 00 0 00 e Rotate 2pt Ref 3pt Ref Apply 3pt Home pq772b_c Figure 2 82 Example of the results that can be achieved with and without a polarization reference frame Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509A B Lightwave Polarization Analyzer operating system software to create a 3pt polarization reference frame using an external polarizer 2 74 Making Measurements Setting up the System Polarization Reference Frame Connect your measurement system as outlined in the following illustration
300. splayed a check mark appears next to the menu selection The following figure shows what the HP 8509 display looks like with the ellipse turned off HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 dBm Clear Trace Markers On Clear Markers so si s2 s3 9 090 0 02 0 08 0 98 Rotate Home 2pt Ref 3pt Ref pq722b_c Figure 5 7 Polarization Ellipse Turned Off The Display Menu 5 5 Exchanging the Poincare Sphere and the Polarization Ellipse HP8509B Lightwave Polarization Analyzer File Edit Measurement MEJJENA System Help Power Display Mark Current Point Display Update Hold F6 Clear Trace F7 Auto Refresh pq723b_c Figure 5 8 The Show Sphere lt gt Ellipse Menu The default configuration has the Poincare sphere and the polarization ellipse displayed as shown in Figure 5 1 You may exchange the two so that the ellipse has the more prominent position by selecting Display Show Sphere lt gt Ellipse The following figure shows what the display looks like with the Poincare sphere and the polarization ellipse exchanged HP8509B Lightwave Polarization Analyzer File Edi
301. ssary to assure a good signal level through the polarizer Select Calibrate ACCURACY ENHANCEMENT NOTE Signal power and DOP must be constant during the calibration process You will hear some clicking from inside the HP 8509 as the calibration is being performed The calibration takes about 60 seconds The HP 8509 automatically averages 250 measurements at each state Calibrate at other wavelengths by repeating the above procedure Calibration Source Type Fixed A Tunable A OF Optical Source A Internal 1510 0 nm 1 Set external source to 1510 0 nm or select new Wavelength 2 Connect source to Optical Input 3 Select Calibrate Calibrate Calibrated Fixed Wavelengths 1311 0 nm Internal 1555 0 nm Internal Delete selection Done pq77b_c Figure 6 5 The Calibration Window 6 8 The System Menu Save and or Apply the Calibration 1 The calibration list see Figure 6 6 for fixed wavelengths provides the following information a The wavelength s that have been calibrated b Whether it is an internal or external source c Whether the calibration has been saved or not 2 To save all calibrations in the list with the New designation select Save new calibrations 3 To apply a calibration select Apply Calibration On in the Calibration
302. suse operation outside of the environ mental specifications for the product or improper site prepa ration or maintenance No other warranty is expressed or implied Agilent Technologies specifically disclaims the implied warranties of merchantability and fitness for a particular pur pose Exclusive Remedies The remedies provided herein are buyer s sole and exclusive remedies Agilent Technologies shall not be liable for any direct indirect special incidental or consequential damages whether based on contract tort or any other legal theory Safety Symbols CAUTION The caution sign denotes a haz ard It calls attention to a proce dure which if not correctly performed or adhered to could result in damage to or destruc tion of the product Do not pro ceed beyond a caution sign until the indicated conditions are fully understood and met WARNING The warning sign denotes a haz ard It calls attention to a proce dure which if not correctly performed or adhered to could result in injury or loss of life Do not proceed beyond a warning sign until the indicated condi tions are fully understood and met The instruction manual symbol The product is marked with this warning symbol when it is neces sary for the user to refer to the instructions in the manual A The laser radiation sym bol This warning symbol is marked on products which have a laser out put The AC symbol is used to
303. t See the Printing Saving and Recalling Measurement Results and Instrument Configurations chapter in this manual In these cases the recalled trace will not be cleared as the sphere is rotated and Hold Click here to Toggle the Hold Function Clear Trace Hold Click here to Clear the Trace From the Poincare Sphere pq752b_c Figure 1 9 Clear Trace and Hold Clear Trace Select Clear Trace to clear the Poincare sphere of previously displayed data points The HP 8509 will immediately resume data display unless the Hold function has been activated Hold When Hold is activated the HP 8509 does not update the Poincare sphere display the power display the DOP display the polarization ellipse or the Stokes parameters in the Marker window When the Hold function is activated there is an X in the Hold box Hold is toggled on and off by selecting Hold see Figure 1 9 Putting the instrument on HOLD dramatically speeds up graphics and computational activity in the computer Put the HP 8509 in HOLD when running other software programs Getting Started 1 11 A and Cal Click here to Invoke Optical Source Box Cal A 1550 0 nm Source Wavelength Box User Calibration On Off Indicator pq753b_c Figure 1 10 A and Cal Select A to show the Optical Source window Refer to The System Menu chapter of this document for more informatio
304. t Configure Files CFG y c ms dos_5 drive pq740b_c Figure 4 13 The Load Window 4 18 Printing Saving and Recalling Measurement Results and Instrument Configurations The Display Menu This chapter contains information on the following subjects Displaying the marker window Displaying the Poincare sphere Displaying the polarization ellipse Exchanging the Poincare sphere and the polarization ellipse Changing the power mode from dBm to watts Marking the current point Changing the display update frequency Holding the data display Clearing the trace from the sphere Setting the display to Auto Refresh mode For Additional Information Other display functions such as zoom rotate and marker functions are discussed in the Getting Started chapter The Display Menu 5 1 The PRESET Configuration The following figure shows the PRESET configuration of the HP 8509 display You can change the display to meet your needs For example the Poincare sphere and the polarization ellipse can be exchanged the power mode can be changed from dBm to Watts and the marker window can be removed HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 dBm Clear Trace ld Gal 1550 0 nm Markers _______ __ On Clear Markers So s2 s3 9 090 0 08
305. t DFARS 252 227 7013 for DOD agencies and subparagraphs c 1 and c 2 of the Commer cial Computer Software Restricted Rights clause at FAR 52 227 19 for other agencies Warranty This Agilent Technologies instru ment product is warranted against defects in material and workmanship for a period of one year from date of shipment Dur ing the warranty period Agilent Technologies will at its option either repair or replace products which prove to be defective For warranty service or repair this product must be returned to a service facility designated by Agi lent Technologies Buyer shall prepay shipping charges to Agi lent Technologies and Agilent Technologies shall pay shipping charges to return the product to Buyer However Buyer shall pay all shipping charges duties and taxes for products returned to Agilent Technologies from another country Agilent Technologies warrants that its software and firmware designated by Agilent Technolo gies for use with an instrument will execute its programming instructions when properly installed on that instrument Agi lent Technologies does not war rant that the operation of the instrument or software or firm ware will be uninterrupted or error free Limitation of Warranty The foregoing warranty shall not apply to defects resulting from improper or inadequate mainte nance by Buyer Buyer supplied software or interfacing unautho rized modification or mi
306. t MS DOS Drive Spec gt Co a 10 40 GetFile lt filename gt 2 a a a a 10 40 GetMarker A BI IC 2 10 40 GetMarker A B C 0 0 0 20 0 0 00000004 10 40 Jones Ck a 10 41 Jones Absolute 1 Relative XE o a 10 41 Jones Calibrate A B C oaa aa a 10 41 Janer lea 10 41 Jones Done a 10 42 Jones External Internal XE o a 10 42 Contents 9 Jones MagRadians MagDegrees Reallmag 10 42 Jones Measure A B C 0 0 00 00 0 0 10 42 Jones NewThruCal 2 1 a 10 43 Jones ReStart 1 2 a a a a 10 43 Load Config Preset aoa oa aa a 10 43 Load Config lt filename gt 2 2 2 a 10 43 Load Single lt filename gt oaoa a a a a aaa a a a 10 43 OperVer T 10 44 OperVer Start Cancel Done y Co ee ee ee ke kk 10 44 PdlMaxMin Ce ek kk 10 44 PdlMaxMin f Max Min y o 10 44 PdlMaxMin Delta e 10 44 PdlMaxMin Reset Clear Done y o 10 44 Poincare Center Stokes AIB IC 10 44 Poincare Clear e 10 45 Poincare Hold 4 Off On y o 10 45 Poincare Marker A B C a L 10 45 Poincare Marker Clear o 10 45 Polarizer 1 A B C None E ooa o L 10 45 Polarizer Angle A B C H lt Degree Value gt ss 10 45 Polarizer Done o 10 45 Polarizer 1 External Internal y Co a 10 46 PolDep Ce a 10 46 PolDep Absolute Relative 12 Co a 10 46 PolDep Calibrate A IBIC e 10 46 PolDep Clear
307. t Measurement Display System Hel Power 7 647 dBm Clear Trace Sal 1539 0 nm Markers On Clear Markers so s1 s2 s3 7 648 0 78 0 46 0 27 2pt Ref 3pt Ref pq728b_c Figure 5 9 Sphere and Ellipse Exchanged 5 6 The Display Menu Changing the Power Display Units File Edit Measurement MDIEENA System Help HP8509B Lightwave Polarization Analyzer Power Display Mark Current Point Watts Display Update Hold F6 Clear Trace F7 Auto Refresh pq724b_c Figure 5 10 The Power Display Menu The default state for the power mode is dBm See Figure 5 1 Change the power mode to Watts by selecting Display Power Display Watts This menu selection allows you to toggle between Watts and dBm A check mark appears next to the menu selection that is currently activated The following figure shows the power mode changed from dBm to Watts Power is Displayed in Watts HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 171 5 uw Clear Trace Markers On Clear Markers s2 s3
308. t be available in future versions Plan your programming to use the alternate command PolDep JonesData PdlData HP 8509B only Jones Absolute Relative 7 Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Absolute Relative HP 8509B only Jones Calibrate A B C Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Calibrate A B IC HP 8509B only Jones Clear Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Clear HP 8509B only Programming 10 41 Jones Done Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep Done HP 8509B only Jones External Internal 7 Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep External Internal 7 HP 8509B only Jones MagRadians MagDegrees RealImag Not Recommended Command may not be available in future versions Plan your programming to use the alternate command PolDep MagRadians MagDegrees RealImag HP 8509B only Jones MeasurelA B c Not Recommended Command may not be available in future versions Plan your programming to use t
309. t path between the automatic polarizer and the polarization receiver The reference frame is appropriate only to the wavelength at which it is set up Since PMD measurements are preformed across a wavelength tange the reference frame feature should not be used Cascade measurements What is a cascade measurement A cascade measurement measures the DGD of a single test device while that test device is connected in series with other elements that demonstrate DGD The measurement is a two step process involving PMD JME measurements of a through path with and without the test device installed This allows the HP 8509B to mathematically remove the differential group delay of the path between the polarizer and the test device Typical applications The cascade method is not used in ordinary PMD measurements in which the device under test is connected by pigtails to the front panel of the instrument as it is not capable of removing the very small amount of differential group delay of the pigtails However it may be used in cases where an optical device with significant PMD such as an isolator is placed between the instrument and the input of the device under test The cascade measurement may also be used to test individual sections of a telecommunications system model or test bed Such systems consist of many sections each of which is made up of one or more amplifier fiber pairs Such systems may provide measurement taps between sections The PMD
310. ta transfers m Set the timeout to at least five seconds to give the PC time to recognize and respond to HP IB activity The HPIB2DDE is polling the HP IB card and needs time to see the request It is important to note that the HP 8509 utilizes only a subset of the HP IB bus capabilities Only two HP IB bus management commands are supported by the current HP 8509 system These are OPC and IDN Other bus management commands commonly supported by Hewlett Packard instrumentation are not available for the remote control of the HP 8509 When receiving HP IB commands the HP 8509 does not lock out manual operation The user must take care not to disrupt remote control through manual command execution Furthermore HP IB commands which lock out manual operations are not currently available for remote control of the HP 8509 When beginning remote operation of the HP 8509 quit then restart the application if there has been any manual operation of the HP 8509 during the current session of the HP 8509 application A second alternative for remote control of the HP 8509 other than using an external PC controller is to use an HP 9000 series 200 300 controller running HP BASIC Version 5 0 or later The platform is the same as that shown in Figure 10 3 except that the PC controller is replaced by an HP 9000 series 200 300 controller The HP 8509 system can be thought of as just another instrument on the HP IB bus IBASIC syntax is fully compatible wit
311. tart Stop Delta H amp lt Wavelength nm gt 10 38 Disper WLen Steps amp lt NumPoints gt 10 39 display tabular format 2 17 Display Angles Degrees Radians 10 39 Display Angles Off On 10 39 display menu 1 4 Display Power Linear Log 10 39 display screen 1 1 display update 7 2 Display Update amp lt NumPoints gt 10 40 DOP display 1 1 1 5 7 2 DOP measurements 2 81 Drive 10 40 Drive amp lt Drive Spec gt 10 23 Drive amp lt MS DOS Drive Spec gt 10 40 Dynamic Data Exchange 10 25 E edit menu 1 4 ellipse display 7 2 end of line 10 25 environmental conditions 9 3 EOL 10 25 extrema first to last 7 18 extrema full scan 7 18 F fiber length 7 12 7 18 file menu 1 4 Jones matrix 4 13 polarization dependence 4 13 polarization mode dispersion 4 13 single sweep trace 4 13 filename 10 23 File Properties 10 23 find minimum of points 7 7 Fixed scale 7 12 format 2 16 frame 10 25 free run 7 22 G general safety considerations v GetFile amp lt filename gt 10 40 GetMarker A B C 10 40 GetMarker gt A B C 10 40 grid 7 18 Grid 7 12 H help menu 1 4 histogram JME 2 18 hold 1 11 7 2 hold functions 1 1 home button rotation 1 10 HP 8167A 7 7 HP 8168A 7 7 HP IB address 7 7 IDN 10 27 internal laser 7 7 J JME 10 25 Jones matrix 4 13 7
312. te entry see Changing the Display Update Frequency in The Display Menu chapter of this manual and less than 1000 The lightwave polarization analyzer will only accept numbers that meet these criteria Turn Display Averaging Off or On from the Averaging window About Display Averaging When display averaging is on every point on the sphere is a running average of the preceding N measurements of the incoming lightwave signal Displays of average power DOP Stokes parameters and the elliptical display are also subject to Display Averaging 6 20 The System Menu Selecting Measurement Averaging The range of numbers that Measurement Averaging will accept is 0 to 100 000 The default number N of measurement samples is 250 To enter a different number of samples select and edit the displayed value About Measurement Averaging Measurement averaging is a straight average of N measurement samples and is used when m a polarizer is used in a measurement and m when markers are set as in the setting of an external reference frame The lower the measurement averaging value the faster measurements can be made There will be an increase in measurement uncertainty if measurement averaging is set too low for the application The System Menu 6 21 Range Range Autorange pq711b_c Figure 6 16 The Range Window Opening the Range Window Open the Range window by selecting S
313. te of polarization as shown on the Poincare sphere The specified marker is turned on and the marker measurement is displayed on the HP 8509A B instrument window The marker measurement is in terms of the normalized Stokes parameters So 51 82 83 Poincare Marker Clear Clears all measurement markers from the Poincare sphere and turns them off Polarizer A B C None 7 When using internal polarizers the command inserts the specified polarizer at the source output The query returns 1 if the particular polarizer is inserted 0 if not Polarizer Angle A B C lt Degree Value gt The lt Degree Value gt parameter sets the angle for the specified external polarizer The user must be careful to enter the correct angles Each polarizer will pertain to a marker as defined by the user The query returns the value of the specified internal or external polarizer depending on the setting Note Using lt Degree Value gt is valid only when the polarizers are External as the internal polarizers are fixed This command will execute when the polarizers are in internal mode but the angles specified will not be used in calculations until the polarizers are put in external mode using Polarizer External See also Polarizer External Internal HP 8509B only Polarizer Done Closes the Polarizers frame in the analyzer window HP 8509B only Programming 10 45 Polarizer External Internal Sets up
314. ted wavelength The wavelength is selected by the slider control arrow keys The keyboard is activated by pressing the Alt and then the arrow keys or by editing the wavelength display Changing The Measurement Format HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 File Edit Measure MEA Display Window v Delay Delay L Delay sqrt L Picoseconds ps v Femtoseconds fs Fiber Length pq7107_c Figure 2 19 Changing the Measurement Format Select Format from the Main Graphs window menu to access the measurement formatting functions The measurement graph may be formatted in either picoseconds or femtoseconds It can also be expressed per kilometer or per root kilometer of fiber length Choose Fiber Length from the Format menu to enter the length of the fiber you have just measured ADDITIONAL INFORMATION If the fiber is long enough to exhibit strong polarization mode cou pling you may wish to express the result in units of time per root length using Format Delay sqrt L The new units are listed and all values are updated on the Y axis and in the measurement summary bar 2 16 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Changing The Graph s Y Scale HP8509 Graphs lt 1 gt PMD JME 1550 0 1551 0 0 1 Edit DEJEN Window Y Annotation F9 Y Cursor Data Symbols y Grid File Measure Format
315. teps Zero the instrument Calibrate the instrument Set up the instrument Connect the device Take data Transfer data SOR WN The actions within each step in the measurement sequence depend upon the type of measurement conducted The instrument should be zeroed prior to starting a measurement sequence Zeroing can be done remotely by sending the ZERO command For accurate measurements it is important that the receiver is not detecting any power while the zeroing routine is being performed 1 If you have an HP 8509A you will be prompted to Block the external laser To do this cover the OPTICAL INPUT connector with a connector cap or a piece of dark paper 2 If you have an HP 8509B you will not be prompted to but you must either cover the OPTICAL INPUT connector as in step 1 above or turn off your external source If the external source is connected to the HP 8509B External Source input its power will be blocked automatically so that no power will emerge from the Optical Output connector during the zeroing operation Programming 10 21 While the zeroing routine is running a green zero message will appear inside the power display in the upper left corner of the HP 8509 basic measurement screen and the mouse pointer appears as an hourglass When the zero message disappears and the mouse pointer changes back to an arrow the zeroing routine is finished Calibrate the Instrument A wavelength calibrat
316. test in kilometers Grid Graphs window Display menu Enables grid lines for the graph of measured results Load WS from database Graphs window File menu Opens a new WS child window and loads stored WS PMD measurement data and selected setup parameters from the database Minimum feature size Graphs window Format menu Specifies the threshold for detection of peaks and valleys in the normalized Stokes parameter graphs Corresponds to the vertical separation of adjacent peak and valley The value is dimensionless and may range from 001 to 1 99 Default value is 0 01 Mode coupling factor k Graphs window Format menu Specifies the value of mode coupling factor for the wavelength scanning formula Use 0 82 for highly mode coupled devices long fibers and 1 0 for most optical components No polarizer Graphs window Format menu Specifies that no internal polarizer will be placed in the source path during the WS PMD measurement Note that a polarized source such as the HP 8167 68A may be connected directly to the device under test HP 8509B only User Interface Reference 7 19 Table 7 7 PMD Wavelength Scanning continued Control or Data Path Description Peaks first to last Graphs window Format menu Analysis gt Counts the number of peaks which occur in the full measurement wavelength scan Subtracts one from the total and uses the result as
317. th An intermediate degree of mode coupling typical of short to medium lengths of optical fiber results in differential group delay which is a relatively weak function of wavelength PMD units Differential group delay is expressed in units of time generally either picoseconds 1 ps 1072 s or femtosecond 1 fs 107 s Short fiber PMD may be expressed in terms of time per meter or kilometer Due to the effects of mode coupling long fiber differential group delay increases as the square root of fiber length Therefore long fiber differential group delay is often expressed in terms of time per square root of fiber length in kilometers 2 30 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Fiber PMD statistics The PMD of a component or fiber is simply the average differential group delay For non mode coupled devices this may be obtained from a single pair of Jones matrix measurements separated by a known wavelength interval although in practice an average of several intervals is used For highly mode coupled devices the measurement is repeated at a many wavelength intervals across a large wavelength range The average differential group delay is simply the average of these individual values Fitting the Maxwell curve to the distribution To determine whether the wavelength dependence of a fiber has been sufficiently sampled in a particular measurement a histogram of the individual differential group d
318. the Windows Program Manager Select the background of the screen and select Program Manager from the dialog box ATTENTION Operating the HP 8509A B requires computer system resources When you run multiple software applications or have several HP 8509A B windows open system resources can be exhausted severely slowing operations such as moving from window to window Check system resources by going to the Program Manager selecting the Help menu and About Program Manager At least 25 of the system resources should be free Close applications or HP 8509A B windows as needed to free up system resources and increase operating speed and responsiveness In addition it is a good idea to re start your computer every day Accuracy Enhancement and Troubleshooting 3 1 AS RY 2 Measurement PR a e i WARES S KY Troubleshooting QS Qe e ss i WN LRU DASE ODAN ANG Matrix SE OVE PS ALS S N KELSA D O SY RY ES SS Sg amp High low power reading power over under range Power variations with wavelength PMF alignment problems Wandering point on Poincare Sphere Polarization reference frame quality is poor Low measurement accuracy repeatability PMD JME Accuracy Symptom PMD WS Accuracy PDL Jones Matrix Accu PDL Power Max Min Accu Jones Matrix Accuracy Polarization Ref Frame Poincare Sphere 4 Degree of Polarization
319. the optical output to the optical input on the HP 8509B Connect your test device between the optical output and the optical input ACCURACY ENHANCEMENT NOTE The fiber path leading from the optical output of the HP 8509to the DUT and from the DUT to the optical input of the HP 8509 must not move during the measurement process Unsupported fiber particularly unjacketed fiber should be taped down or placed against stationary objects Movement of the fiber may jeopardize PMD measurement accuracy CAUTION Observe proper connection techniques Refer to the Lightwave Connector Care chapter in this manual HP8509B Lightwave Polarization Analyzer File Edit BREE Display System Help PMD Jones Matrix Eigenanalysis PMD Wavelength Scanning Shift F2 PDL Jones Matrix F3 PDL Power Max Min Shift F3 Jones Matrix F4 PM Fiber Launch F5 Marker Angles Timed Measurement pq792b_c Figure 2 9 JME Measurement Selection Select Measurement from the main menu and then select PMD Jones Matrix Elgenanalysis F2 2 8 Making Measurements PMD Measurement Jones Matrix Eigenanalysis Method Optical Source Setup for PMD Jones Matrix Eigenanalysis r OpticalSourceS election Wavelength r Power HP8168A HP 1B y on Oot HP IB Address 724 Start 1460 0 Stop 1560 0 r Settling Time ms Delta 5 0 Points 21
320. the type of analysis performed on the traces and the minimum feature size The value of the mode coupling factor k is also shown These topics are discussed in detail in the Concepts section under the title Analysis Mode and Minimum Feature Size The measurement annotation area can be toggled on and off by selecting Display from the main window menu and then Annotation Using The Cursor Cursor Bar Avg DGD 0 1525 s1 0 2288 s2 0 098 s3 0 1307 MET mp 1460 0 o 081737 PS ITA RA Start AA T gt 0 005 Fiber Length 0 km Stop k 10 82 Source level OjuWatt Delta Source atten dB Points Continue pq7117_c Figure 2 42 The Cursor Bar Use the arrow button in one of the graphs to expand the graph Activate the Cursor Bar by selecting Display and then Cursor Bar from the Graphs window menu The cursor bar appears between the Measurement Summary Bar and the Measurement Annotation area The cursor display shows the normalized stokes parameters for a selected wavelength The wavelength is selected by the slider control arrow keys or by editing the wavelength display 2 38 Making Measurements PMD Measurement Wavelength Scanning Method Changing The Measurement Format HP8509 Graphs lt 2 gt PMD WS 1460 0 1560 0 5 0 Edit File Measure geldaria Display Wi
321. the value of the setting in nanometers Using the lt Wavelength nm gt parameter sets the value Note The Start and Stop values can never have the same value For example when segmenting a wavelength range over several measurements and sweeping from low to high always issue the command WaveScan WLen Stop before the command WaveScan WLen Start when specifying the next wavelength segment This will prevent the Start and Stop values from being equal when switching from one segment to the next WaveScan WLen Points lt NumPoints gt Sets the number of points between the start and stop wavelengths for the polarization mode display PMD measurement Each point corresponds to a wavelength for PMD measurement If the number of points does not correlate with the delta value and the start and stop wavelengths the delta value is reset to accommodate the number of points according to WLenDelta WLenStop WLenStart WLenPoints 1 The query returns the number of points specified in the current PMD WS measurement settings Zero Causes the measurement offsets to be referenced as a zero measurement state The measurement offsets correspond to the voltages generated by the receiver photodiodes under a zero input condition A zero valued measurement state can thus be established by the user at any time during a measurement process Programming 10 63 Example Programs The example programs are provided on two disks that
322. this this first second pq790b_c Figure 2 54 3pt Reference Applied Select 3pt Ref from the Markers Area on the Main Screen wait 5 seconds and then select Apply 3pt ADDITIONAL INFORMATION Creating and applying a 3pt reference frame allows measurement of polarization state within a physical frame of reference In this case the reference frame is located inside the internal polarizer assembly 2 48 Making Measurements PDL Measurement Jones Matrix Method The Active Point is neara Pole HP8509B Lightwave Polarization Analyzer File Edit Measurement Display System Hel Power 9 090 Bm Clear Trace T call 42 1550 0 nm The Polarization Ellipse is almost circular Markers On Clear Markers so si s2 s3 9 090 0 02 0 08 0 98 Rotate 2pt Ref 3 Apply Bed Home s3 is greater than 0 90 pq791b_c Figure 2 55 Circular Polarization Adjust the External Source Polarization knobs on the front panel of the HP 8509B until the active point on the Poincare sphere approaches a pole and the absolute value of the s3 marker is greater than 0 90 The active point is easier to see by marking the current point select Display and then Mark Current Point Also notice that the polarizati
323. three dimensional graphing system showing all possible states of polarization A dot or trace on the sphere represents the polarized portion of the lightwave signals as measured inside the instrument s receiver The reference frame feature allows the Poincare sphere to display a signal s state of polarization relative to a user defined reference frame ADDITIONAL INFORMATION Since the Poincare sphere is a three dimensional representation it is helpful to know that the graticules equator and longitude lines are solid lines on the front of the sphere and broken lines on the back of the sphere Data on the front of the sphere is shown in red and data on the back of the sphere is shown in blue Polarization Ellipse The polarization ellipse provides a two dimensional visual representation of the state of polarization of an optical signal and corresponds with points on the Poincare sphere Getting Started 1 5 The Marker Functions Clear the Markers Markers On Off O Clear Markers Current Point s1 s2 s3 Stokes Parameters 0 02 0 08 0 98 Rotate a Marker or Point to Center Set a Marker 2pt Ref 3pt Ref Define a Apply a Reference Frame Reference Frame pq746b_c Figure 1 2 The Marker Window The marker window in the lower left corner of the HP 8509 display always displays the Sto
324. tical source information 1 1 1 12 optical source selection 7 7 Optical Source Setup 10 25 Optional Selection 10 23 OSS 10 25 overrange message 1 5 P PDL 10 25 Jones matrix 7 2 power max min 7 2 PDL Jones matrix measurement 2 45 PdlMaxMin 10 44 PDL power meter measurement 2 52 peaks first to last 7 18 peaks full scan 7 18 picoseconds femtoseconds 7 12 pipe 10 23 PMD 10 25 11 1 Jones matrix eigenanalysis 7 2 Index 3 wavelength scanning 7 2 PMD measurement Jones matrix eigenanalysis 2 2 wavelength scanning 2 33 PMF alignment 2 68 PM fiber launch 7 2 poincare sphere 1 1 1 5 trace recalled 4 1 trace saved 4 1 poincare sphere 7 2 points 7 7 point to center markers 1 6 polarization coordinate system 12 1 right handed circular 12 1 polarization dependence 4 13 Polarization Dependent Loss 10 25 polarization ellipse 1 1 1 5 polarization maintaining fiber launch 2 68 polarization mode dispersion 4 2 4 13 11 1 Polarization Mode Dispersion 10 25 polarization reference frame 2 74 polarizer A 7 18 polarizer B 7 18 polarizer C 7 18 polarizers 7 2 power display 1 1 1 5 7 2 overrange message 1 5 underrange message 1 5 zero message 1 5 power meter measurement PDL 2 52 power on off 7 7 print graph 2 23 tabular format 2 17 print graph 7 12 print graph amp annotation 7 12 print graph annotation amp data 7 12 print graphs amp annotation 7 18
325. timeout Single mode Single Main window Sets instrument to collect a single data point each time it is triggered by the user 7 22 User Interface Reference Table 7 8 Timed Measurements continued Control or Data Path Description Start sample sequence selection Main window Measurement menu Timed measurement Timed or free run mode Starts a measurement series in the free run or timed mode Take sample Main window Triggers a single sample in the single mode selection Measurement menu Timed measurement Single mode Timed Main window Set instrument to collect data at intervals set by the mode selection Measurement menu Timed measurement mode timing controls User Interface Reference 7 23 PDL Jones Matrix amp Jones Matrix The PDL JONES MATRIX feature determines the PDL of a two port device from measurement of the Jones matrix The resulting value corresponds to the variation of optical insertion loss or gain for all possible states of polarization Table 7 9 PDL Jones Matrix amp Jones Matrix Control or Data Path Description Cal at angle Main window These three controls appear when using external Measurement menu PDL Jones Matrix using internal polarizers selection Measurement menu polarizers The angles given are those which appear PDL Jones Matrix in the Polarizers control frame to be found under the
326. to con il marchio Hewlett Packard Tale marchio stato traformato in Agilent Technologies I due prodotti sono identici dal punto di vista funzionale il cambiamento ha riguardato soltanto il nome della societa Nella documentazione sono ancora presenti riferimenti ai prodotti Hewlett Packard alcuni dei quali tuttavia sono passati sotto il marchio Agilent Technologies Transici n de Hewlett Packard a Agilent Technologies Esta documentacion proporciona informacion t cnica sobre un producto que anteriormente se distribu a bajo el nombre de marca de la compa a Hewlett Packard Dicho nombre de marca ha cambiado ahora a Agilent Technologies Los dos productos son funcionalmente id nticos s lo ha cambiado nuestro nombre Este documento a n incluye referencias a productos de Hewlett Packard algunos de los cuales han pasado a Agilent Technologi Vi3zmenenne TOproBo mapku Hewlett Packard Ha Agilent Technologies Ta JOKYMCHTALMA OTHOCHTCA K IIPOMYKTY KOTOPBI paHee MOCTABJIAJICA NOA TOProBo mapko Hewlett Packard Tenepb TOproBaa mapka nm3menena Ha Agilent Technologies npn 3TOM PyHKIMOHAJIBHBIE BO3MOXHOCTH NPO AYKTA He H3MCEHHJIHCE B AOKYyMEHTE MOTyT BCTpeyaTBCA CCBLIKM Ha nMpo1ykTbl Hewlett Packard 0o IHHAKO HeKOTOpbIe H3 HHX TENepb ABJLAIOTCA IPpoAykTamn Agilent Technologies Hewlett Packard Agilent Technologies 443 32 aud E 4382 1422 Hewlett Packard 3A I Z2 SA eS 19 ASE 22407 439 Agilent Technologies AAA A Y
327. todiodes photodarlingtons and phototransistors differential group delay The difference in propagation time of the polarization modes of a lightwave signal through a test device The differential group delay may be a function of wavelength especially in optical fibers The average differential group delay over wavelength is commonly referred to as PMD Glossary 2 distortion An undesirable change of signal waveform shape DOP See degree of polarization ellipse See polarization ellipse ellipticity The ratio of optical powers corresponding to the minor and major axes respectively of the polarization ellipse effective DOP The degree of polarization DOP of a lightwave signal is defined as the ratio of the power of the polarized component of the signal to the total power The HP 8509 calculates DOP from the square root of the sum of the squares of the normalized Stokes parameters which in turn are calculated from the ratios of the measured Stokes parameters to the total power The HP 8509 can be used to measure the effective DOP of a polarization modulated signal by taking advantage of the display averaging feature This is called effective DOP When display averaging is used every normalized Stokes parameter produced by the measurement system represents the average of the most recent N measurement samples where N is the number of display averages selected by the user Because DOP is calculated from these averaged normalized St
328. ts gt Sets the number of sample points used in the reading of a timed measurement trace Single Start Triggers the reading of a timed measurement trace Source Upon command reception the analyzer returns a string which specifies the source settings of the HP 8509 analyzer window In addition the wavelength in nm of the active source is returned If a source is not currently turned on the parameter off is returned instead of the source wavelength The string is in the form of lt Name of Laser Source gt f lt Wavelength nm gt off The names of the laser sources are Voltage tuned HP8167A HP IB HP8168A HP IB Internal Manually tuned Note The source settings for the analyzer window the PMD JME window and the PMD WS window are independently set When a polarization mode dispersion measurement PMD is initiated the analyzer window inherits the settings of that PMD measurement The Source command returns the setting of the analyzer window at the time of the command Programming 10 53 Source External The analyzer returns the wavelength in nm of the currently activated external source for the analyzer window Source External Off On Not Recommended Command may not be available in future versions Plan your programming accordingly Specifies the use of an external source and the state Off On of the utilized external source DDE only Note The external TLS controlled is the
329. u begin remote operation of the HP 8509 quit then restart the application if there has been any manual operation of the HP 8509 during the current session of the HP 8509 application Table 10 1 Conventions colon Command Separates parameters A parameter must be supplied Separator to the right of every colon question Query The command causes the instrument to prepare a response No further commands may be sent until the response is retrieved braces Mandatory Select one of the options in the braces as a Selection parameter If braces indicate option is part of a parameter select option and append it to the parameter brackets Optional Selection Similar to Mandatory Selection except that selecting a parameter is optional pipe Selection Separator Separates mandatory selection and optional selection parameters Spaces may be added in this document for clarity lt gt angle brackets Described parameter A description of the parameter Supply a parameter corresponding to the description in the brackets lt filename gt The filename of the file to save or load The path if specified should exist or an error will occur If the path is not specified the default path will be used The default path for any filename is the windows working directory This is usually the same as the HP8509 application directory but can be changed in the Windows Program Manager by
330. urement method to use m Measurement speed is slightly faster than the JME method m The method can be performed with the HP 8509A or B m The method provides more optical power to the DUT than the JME method does a A single PMD value or average differential group delay is produced from measurement across a wavelength span a Broad wavelength ranges are required for measurement of low PMD values m The measurement is influenced by pigtail position and polarization launch condition particularly for low values of PMD Making Measurements 2 33 PMD Measurement Wavelength Scanning Method Basic Measurement The following measurement procedure illustrates the simplest and most straightforward path in using the HP 8509A B Lightwave Polarization Analyzer operating system software to make a wavelength scanning PMD measurement Setting up the System Connect your measurement system as outlined in the following illustration HP 8509B External Source Polarization External Source Optical Optical Input Output Input Q Q Q Tunable e ZA k Lightwave Source J Thru DUT Cable pq761b c Figure 2 35 Wavelength Scanning System Setup If the source signal is applied to the External Source Input of the HP 8509B External Source Polarization should be adjusted for circular polarization as described in External Source Preparation in this chapter Connecting the tunable laser directly to the D
331. uring normal operation of the HP IB to DDE Gateway the individual commands that are being transmitted to the HP 8509 also appear in this text box When checked HP IB bus transactions are recorded to the file selected with Pick File and the Pick File button is disabled The ErrorsOnly feature may be turned on and off by clicking the right mouse button on the Log On check box Pick File Selects a file for logging HP IB bus transactions This button is disabled when Log On is selected This filename is saved in the file C Windows WIN INI under the heading HPIB2DDE and is restored the next time the HPIB2DDE application is started Execute Cmd Sends the command in the Command text box via DDE to the HP 8509 application Get Data Retrieves data via DDE from the HP 8509 application The data is linked to the text boxes found in the Dynamic Data Exchange DDE window Gi Closes the HPIB2DDE gateway application 10 8 Programming HP IB Frame This frame provides you with an interface to the HP IB bus parameters The elements of the HP IB window are described below To LPA Shows the user the command being sent to the HP 8509 that was received on the HP IB bus To HP IB Shows the user the data being sent to the HP IB bus that was read from the HP 8509 Status Shows the HP IB card status and the time and date of any error HP IB bus errors DDE errors and Windows system errors are also logged to a file when is s
332. us to HP8509 operation The programmer should hard code appropriate delays in the controlling program after sending HP8509 commands that take more than 30 seconds or 1 2 the timeout limit to complete Remember commands may still be in the HP IB to DDE Gateway command queue when the controlling program requests data The execution time to complete the commands still in the queue may exceed the timeout limit HP 8509 Control Frame The elements in this frame provide a path for the development of HP IB remote programs With the HPIB to DDE Gateway you can send HP IB commands retrieve data and save bus Programming 10 7 traffic to a file for later analysis The elements of the HP 8509 Control Window are described below HP 8509 Status Shows the status of the current DDE operation Valid choices are PASS the remote command successfully completed FAIL the remote command failed and did not complete PROBLEMS the remote command experienced a problem during execution UNKNOWN the remote command was not recognized BUSY the remote command is in the process of execution NO DDE LINK the DDE link is not established List This is a list of all the DDE commands This list drops down to select a command for the Command text box This list box is loaded by reading in the file DDE_CMD TXT located in the application directory Command This text box is used to specify a command to send via DDE to the HP 8509 application D
333. ut O Output Input Q Y pq7166_c Figure 9 1 Laser Aperture Location 9 4 Safety and Regulatory Information 10 Programming This chapter is an introduction to programming the HP 8509 polarization analyzer over HP IB Hewlett Packard Interface Bus and over the DDE dynamic data exchange Its purpose is to provide concise information about the operation of the instrument under remote control Some background information on the HP IB and DDE is provided A tutorial introduction using elementary programming examples illustrates the basics of HP 8509 remote control The document also provides a command reference with a brief description of each HP IB DDE command recognized by the HP 8509 Examples are provided on two disks that are included with the HP 8509 Users Reference Guide The programs on these two disks illustrate the exact executable syntax but the code is not explained in great detail See the README TXT files on each disk for more information Example Programs Disk DOS Format IBASIC and VISUAL BASIC DDE example Example Programs Disk LIF Format HP BASIC example for an HP 9000 series 200 300 controller The main focus of this chapter is on HP IB control of the HP 8509 polarization analyzer through an external PC controller running IBASIC for Windows Most of the commands in the command reference section 8 are available using Microsoft Windows DDE as well as HP IB The material presented in this chapter
334. velength Scanning Shift F2 Optical Source Setup for PMD Wavelength Scanning r OpticalSourceSelection Wavelength HP8168A HP IB y HP IB Address 724 Start 1460 0 Stop 1560 0 rSettlingTime ms Delta 0 5 Points 5 Start 2000 perPoint 100 Cancel pa71i13_c Figure 2 37 Optical Source Setup for PMD Wavelength Scanning Verify that the source and wavelength are correct for your measurement and that the power is on If the screen on your computer looks like the previous illustration select Done ADDITIONAL INFORMATION a A broader measurement wavelength range produces a more accurate measurement a If you wish to maintain leveled power during the measurement enter into the power level display of the optical source setup window a value no greater than the minimum power shown in the lasers display of available laser power m Single mode fiber lengths in the range of 10 km or low PMD fibers generally may be adequately measured by using a wavelength delta of 1 nm m Single mode fibers that are much longer than 10 km or have high PMD fibers are best measured with wavelength deltas of 0 25 nm Making Measurements 2 35 PMD Measurement Wavelength Scanning Method Avg DGD MN ps Start Measurement 1 Configure laser with Optical Source Setup
335. veraging Bange Analog Outputs Reference Frame Info Operation Verification pq780b_c Figure 2 77 System Menu Select System from the main menu and then select Optical Source Optical Source Setup rOpticalSourceSelection r Power HP8168A HP IB HP IB Address 724 On O Off Level _ 100 0 Wavelength cw 1551 0 Cancel pq71b_c Figure 2 78 Optical Source Setup Select the external laser source and set the CW wavelength for your measurement Use the default power level or set as desired If the screen on your computer looks similar to the previous illustration select Done 2 70 Making Measurements Polarization Maintaining Fiber Launch Making the Measurement At this point you are ready to make your first PMF alignment For our purposes we are going to align a short length of fiber optic cable ADDITIONAL INFORMATION The PMF alignment or launch method is based on the fact that if the launch into the PMF cable is misaligned then optical power is being sent into the orthogonal fast and slow axes of the PMF cable The relative velocity or phase relationships between these two paths can be changed by slightly pulling or heating the fiber This changes the cables output polarization and traces an arc on the Poincare sphere The analyzer calculates th
336. ving the Graphs window Display all of your measurements in one window using windows tile or cascade modes The Measurement Summary Bar Measurement Summary Bar cl 0 05418 Ped 0 10086 VES 0 11546 Y 0 06091 Jem 0 01823 Start 1460 0 nm Fiber Length 0 km Stop _1560 0 nm Source level OjuWatt Delta 5 0 nm Source atten dB Points 21 Continue pq7104_c Figure 2 16 The Measurement Summary The Measurement Summary Bar displays the PMD results obtained up to the current wavelength All of the displays have the same units which are user selectable but default to picoseconds The bar displays the average current maximum minimum and standard deviation of the differential group delay up to the current wavelength 2 14 Making Measurements The Measurement Annotation Area Fiber Length Source level Source atten PMD Measurement Jones Matrix Eigenanalysis Method Start 0 km Stop OJuWatt Delta dB Points Measurement Annotation Area 1460 0 1560 0 5 0 21 nm nm nm cla 0 08416 femelle 0 10086 Meee 0 11546 BI 0 06091 fom 0 01823 Continue pq7105_c Figure 2 17 The Measurement Annotation Area When the measurement ends the control panel at the bottom of the Graphs window is replaced by Measurement Annotation This area lists the date and time of the start o
337. wavelengths of the first and last feature peak or peak valley as appropriate For a detailed discussion of the Analysis modes see the PMD WS Concepts section with that title o Extrema Full Scan Causes the HP 8509A B to count both peaks and valleys and to use the endpoints of the wavelength scan in the wavelength scanning formula o Extrema First to Last Causes the HP 8509A B to count both peaks and valleys and to use the wavelengths of the first and last feature peak or valley in the wavelength scanning formula Peaks Full Scan Causes the HP 8509A B to count only peaks and to use the endpoints of the wavelength scan in the wavelength scanning formula O Peaks First to Last Causes the HP 8509A B to count only peaks and to use the wavelengths of the first and last peak in the wavelength scanning formula Making Measurements 2 39 PMD Measurement Wavelength Scanning Method Minimum Feature Size The value entered here is the amplitude change in linear units required between a feature and both of its nearest neighbors in order to be recognized as a feature peak or valley For more details see the PMD WS Concepts section of the same title m Mode Coupling Factor k The mode coupling factor must be set according to the type of test device See the PMD WS Concepts section of the same title for details m Polarizer A Polarizer B Polarizer C No Polarizer These selections control the use of the internal polarizer and are availab
338. window See Applying Your Calibration later in this chapter Also refer to Fixed Wavelength Source Calibrations later in this chapter ADDITIONAL INFORMATION A calibration does not have to be saved in order to be applied However unsaved calibrations will be lost when the HP 8509A B software is closed Calibrated Fixed Wavelengths 1311 0nm Internal 1539 0nm_ Internal New Save new calibrations Delete selection pq78b_c Figure 6 6 The Calibration List The System Menu 6 9 Calibrating For Use With a Tuneable Wavelength Source Make sure the instrument has warmed up for at least one hour and then zero the instrument Refer to Zero earlier in this chapter for information on how to zero the instrument Select External Source and Input Wavelength 1 Open the Optical Source window shown below by selecting A 2 Select an external source such as the HP 8168A 3 Select Manually tuned for other non automatic tunable sources 4 Input the first wavelength you want to calibrate Optical Source Setup rc OpticalS ourceSelection Manually tuned y Wavelength CW 1550 5 Cancel pq72b_c Figure 6 7 The Optical Source Window 6 10 The System Menu Calibrate at the Selected Wavelength 1 Open the Calibration
339. wlett Packard to Agilent Technologies Transition This documentation supports a product that previously shipped under the Hewlett Packard company brand name The brand name has now been changed to Agilent Technologies The two products are functionally identical only our name has changed The document still includes references to Hewlett Packard products some of which have been transitioned to Agilent Technologies Hewlett Packard to Agilent Technologies Transition FRE This documentation supports a product that previously shipped under the Hewlett Packard company brand name The brand name has now been changed to Agilent Technologies The two products are functionally identical only our name has changed The document still includes references to Hewlett Packard products some of which have been transitioned to Agilent Technologies Umbenennung Hewlett Packard in Agilent Technologies Diese Dokumentation geh rt zu einem Produkt das fr her unter dem Markennamen Hewlett Packard ausgeliefert wurde Der Markenname lautet in der Zwischenzeit Agilent Technologies Die Funktionalit t der beiden Produkte ist identisch nur der Name hat sich ge ndert Im Dokument wird zum Teil immer noch auf Hewlett Packard verwiesen An anderer Stelle wurde die Marke in Agilent Technologies umbenannt Hewlett Packard e la transizione ad Agilent Technologies La presente documentazione fornita a supporto di un prodotto che in precedenza veniva commercializza
340. wo waves of different propagation velocity according to polarization state The difference of propagation time between the fast and slow mode at a given wavelength is called the differential group delay DGD The term PMD also refers to the average DGD across a wide wavelength range of across a wide range of environmental conditions polarization reference frame A polarization reference frame may be created at any point in an open beam environment with the use of a precision rotatable polarizer and the Jones matrix measurement capability of the HP 8509A B Lightwave Polarization Analyzer Reference frames are of two types The 3pt frame of reference mathematically removes birefringence and polarization dependent loss from the path between the reference polarizer and the polarization analyzer receiver This method requires that the reference polarizer be set precisely to the angles listed in the polarizers display found by selecting the Polarizers from the System menu in the main window Glossary 8 The 2pt frame of reference mathematically removes only birefringence from the path between the reference polarizer and the polarization analyzer receiver This method requires only two orientations of the polarizer and the angle between them is not critical Following application of a reference frame rotation of the reference polarizer should cause the point on the Poincare sphere to move along the equator polarizer An optical device someti
341. ystem Range Selecting Autorange The default condition for Range is Autorange Note that when autorange is selected there is an X in the box next to it Selecting a Specific Gain State 1 Deselect Autorange 2 To accommodate high signal levels select 4 For operation with low level signals select y 3 Continue pressing 4 or y until the power display in the upper left corner of the lightwave polarization analyzer measurement screen reads Overrange or Underrange 4 Once you have reached the Overrange or Underrange condition press 4 or y once to remove the Overrange or Underrange indication on the power display 5 The gain will stay in this state until a different range is selected or until Autorange is selected About Range To provide the large input dynamic range the lightwave polarization analyzer operates over seven possible gain states or input power ranges In some measurements it is helpful to put the instrument in a specific gain state This eliminates interruption of data taking by the gain switching process and allows operation at levels below 55 dBm 6 22 The System Menu Analog Outputs Analog outputs are disabled when using a Vtune source Analog Outputs 10 volts to 10 volts e Off A DOPB s1 C s2 D s3 O Raw diode currents A Ch1 B Ch2 C Ch3 D Ch4 Done pq712b_ Figure 6 17 The Analog Outputs Window The analog
342. ystem menu Calibration Exits the calibration form No calibration data is lost Optical source display Main window System menu Calibration Specifies whether the selected source is a laser internal to the HP 8509B or is an external source and lists the type of external source Save new calibration selection Main window System menu Calibration Saves any calibration performed since the previous save Calibrations are saved to hard disk User Interface Reference 7 9 Table 7 3 Calibration continued Control Path Description or Data Source type Main window Specifies which of two categories of wavelength fixed wavelength System menu calibrations is to receive the focus of the wavelength tunable wavelength Calibration calibration form The fixed wavelength calibration should be used for single wavelength sources internal or external The tunable wavelength calibration should be used for a tunable external source Wavelength display Main window When the calibration is performed the resulting System menu calibration data is assigned to the wavelength Calibration displayed here Optical source Wavelength selection Main window Provides convenient access to the optical source System menu setup window for the main window Calibration 7 10 User Interface Reference Operation Verification The operation verification feature checks the functionality of the HP 850
343. ze and Analog Output Range Table 11 11 Other Characteristics Other Characteristics Compatible fiber 9 125 micron 10 volts Analog output range Specifications and Characteristics 11 7 12 Coordinate System and Generation of Right Hand Circularly Polarized Light An explicit coordinate system must be specified in order to unambiguously describe a state of polarization For description of polarization a conventional coordinate system is oriented so that the z axis is horizontally oriented in the direction of propagation of the light The y axis is vertically oriented pointing up and the x axis is horizontally oriented to form a right handed rectangular coordinate system Angles are measured referenced to the x axis a positive angle indicating the sense of rotation from x toward y The electric field vector of elliptically polarized light is said to rotate in either a right hand sense or a left hand sense corresponding to either a positive or negative third normalized Stokes parameter respectively In the case of right hand circularly polarized light at any instant in time the electric field of the wave is a function of z and is described by a right handed helix like a screw thread As this helix propagates through a fixed xy plane the electric field vector in that plane rotates in a clockwise sense when viewed looking in the direction of propagation Right handed circularly polarized light can be generat

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