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86120C User Manual - Custom-Cal

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1. PRESet Turns off any CALCulate3 calculation that is on CALCulate3 PRESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only This command turns off any CALCulate3 calculation delta drift Fabry Perot or signal to noise that is on 4 68 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR AUTO Selects the reference frequency value for measuring noise in the sig nal to noise calculation CALCulate3 SNR AUTO ON OFF 1 0 Constant Description ON Selects internally generated reference frequency OFF Selects user entered reference frequency Preset State on RST State on SCPI Compliance instrument specific The command argument allows you to select either an internally gen erated or a user entered frequency reference for measuring the noise To enter a value to use as the reference use the SNR REFerence FRE Quency SNR REFerence WAVelength and SNR REFerence WNUMber commands 4 69 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR REFerence FREQuency Enters a frequency that can be used for the noise measurement refer ence in signal to noise calculations CALCulate3 SNR REFerence FREQuency lt real gt MINimum MAXimum lt real gt is a frequency value that is within the following limits Constant Description MINimum 181 692
2. real is a wave number value that is within the following limits Constant Description MINimum 6060 cm 1650 MAXimum 7874 cm 1270 nm Preset State unaffected by RST State 6451 614 cm 1550 nm SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The wave number entered is converted internally to the corresponding frequency The default units for the real parameter are m1 4 72 Syntax Attribute Summary Programming Commands CALCulate3 Subsystem SNR STATe Turns the signal to noise calculation on and off CALCulate3 SNR STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 73 Programming Commands CONFigure Measurement Instruction CONFigure Measurement Instruction For information on the CONFigure measurement instruction refer to Measurement Instructions on page 4 15 4 74 Programming Commands DISPlay Subsystem DISPlay Subsystem The commands in this subsystem have the following command hi
3. 222 223 224 230 232 273 String data not allowed Invalid block data Block data not allowed Expression error Invalid expression Expression data not allowed Execution error Trigger ignored Caused by sending the TRG command when the instrument is already taking a measurement or when the instrument is in continuous measurement mode nit ignored Caused by sending an INIT I MM READ or MEASure command while a measurement is already in progress or while the instrument is in continuous measurement mode Settings conflict Caused by trying to set the instrument to a state that is not allowed For example turning on drift maximum and drift minimum state simultaneously or turning on SNR state while drift or delta state is on Data out of range Too much data Illegal parameter value Data corrupt or stale Caused by trying to query measurement data immediately after a RST command For example sending RST FETCh or sending RST CALC2 DATA pow Data questionable Caused by sending a resolution value in one of the measurement functions that is outside the instrument s range Illegal macro label 7 15 Reference Error Messages Table 5 24 General SCPI Error Messages 3 of 3 Error Number Description 310 System error 321 Qut of memory 350 Too many errors 400 Query error 410 Query INTERRUPTED
4. 4 97 Syntax Attribute Summary Description Query Response Example Programming Commands SYSTem Subsystem ERRor Queries an error from the error queue SYSTem ERRor Preset State none RST State none SCPI Compliance standard Query Only The Agilent 86120C has a 30 entry error queue The queue is a first in first out buffer Repeatedly sending the query SYSTEM ERROR returns the error numbers and descriptions in the order in which they occur until the queue is empty Any further queries returns 0 No errors until another error occurs For a complete list of error messages refer to Error Messages on page 7 11 value string value is an integer string is the text of the error message The following is an example of a response 113 Undefined header DIM Error 250 OUTPUT 720 SYSTEM ERROR ENTER 720 Error PRINT Error 4 98 Syntax Attribute Summary Description Programming Commands SYSTem Subsystem HELP HEADers Queries a listing of all the remote programming commands available for the Agilent 86120C SYSTem HELP HEADers Preset State none RST State none SCPI Compliance instrument specific Query Only The returned ASCII string of commands is in the IEEE 488 2 arbitrary block data format The first line indicates the total number of bytes returned to the computer That is the character is followed by one digit which indica
5. LIGT ORT a Il Contact us for your service needs Phone 888 530 9009 Email sales custom cal com Custom Calibration Solutions LLC Aa ilent HP 86120C User Manual Custom Cal has in depth experience having repaired over 1000 86120 s with a success rate of over 99 Our typical repair time is less than 5 business days as we have most replacement parts in stock We repair the E14 error using NEW original manufacturer parts which come with a one year manufacturer warranty which we will extend for three years We don t use refurbished or cheap generic parts Agilent 86120C Repair E14 E7 E4 E34 Agilent 86120C Multi Wavelength Meter User s Guide Notices This document contains propri etary information that is pro tected by copyright All rights are reserved No part of this document may reproduced in including elec tronic storage and retrieval or translation into a foreign lan guage without prior agreement and written consent from Agilent Technologies Deutschland GmbH as governed by United States and international copywright laws Copyright 2001 2004 by Agilent Technologies Deutschland GmbH Herrenberger Str 130 71034 B blingen Germany Subject Matter The material in this document is subject to change without notice Agilent Technologies makes no warranty of any kind with regard to this printed material includ ing but not limited to the implied warranties of merchantability a
6. Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DRIFt PRESet Turns off all the drift states for DIFFerence MAXimum MINimum and REFerence CALCulate3 DRIFt PRESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only This command allows the CALC3 DATA query to return the difference between the current measurement and the reference DRIFt REFerence RESet Places the current list of laser lines into the reference list CALCulate3 DRIFt REFerence RESet Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Command Only 4 59 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt REFerence STATe Turns on and off the drift reference state CALCulate3 DRIFt REFerence STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When this command is set to on the CALC3 DATA command returns the reference laser lines Use the CALC3 DRIF PRES command to turn off all the drift states before turning on the drift reference state Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 fo
7. Syntax SAV lt integer gt lt integer gt range is 1 to 4 Description The following constitutes an instrument state single continuous mea surement mode power bar on off vacuum STD air mode normal fast update list by WL list by Pwr peak or avg display mode frequency units power units elevation peak excursion peak threshold power 4 9 Syntax Description Programming Commands Common Commands Offset signal to noise auto mode on off wavelength limit on off wave length limit start wavelength limit stop and signal to noise average count SRE The SRE service request enable command sets the bits in the service request enable register SRE lt integer gt SRE integer is defined as an integer mask from to 255 The service request enable register contains a mask value for the bits to be enabled in the status byte register A bit set to one in the service request enable register enables the corresponding bit in the status byte register to generate a service request A zero disables the bit The fol lowing table lists the bits in the service request enable register and what they mask The service request enable register is cleared when the instrument is turned on The RST and CLS commands do not change the register The SRE query returns the value of the service request enable regis ter Table 4 16 Service Request Enable Register Bit Bit Weight Enables 7 128 Not Use
8. A U N me Making Measurements Changing the Units and Measurement Rate To change the measurement speed Press the Setup key Press the MORE softkey Press the UPDATE softkey Select either NORMAL or FAST Continuous or single measurements The Agilent 86120C continuously measures the input spectrum at the front panel OPTICAL INPUT connector Whenever measurements are being acquired an asterisk is displayed in the display s upper right corner When you switch between normal and fast update modes the rate that the asterisk blinks changes You can specify that the instrument perform a measurement only when the front panel Single key is pressed This is the single acquisition measurement mode and it is useful for capturing and preserving data After capturing the data you can display it using many of the proce dures included in this chapter You can return to continuous measure ment mode at any time by pressing the Cont key To select single measurement acquisition Press the Single key 2 14 Making Measurements Defining Laser Line Peaks Defining Laser Line Peaks The Agilent 86120C uses two rules to identify valid laser line peaks Understanding these rules is essential to getting the most from your measurements For example these rules allow you to hide AM mod ulation sidebands or locate laser lines with small amplitudes In order to identify a laser line the laser line must meet both of the fol
9. Attribute Summary Description Programming Commands CALCulate2 Subsystem When there is no input signal the POWer query returns 200 dBm the WAVelength query returns 100 nm 1 0E 7 PEXCursion Sets the peak excursion limit used by the Agilent 86120C to determine valid laser line peaks CALCulate2 PEXCursion integer MINimum MAXimum DEFault integer represents logarithmic units in dB Valid range is 1 to 30 dB Constant Description MINimum 1 dB MAXimum 30 dB DEFault 15 dB Non sequential command Preset State 15 dB RST State 15 dB SCPI Compliance instrument specific A laser line is identified as a valid peak if its amplitude is greater than the peak excursion plus the amplitudes of the closest local min ima on either side of the peak This command works in conjunction with the peak threshold setting Refer to PTHReshold on page 4 34 Changing the peak excursion limit causes the instrument to reprocess the current set of data Refer also to Defining Laser Line Peaks page 2 15 The query response is the current value For example if the current value is set to 15 dB the following value is returned 15 4 33 Syntax Attribute Summary Description Query Response Syntax Programming Commands CALCulate2 Subsystem Non sequential command Always use an query or a WAI command to ensure that this command has the time to complete before send
10. Error msg PRINT The program is aborted due to ERRM END Err mngmt SUB mngmt OPTIONAL Cmd_msg COM Instrument 9 Mwmt DIM Err_msg 255 INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg IF gt 0 AND NOT POS Err_msg 0 THEN PRINT This command Cmd_msg makes the following error IF NOT POS Err_msg 0 THEN PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err_msg 0 Subend SUBEND Set_ese SUB Set_ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNidentity COM Instrument Mwm DIM Identity 33 Identity OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm Opc done OUTPUT Mwm IDN ENTER Mwm Identity RETURN Identity FNEND Cmd_opc SUB opc Set cmd COM Instrument Mwm OUTPUT Mwm Set cmd OUTPUT Mwm OPC ENTER Mwm Opc_done SUBEND 3 38 Programming Example Programs Example 5 Measure signal to noise ratio of each WDM channel This program measures signal to noise ratios on a WDM system It measures the ratio for each line using commands from the CALCulate3 subsystem Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 DIM Key 1 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wave
11. Laser line separation Laser drift wavelength and power Signal to noise ratios Fabry Perot lasers The Agilent 86120C At a Glance In addition to these measurements a power bar is displayed that shows power changes like a traditional analog meter You can see the power bar shown in the following figure of the Agilent 86120C s dis play 1551 314 6 92 5 rmes PREY J HE T CAUTION peakwl The input circuitry of the Agilent 86120C can be damaged when total input power levels exceed 18 dBm To prevent input damage this specified level must not be exceeded Print measurement results You can get hardcopy results of your measurements by connecting a printer to the rear panel PARALLEL PRINTER PORT connector Program the instrument for automatic measurements The Agilent 86120C offers an extensive set of GPIB programming com mands These commands allow you to perform automated measure ments on manufacturing production lines and remote sites Chapter 3 Programming and Chapter 4 Programming Commands provide all the information you l need to know in order to program the Agilent 86120C Display wavelengths as if measured in vacuum or standard air Although all measurements are made in air displayed results are cor rected for air dispersion to accurately show wavelength values in vac uum or in standard air To ensure accurate wavelength
12. sure URLs 86120C 1270 1650 nm 0 Agilent MULTEWAVELENGTH METER Input Connector inptconn vi WARNING WARNING WARNING WARNING WARNING General Safety Considerations If this instrument is not used as specified the protection provided by the equipment could be impaired This instrument must be used in a normal condition in which all means for protection are intact only No operator serviceable parts inside Refer servicing to qualified personnel To prevent electrical shock do not remove covers To prevent electrical shock disconnect the Agilent 86120C from mains before cleaning Use a dry cloth or one slightly dampened with water to clean the external case parts Do not attempt to clean internally This is a Safety Class 1 product provided with protective earth 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 productis likely to make the product dangerous Intentional interruption is prohibited For continued protection againstfire hazard replace line fuse only with same type and ratings type F 6 3A 250V IEC 60127 type 5x20mm The use of other fuses or materials is prohibited Verify that the value of the line voltage fuse is correct General Safety Considerations CAUTION This product complies with Overvoltage Category Il and Polluti
13. 23 measurement instructions 23 non sequential 12 29 34 35 37 38 39 40 41 42 43 85 105 106 standard SCPI 23 termination 27 common commands CLS clear status 3 ESE event status enable 28 3 ESR event status register 5 IDN identification number 29 6 OPC operation complete 29 7 RST reset 29 8 SRE service request enable 10 STB status byte 12 TRG trigger 13 TST test 13 WAI wait 14 definition 23 sending 25 computer control 5 CONFigure measurement instruction 15 connector care 40 connector care 40 Cont key 14 23 CONT softkey 39 CONTinuous programming command 105 cotton swabs 48 covers dust 17 cursor 6 D damaged shipment 4 data corrupt or stale 26 8 15 data questionable 15 DATA programming command 26 32 49 88 DBM softkey 13 default GPIB address 3 Delta Off softkey See Off Delta On softkey See On DEVICES softkey 9 DFB lasers 9 dispersion See calibration measurements display annotation See annotation cursor 6 modes 3 resolution 4 6 9 scrolling through 6 setting update rate 14 softkeys blanked 3 update rate 13 DISPlay subsystem 75 down arrow softkey 6 DRANge programming command 34 DRIFT annotation 22 softkey 23 drift laser See laser drift dust caps 48 dust covers 17 E E15 MAX NUMBER OF SIGNALS FOUND message 17 E46 NUM LINES lt NUM REFS message 23 E47 NUM LINES gt NUM REFS message 23 E
14. For the CALC3 DATA query the power data returned is the array of absolute powers measured for each laser line The frequency data is the array of frequency values normalized to the frequency of the refer ence laser line The frequency of the reference laser line is returned as an absolute frequency unnormalized Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 54 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa WPOWer STATe Turns the delta wavelength and power measurement mode on and off CALCulate3 DELTaWPOWer STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When on the wavelength of the reference laser line is subtracted from the wavelength values of all laser lines except the reference The power value of the reference is subtracted from the power values of all laser lines except the reference For the CALC3 DATA query the power data returned is the array of powers normalized to the power of the reference laser line The power of the reference laser line is returned as an absolute power unnor malized The frequency data is the array of frequency values normalized
15. Notice in the example above that the commands are sent to an instru ment address of 720 This indicates address 20 on an interface with select code 7 Pressing the green Preset key does not change the GPIB address Set single acquisition mode An advantage of using the RST command is that it sets the Agilent 86120C into the single measurement acquisition mode Because the READ and MEASure data queries expect this mode their proper operation is ensured To change the GPIB address 1 Press the Setup key 2 Press MORE twice then GPIB 3 Use the and softkeys to change the GPIB address 4 Press RETURN 3 4 Programming Making Measurements Making Measurements Making measurements remotely involves changing the Agilent 86120C s settings performing a measurement and then returning the data to the computer The simplified block diagram of the Agilent 86120C shown here lists some of the available programming commands Each command is placed next to the instrument section it configures or queries data from Notice that there are two buffers from which data can be queried an uncorrected data buffer and a corrected data buffer With each scan of the input wavelength range the analog to digital converter loads 65 536 data values into the uncorrected data buffer This is considered to be one measurement A fast update measurement mode is avail able for quicker measurement acquisition But because only 32 768 data va
16. and K M Evenson 1979 Frequency measurement of the 260 THz 1 15 micron He Ne laser Optics Letters Vol 4 No 5 May 129 130 6 3 Sensitivity Selectivity Input Power Maximum Number of Lines Input Input Return Loss Measurement Cycle Time Specifications and Regulatory Information Definition of Terms of one laser line Polarization Dependence indicates the maximum displayed power variation as the polarization of the input signal is varied Display Resolution indicates the minimum incremental change in displayed power Sensitivity is defined as the minimum power level of a single laser line input to measure wavelength and power accurately A laser line with less than the min imum power may be measured but with reduced wavelength and power accu racy For multiple laser lines input sensitivity may be limited by total input power Selectivity indicates the ability to measure the wavelength and power of a weak laser line in the proximity of a specified stronger laser line and separated by the specified amount Maximum displayed level indicates the maximum total input power total of all laser lines present to accurately measure wavelength and power Maximum safe input power indicates the maximum total input power total of all laser lines present to avoid permanent optical damage to the instrument Maximum number of lines input is the maximum number of displayed lines If more than 200 lines are input o
17. take place in order for a laser line to be recognized The rise and fall can be out of the noise or in the case of two closely spaced signals out of the filter skirts of the adjacent signal The peak excursion s default value is 15 dB Any laser line that rises by 15 dB and then falls by 15 dB passes the rule You can set the peak excursion value from 1 to 30 dB In the following figure three laser lines are identified responses 1 3 and 4 Response 2 is not identified because it is below the peak threshold The portion of each signal that is within the peak excursion limits is shown in bold lines Because of the peak excursion rule responses 4 and 5 are identified as one laser line the minimum point between 4 and 5 does not drop to the peak excursion limit This response has the highest power shown which is peak 4 Whenever the peak threshold limit or peak excursion value is changed the new limits are applied to the current displayed measurements even if the instrument is in the Single measurement mode 15 dB peak excursion 10 20 10 dB peak threshold Power dBm 30 40 50 Wavelength wavlth15 To define laser line peaks Press the Setup key Press the THRSHLD softkey Making Measurements Defining Laser Line Peaks 3 Press PX EXC and enter the peak excursion value Use the softkey to select the digit that requires editing Use the and softkeys to change the value The peak excur
18. use two FETCh commands to return wavelength and then power values for the same measurement This is shown in the follow ing program fragment OUTPUT 720 INIT CONT OFF OUTPUT 720 CONF ARR POW MAX OUTPUT 720 INIT IMM OUTPUT 720 FETC ARR POW ENTER 720 powers OUTPUT 720 FETC ARR POW WAV ENTER 720 wavelengths In the example above the data in the power and wavelength arrays are returned in the same order so that powers can be matched to wave lengths Programming Making Measurements Also because new data is not collected FETCh is especially useful when characterizing transient data FETCh does not reconfigure the display For example if the display is in the Peak WL mode sending FETCh ARRay does not configure the display to the List by WL even though an array of data is returned to the computer A common programming error occurs when the FETCh command is used after an RST command This generates error number 230 Data corrupt or stale In this instance you must send INIT IMM after the RST command and before the FETCh command to capture a new array of measurement data CONFigure command The CONFigure command changes measurement settings without taking a measurement The instrument is placed in the List by WL List by Ampl or Peak WL display application CONFigure can be queried The query returns the last configuration setup by the CONFigure command The instrument returns a string w
19. 000 1 51855500E 000 1 49902300E 000 1 47949200E 000 1 50488300E 00 0 1 53320300E 000 1 50097700E 000 1 47265600E 000 1 50293000E 000 1 50781300E 0 00 1 51171900 000 1 48242200 000 1 50097700 000 1 51855500 000 1 50683600 000 1 48632800 000 1 50488300 000 Notice that only values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure com mands 4 89 Programming Commands STATus Subsystem STATus Subsystem Use the commands in this subsystem to control the Agilent 86120C s status reporting structures These structures provide registers that you can use to determine if certain events have occurred The commands in this subsystem have the following command hierar chy STATus OPERation CONDition ENABle EVENt PTRansition NTRansition PRESet QUEStionable CONDition ENABle EVENt PTRansition NTRansition 4 90 Syntax Query Response Attribute Summary Description Example Programming Commands STATus Subsystem OPERation QUEStionable CONDition Queries the value of the questionable or operation condition register STATus OPERation QUEStionable CONDition 0 to 32767 Preset State none RST State none SCPI Compliance standard Query Only Use this command to read the value of the OPERation Status or QUEStionable Status
20. 29 positions for the error messages and 1 position for the Queue overflow message The error queue is read with the SYSTEM ERROR query Executing this query reads and removes the oldest error from the head of the queue which opens a position at the tail of the queue for a new error When all the errors have been read from the queue subsequent error queries return 0 No error For more information on reading the error queue refer to ERRor on page 4 98 For a list of errors messages refer to Error Messages on page 7 11 3 22 Programming Reviewing SCPI Syntax Rules Reviewing SCPI Syntax Rules SCPI command are grouped in subsystems In accordance with IEEE 488 2 the instrument s commands are grouped into subsystems Commands in each subsystem perform sim ilar tasks The following subsystems are provided Measurement Instructions Calculatel Subsystem Calculate2 Subsystem Calculate3 Subsystem Display Subsystem Hcopy Subsystem Sense Subsystem Status Subsystem System Subsystem Trigger Subsystem Unit Subsystem Sending a command It s easy to send a command to the instrument Simply create a com mand string from the commands listed in this book and place the string in your program language s output statement For commands other than common commands include a colon before the subsystem name For example the following string places the cursor on the peak laser line and returns the power level
21. 8 Programming Making Measurements Measurement instructions give quick results The easiest way to measure wavelength frequency or power is to use the MEASure command The MEASure command is one of four mea surement instructions MEASure READ FETCh and CONFigure The syntax for measurement instructions is documented in Measurement Instructions on page 4 15 Each measurement instruction has an argument that controls the mea surement update rate This is equivalent to using the NORMAL and FAST softkeys MEASure command MEASure configures the Agilent 86120C captures new data and que ries the data all in one step For example to measure the longest wavelength send the following command MEASure SCALar POWer WAVelength MAX Table 2 5 The Different Forms of MEASure Desired Measurement Data Use this MEASure Query Display Format Power W dBm Frequency Hz Wavelength m Wavenumber MEASure ARRay POWer List by Power MEASure SCALar POWer single wavelength mode MEASure ARRay POWer FREQuency List by WL frequency MEASure SCALar POWer FREQuency single wavelength mode MEASure ARRay POWer WAVelength List by WL MEASure SCALar POWer WAVelength single wavelength mode MEASure ARRay POWer WNUMber List by WL MEASure SCALar POWer WNUMber single wavelength mode Specifying SCALar places the display in the single wavelength format and returns a single value to the computer Specifyi
22. 93854100 014 1 93653000 014 1 93452000 014 1 93250900 0 14 1 93050000E 014 4 20 Syntax Description expected value Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer WAVe length Returns wavelength values POWer WAVelength expected value resolution Used With expected value resolution SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resolution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a wavelength that is closest to the expected value parameter Default units for expected value parameter are in meters When used with an ARRay command an array of wavelengths is returned The display is placed in the list by wavelength mode The resolution parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 001 whichever is closer Returned values are in meters Displayed units are nanometers Power units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question ma
23. ASSIGN Mwm TO 720 DIM Key 1 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNidentity ON TIMEOUT 7 5 CALL Err_mngmt Cmd_opc RST Change to list by wavelength display Cmd_opc CONF ARR POW WAV Trigger and wait for one measurement Cmd_opc INIT Cmd opc WAI Turn on delta mode Cmd_ope CALC3 DELT WPOW STAT ON Set first wavelength as reference opc CALC3 DELT REF WAV MIN Query number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Delta wl 1 Nb pt ALLOCATE Delta pwr 1 Nb pt Query wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm Delta wl OUTPUT Mwm CALC3 DATA POW ENTER Mwm Delta_pwr OFF TIMEOUT FOR 1 1 TO Nb_pt 1 PRINT USING 6A 2D 17A M4D 3D 31A S2D 2D 4A Line wavelength is 3 37 Programming Example Programs x Delta wI D NOT Iz1 Delta w1 1 1 0E 9 nm Absolute line level is Delta pwr D NOT Iz1 Delta pwr 1 dBm PRINT USING 17A 2D 6A M4D 3D 23A 2D 6A S2D 2D 3A Delta 1 to line I 1 is Delta wl I 1 NOT I 1 Delta_wl 1 1 E 9 nm Delta Pwr to line I 1 is XIz1 Delta pwr L 1 NOT Iz1 Delta pwr I 1 Delta pwr I dB NEXT I PRINT USING 6A 2D 17A M4D 3D 31A S2D 2D 4A Line 1 wavelength is Delta wl 1 Delta wl Nb pt 1 0E 9 nm Absolute line level is Delta pwr 1 Delta pwr Nb pt
24. ELTa WPOWer STATe Turns the delta wavelength and power measurement mode on and off CALCulate3 DRIFt DIFFerence STATe Sets the drift calculation to subtract the minimum values measured from the maximum values measured CALCulate3 D RIFt MAXimum STATe Sets the drift calculation to return the maximum power frequency values measured CALCulate3 DRIFt MINimum STATe Sets the drift calculation to return the minimum power frequency values measured CALCulate3 DRIFt PRESet Turns off all the drift states for DIFFerence MAXimum MINimum and REFerence CALCulate3 DRIFt REFerence RESet Places the current list of signals into the reference list CALCulate3 DRIFt REFerence STATe Turns the drift state on and off so that CALC3 DATA will return the reference signal list CALCulate3 DRIFt STATe Turns the drift measurement calculation on and off CALCulate3 FPERot STATe Turns the Fabry Perot measurement mode on and off CALCulate3 FPERot MEAN WAVelength Queries the mean wavelength of the selected modes CALCulate3 FPERot MEAN FREQuency Queries the mean frequency of the selected modes CALCulate3 FPERot MEAN WNUMber Queries the mean wavenumber of the selected modes CALCulate3 FPERot PEAK WAVelength Queries the peak wavelength of the selected modes CALCulate3 FPERot PEAK FREQuency Queries the peak frequency of the selected m
25. Nitrogen gas or compressed dust remover can also be used Do not shake tip or invert compressed air canisters because this releases par ticles in the can into the air Refer to instructions provided on the com pressed air canister 2 50 Addressing and Initializing the Instrument 3 3 To change the GPIB address 3 4 Making Measurements 3 5 Commands are grouped in subsystems 3 7 Measurement instructions give quick results 3 9 The format of returned data 3 15 Monitoring the Instrument 3 16 Status registers 3 17 Queues 3 22 Reviewing SCPI Syntax Rules 3 23 Example Programs 3 28 Example 1 Measure a DFB laser 3 30 Example 2 Measure WDM channels 3 32 Example 3 Measure WDM channel drift 3 34 Example 4 Measure WDM channel separation 3 37 Example 5 Measure signal to noise ratio of each WDM channel 3 39 Example 6 Increase a source s wavelength accuracy 3 41 Lists of Commands 3 43 Programming Programming Programming Programming This chapter explains how to program the Agilent 86120C The pro gramming syntax conforms to the IEEE 488 2 Standard Digital Inter face for Programmable Instrumentation and to the Standard Commands for Programmable Instruments SCPI Where to begin The programming examples for individual commands in this manual are written in HP BASIC 6 0 for an HP 9000 Series 200 300 Control ler For more detailed information regarding the GPIB the IEEE 488 2 standard or the SCPI standard refer to
26. Setup key Press the SAV RCL softkey Press the SAVE softkey Press one of the four SAVE softkeys to save the instrument state To recall an instrument state Press the Setup key Press the SAV RCL softkey Press the RECALL softkey Press one of the four RCL softkeys to recall an instrument state Power bar To control the power bar Press the Setup key Press MORE twice and then PWR BAR Press BAR ON to display the power bar and press BAR OFF to hide the power bar display Making Measurements Changing the Units and Measurement Rate Changing the Units and Measurement Rate This section includes step by step instructions for changing the units and measurement rate This section includes Displayed units 2 12 Measurement rate 2 13 Continuous or single measurements 2 14 Displayed units As described below it s easy to change the wavelength and amplitude units You can choose between the following units Table 2 1 Available Units Wavelength Frequency Power nm dBm cm mW THz uw To change the units of measure Press Setup Press the MORE softkey Press the UNITS softkey 2 12 Making Measurements Changing the Units and Measurement Rate 4 Press WL and select one of the following units Then press RETURN to complete your selection NM for nanometers THZ for Tera Hertz CM for wave number 5 Press POWER and select one of the following units DBM for decibels relati
27. Turns the delta power measurement mode on and off CALCulate3 DELTa POWer STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When this state is on the power of the reference laser line is sub tracted from the power values of all laser lines except the reference The power data returned by the CALC3 DATA query is the array of laser line power levels normalized to the power level of the reference laser line The power of the reference laser line is returned as an absolute power unnormalized The frequency data returned is the array of absolute frequency values Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements DELTa PRESet Turns off all delt measurement states CALCulate3 DELTa PRESet Preset State not affected RST State not affected SCPI Compliance instrument specific Command Only 4 50 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DELTa REFerence FREQuency Selects the reference laser line for DELTa calculations CALCulate3 DELTa REFerence FREQuency lt real gt MINimum MAXimum real is a frequency value that is wi
28. become blanked If in the middle of a measurement the number of laser lines present changes the measurement stops until the original number of lines returns You ll notice that a CLEAR softkey appears and one of the following message is displayed E46 NUM LINES NUM REFS E47 NUM LINES gt NUM REFS To view the data measured before the conditions changed press CLEAR and then MAX MIN Notice that the measurement acquisition is changed from con tinuous to single To restart testing press CLEAR the CONT key and then RESET to use the new number of lines as the reference Pressing CONT restarts continuous measure ment acquisition Or you can restore the original number of lines on the input so that the drift measurement can continue To measure drift Press the front panel Preset key Press Peak WL List by WL or List by Power to select the display style for observing drift Press Appl s and then DRIFT Pressing DRIFT sets the current laser line values as the reference from which to compare all drift Press MAX MIN for the desired type of drift measurement as described in the following paragraphs Display shows the current values of laser lines relative to the wavelength and power values measured when the test was begun or the RESET softkey was pressed Display shows absolute maximum values since the drift measurement was started This measurement gives the longest wavelength and greatest power measured The l
29. cable is the Agilent Technologies part number for the complete cable including the plug Agilent Technologies Service Offices 7 18 Reference Agilent Technologies Service Offices Before returning an instrument for service call the Agilent Technologies Instrument Support Center at 1 877 447 7278 visit the Test and Measurement Web Sites by Country page at http www agilent com comms techsupport select your country and enter the Technical Support link or call one of the numbers listed below Agilent Technologies Service Numbers Austria Belgium Brazil China Denmark Finland France Germany India Italy Ireland Japan Korea Mexico Netherlands Norway Russia Spain Sweden Switzerland United Kingdom United States 0820 87 44 11 432 0 2 404 9340 11 7297 8600 800 810 0508 445 70 131515 358 0 10 855 2100 0825 010 700 01805 24 6337 1600 112 626 39 02 9260 8484 353 1890 924 204 0120 421 345 080 769 0800 5 258 4826 31 0 20 547 2111 447 67101 080 7 095 797 3930 34 91 631 3300 0200 88 22 55 0800 80 5353 44 0 7004 666666 1 877 447 7278 7 19 Index ASNR 48 Numerics 1 nm annotation 27 30 A ABORt programming command 104 ABORT softkey 39 ac power cables 6 adapters fiber optic 17 adding parameters 25 address See GPIB address Agilent Technologies offices 18 air neasurements in 37 AM modulation 15 34 amplitude off
30. difference between the PC phys ical contact and the Super PC connectors Most connectors today are physical contact which make glass to glass connections therefore it is critical that the area around the glass core be clean and free of scratches Although the major area of a connector excluding the glass may show scratches and wear if the glass has maintained its polished smoothness the connector can still provide a good low level return loss connection 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 Typ ical values are less than 0 5 dB of loss and sometimes as little as 0 1 dB of loss with high performance connectors Return loss 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 losses better than 50 dB although 30 to 40 dB is more common 2 46 WARNING Making Measurements Cleaning Connections for Accurate Measurements Visual inspection of fiber ends Visual inspection of fiber ends can be helpful Contamination or imperfections on the cable end face can be detected as well as cracks or chips in the fiber itself Use a microscope 100X to 200X magnifica tion to inspect the entire end face for contamination raised metal or dents in th
31. drift 22 laser line separation 18 modulated lasers effects of 34 monitoring performance over time 22 multiple laser lines 6 12 of broadband devices 9 PRBS format present 27 35 relative power 18 relative wavelength 18 repetitive data formats 27 signal to noise 25 28 single acquisition 14 SONET format present 27 35 speed 13 9 29 88 total power 8 units 12 update rate 9 29 88 in vacuum 37 measuring chirped lasers 9 EDFA amplifiers 9 menu maps 4 messages error 11 microwatts 13 milliwatts 13 modulated lasers 34 monitoring the instrument 16 MW softkey 13 nanometers 13 NARROW softkey 9 narrowband mode 9 new line character 27 NEXT PK softkey 5 NEXT programming command 77 NEXT WL softkey 5 NM softkey 13 noise declaration 13 noise power automatic interpolation 26 bandwidth 27 30 user entered wavelength 27 non sequential command 12 29 34 35 37 38 39 40 41 42 43 85 105 106 NORMAL softkey 14 9 88 notation definitions 2 NTRansition programming command 94 NUM LINES NUM REFS 23 NUM LINES NUM REFS 23 numbers 25 Index 4 0 Off key 20 menu map 8 On key 20 menu map 7 OPC 29 3 7 OPTICAL INPUT connector iii vi 14 output queue 22 27 P packaging for shipment 13 PARALLEL PRINTER PORT connector 6 39 parameters adding 25 PEAK annotation 4 softkey 5 28 peak definition of 15 excursion 9 16 power iii 4 threshol
32. editing Use the i and softkeys to change the value Power offset values are added to the display power readings For example if you placed a 10 dB attenuator on the front panel connec tor enter a power offset value of 10 dB Negative values can also be entered if you connect an amplifier instead of an attenuator 2 36 Making Measurements Calibrating Measurements Calibrating Measurements The wavelength of light changes depending on the material that the light is passing through To display meaningful wavelength measure ments the Agilent 86120C performs two steps Measures the wavelength in air Converts the wavelength to show values in either a vacuum or standard alr For example a laser line with a wavelength of 1550 000 nm in a vac uum would have a wavelength in standard air of 1549 577 nm Because all measurements made inside the Agilent 86120C are per formed in air the density of air due to elevation affects the wave length results You must calibrate the Agilent 86120C by entering the elevation Elevations from 0 to 5000 meters can be entered The eleva tion correction is immediately applied to the current measurement even if the instrument is in the single measurement acquisition mode Annotation on the display shows the current calibration elevation in meters and whether the wavelength measurements are shown for a vacuum VAC or standard air STD AIR If you select frequency instead of
33. instrument are executed after the instruction terminator is received The terminator may be either a new line NL character the End Or Identify EOI line asserted or a combination of the two All three ways are equivalent Asserting the EOI sets the EOI control line low on the last byte of the data message The NL character is an ASCII linefeed decimal 10 The NL terminator has the same function as an EOS End Of String and EOT End Of Text terminator Querying data Data is requested from the instrument using a query Queries can be used to find out how the instrument is currently configured They are also used to get results of measurements made by the instrument with the query actually activating the measurement String responses are returned as upper case letters Queries usually take the form of a command followed by a question mark After receiving a query the instrument places the answer in its output queue The answer remains in the output queue until it is read or another command is issued For example the query OUTPUT 720 CALCULATE2 POINTS places the number of points in the data set in the output queue In HP BASIC the controller input statement ENTER 720 Range passes the value across the bus to the controller and places it in the variable Range A newline character is appended to the response Sending another command or query before reading the result of a query causes the output queue to be cleared and
34. is an example of a returned string when MEAS SCAL POW MAX is sent 5 88346500E 000 If six laser lines are located and MEAS ARR POW is sent the follow ing string could be returned Notice that the first returned number indicates the number of laser line values returned in the query The measurement units are in dBm 6 1 37444400E 001 1 10996100E 001 9 62396600E 000 7 94024500E 000 7 01303200E 000 1 04536200E 001 4 18 Syntax Description expected value Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer FREQuen cy Returns frequency values POWer FREQuency lt expected_value gt lt resolution gt Used With lt expected_value gt lt resolution gt SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resolution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode the marker is placed on the signal having a frequency that is closest to the expected value parameter Default units for expected value parameter are in Hz When used with an ARRay command an array of frequencies is returned The display is placed in the list by wave length mode The resolution parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 0
35. nm RST State 1650 nm SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default units for the lt real gt parameter are meters The stop wavelength value must be greater than or equal to the start wavelength value or the stop wavelength will be clipped to the start wavelength and a Data out of range error will be generated Setting the start wave length is equivalent to setting the start frequency wavenumber because of the inverse relationship of frequency to wavelength Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 42 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP WNUMber Sets the stopping wavenumber for the wavelength limit range CALCulate2 WLIMit STOP WNUMber lt real gt MINimum MAXimum real is a wavenumber value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 7874 cm 1270 nm Non sequential command Preset State 7 87401E5 m RST State 7 87401E5 m SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default uni
36. of this peak OUTPUT 720 MEAS SCAL POW MAX Use either short or long forms Commands and queries may be sent in either long form complete spelling or short form abbreviated spelling The description of each command in this manual shows both versions the extra characters for the long form are shown in lowercase The following is a long form of a command OUTPUT 720 MEASure SCALar POWer MAXimum And this is the short form of the same command 3 23 Programming Reviewing SCPI Syntax Rules OUTPUT 720 MEAS SCAL POW MAX Programs written in long form are easily read and are almost self doc umenting Using short form commands conserves the amount of con troller memory needed for program storage and reduces the amount of I O activity The rules for creating short forms from the long form is as follows The mnemonic is the first four characters of the keyword unless the fourth character is a vowel in which case the mnemonic is the first three characters of the keyword This rule is not used if the length of the keyword is exactly four char acters Table 3 8 Examples of Short Forms Long Form Equivalent Short Form ROUTE ROUT LAYER LAY SYSTEM SYST ERROR ERR You can use upper or lowercase letters Program headers can be sent using any combination of uppercase or lowercase ASCII characters Instrument responses however are always returned in uppercase Combine commands in the same subsystem Yo
37. optic cable to the front panel OPTICAL INPUT connector 2 Press the green Preset key 3 Press List by WL to display the laser lines from the shortest wavelength to the longest wavelength 4 Press List by Power to display the laser lines in order of decreasing amplitudes 2 6 Making Measurements Measuring Wavelength and Power Total power and average wavelength In the third available display mode the Agilent 86120C displays the average wavelength as shown in the following figure The displayed power level is the total input power to the instrument It is the sum of the powers of each laser line it is not a measure of the average power level of the laser lines 1549 5380 1 51 Utes The following equation shows how individual wavelengths of laser lines are summed together to obtain the average wavelength value n Y Pihi i l where n is the number of laser lines included in the average is the peak power of an individual laser line Power units are in Watts linear 2 7 A U N me Making Measurements Measuring Wavelength and Power The following equation shows how individual powers of laser lines are summed together to obtain the total power value n 1 where n is the number of laser lines included in the measurement is the peak power of an individual laser line Power units are in Watts linear To display average wavelength and to
38. power scale is a fixed dB scale with 10 dBm at the display top and 53 dBm at the display bottom The power scale is not affected by the Power Offset value In most cases the noise floor will be visible if the total input power is greater than about 5 dBm 1548 8 1568 0 The Agilent 86120C graphical display The Peak Threshold value is displayed as a dotted line All peaks above this dotted line are displayed in the List by Wavelength and List by Power modes All peaks below this line are not displayed Adjust the Peak Threshold value with the Setup key and the THRSHLD softkey The wavelength limit start and stop wavelength values are used for the graphical display even if the wavelength limit function is off The graphical display cannot be printed To see the graphical display 1 Press the List by WL or List by Power key 2 Press the GRAPH softkey 3 To exit the graphical display press any softkey 2 10 Making Measurements Measuring Wavelength and Power Instrument states Four different instrument states can be saved and recalled at a later time The actual instrument conditions that are saved are identical to those saved from the previous state after power is turned on These conditions are shown in Table 5 22 on page 7 2 If drift measurements or an application such as signal to noise is on when an instrument state is saved it is off when that state is recalled To save an instrument state Press the
39. provides four registers which you can query to monitor the instrument s condition These registers allow you to deter mine the following items Status of an operation Availability of the measured data Reliability of the measured data All four registers are shown in the figure on the following page and have the following uses Register Definition Status Byte Monitors the status of the other three registers Standard Event Status This is the standard IEEE 488 2 register Contains bits which indicate the status of the other two regis ters OPERation Status Contains bits that report on the instrument s normal operation QUEStionable Status Contains bits that report on the condition of the sig nal Status Byte register The Status Byte Register contains summary bits that monitor activity in the other status registers and queues The Status Byte Register s bits are set and cleared by the presence and absence of a summary bit from other registers or queues Notice in the following figure that the bits in the Standard Event Status OPERation status and QUEStionable status registers are or d to control a bit in the Status Byte Register If a bit in the Status Byte Register goes high you can query the value of the source register to determine the cause 3 17 Programming Monitoring the Instrument not used not used not used POWer not used not used not used not used not used Maximum Signals Drift Refer
40. registers Refer to Monitoring the Instrument on page 3 16 OUTPUT 720 STATUS OPERATION CONDITION 4 91 Syntax Attribute Summary Description Example Query Response Programming Commands STATus Subsystem OPERation QUEStionable ENABle Sets the enable mask for the questionable or operation event register STATus OPERation QUEStionable ENABle lt value gt integer an integer from to 65535 Preset State none RST State none SCPI Compliance standard The enable mask selects which conditions in the event register cause the summary bit in the status byte to be set If a bit in the enable mask is set true and the corresponding event occurs the summary bit bit 3 for the questionable status or bit 7 for the operation status in the status byte will be set OUTPUT 720 STATUS QUESTIONABLE ENABLE 1024 When queried the largest value that can be returned is 65535 This is because the most significant register bit cannot be set true 4 92 Syntax Query Response Attribute Summary Description Example Programming Commands STATus Subsystem OPERation QUEStionable EVENt Queries the contents of the questionable or operation event registers STATus OPERation QUEStionable EVENt 0 to 32767 Preset State none RST State none SCPI Compliance standard Query Only The response will be a number from 0 to 32767 indicating which bits are set Reading
41. result from using packaging materials other than the original materials Never use styrene pellets as packaging material They do not adequately cushion the instrument or prevent it from shifting in the carton They may also cause instrument damage by generating static electricity 1 12 Getting Started Returning the Instrument for Service 3 Pack the instrument in the original shipping containers Original materials are available through any Agilent Technologies office Or use the following guidelines Wrap the instrument in antistatic plastic to reduce the possibility of damage caused by electrostatic discharge e For instruments weighing less than 54 kg 120 lb use a double walled corrugated cardboard carton of 159 kg 350 Ib test strength The carton must be large enough to allow approximately 7 cm 3 inches on all sides of the instrument for packing material and strong enough to accommodate the weight of the instrument Surround the equipment with approximately 7 cm 3 inches of pack ing material to protect the instrument and prevent it from moving in the carton If packing foam is not available the best alternative is S D 240 Air Cap from Sealed Air Corporation Commerce Califor nia 90001 Air Cap looks like a plastic sheet filled with air bubbles Use the pink antistatic Air Cap to reduce static electricity Wrap ping the instrument several times in this material will protect the instrument and prev
42. shipment is damaged or incomplete save the packing materials and notify both the shipping carrier and the nearest Agilent Technologies sales and service office Agilent Technologies will arrange for repair or replacement of damaged or incomplete shipments without waiting for a settlement from the transportation company Notify the Agilent Technologies customer engineer of any problems 2 Make sure that the serial number and options listed on the instrument s rear panel label match the serial number and options listed on the shipping document The following figure is an example of the rear panel serial number label Se Agi lent Mave IN GERMANY 86120 C ATO 1234 DE44101234 Option lt Empty gt Getting Started Step 2 Connect the Line Power Cable Step 2 Connect the Line Power Cable WARNING This is a Safety Class Product provided with protective earth 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 instrument is likely to make the instrument dangerous Intentional interruption is prohibited CAUTION Always use the three prong AC power cord supplied with this instrument Failure to ensure adequate earth grounding by not using this cord may cause instrument damage CAUTION Do not connect ac power until you have verified the line voltage is correct as described in the followin
43. the appropriate IEC laser class WARNING Please pay attention to the following laser safety warnings Under no circumstances look into the end of an optical cable attached to the optical output when the device is operational The laser radiation can seriously damage your eyesight Do not enable the laser when there is no fiber attached to the optical output connector Pressing the active button enables the laser The laser is on when the green LED is lit The use of optical instruments with this product will increase eye haz ard Refer servicing only to qualified and authorized personnel 6 12 Specifications and Regulatory Information Compliance with Canadian EMC Requirements Compliance with Canadian EMC Requirements This ISM device complies with Canadian ICES 001 Cet appareil ISM est conforme la norme NMB 001 du Canada Notice for Germany Noise Declaration Acoustic Noise Emission Ger uschemission LpA 70 dB LpA 70 dB Operator position am Arbeitsplatz Normal position normaler Betrieb per ISO 7779 nach DIN 45635 1 6 13 Specifications and Regulatory Information Declaration of Conformity Declaration of Conformity Agi DECLARATION OF CONFORMITY Agilent Technologies According to ISO IEC Guide 22 and CEN CENELEC EN 45014 Manufacturer s Name Agilent Technologies International sarl Manufacturer s Address Rue de la Gare 29 CH 1110 Morges Switzerland Decl
44. the following points 1270 1650 maximum input wavelength range 10 dBm maximum total displayed input power Laser linewidths assumed to be less than 5 GHz If you change the elevation where you will be using your Agilent 86120C refer to Calibrating Measurements on page 2 37 Press the green Preset key to return the Agilent 86120C to its default state Do not exceed 18 dBm source power The Agilent 86120C s input circuitry can be damaged when total input power exceeds 18 dBm You can measure power levels that are greater by adding attenuation and entering a power offset as described in To measure total power exceeding 10 dBm on page 2 36 2 2 Making Measurements Measuring Wavelength and Power Measuring Wavelength and Power This section gives you step by step instructions for measuring peak wavelength average wavelength peak power and total input power There are three display modes Peak wavelength List by wavelength or power Average wavelength and total power If the measured amplitudes are low clean the front panel OPTICAL INPUT connector This section includes Peak WL mode 2 4 List by WL or Power modes 2 6 Total power and average wavelength 2 7 Limiting the wavelength measurement range 2 8 Measuring broadband devices and chirped lasers 2 9 Graphical display of optical power spectrum 2 10 Instrument states 2 11 Power bar 2 11 2 3 Making Measurements Measuring Wavelength and Power P
45. the register clears the register OUTPUT 720 STATUS OPERATION EVENT 4 93 Syntax Attribute Summary Description Example Programming Commands STATus Subsystem OPERation QUEStionable NTRansition Selects bits in the event register which can be set by negative transi tions of the corresponding bits in the condition register STATus OPERation NTRansition lt integer gt integer an integer from to 65535 Preset State none RST State none SCPI Compliance standard Changes in the state of a condition register bit causes the associated OPERation Status or QUEStionable Status register bit to be set This command allows you to select a negative bit transition to trigger an event to be recognized A negative transition is defined to occur when ever the selected bit changes states from a 1 to a 0 You can enter any value from 0 to 65535 When queried the largest value that can be returned is 32767 This is because the most significant register bit cannot be set true OUTPUT 720 STATUS OPER NTRansition 16 4 94 Syntax Attribute Summary Description Example Programming Commands STATus Subsystem OPERation QUEStionable PTRansition Selects bits in the event register which can be set by positive transi tions of the corresponding bits in the condition register STATus OPERation PTRansition lt integer gt integer an integer from to 65535 Preset Sta
46. to above listed products placed on the EU market after s Mlartin Fischer 2004 August 01 Date Product Regulations Representative PMD DVS Agilent Technologies Title For further information please contact your local Agilent Technologies sales office agent or distributor 6 14 Specifications and Regulatory Information Product Overview Product Overview ilent 86120A 700 1650 nm gi MULTI WAVELENGTH METER ise LAY frntview Front view of instrument m m onion FUSE FON 250V onan rearview Rear view of instrument 6 15 Specifications and Regulatory Information Product Overview Instrument Preset Conditions 7 2 Menu Maps 7 4 Error Messages 7 11 Front Panel Fiber Optic Adapters 7 17 Power Cords 7 18 Agilent Technologies Service Offices 7 18 Reference Reference Reference Reference Instrument Preset Conditions Table 5 22 Instrument Preset Conditions 1 of 2 itam Settings after Preset Settings after Power Key Pressed Turned On Display mode single wavelength last state Wavelength range limiting on last state Start wavelength 1270 nm last state Stop wavelength 1650 nm last state Graphical display off off Measurement acquisition continuous last state Wavelength calibration vacuum last state Elevation correction value not affected last state Wavelength units nm last state Amplitude units dBm last state Power of
47. to the frequency of the reference laser line The frequency of the reference laser line is returned as an absolute frequency unnormalized Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 55 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt DIFFerence STATe Sets the drift calculation to subtract the minimum values measured from the maximum values measured CALCulate3 DRIFt DIFFerence STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the max imum power and frequency minus the minimum power and frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 56 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFtMAXimum STATe Sets the drift calculation t
48. 0 Subend SUBEND Set_ese SUB Set ese COM Instrument Mwm OUTPUT ESE IVAL 00110100 2 SUBEND Identity DEF FNidentity COM Instrument Mwm DIM Identity 50 Identity OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm Opc done OUTPUT GMwm IDN ENTER Mwm Identity RETURN Identity FNEND 3 33 Programming Example Programs Example 3 Measure WDM channel drift This program measures the drift of channels in a WDM system It measures drift in both power and wavelength of each line First the program sets the Agilent 86120C in the continuous acquisition mea surement mode Then it measures drift using commands from the CALCulate3 subsystem Notice the use of the Tempo subroutine to pause the program for 10 seconds while the Agilent 86120C measures the drift on the system The use of the Err mngmt subroutine is optional Refer to the intro duction to this section for a description of each subroutine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 DIM Key 1 N ERROR GOTO Error msg et ese RINT USING 37A 33A Multi Wavelength Meter Identity is FNIdentity N TIMEOUT 7 5 CALL mngmt md opc RST md opc INIT IMM md_opc OPC md_opc CONF ARR POW WAV NO C2C2C20C2 0c 0 Turn on the drift calculation Cmd opc CALC3 DRIF STAT ON Err_mngmt CALC3 DRIF STAT ON Turn off all drift states Cmd opc CALC3 DRIF PRES
49. 01 whichever is closer MAXimum resolution is equivalent to the FAST measurement update mode MINimum resolution is equivalent to the NORMAL measurement update mode Returned values are in Hz display is in THz Power units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum The highest frequency signal MINimum The lowest frequency signal 4 19 resolution Constants Examples Query Response Programming Commands Measurement Instructions DEFault The current marker position MAXimum 0 01 resolution fast update MINimum 0 001 resolution normal DEFault Current resolution CONF ARR POW FREQ DEF MIN FETCCARR POW FREQ DEF MAX READ ARR POW FREO MEAS ARR POW FREO CONF SCAL POW FREQO 230 8THZ MAX FETC SCAL POW FREQ 230 8THZ MIN READ SCAL POW FREQ 230 8THZ MEAS SCAL POW FREQ 230 8THZ The following line is an example of a returned string when MEAS SCAL POW FREQ MAX is sent 1 940551 76E 014 If six laser lines are located and MEAS ARR POW FREQ is sent the following string is an example of the returned data Notice that the first returned number indicates the number of laser line values returned in the query 6 1 94055100 014 1
50. 12 OR Diff diffz0 END 3 42 Programming Lists of Commands Lists of Commands Table 3 10 Programming Commands 1 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command Common Commands CLS Clears all event registers and the error queue ESE Sets the bits in the standard event status enable register ESR Queries value standard event status register IDN Queries instrument model number and firmware version OPC Sets operation complete bit of the standard event status register RCL Recalls a saved instrument state RST Resets instrument SAV Saves an instrument state SRE Sets bits in service request enable register STB Queries value of status byte TRG Triggers acquisition of measurement data TST Performs an instrument self test WAI Causes instrument to finish processing current command before continuing Measurement Instructions CONFigure Configures instrument for wavelength wavenumber frequency power and measurements FETCh Queries wavelength wavenumber frequency power and measurements that have already been captured MEASure Configures measures and queries wavelength wavenumber frequency power and measurements READ Measures and queries wavelength wavenumber frequency power and measurements 3 43 Progr
51. 4 COH LEN Y RETURN PEAK NUM AVG EXIT 4 MAX MIN RESET EXIT mappls 7 5 Reference Menu Maps Display Avg WL Menu There is no menu associated with this key Measurement Cont Menu There is no menu associated with this key Display List by Power Menu Power Y PEAK GRAPH SELECT mlistpwr 7 6 Reference Menu Maps Display List by WL Menu List by 4 PEAK GRAPH SELECT mlistwl Delta On Menu RETURN SELECT RESET EXIT 7 7 Reference Menu Maps Delta Off Menu Off 4 PEAK SELECT Display Peak WL and System Preset Menus Peak WL PREV WL NEXT WL PEAK PREV PK NEXT PK mpreset Measurement Single Menu There is no menu associated with this key 7 8 Reference Menu Maps System Print Menu CONT ABORT mprint 7 9 Reference Menu Maps System Setup Menu LIM ON SAVE 1 LIM OFF SAVE2 START WL STOPWL SAVE 4 RETURN RETURN WL LIM THRSHLD SAV RCL MORE SAVE RCL 1 RETURN NORMAL RECALL BOLA FAST RCL 3 RCL 4 RETURN UPDATE UNITS NM WL CAL CM 1 MORE TU RETURN RETURN RETURN VACUUM MW STD AIR uw ELEV PWR OFS RETURN 4 RETURN Y gt CANCEL HP IB RETURN PWR BAR DEVICE BAR ON NARROW BAR OFF RETURN BROAD RETURN RETURN msetup Reference Error Mes
52. 4 THz MAXimum 236 0571 THz Preset State unaffected by RST State 193 4145 THz 1550 0 nm in a vacuum SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The default units for the lt real gt parameter are Hz 4 70 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR REFerence WAVelength Sets the wavelength used for the noise measurement reference in the signal to noise calculation CALCulate3 S NR REFerence WAVelength real MINimum MAXimum real is a wavelength value that is within the following limits Constant Description MINimum 1270 nm MAXimum 1650 nm Preset State unaffected by RST State 1550 0 nm in a vacuum SCPI Compliance instrument specific After entering this value use the SNR AUTO command to configure the instrument to use this value in subsequent signal to noise calculations The number entered is converted internally to the corresponding fre quency The default units for the lt real gt parameter are meters 4 71 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem SNR REFerence WNUMber Sets the wave number used for the noise measurement reference in the signal to noise calculation CALCulate3 SNR REFerence WNUMber lt real gt MINimum MAXimum
53. 420 Query UNTERMINATED 430 Query DEADLOCKED 440 Query UNTERMINATED after indef resp Query was unterminated after an indefinite response Reference Front Panel Fiber Optic Adapters Front Panel Fiber Optic Adapters Front Panel Fiber Optic Adapter Description Agilent Part Number Sum Diamond HMS 10 81000AI E 8100081 D4 8100061 SC 81000KI DIN 8100081 ST 81000VI 81000WI a The FC PC is the default front panel optical connector Dust Covers Agilent Part Number FC connector 1005 0594 Diamond HMS 10 connector 1005 0593 DIN connector 1005 0595 ST connector 1005 0596 SC connector 1005 0597 7 17 Reference Power Cords Power Cords Plug Type Cable Part Country No 250V 8120 1351 United Kingdom Cyprus Nigeria Zimbabwe 250V Q 8120 1369 Australia New Zealand China 250V 4 8120 1689 East and West Europe Saudi Arabia So Africa India unpolarized in many nations 125V 8120 1378 United States Canada Mexico Philippines S Taiwan 250V 8120 2104 Switzerland TR 220V TB 8120 3997 Denmark 250V 8120 4211 Republic of South Africa India 100V FO 8120 4753 Japan 8120 5182 Israel 8120 6868 Argentinia 8120 6979 Chile 8120 8376 China 8120 8871 Brazil Thailand Part number shown for plug is the industry identifier for the plug only Number shown for
54. 58 0 Low frequency 10 kHz AM modulation graph showing rounded sideband spurs 2 34 Making Measurements Measuring Modulated Lasers The graphical display is useful for locating these spurious wavelengths Their amplitude will be below that of the correct wavelength and they will be broad rounded peaks compared to the sharp peak of the cor rect wavelength Use the Peak Threshold function to place the dotted line above the spurious peaks so they will not be displayed in the List by WL or List by Power table A laser modulated at high frequency in the RF or microwave range can also cause spurious wavelengths to be displayed especially when the modulation is of a repetitive nature such as that of PRBS or SONET digital formats In general no spurious wavelengths will be dis played using preset instrument conditions The preset condition includes peak excursion peak threshold and wavelength range limit ing However increasing peak threshold can cause spurious wave lengths to be displayed Even when the laser being tested is modulated with repetitive formats the carrier s correct wavelength and power is displayed the wave length and power of the spurious sidebands are incorrect The graphical display is useful to see the effects of high frequency modulation Without modulation the noise floor is typically 45 dB below the laser power In general high frequency modulation will raise the noise floor to about 25 dB below t
55. 6 Syntax Description expected value Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer Returns amplitude values POWer lt expected_value gt lt resolution gt Used With expected value resolution SCALar optional ignored ARRay ignored ignored When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a power level that is closest to the expected value parameter When used with an ARRay command an array of amplitudes is returned The display is placed in the list by power mode Returned values are in the current power units Wavelength units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum Displays the highest power signal MINimum Displays the lowest power signal DEFault Displays the signal at the current marker position 4 17 Examples Query Response Programming Commands Measurement Instructions CONF ARR POW FETC ARR POW READ ARR POW MEAS ARR POW CONF SCAL POW 10 dBm FETC SCAL POW MAX READ SCAL POW MIN MEAS SCAL POW DEF The following line
56. 6 Specifications and Regula tory Information as the performance standard All of the tests are done manually without the aid of a computer None of these tests require access to the interior of the instrument Test 1 Absolute Wavelength Accuracy 5 3 Test 2 Sensitivity 5 4 Test 3 Polarization Dependence 5 5 Test 4 Optical Input Return Loss 5 6 Test 5 Amplitude Accuracy and Linearity 5 9 Allow the Agilent 86120C to warm up for 15 minutes before doing any of the performance tests Calibration Cycle This instrument requires periodic verification of performance The instrument should have a complete verification of specifications once every two years 5 2 Description CAUTION Procedure Performance Tests Test 1 Absolute Wavelength Accuracy Test 1 Absolute Wavelength Accuracy Wavelength accuracy is verified using traceable light sources such as the following devices Stable lasers Gas lamps HeNe gas lasers Do not exceed 18 dBm source power The Agilent 86120C s input circuitry can be damaged when total input power exceeds 18 dBm Use three or four light standards that cover the Agilent 86120C s wavelength range Connect the traceable sources to the Agilent 86120C and verify that the Agilent 86120C is reading the sources to within the absolute wavelength accuracy specification 5 3 Description CAUTION Procedure Performance Tests Test 2 Sensitivity Test 2 Sensiti
57. 720 INIT CONT ON Separate multiple parameters with a comma Spaces can be added around the commas to improve readability OUTPUT 720 MEAS SCAL POW FREQ 1300 MAX White space White space is defined to be one or more characters from the ASCII set of 0 through 32 decimal excluding 10 NL White space is usually optional and can be used to increase the readability of a program Numbers All numbers are expected to be strings of ASCII characters Thus when sending the number 9 you would send a byte representing the ASCII code for the character 9 which is 57 A three digit number like 102 would take up three bytes ASCII codes 49 48 and 50 This 3 25 Programming Reviewing SCPI Syntax Rules is taken care of automatically when you include the entire instruction in a string Several representations of a number are possible For example the following numbers are all equal 28 0 28E2 280E 1 28000m 0 028K 28E 3K If a measurement cannot be made no response is given and an error is placed into the error queue For example RST FETCh POW will timeout the controller and place a Data stale or corrupt error in the error queue Table 3 9 Suffix Multipliers Multiplier Mnemonic 1E18 EX 1E15 PE 1E12 T 1E9 G 1E6 MA 1E3 K 1E 3 M 1E 6 U 1E 9 N 1E 12 P 1E 15 F 1E 18 A 3 26 Programming Reviewing SCPI Syntax Rules Program message terminator The string of instructions sent to the
58. AL measurement mode is selected the uncorrected fre quency domain data consists of 64K values Only the frequency domain data corresponding to 1270 1650 wavelength in vacuum is returned 15 047 values In FAST measurement mode the data consists of 32K values of which 7 525 values are returned In NORMAL measurement mode the frequency spacing between values is uniform and is equal to 3 613378 GHz Note that the spacing between values is not uniform in wavelength units The values returned are in ascending optical frequency The first value of the uncorrected frequency data corresponds to an optical frequency of 181 6915 THz 1650 008 nm The last value of the uncorrected frequency data corresponds to an optical frequency of 236 0584 THz 1269 993 nm For example a laser line peak located at the 3 000th returned value has an optical frequency of frequency 181 6915 THz 2 999 3 613378 GHz 192 5280 THz or 1557 137 nm in vacuum When FAST measurement mode is selected the frequency spacing between elements is uniform and is equal to 7 226756 GHz Note the spacing between values is not uniform in wavelength units The values returned are in ascending optical frequency Only the frequency domain data corresponding to 1270 1650 wavelength in vacuum is returned 7 525 values The first value of the uncorrected frequency data corresponds to an optical frequency of 181 6879 THz 1650 041 nm The last value of the uncorrected f
59. C Requirements 13 Declaration of Conformity 14 Product Overview 15 Reference Instrument Preset Conditions 2 Contents 2 Contents Menu Maps 4 Error Messages 11 Front Panel Fiber Optic Adapters 17 Power Cords 18 Agilent Technologies Service Offices 18 Contents 3 Step Step Step Step Step Step Step 1 2 3 4 6 Inspect the Shipment 1 4 Connect the Line Power Cable 1 5 Connect a Printer 1 6 Turn on the Agilent 86120C 1 7 Enter Your Elevation 1 8 Select Medium for Wavelength Values 1 9 Turn Off Wavelength Limiting 1 10 Returning the Instrument for Service 1 11 Getting Started CAUTION CAUTION CAUTION CAUTION Getting Started Getting Started Getting Started The instructions in this chapter show you how to install your Agilent 86120C You should be able to finish these procedures in about ten to twenty minutes After you ve completed this chapter continue with Chapter 2 Making Measurements Refer to Chapter 6 Specifications and Regulatory Information for information on operating conditions such as temperature If you should ever need to clean the cabinet use a damp cloth only This product has autoranging line voltage input Be sure the supply voltage is within the specified range The front panel LINE switch disconnects the mains circuits from the mains supply after the EMC filters and before other parts of the instrument Ins
60. Commands for the correct syntax for these com mands 3 7 Programming Making Measurements Table 2 4 Commands for Capturing Data Desired Measurement Command to Configure Measurement partial listing Command to Query Data Wavelength nm CONFigure FETCh READ and MEASure MEASure ARRay POWer WAVelengt h Frequency THz CONFigure FETCh READ and MEASure MEASure ARRay POWer FREQuency Wavenumber CONFigure FETCh READ and MEASure MEASure ARRay POWer WNUMber Power W dBm CONFigure FETCh READ and MEASure MEASure ARRay POWer Average Wavelength Wavenumber or Frequency CALCulate2 PWAVerage STATe CALCulate2 DATA Total Power W dBm CALCulate2 PWAVerage STATe CALCulate2 DATA Fabry Perot Laser CALCulate3 FPERot Refer to FPERot STATE on page 4 62 Laser Line Separation CALCulate3 DELTa REFerence CALCulate3 DATA Laser Line Drift CALCulate3 DRIFt STATe CALCulate3 DATA Signal to Noise Ratio CALCulate3 SNR STATe CALCulate3 DATA Signal to Noise Ratio Average CALCulate3 ASNR STATe CALCulate3 DATA Time Domain Data CALCulate1 TRANsform FREQuency POINt s Corrected Frequency Domain CALCulate1 TRANsform FREQuency POINt CALCulate2 DATA Data S Uncorrected Frequency Domain Data CALCulate1 TRANsform FREQuency POINt s CALCulate1 DATA 3
61. Cont INITiate CONTinuous ON DBM UNIT POWer DEVICE SENSe CORRection DEVice DRIFT CALCulate3 DRIFt STATe ELEV SENSe CORRection ELEVation EXIT State dependent FAST See UPDATE FP TEST CALCulate3 FPERot STATe GPIB none List by Power CONFigure ARRay POWer List by WL MEASure ARRay POWer WAVelength MAX MIN CALCulate3 DRIFEMINimum STATe and CALCulate3 DRIFt MAXimum STATe MW UNIT POWer NARROW SENSe CORRection DEVice NARRow NEXT PK DISPlay MARKer MAXimum NEXT NEXT WL DISPlay MARKer MAXimum RIGHt NM MEASure ARRay POWer WAVelength NORMAL See UPDATE OFF CALCulate3 DELTa POWer STATe ON CALCulate3 DELTa POWer STATe PEAK DISPlay MARKer MAXimum 3 48 Programming Lists of Commands Table 3 11 Keys Versus Commands 2 of 2 Key Equivalent Command Peak WL See NEXT PK NEXT WL PEAK PREV PK and PREV WL PK EXC CALCulate2 PEXCursion PK THLD CALCulate2 PTHReshold POWER UNIT POWer Preset SYSTem PRESet PREV PK DISPlay MARKer MAXimum PREVious PREV WL DISPlay MARKer MAXimum LEFT Print HCOPy IMMediate PWR BAR See BAR ON and BAR OFF PWR OFF SENSe CORRection 0FFSet MAGNitude RESET CALCulate3 DRIFtREFerence RESet S N CALCulate3 SNR STATe S N AVG CALCulate3 ASNR STATe SELECT CONFigure POWer Setup See CAL UNITS and UPDATE Single INITiate CONTinuous OFF START WL CALCulate2 WLIMItSTARt STOP W
62. Culate3 DELTa CALCulate3 DATA DRIFt FETCh SNR READ MEASure flow2 3 6 Programming Making Measurements Commands are grouped in subsystems The Agilent 86120C commands are grouped in the following sub systems You ll find a description of each command in Chapter 4 Pro gramming Commands Subsystem Purpose of Commands Measurement Instructions Perform frequency wavelength and wavenumber measurements CALCulatel Queries uncorrected frequency spectrum data CALCulate2 Queries corrected peak data and sets wavelength limits CALCulate3 Performs delta drift signal to noise and Fabry Perot measurements DISPlay Applies markers and displays power bars HCOPy Prints measurement results SENSe Sets elevation correction values selects readings for air or vacuum and enters amplitude offsets Queries time domain values of the input data STATus Queries instrument status registers SYSTem Presets Agilent 86120C and queries error messages TRIGger Stops current measurement Acquires new measurement data Also used to select single or continuous acquisition of measurement data UNIT Sets the amplitude units to watts or dBm Table 2 4 on page 3 8 shows the kinds of measurements that the Agilent 86120C can perform and the associated programming com mands used to return that data In some cases there is more than one method that can be used to obtain the desired data Refer to Chapter 4 Programming
63. DFA amplifier 9 ELEV softkey 8 38 elevation changing feet to meters 8 38 effects of 37 entering 8 38 ELEVation programming command 84 85 ENABle programming command 92 EOI signal 27 Err_mngmt subroutine 29 error messages 11 queue 22 ERRor programming command 98 Error msg subroutine 28 ESE 28 3 ESR 5 EVENT programming command 91 93 event status enable register 28 4 example programs 28 Index 2 increase source accuracy 41 measure DFB laser 30 measure SNR 39 measure WDM channel drift 34 measure WDM channel separation 37 measure WDM channels 32 external attenuation 36 F Fabry Perot lasers iii 9 measuring 15 31 fast fourier transform 29 FAST softkey 14 9 88 FETCh measurement instruction 15 fiber optics adapters 17 care of v cleaning connections 40 connectors covering 12 firmware version displayed 7 over GPIB 6 flatness 3 6 9 FNIdentity function 29 FP TEST softkey 31 FPERot programming command 62 67 FREQuency programming command 19 51 70 front panel adapters 17 labels 15 lockout 3 fuse values vii G GPIB address 3 address changing from front panel 4 address default 3 softkey 4 H hardcopy See printer HCOPy subsystem 80 HELP HEADers programming command 99 Index HP BASIC 2 28 IDN 29 6 IEC Publication 1010 vi IEEE 488 2 standard 2 IMMediate programming command 80 106 init ignored 15 initializing the in
64. ECTED 41 PRINTER TIMED OUT 7 12 Reference Error Messages Table 5 23 Instrument Specific Error Messages 3 of 3 Error Number Error Message 42 43 44 45 46 47 48 49 50 51 PRINTOUT WAS ABORTED NOT ALLOWED IN FABRY PEROT NOT ALLOWED IN S N UNKNOWN KEYPRESS NUM LINES NUM REFS NUM LINES NUM REFS NO REFERENCE SIGNAL GAIN RANGING ERROR INCOMPATIBLE HARDWARE UNKNOWN ERROR 7 13 Reference Error Messages Table 5 24 General SCPI Error Messages 1 of 3 Error Number Description 0 No errors 100 Command error unknown command 101 Invalid character 102 Syntax error 103 Invalid separator 104 Data type error 105 GET not allowed 108 Parameter not allowed 109 Missing parameter 112 Program mnemonic too long 113 Undefined header 120 Numeric data error 121 Invalid character in number 123 Exponent too large 124 Too many digits 128 Numeric data not allowed 131 Invalid suffix 134 Suffix too long 138 Suffix not allowed 141 Invalid character data 148 Character data not allowed 150 String data error 151 Invalid string data 7 14 Reference Error Messages Table 5 24 General SCPI Error Messages 2 of 3 Error Number Description 158 161 168 170 171 178 200 211 213 221
65. Err_mngmt CALC3 DRIF PRES Turn on drift reference state Cmd_opc CALC3 DRIF REF STAT ON Err_mngmt CALC3 DRIF REF STAT ON Query the number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Current ref wl 1 Nb pt ALLOCATE Current ref pwr T Nb pt 3 34 Programming Example Programs Query reference wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm USING it K Current wl OUTPUT Mwm CALC3 DATA POW ENTER Mwm USING K Current_ref_pwr Turn off drift reference state Cmd_ope CALC3 DRIF REF STAT OFF Err_mngmt CALC3 DRIF REF STAT OFF Turn on drift max min calculation Cmd_opc CALC3 DRIF DIFF STAT ON Err_mngmt CALC3 DRIF DIFF STAT ON Tempo 10 ALLOCATE Current diff wl 1 Nb pt ALLOCATE Current diff pw 1 Nb Query drift wavelengths and powers OUTPUT Mwm CALC3 DATA WAV ENTER Mwm USING K Current_diff_wil OUTPUT Mwm CALC3 DATA POW ENTER Mwm USING K Current_diff_pw OFF TIMEOUT FOR 1 1 TO Nb pt PRINT USING 18A 2D 6A M4D 2DE 3A 21A MDD 3DE 3A Wavelength number b is Current ref wl D m with a drift from Current diff wl D m PRINT USING 28A SDD 2DE 4A 20A MDD 3DE 3A it has a power level of Current ref pwr D dBm with a drift from Current diff pw D dB NEXT I STOP Error msg PRINT The program is aborted due to ERRM END Err_m
66. I Version Instrument Serial Prefix 1995 0 US3545 and above 4 102 Programming Commands TRIGger Subsystem TRIGger Subsystem The SCPI definition defines the TRIGger subsystem to include ABORt ARM INITiate and TRIGger commands The Agilent 86120C has no ARM or TRIGger commands The commands in this subsystem have the following command hierar chy ABORt INITiate CONTinuous IMMediate 4 103 ABORt Halts the current measurement sequence and places the instrument in the idle state Syntax ABORt Attribute Preset State not affected Summary SCPI Compliance standard Command Only Description If the instrument is configured for continuous measurements a new measurement sequence will begin Otherwise the instrument stays in the idle state until a new measurement is initiated Programming Commands TRIGger Subsystem INITiate CONTinuous Selects single or continuous measurement acquisition Syntax INITiate CONTinuous ON OFF 1 0 Attribute Non sequential command Summary Preset State on RST State off SCPI Compliance standard Description When on is specified the instrument continuously measures the input Spectrum Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands o
67. IGHt Moves marker to the next higher wavelength or frequency 1 DISPlay WINDow GRAPhics STATe Turns the instrument display of the power bars on and off S HCOPy Subsystem HCOPy IMMediate Starts a printout S SENSe Subsystem SENSe CORRection DEVice Configures wavelength measurements for narrowband or wideband devices 3 46 Table 3 10 Programming Commands 5 of 5 Programming Lists of Commands Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command SENSe CORRection ELEVation Sets the elevation value used by the instrument to compensate for air dispersion SENSe CORRection OFFSet MAGNitude Sets the power offset value used by the instrument S SENSe CORRection MEDium Sets the instrument to return the wavelength reading in a vacuum when the parameter is on Parameters are VAC and AIR SENSe DATA Queries the time domain samples of the input signal STATus Subsystem STATus OPERation QUEStionable CONDitio Returns the value for the condition register for the node S n STATus OPERation QUEStionable EVENt Returns the value of the event register for the node S STATus OPERation QUEStionable ENABle Sets the enable register S STATus OPERation QUEStionable PTRansit Sets the positive transition filter register S ion STATus OPERation QUEStiona
68. L CALCulate2 WLIMit STOP STD AIR SENSe CORRection MEDium AIR THRSHLD See PK EXC and PK THLD THZ MEASure ARRay POWer FREQuency UNITS UNIT POWer UPDATE Measurement Instructions and CALCulate1 TRANsform FREQuency POINts USER CALCulate3 SNR AUTO OFF USER WL CALCulate3 SNR REFerence WAVelength UW UNIT POWer VACUUM SENSe CORRection MEDium VACuum WL See CM NM and THZ WL REF See AUTO USER and USER WL 3 49 Programming Lists of Commands 3 50 Common Commands 4 3 Measurement Instructions 4 15 CALCulatel Subsystem 4 25 CALCulate2 Subsystem 4 31 CALCulate3 Subsystem 4 44 CONFigure Measurement Instruction 4 74 DISPlay Subsystem 4 75 FETCh Measurement Instruction 4 79 HCOPy Subsystem 4 80 MEASure Measurement Instruction 4 81 READ Measurement Instruction 4 82 SENSe Subsystem 4 83 STATus Subsystem 4 90 SYSTem Subsystem 4 97 TRIGger Subsystem 4 103 UNIT Subsystem 4 107 Programming Commands Programming Commands Programming Commands Programming Commands This chapter is the reference for all Agilent 86120C programming com mands Commands are organized by subsystem Table 4 12 Notation Conventions and Definitions Convention Description lt gt Angle brackets indicate values entered by the programmer Or indicates a choice of one element from a list Square brackets indicate that the enclosed items are optional When several items are enclosed by braces one and only
69. LC3 DRIF STAT drift CALC3 SNR STAT signal to noise ratios CALC3 ASNR STAT signal to noise ratio averaging If you select a drift measurement you can select one of the following additional states CALC3 DRIF DIFF STAT difference CALC3 DRIF MAX STAT maximum drift CALC3 DRIF MIN STAT minimum drift CALC3 DRIF REF STAT drift reference values The CALCulate3 DRIFt PRESet command turns off the minimum max imum difference and reference states but leaves the drift state on Attempting to turn more than one state on at a time results in an 221 Settings Conflict error The RST and SYSTem PRESet commands turn all calculations off CALCulate3 PRESet turns off any CALCulate3 calculations 3 14 Programming Making Measurements The format of returned data Measurements are returned as strings All measurement values are returned from the Agilent 86120C as ASCII strings When an array is returned the individual values are separated by the comma character Determine the number of data points When a FETCh READ or MEASure command is used with ARRay specified the first returned value indicates the total number of mea surement values returned in the query If you use the CALCulate1 DATA CALCulate2 DATA or CALCulate3 DATA queries to query data send the POINts query first to determine the number of values returned in the string The string does not contain a first value which specifies the string leng
70. MEAS ARR POW WNUM CONF SCAL POW WNUM 6451 FETC SCAL POW WNUM 6451 MIN READ SCAL POW WNUM 6451 MEAS SCAL POW WNUM 6451 If the MEAS SCAL POW WNUM 6451 command is sent and a 1550 nm laser line is present the following response would be returned to the computer 6 45286262E 005 Notice that the returned units are m If six laser lines are measured and MEAS ARR POW WNUM is sent the following response is returned Notice that the first returned number indicates the number of laser line values returned in the query 6 6 47298400E 005 6 46627900E 005 6 45957000E 005 6 45286300E 005 6 44615600E 0 05 6 43945300E 005 4 24 Programming Commands CALCulate1 Subsystem CALCulatel Subsystem Use the CALCulatel commands to query uncorrected frequency spec trum data In NORMAL measurement update mode 15 047 values are returned If the Agilent 86120C is set for FAST measurement update mode low resolution 7 525 values are returned The commands in this subsystem have the following command hierar chy CALCulatel DATA TRANsform FREQuency POINts 4 25 Syntax Attribute Summary Description Programming Commands CALCulate1 Subsystem DATA Queries uncorrected frequency spectrum data of the input laser line CALCulate1 DATA Preset State not affected SCPI Compliance standard Query Only The returned values are proportional to squared Watts linear units No amplitude or
71. NUMber Constant Description FREQuency Queries the array of laser line frequencies after the peak search is completed If CALC2 PWAV STAT is on the power weighted average frequency is returned POWer Queries the array of laser line powers after the peak search is completed If CALC2 PWAV STAT is on the total input power is returned WAVelength Queries the array of laser line wavelengths after the peak search is completed If CALC2 PWAV STAT is on the power weighted average wavelength is returned WNUMber Queries the array of laser line wave numbers after the peak search is completed If CALC2 PWAV STAT is on the power weighted average wave number is returned Preset State not affected SCPI Compliance standard Query Only Use the CALC2 POIN query to determine the number of points the CALC2 DATA query will return The following string is a typical example of the first few returned values when WAVelength is specified 1 54488600E 006 1 54649100E 006 1 54808300E 006 1 54969600E 006 1 55131200E 006 1 55293000E 006 This next string resulted by specifying the WNUMber argument 6 47296600E 005 6 46625000E 005 6 45959900E 005 6 45287500E 005 6 44615500E 00 5 6 43943900 005 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands 4 32 Syntax
72. No syntax error will be generated if a size parameter is sent Always force the Agilent 86120C to wait for non sequential com mands The Agilent 86120C normally processes its remote programming com mands sequentially The instrument waits until the actions specified by a particular command are completely finished before reading and exe cuting the next command However there are a few non sequential commands where this is not true Non sequential commands do not finish executing before the next command is interpreted The following is a list of the Agilent 86120C s non sequential com mands CALCulate1 TRANsform FREQuency POINTs CALCulate2 PEXCursion CALCulate2 PTHReshold CALCulate2 WLIMit S TARtFREQuency CALCulate2 WLIMit STARtWAVelength CALCulate2 WLIMit STAREWNUMber CALCulate2 WLIMit STOP FREQuency CALCulate2 WLIMit STOP WAVelength CALCulate2 WLIMit STOP WNUMber CALCulate3 SNR AUTO SENSe CORRection ELEVation INITiate CONTinuous INITiate IM Mediate The following additional commands are also non sequential commands if CALCulate3 SNR AUTO is set to OFF CALCulate3 REFerence FREQuency CALCulate3 REFerence WAVelength CALCulate3 REFerence WNUMber 3 12 Programming Making Measurements The benefit of non sequential commands is that in some situations they can reduce the overall execution times of programs For example you can set the peak excursion peak threshold and elevat
73. T programming command 78 RST 3 29 8 S S N AUTO annotation 25 S N softkey 28 S N USER annotation 25 safety vi vii laser classification vii symbols iii sales and service offices 18 SCALar programming command 15 SCPI standard commands for programmable in struments standard 2 syntax rules 23 SELECT softkey 6 19 selectivity 4 6 9 semicolon 23 sending common commands 25 SENSe subsystem 83 sensitivity 4 6 9 serial number instrument 4 service 11 request enable register 21 10 returning for 11 sales and service offices 18 Set ese subroutine 28 settings conflict error 14 36 48 50 54 55 57 58 60 61 73 15 Setup key 10 11 4 menu map 10 shipping procedure 12 short form commands 23 signal to noise measurements 25 noise calculation 25 69 ratios iii specification 7 10 Single key 14 16 31 softkey menus 4 SONET 27 35 specifications 2 5 and wideband mode 9 definition of terms 2 operating 11 spurious signals suppressing 15 SRE 10 standard air 9 37 event status register 5 SCPI commands 23 STATe programming command 35 50 54 55 56 57 58 60 61 73 78 status byte register 12 reporting 16 STATus subsystem 90 STB 12 STD AIR annotation 37 softkey 9 38 subsystems 23 swabs 48 syntax rules 23 27 SYSTem subsystem 97 T Tempo subroutine 29 terahertz 13 THRSHLD softkey 16 THZ softkey 13 total power iii 8 maximum measur
74. The modes are defined by the peak excursion and peak threshold commands FPERot FWHM Queries the full width half maximum data of the selected modes CALCulate3 FPERot FWHM WAVelength FREQuency WNUMber Argument Description WAVelength Returns the full width half maximum wavelength of the selected modes FREQuency Returns the full width half maximum frequency of the selected modes WNUMber Returns the full width half maximum wavenumber of the selected modes WAVelength 5 47128800 009 FREQuency 6 93436400E 011 WNUMber 2 31306200E 001 4 62 Attribute Summary Syntax Example Query Response Attribute Summary Programming Commands CALCulate3 Subsystem Preset State not affected RST State not affected SCPI Compliance instrument specific Query only FPERot MEAN Queries the mean data of the selected modes CALCulate3 FPERot MEAN WAVelength FREQuency WNUMber Argument Description WAVelength Returns the mean wavelength of the selected modes FREQuency Returns the mean frequency of the selected modes WNUMber Returns the mean wavenumber of the selected modes WAVelength 1 53878000E 006 FREQuency 1 94824800E 014 WNUMber 6 49865400E 003 Preset State not affected RST State not affected Query only SCPI Compliance instrument specific 4 63 Syntax Example Query Response Attribute Summary Programming Commands CALCulate3 Subsystem FPERo
75. Use the Off key to turn off the measurement Select the type of separation to observe A WL displays channel separation A WL A PWR displays both channel separation and differences in power Use the and softkeys to select the reference laser line Press SELECT Press SELECT at any time to select a new reference Press RESET at any time to turn off the delta calculation 2 20 dq OC Un Q Making Measurements Measuring Laser Separation Measuring flatness You can use relative power measurements to measure flatness pre emphasis in a WDM system Simply select one carrier as the reference and measure the remaining carriers relative to the reference level The power differences represent the system flatness Press RESET to turn off the delta calculations so that all responses are shown in absolute wavelength and powers To measure flatness Press the front panel Preset key Press List by Power This lists the input signals by power with the largest response listed first Press the Delta On key Select A PWR Use the and softkeys to select the first laser line Press SELECT Since the largest power signal is the reference the relative power measurements for the other responses shows system flatness 2 21 Making Measurements Measuring Laser Drift Measuring Laser Drift In this section you ll learn how the Agilent 86120C can be used to monitor drift changes to a laser s wavelength a
76. XT WL to select next longer wavelength PEAK to signal with greatest power e PREV PK to select next lower power signal e NEXT PK to select next higher power signal 2 5 Making Measurements Measuring Wavelength and Power List by WL or Power modes In the list by wavelength or list by power modes the measurements of five laser lines can be displayed at any one time Use the and softkeys to move the cursor through the list of signals the list can contain up to 200 entries Press the SELECT key and the display changes to peak wavelength mode with the signal at the cursor dis played Annotation in the upper right corner of the display indicates whether the signals are ordered according to wavelength BY WL or power BY PWR The cursor shows the currently selected laser line As you scroll through the responses the current position of the selection cursor is shown along the screen s right side Laser Line Selection Cursor Power Bars Position of 1546 495mnm 16 76d Bm Selection 1548 84 3 46 ee EY d Cursor in List 1549 698 r 81 m 13551 3514 6 92 1552 933 10 30 0 m am Medium for Softkey _ _ ee L eter listwl Figure 2 2 Display after List by WL key pressed Also notice that power bars graphically show the relative power levels between laser lines To display multiple laser lines 1 Connect the fiber
77. able 36 measuring 7 transient data 11 TRG 13 trigger ignore 15 TRIGger subsystem 103 TST 13 U UNIT subsystem 107 Index 6 units of measure 12 UNITS softkey 12 up arrow softkey 6 UPDATE softkey 14 uppercase letters 24 USER softkey 28 USER WL softkey 28 UW softkey 13 V VAC annotation 37 VACuum programming command 86 VACUUM softkey 9 38 vacuum measurements in 37 VERSion programming command 102 W WAI 14 wave number 13 wavelength definition of 3 input range 2 peak 4 range 37 separation 18 specifications 5 8 WAVelength programming command 21 52 71 WDM flatness 21 system 18 white space characters 25 WL LIM softkey 10 WL REF softkey 28 A WL softkey 20 WL softkey 13 A WL PWR softkey 20 WLIMit programming command 37 38 40 41 42 43 WNUMber programming command 23 53 72 Index Index 7 www agilent com O Agilent Technologies GmbH 2004 Printed in Germany August 2004 Second edition August 2004 86120 90C03 ti Agilent Technologies
78. alculate the mean wavelength N hj MeanWavelength 1 where P is total power as defined in this section The mean wavelength spacing between the individual spectral components of the laser The power level of the peak spectral component of the laser The wavelength of the peak spectral component An rms calculation of the spectral width of the laser based on a Gaussian distribution The power and wavelength of each spectral component is used to calculate mean wavelength where X is the mean wavelength as defined above P is the power of a single peak P is total power as defined in this section 2 32 Making Measurements Measuring Fabry Perot FP Lasers PWR The summation of the power in each of the selected peaks or modes that satisfy the peak excursion and peak threshold criteria N Total Power E i The peak excursion and peak threshold settings define the laser modes included in the measurement Because the default peak excursion value is 10 dB measurement results normally include all laser modes within 10 dB of the peak response Use the PK THLD softkey to change the number of laser modes used in the measurements Refer to Defining Laser Line Peaks on page 2 15 for information on the peak threshold and peak excursion settings The peak excursion value in dB can also be used to determine which side modes are included in the measurements To be a
79. amming Lists of Commands Table 3 10 Programming Commands 2 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command CALCulate1 CALC1 Subsystem CALCulate1 DATA Queries the uncorrected frequency spectrum data of the S input signal CALCulate1 TRANsform FREQuency POINts Sets and queries the number of points in the data set S CALCulate2 CALC2 Subsystem CALCulate2 DATA Queries the corrected frequency spectrum data of the S input signal CALCulate2 PEXCursion Sets the peak excursion limit CALCulate2 POINts Queries the number of points in the data set CALCulate2 PTHReshold Sets the peak threshold limit CALCulate2 PWAVerage STATe Places the instrument in the average wavelength mode Data queries return the power weighted average frequency wavelength or wavenumber or total power CALCulate2 WLIMit STATe Turns wavelength limiting on and off CALCulate2 WLIMit STARt FREQuency Sets the starting frequency for the wavelength limit range CALCulate2 WLIMit STARt WAVelength Sets the starting wavelength for the wavelength limit CALCulate2 WLIMit STARt WNUMber Sets the starting wavenumber for the wavelength limit CALCulate2 WLIMit STOP FREQuency Sets the stopping frequency for the wavelength limit range CALCulate2 WLIMit STOP WAVelength Sets the
80. and amplitude units In addition the mode spacing measurement always shows results in fre quency as well as the selected wavelength units Refer to Displayed units on page 2 12 to learn how to change the units The number of laser lines included in the measurement results is also listed as shown in the following figure 3 195nm SS SWE 1 530 1 3246 mem SHELTE 1548 084 F 44dBm mem s OF 1 613 1 B5dB m B3B 52dB weer 8 M To characterize a Fabry Perot laser Press Appl s Press FP TEST to measure the Fabry Perot laser s characteristics If you want to stop the updating of measurement data with each sweep press Single Because Fabry Perot lasers are sensitive to reflec tions it is good measurement practice to place an optical isolator or attenuator between the laser and the Agilent 86120C 2 31 Making Measurements Measuring Fabry Perot FP Lasers Measurement FWHM MEAN MODE PEAK SIGMA Description FWHM full width at half maximum describes the spectral width of the half power points of the laser assuming a continuous Gaussian power distribution The half power points are those where the power spectral density is one half that of the peak amplitude of the computed Gaussian curve FWHM 2 3556 where o is sigma as defined below The wavelength representing the center of mass of selected peaks The power and wavelength of each spectral component are used to c
81. ares under sole responsibility that the product as originally delivered Product Name Multi Wavelength Meter Product Numbers 86120B 86120C Product Options This declaration covers all options of the above products complies with the essential requirements of the following applicable European Directives and carries the CE marking accordingly Low Voltage Directive 73 23 EEC amended by 93 68 EEC The EMC Directive 89 336 EEC amended by 93 68 EEC and conforms with the following product standards Standard Limit EMC IEC 61326 1997 A1 1998 A2 2000 EN 61326 1997 A1 199B A2 2001 CISPR 11 19974A1 1999 EN 55011 1998 1 1999 Group 1 Class A IEC 61000 4 2 2001 EN 61000 4 2 1995 1 1998 42 2001 4kV CD BkV AD IEC 61000 4 3 2002 EN 61000 4 3 2002 3 Vim 80 1000 MHz IEC 61000 4 4 2001 EN 61000 4 4 1995 A1 2001 A2 2001 0 5 kV signal lines 1 kV power lines IEC 61000 4 5 2001 EN 61000 4 5 1995 A1 2001 0 5 KV line line 1 kV line ground IEC 61000 4 6 1995 A1 2000 EN 61000 4 6 1996 1 2001 3 V 0 15 80 MHz IEC 61000 4 8 2001 EN 61000 4 8 1993 A1 2001 30 IEC 61000 4 11 1994 A1 2000 EN 61000 4 11 1994 A1 2001 1 cycle 100 Canada ICES 001 1998 Australia New Zealand AS NZS 2064 1 Safety IEC 81010 1 2001 EN 61010 1 2001 Canada CSA C22 2 No 1010 1 1992 USA UL 3111 1 1994 Supplementary Information The products were tested in a typical configuration with Agilent Technologies test systems This DoC applies
82. aser line of interest may have since drifted to a lesser value Note that the 2 23 Making Measurements Measuring Laser Drift maximum wavelength and maximum power may not have occurred simultaneously Display shows absolute minimum values since the drift measurement was started This measurement gives the shortest wavelength and smallest power measured The laser line of interest may have since drifted to a greater value Note that the minimum wavelength and minimum power may not have occurred simultaneously Display shows the total drift from the reference since the drift measurement was started Values represent the minimum wavelength and power drift values subtracted from the maximum drift values In the List by WL and List by Power displays use the and softkeys to view the reference values wavelength and power values of each laser line before the test was started During the measurement you can change the display mode to Peak WL List by WL List by Power or Avg WL When List by WL or List by Power is selected the signal list is sorted by reference values and not by the current maximum or minimum values To restart the drift measurements press RESET This resets the refer ence values 2 24 Making Measurements Measuring Signal to Noise Ratios Measuring Signal to Noise Ratios Signal to noise measurements provide a direct indication of system performance Signal to noise measurements are especia
83. ation in meters Entries jump in 500 meter steps from 0 m to 5000 m The elevation value selected with the softkeys must be within 250 meters of the actual elevation 6 Press RETURN to complete the entry Converting feet to meters If you know your elevation in feet you can convert this value to meters by using the following equation 2 21 3 281 1 8 Getting Started Step 6 Select Medium for Wavelength Values Step 6 Select Medium for Wavelength Values Because wavelength varies with the material that the light passes through the Agilent 86120C offers wavelength measurements in two mediums vacuum and standard air Press the Setup key Press the MORE softkey Press the CAL softkey Make the following selection Press VACUUM for wavelength readings in a vacuum Press STD AIR for wavelength readings in standard air Press RETURN to complete the entry Definition of standard air Standard air is defined to have the following characteristics Barometric pressure 7013 mbar Temperature 59 Relative humidity 0 Getting Started Step 7 Turn Off Wavelength Limiting Step 7 Turn Off Wavelength Limiting The instrument s Preset key sets the entire Agilent 86120C wavelength range of 1270 1650 nm If a user defined wavelength range limit was set using WL LIM the following procedure will ensure that responses across the full wavelength are measured by returning the instrume
84. bing the failure please be as specific as possible about the nature of the problem Include copies of additional failure information such as the instrument failure settings data related to instrument failure and error messages along with the instrument being returned CAUTION CAUTION Getting Started Returning the Instrument for Service Preparing the instrument for shipping Write a complete description of the failure and attach it to the instrument Include any specific performance details related to the problem The following information should be returned with the instrument Cover all front or rear panel connectors that were originally covered Type of service required Date instrument was returned for repair Description of the problem Whether problem is constant or intermittent Whether instrument is temperature sensitive Whether instrument is vibration sensitive Instrument settings required to reproduce the problem Performance data Company name and return address Name and phone number of technical contact person Model number of returned instrument Full serial number of returned instrument List of any accessories returned with instrument when you first received the instrument Cover electrical connectors to protect sensitive components from electrostatic damage Cover optical connectors to protect them from damage due to physical contact or dust Instrument damage can
85. ble NTRansit Sets the negative transition filter register S ion STATus PRESet Presets the enable registers for all status nodes S SYSTem Subsystem SYSTem ERRor Queries an error from the error queue S SYSTem HELP HEADers Queries an ASCII listing of all Agilent 86120C remote commands SYSTem PRESet Performs the equivalent of a front panel PRESET key S press SYSTem VERSion Queries the version of SCPI with which this instrument is S compliant TRIGger Subsystem ABORt Stops the current measurement sequence S INITiate IMMediate Places the instrument into the initiated state and initiates S a new measurement sequence INITiate CONTinuous Sets the instrument for single or continuous S measurement UNIT Subsystem UNIT POWer Sets the power units to watts linear or dBm logarithmic 3 47 Programming Lists of Commands Table 3 11 Keys Versus Commands 1 of 2 Key Equivalent Command A PWR CALCulate3 DELTa POWer STATe AWL CALCulate3 DELTa WAVelength STATe A WL PWR CALCulate3 DELTa WPOWer STATe Appl s See DRIFT S N and FP TEST AUTO CALCulate3 SNR AUTO ON Avg WL CALCulate2 PWAVerage STATe BAR OFF DISPlay WINDow GRAPhics STATe BAR ON DISPlay WINDow GRAPhics STATe BROAD SENSe CORRection DEVice BROad CAL See ELEV PWR OFS STD AIR and VACUUM CM 1 MEASure ARRay POWer WNUMber
86. bset of the uncorrected data buffer shown in the figure that is located in Making Measurements on page 3 5 Changing the number of points causes the instrument to reprocess the current set of data The query form of the command returns the number of points in the data set This is the number of measurement points that will be returned by the CALC1 DATA query Non sequential command Always use OPC query WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 29 Query Response Programming Commands CALCulate1 Subsystem For normal update 15 047 For fast update 7 525 4 30 Programming Commands CALCulate2 Subsystem CALCulate2 Subsystem Use the CALCulateZ commands to query corrected values frequency spectrum data The commands in this subsystem have the following command hierar chy CALCulate2 DATA PEXCursion POINts PTHReshold PWAVerage STATe WLIMit STATe STARt FREQuency WAVelength WNUMber STOP FREQuency WAVelength WNUMber 4 31 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem DATA Queries the corrected peak data of the input laser line CALCulate2 DATA FREQuency POWer WAVelength W
87. ccepted each trace peak must rise and then fall by at least the peak excursion value about a given spectral component Setting the peak excursion value too high results in failure to include the smaller responses near the noise floor Setting the value too low may cause unwanted responses including noise spikes to be identified Use PK EXC to change the peak excursion value 2 33 Making Measurements Measuring Modulated Lasers Measuring Modulated Lasers A laser that is amplitude modulated at low frequencies for example modulated in the audio frequency range can cause spurious wave lengths to be displayed below and above the correct wavelength The power of these spurious wavelengths is below that of the correct wavelength These spurious signals can be eliminated by decreasing the peak threshold Refer to Defining Laser Line Peaks on page 2 15 Even when the laser is amplitude modulated the correct wavelength and power is displayed The spurious wavelengths caused by low frequency amplitude modula tion will be located above and below the correct wavelength by the fol lowing wavelength spacing spacing 6x10 FA where is the modulation frequency in Hz and is the correct wave length in nm For example an amplitude modulation of 10 kHz on a 1550 nm laser will produce spurious wavelengths spaced by 15 nm from the correct wavelength and the spurious wavelengths will be at 1535 and 1565 nm 15
88. ce Relative wavelength absolute power Relative power absolute wavelength Relative wavelength and power This section includes Channel separation 2 19 Measuring flatness 2 21 2 18 Making Measurements Measuring Laser Separation Channel separation Suppose that you want to measure separation on a system having the spectrum shown in the following figure Heference 1541 747 nm 5 46 dBm 2 606 nm 1 302 nm 7 26 dB 1 98 dB 1 300 nm 2 596 nm 2 42 dB 4 41 dB peaks The Agilent 86120C displays separation on this spectrum as shown in the following figure Notice that the 1541 747 nm laser line is selected as the reference It is shown in absolute units The wavelengths and powers of the remaining responses are shown relative to this refer ence For example the first response is 2 596 nm below the reference 2 536nm 4 41dE mme 1 388 2 24 peer us uei 1541 747 S 46dEm 6 OF 1 362 1 m 9 Wa 2 685 Sr ibdb deem acces 8 M To determine channel spacing simply read the relative wavelength measurement of the laser lines immediately preceding and following the reference Use the and SELECT softkeys to change the ref erence laser line and read the channel spacing between each channel 2 19 Making Measurements Measuring Laser Separation To measure channel separation Press the front panel Preset key Press List by WL Press the Delta On key
89. cept the drift and signal to noise modes Specifying off prevents the display of power bars for all instrument modes 4 78 Programming Commands FETCh Measurement Instruction FETCh Measurement Instruction For information on the FETCh measurement instruction refer to Mea surement Instructions on page 4 15 4 79 Syntax Attribute Summary Description Programming Commands HCOPy Subsystem HCOPy Subsystem Use the command in this subsystem to print the displayed measure ment results to a printer This subsystem has the following command hierarchy HCOPy IMMediate IMMediate Prints measurement results on a printer HCOPy IMMediate Preset State none RST State none SCPI Compliance standard Command Only Connect the printer to the Agilent 86120C s rear panel PARALLEL PRINTER PORT connector The output to the printer is ASCII text 4 80 Programming Commands MEASure Measurement Instruction MEASure Measurement Instruction For information on the MEASure measurement instruction refer to Measurement Instructions on page 4 15 4 81 Programming Commands READ Measurement Instruction READ Measurement Instruction For information on the READ measurement instruction refer to Mea surement Instructions on page 4 15 4 82 Programming Commands SENSe Subsystem SENSe Subsystem Use the SENSe commands to correct measurement results for elevatio
90. chcord 1 to 2 connector pair is to under measure the return loss by twice the FC APC patchcord 1 to 2 loss For example if this connector pair loss is 0 5 dB then the actual return loss caused by the 14 6 dB Fresnel reflection is 15 6 dB but we enter 14 6 dB as an R value Then if the device under test return loss is exactly 40 dB below that of the 14 6 dB Fresnel reflection the optical return loss module will display 53 6 dB because the 0 5 dB connector pair loss seen twice is removed In reality the return loss is 54 6 dB exactly 40 dB below 14 6 dB better than that displayed 5 8 Equipment Procedure Performance Tests Test 5 Amplitude Accuracy and Linearity Test 5 Amplitude Accuracy and Linearity Amplitude linearity is performed using the following devices 1550 nm DFB lasers Optical attenuator Agilent 11896A polarization controller Optical power meter Polarization sensitivity To ensure measurement accuracy minimize the movement of any fiber optic cables during this procedure Moving cables causes polarization changes which affect amplitude measurements Turn on the laser and allow it to warm up Connect the laser s output to the optical attenuator s input Connect the optical attenuator s output to the polarization controller s optical input Connect the polarization controller s optical output to the optical power meter Configure the optical power meter for 1550 nm Adjust the
91. cting connectors Turn the source module s output off Connect a single mode patchcord between the source module s optical output and the return loss module s INPUT SOURCE connector Set the return loss module s wavelength to 1550 nm and select an average time of 1 second Locate an HMS 10 HRL to FC APC angled FC patchcord Connect the HMS 10 HRL end of the patchcord to the return loss module s OUTPUT connector Terminate the FC APC end of the cable Zero the return loss module Turn on the source module Remove the termination from the cable and connect the FC APC end of an FC APC to FC PC cable to the free end of this cable Leave the cable s free end uncovered The return loss module measures the reflection reference 14 6 dB return loss of the patchcord s FC PC connector in air Disconnect the FC APC to FC PC cable Make low reflection termination in the HMS 10 HRL to FC APC patchcord Do this by wrapping the cable 6 times around a 5 mm diameter mandrel The return loss module measures the termination parameter Connect the HMS 10 HRL to FC APC patchcord to the Agilent 86120C s front panel OPTICAL INPUT connector The lightwave multimeter measures the return loss Compare this measurement with the specification listed in Chapter 6 Specifications and Regulatory Information 5 7 Performance Tests Test 4 Optical Input Return Loss FC APC patchcord loss The effect of having loss in the FC APC pat
92. d 6 64 Not Used 5 32 Event Status Bit ESB 4 16 Message Available MAV 3 8 Not Used 2 4 Error queue status 1 2 Not Used 0 1 Not Used a High enables the status byte register bit Query Response Example Programming Commands Common Commands integer from 0 to 63 or from 128 to 191 OUTPUT 720 SRE 32 In this example the command enables ESB event summary bit 5 in the status byte register to generate a service request Syntax Description Query Response Example Programming Commands Common Commands STB The STB status byte query returns the current value of the instru ment s status byte STB The master summary status MSS bit 6 indicates whether or not the device has at least one reason for requesting service When you read the status byte register the value returned is the total of the bit weights of all of the bits set to one at the time you read the byte The following table shows each bit in the status byte register and its bit weight The STB query does not affect the contents of the status byte register Table 4 17 Status Byte Register Bit Bit Weight Condition 7 128 Not Used 6 64 Master Summary Status MSS 5 32 Event Status Bit ESB 4 16 Message Available MAV 3 8 Not Used 2 4 Error queue status 1 2 Not Used 0 1 Not Used integer from to 255 OUTPUT 720 STB ENTER 720 Value PRINT Value 4 12 Syntax Descripti
93. d Step 4 Turn on the Agilent 86120C Step 4 Turn on the Agilent 86120C 1 Press the front panel LINE key After approximately 20 seconds the display should look similar to the figure below The front panel LINE switch disconnects the mains circuits from the mains supply after the EMC filters and before other parts of the instru ment HO SIGNAL a CINES Wal L JC Jere JD 2 If the Agilent 86120C fails to turn on properly consider the following possibilities Is the line fuse good Does the line socket have power Is it plugged into the proper ac power source If the instrument still fails return it to Agilent Technologies for repair Refer to Returning the Instrument for Service on page 1 11 Instrument firmware version When the instrument is first turned on the display briefly shows the instrument s firmware version number In the unlikely event that you have a problem with the Agilent 86120C you may need to indicate this number when communicating with Agilent Technologies Getting Started Step 5 Enter Your Elevation Step 5 Enter Your Elevation In order for your Agilent 86120C to accurately measure wavelengths and meet its published specifications you must enter the elevation where you will be performing your measurements 1 Press the Setup key 2 Press the MORE softkey 3 Press the CAL softkey 4 Press ELEV 5 Use the and softkeys to enter the elev
94. d limit 15 17 35 wavelength iii 4 Peak WL key 4 menu map 8 softkey 4 23 performance tests 2 PEXCursion programming command 33 PK EXC softkey 17 PK THLD softkey 17 POINts programming command 29 34 68 polarization dependence 4 6 9 power bar iv 4 11 maximum before damage 2 maximum input iv maximum measurable 2 measuring total 7 32 35 peak 4 separation 18 state when turned on 100 2 tuning laser 4 POWer programming command 17 51 107 POWER softkey 13 Index PRBS 27 35 Preset conditions set by 100 2 key 2 9 4 menu map 8 PRESet programming command 50 59 96 100 PREV PK softkey 5 PREV WL softkey 5 PREVious programming command 77 Print key 39 menu map 9 printer cable 6 connecting 6 output 39 programming 2 command notation convention 2 examples See example programs list of commands by key 48 list of commands by subsystem 43 measurement instructions 15 programming command 48 PTRansition programming command 95 PWR BAR softkey 11 PWR OFS annotation 36 softkey 36 A PWR softkey 21 0 queries 27 multiple 27 queues 22 radiation exposure vi range wavelength 37 READ measurement instruction 15 rear panel labels 15 regulatory duration 2 Remote annotation 3 repetitive data formats 27 RESet programming command 59 RESET softkey 21 23 24 Index 5 Index return loss 4 7 10 returning data 27 for service 11 RF modulation 35 RIGH
95. e Exiting this subroutine is only possible if no errors have occurred Notice that the logic test in the subroutine tests for the same event status register bits enabled by the Set ese subroutine BIT Cme 5 BIT Cme 4 BIT Cme 2 This subroutine is called in Examples 1 through 5 However it is mod ified in Examples 3 4 and 5 to allow it to indicate the last program ming command that was sent to the instrument before an error occurred This is accomplished by adding an optional argument string Cmd opc subroutine The opc subroutine found in Examples 3 4 and 5 pauses the program until a non sequential command has finished executing on the Agilent 86120C It uses the OPC query For more information on non sequential commands refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 Tempo subroutine This subroutine which is only found in Example 3 pauses the pro gram for a few seconds while the Agilent 86120C measures the drift on a laser The argument in the example sets the pause for 10 seconds 3 29 Programming Example Programs Example 1 Measure a DFB laser This program measures the power and wavelength of a DFB laser It first sets the Agilent 86120C in the single acquisition measurement mode Then it triggers the Agilent 86120C with the MEASure com mand to capture measurement data of the input spectrum Because the data is stored in the instrument s memor
96. e First the pro gram sets the Agilent 86120C in the single acquisition measurement mode Then it triggers the Agilent 86120C with the MEASure com mand to capture measurement data of the input spectrum Because the data is stored in the instrument s memory it can be queried as needed Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 ON ERROR GOTO Error msg Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNIdentity OUTPUT GMwm INIT CONT OFF ON TIMEOUT 7 5 CALL mngmt OUTPUT Mwm MEAS ARR POW WAV ENTER Mwm USING K Nb_wl ALLOCATE Current wl 1 Nb wl TER Mwm USING K Current_wl UTPUT GMwm FETC ARR POW TER Mwm USING K Nb_wl LLOCATE Current pwr 1T Nb wl NTER Mwm USING K Current_pwr Iz1 TO Nb wl PRINT USING 22A 2D 6A 4D 2DE 4A S2D 2D 3A The wavelength number Current wI D at Current pwr D dBm NEXT I OFF TIMEOUT STOP gt mom Tn m Error msg PRINT the prgm is aborted due to ERRM END Err_mngmt SUB Err_mngmt COM Instrument 9 Mwm DIM Err msg 255 INTEGER Cme CLEAR 7 REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT GMwm SYST ERR ENTER Mwm Err_msg 3 32 Programming Example Programs PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND Err 4
97. e Peaks 15 Measuring Laser Separation 18 Measuring Laser Drift 22 Measuring Signal to Noise Ratios 25 Measuring Signal to Noise Ratios with Averaging 29 Measuring Fabry Perot FP Lasers 31 Measuring Modulated Lasers 34 Measuring Total Power Greater than 10 dBm 36 Calibrating Measurements 37 Printing Measurement Results 39 Cleaning Connections for Accurate Measurements 40 Programming Addressing and Initializing the Instrument 3 Making Measurements 5 Monitoring the Instrument 16 Reviewing SCPI Syntax Rules 23 Example Programs 28 Lists of Commands 43 Contents 1 Contents Programming Commands Common Commands 3 Measurement Instructions 15 CALCulatel Subsystem 25 CALCulate2 Subsystem 31 CALCulate3 Subsystem 44 CONFigure Measurement Instruction 74 DISPlay Subsystem 75 FETCh Measurement Instruction 79 HCOPy Subsystem 80 MEASure Measurement Instruction 81 READ Measurement Instruction 82 SENSe Subsystem 83 STATus Subsystem 90 SYSTem Subsystem 97 TRIGger Subsystem 103 UNIT Subsystem 107 Performance Tests Test 1 Absolute Wavelength Accuracy 3 Test 2 Sensitivity 4 Test 3 Polarization Dependence 5 Test 4 Optical Input Return Loss 6 Test 5 Amplitude Accuracy and Linearity 9 Specifications and Regulatory Information Definition of Terms 3 Specifications NORMAL Update Mode 5 Specifications FAST Update Mode 8 Operating Specifications 11 Laser Safety Information 12 Compliance with Canadian EM
98. e WLIMit STOP When this function is off the instrument displays peaks over the full wavelength range The graphics display always shows the range between WLIMit STARt and WLIMit STOP regardless of the state of this command Whenever the Agilent 86120C receives this command it reprocesses the data and performs a new peak search Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 37 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STARCFREQuency Sets the start frequency for the wavelength limit range CALCulate2 WLIMit STARtFREQuency lt real gt MAXimum real is a frequency value that is within the following limits Constant Description MINimum 181 6924 THz 1650 nm MAXimum wavelength limit stop value Non sequential command Preset State 181 6924 THz RST State 181 6924 THz SCPI Compliance instrument specific This command sets the starting range for the wavelength limit in hertz The start frequency value must be less than or equal to the stop fre quency value or the start frequency will be clipped to the stop fre quency and a Data out of range error will be generated The defau
99. e metal as well as any other imperfections Inspect the fiber for cracks and chips Visible imperfections not touching the fiber core may not affect performance unless the imperfections keep the fibers from contacting Always remove both ends of fiber optic cables from any instrument system or device before visually inspecting the fiber ends Disable all optical sources before disconnecting fiber optic cables Failure to do so may result in permanent injury to your eyes Cleaning Connectors The procedures in this section provide the proper steps for cleaning fiber optic cables and Agilent Technologies universal adapters The ini tial cleaning using the alcohol as a solvent gently removes any grit and oil If a caked on layer of material is still present this can hap pen if the beryllium copper sides of the ferrule retainer get scraped and deposited on the end of the fiber during insertion of the cable a second cleaning should be performed It is not uncommon for a cable or connector to require more than one cleaning 2 4 CAUTION CAUTION Making Measurements Cleaning Connections for Accurate Measurements Agilent Technologies 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 manufacture
100. e powers after the calculation is completed FREQuency Queries the array of laser line frequencies after the calculation is completed WAVelength Queries the array of laser line wavelengths after the calculation is completed WNUMber Queries the array of laser line wave numbers after the calculation is completed Preset State not affected SCPI Compliance standard Query Only The data returned by the query depends upon which calculation state is on If no calculation state is on an error is generated The returned data is comma delimited The following string is a typical example of six values returned when POWer is specified from a delta power mea surement 7 42833100E 000 1 00087200E 000 2 52121400E 000 3 41918900E 000 3 80437200E 000 6 36282900E 000 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands Use the CALC3 POIN query to determine the number of points the CALC3 DATA query returns In the SNR or ASNR calculation only the POWer argument is valid The other arguments will generate a Settings conflict error Use the CALC2 DATA query to retrieve the signal wavelengths and powers 4 49 Syntax Attribute Summary Description Syntax Attribute Summary Programming Commands CALCulate3 Subsystem DELTa POWer STATe
101. e wavelength limit range CALCulate2 WLIMit STOP FREQuency real MINimum MAXimum real is a frequency value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 236 0571 THz 1270 nm Non sequential command Preset State 236 0571 THz RST State 236 0571 THz SCPI Compliance instrument specific This command sets the stopping range for the wavelength limit The default units for the lt real gt parameter are Hz The stop frequency value must be greater than or equal to the start frequency value or the stop frequency will be clipped to the start frequency and a Data out of range error will be generated Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 41 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP WAVelength Sets the stopping wavelength for the wavelength limit range CALCulate2 WLIMit STOP WAVelength lt real gt MAXimum lt real gt is a wavelength value that is within the following limits Constant Description MINimum start wavelength limit MAXimum 1650 0 nm Non sequential command Preset State 1650
102. e3 Subsystem FPERot POWer Queries the total power data of the selected modes CALCulate3 FPERot POWer DBM WATTs Argument Description DBM Returns the total power in dBm WATTs Returns the total power in watts dBm DBM 4 46895600E 000 watts WATTs 3 57358800 004 Preset State not affected RST State not affected SCPI Compliance instrument specific Query only 4 66 Syntax Example Query Response Attribute Summary Programming Commands CALCulate3 Subsystem FPERot SIGMa Queries the sigma data of the selected modes CALCulate3 FPERot SIGMa WAVelength FREQuency WNUMber Argument Description WAVelength Returns the sigma wavelength of the selected modes FREQuency Returns the sigma frequency of the selected modes WNUMber Returns the sigma wavenumber of the selected modes WAVelength 2 32784700E 009 FREQuency 2 94452900E 011 WNUMber 9 82124900E 000 Preset State not affected RST State not affected SCPI Compliance instrument specific Query only 4 67 Syntax Attribute Summary Description Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem POINts Queries the number of points in the data set CALCulate3 POINts Preset State unaffected by RST State unaffected by SCPI Compliance instrument specific Query Only The value returned is the number of points returned by the CALC3 DATA query
103. eak WL mode When Peak WL is pressed the display shows the largest amplitude line in the spectrum The word PEAK is shown on the screen If multiple laser lines are present at the input the number of lines located will be shown along the right side of the screen In peak wavelength mode the Agilent 86120C can measure up to 200 laser lines simultaneously Displayed Laser Line has the Measurement Greatest Power Wavelength Power Acquisition Power Bar peakwl2 X 3 Laser Lines Found 1551 314 SEF apm 6 ES nm PUR eL Power Offset nov HM Applied Elevati evation Calibration Figure 2 1 Display after Peak WL key pressed In addition to the digital readouts there is a power bar It provides a convenient analog meter movement for tuning laser power Although the Peak WL mode shows one signal at a time softkeys are provided that allow you to scroll through and display all the measured laser lines You can scroll through the list according to the wave lengths or powers measured To display peak wavelength and power Connect the fiber optic cable to the front panel OPTICAL INPUT connector To display the peak wavelength and power do one of the following Press the green Preset key Press Peak WL 2 4 Making Measurements Measuring Wavelength and Power 3 To move the cursor to view other signals press PREV WL to select next previous shorter wavelength NE
104. easurements are actually improved by backing off the connec 2 45 Making Measurements Cleaning Connections for Accurate Measurements tor pressure Also if a piece of grit does happen to get by the cleaning procedure the tighter connection is more likely to damage the glass Tighten the connectors just until the two fibers touch Keep connectors covered when not in use Use fusion splices on the more permanent critical nodes Choose the best connector possible Replace connecting cables regularly Frequently measure the return loss of the connector to check for degradation and clean every connector every time All connectors should be treated like the high quality lens of a good camera The weak link in instrument and system reliability is often the inappropriate use and care of the connector Because current connec tors are so easy to use there tends to be reduced vigilance in connec tor care and cleaning It takes only one missed cleaning for a piece of grit to permanently damage the glass and ruin the connector Measuring insertion loss and return loss Consistent measurements with your lightwave equipment are a good indication that you have good connections Since return loss and inser tion loss are key factors in determining optical connector performance they can be used to determine connector degradation A smooth pol ished fiber end should produce a good return loss measurement The quality of the polish establishes the
105. ecifications apply when the device is set to NARRow Specifications do not apply in BROad mode The query form returns the previously selected device NARRow 4 84 Syntax Attribute Summary ODescription Query Response Programming Commands SENSe Subsystem CORRection ELEVation Sets the elevation value used by the instrument to compensate for air dispersion SENSe CORRection ELEVation lt integer gt MAXimum integer is the altitude in meters Constant Description MINimum 5000 Non sequential command Preset State unaffected by RST sets this value to the minimum SCPI Compliance instrument specific Changing the elevation value causes the current data to be repro cessed The query form returns the current elevation setting as shown in the following example 1500 Non sequential command page 3 12 for more information Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on 4 85 Syntax Attribute Summary Description Programming Commands SENSe Subsystem CORRection MEDium Sets the Agilent 86120C to return wavelength readings in a vacuum or standard air SENSe CORRection MEDium AIR VACuum Argument Description AIR Selec
106. el spacing 2100 GHz channel spacing 250 GHz Signal to Noise Ratio with Averaging modulated lasers characteristic channel spacing 2100 GHz channel spacing 250 GHz gt 35 dB gt 27 dB gt 35 dB with 100 averages gt 27 dB with 100 averages 0 1 nm noise bandwidth lines above 25 dBm 6 7 Specifications and Regulatory Information Specifications FAST Update Mode Specifications FAST Update Mode Each laser line is assumed to have a linewidth including modulation side bands of less than 10 GHz All specifications apply when the instrument is in the following modes FAST update mode unless noted Refer to Measurement rate on page 2 13 Configured to measure narrowband devices Specifications do not apply when the instrument is configured to measure broadband devices Refer to Measuring broadband devices and chirped lasers on page 2 9 Wavelength Range 1270 1650 Absolute accuracy lines separated by 230 GHz 3 ppm 0 005 nm at 1550 nm 0 004 nm at 1310 nm Differential accuracy characteristic 2 ppm Minimum resolvable separation characteristic 20 GHz 0 16 nm at 1550 nm 0 11 nm at 1300 nm Display resolution 0 001 nm a Signals of equal amplitude For lines that are separated by less than 30 GHz wavelength accuracy is reduced 6 8 Amplitude Specifications and Regulatory Information Specifications FAST Update Mode Calibration accuracy at calibrat
107. ence Delta Reference not used not used Command Warning not used not used SETTIing RANGing not used MEASuring not used not used not used not used Processing Hardcopy Averaging not used not used not used not used Operation Complete Request Control Query Error Device Dependent Error Execution Error Command Error User Request Power On 0 1 2 3 4 5 6 7 8 9 QUEStionable Status WV OPERation Status gt NA WY Standard Event Status Register 0 NOORWN V Error Event Queue Status Byte 0 1 2 3 MAV 4 5 RQS 7 stat 3 18 Programming Monitoring the Instrument The Status Byte Register can be read using either the STB common command or the GPIB serial poll command Both commands return the decimal weighted sum of all set bits in the register The difference between the two methods is that the serial poll command reads bit 6 as the Request Service RQS bit and clears the bit which clears the SRQ interrupt The STB command reads bit 6 as the Master Sum mary Status MSS and does not clear the bit or have any effect on the SRQ interrupt The value returned is the total bit weights of all of the bits that are set at the present time OPERation Status and QUEStionable Status registers You can query the value of the OPERation Status and QUEStionable Status registers using commands in the STATus subsystem The STATus subsystem also has tra
108. ent 86120C to a known condition RST For a listing of reset conditions refer to the following table This com mand cannot be issued as a query Since this command places the instrument in single measurement acquisition mode any current data is marked as invalid and a measurement query such as FETCh results in error number 230 Data corrupt or stale You must ini tiate a new sweep with INIT IMM before you can use the FETCh com mand Table 4 15 Conditions Set by RST Reset 1 of 2 Item Setting Display mode Start wavelength Stop wavelength Graphical display Measurement acquisition Wavelength calibration Elevation correction value Wavelength units Amplitude units Power offset Peak threshold Peak excursion Measurement speed single wavelength 1270 nm 1650 nm off single vacuum 0 meters nm dBm 0dB 10 dB 15 dB normal 4 8 Table 4 15 Conditions Set by RST Reset 2 of 2 Programming Commands Common Commands Item Setting Number of uncorrected data points 15 047 Delta Measurements A power off A wavelength off A wavelength and power off reference signal position 1270 nm Drift measurements off Signal to Noise Measurements measurement off wavelength reference auto reference user wavelength number of averages count GPIB address Power bar display 1550 nm in vacuum 100 not affected on SAV This command saves an instrument state
109. ent it from moving in the carton 4 Seal the carton with strong nylon adhesive tape 5 Mark the carton FRAGILE HANDLE WITH CARE 6 Retain copies of all shipping papers 1 13 Getting Started Returning the Instrument for Service 1 14 Getting Started Returning the Instrument for Service 1 15 Measuring Wavelength and Power 2 3 Peak WL mode 2 4 List by WL or Power modes 2 6 Total power and average wavelength 2 7 Limiting the wavelength measurement range 2 8 Measuring broadband devices and chirped lasers 2 9 Graphical display of optical power spectrum 2 10 Instrument states 2 11 Power bar 2 11 Changing the Units and Measurement Rate 2 12 Displayed units 2 12 Measurement rate 2 13 Continuous or single measurements 2 14 Defining Laser Line Peaks 2 15 Measuring Laser Separation 2 18 Channel separation 2 19 Measuring flatness 2 21 Measuring Laser Drift 2 22 Measuring Signal to Noise Ratios 2 25 Measuring Signal to Noise Ratios with Averaging 2 29 Measuring Fabry Perot FP Lasers 2 31 Measuring Modulated Lasers 2 34 Measuring Total Power Greater than 10 dBm 2 36 Calibrating Measurements 2 37 Printing Measurement Results 2 39 Cleaning Connections for Accurate Measurements 2 40 Making Measurements CAUTION Making Measurements Making Measurements Making Measurements In this chapter you ll learn how to make a variety of fast accurate measurements As you perform these measurements keep in mind
110. er ESE integer ESE 4 3 Description Query Response Example Programming Commands Common Commands integer is a mask from 0 to 255 The event status enable register contains a mask value for the bits to be enabled in the event status register A bit set to one 1 in the event status enable register enables the corresponding bit in the event status register to set the event summary bit in the status byte register A zero 0 disables the bit Refer to the following table for information about the event status enable register bits bit weights and what each bit masks The event status enable register is cleared at power on The RST and CLS commands do not change the register The ESE query returns the value of the event status enable register Table 4 13 Event Status Enable Register Bit Bit Weight Enables 7 128 PON Power On 6 64 Not Used 5 32 Command Error 4 16 EXE Execution Error 3 8 DDE Device Dependent Error 2 4 QYE Query Error 1 2 Not Used 0 1 OPC Operation Complete a A high enables the event status register bit lt integer gt is a mask from 0 to 255 OUTPUT 720 ESE 32 In this example the ESE 32 command enables CME event summary bit bit 5 of the event status enable register Therefore when an incor rect programming command is received the CME command error bit in the status byte register is set 4 4 Syntax Description Que
111. erar chy DISPlay MARKer MAXimum LEFT NEXT PREVious RIGHE WINDow GRAPhics STATe 4 75 Syntax Attribute Summary Syntax Attribute Summary Description Programming Commands DISPlay Subsystem MARKer MAXimum Sets the marker to the laser line that has the maximum power DISPlay MARKer MAXimum Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only MARKer MAXimum LEFT Moves the marker left to the next laser line DISPlay MARKer MAXimum LEFT Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only Moves the marker from the current marker position to the next laser line having the following characteristic shorter wavelength lower frequency lower wave number If the display is in the List by Ampl mode it will be changed to List by WL before the marker is moved 4 76 Syntax Attribute Summary Description Syntax Attribute Summary Description Programming Commands DISPlay Subsystem MARKer MAXimum NEXT Moves the marker to the laser line with the next lower power level DISPlay MARKer MAXimum NEXT Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Co
112. ering is also the chief liabil ity of the connector The soft material is easily damaged Care must be taken to minimize excessive scratching and wear While minor wear is not a problem if the glass face is not affected scratches or grit can cause the glass fiber to move out of alignment Also if unkeyed con nectors are used the nickel silver can be pushed onto the glass sur face Scratches fiber movement or glass contamination will cause loss of signal and increased reflections resulting in poor return loss Inspecting Connectors Because fiber optic connectors are susceptible to damage that is not immediately obvious to the naked eye poor measurements result with out the user being aware Microscopic examination and return loss measurements are the best way to ensure good measurements Good cleaning practices can help ensure that optimum connector perfor mance is maintained With glass to glass interfaces any degradation of a ferrule or the end of the fiber any stray particles or finger oil can have a significant effect on connector performance Where many repeat connections are required use of a connector saver or patch cable is recommended Figure 2 6 shows the end of a clean fiber optic cable The dark circle in the center of the micrograph is the fiber s 125 um core and cladding which carries the light The surrounding area is the soft nickel silver ferrule Figure 2 7 shows a dirty fiber end from neglect or perhaps impro
113. ess control Safety Notices CAUTION Caution denotes a hazard It calls attention to a procedure which if not correctly performed or adhered to could result in dam age to or destruction of the prod uct Do not proceed beyond a caution sign until the indicated conditions are fully understood and met WARNING Warning denotes a hazard It calls attention to a procedure 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 conditions are fully understood and met The instruction manual A 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 The laser radiation sym bol This warning symbol is marked on products which have a laser out put The AC symbol is used to A indicate the required nature of the line module input power The ON symbols are used to mark the posi tions of the instrument power line switch n The OFF symbols are used to mark the posi tions of the instrument power line switch The CE mark is a regis tered trademark of the European Community The CSA mark is a regis tered trademark of the Canadian Standards Association The C Tick mark is a reg istered trademark of the Australian Spectrum Management Agency IVER This text denotes the instrument is an Indus trial Scientific and Medi cal Group 1 Cla
114. ference laser To verify absolute wavelength accuracy an external laser is measured during manufacturing at 1523 488 nm or 196 7804 THz Differential Accuracy indicates the maximum wavelength error in measuring the wavelength difference between two signals that are simultaneously present Minimum Resolvable Separation indicates the minimum wavelength separa tion of two laser lines required to measure each wavelength simultaneously Two laser lines closer in wavelength than the minimum resolvable separation are not resolved and one average wavelength is displayed Display Resolution indicates the minimum incremental change in displayed wavelength Calibration Accuracy indicates the maximum power calibration error at the specified wavelengths over the allowed environmental conditions The ampli tude calibration accuracy is traceable to a National Institute of Standards and Technology NIST calibrated optical power meter NIST is the national stan dards laboratory of the United States Flatness refers to the maximum amplitude error in a measurement between two lines that are separated in wavelength by no more than the specified amount Linearity indicates the maximum power error in measuring the change in power Obarski G E 1990 Wavelength Measurement System for Optical Fiber Communications NIST Technical Note 1336 February 18 Take the average of the two frequencies straddling gain center D A Jennings F R Peterson
115. ffset value as shown in the following equation offset minimum drift maximum drift _ Pwr Enter the calculate value on the following line power correction offset Change the attenuator to the settings shown in Table 5 21 For each setting record the power measured on the Agilent 86120C After completing this step the table s column titled Agilent 86120C Power Reading should be completely filled in Calculate the Linearity value for each row in the table using the following equation Linearity Power Meter Reading 86120C Power Reading offset Compare the linearity values with the specification listed in Chapter 6 Specifications and Regulatory Information The data may show multiple amplitude plateaus separated by small amplitude steps This is not a problem as long as the amplitude steps are within the linearity specification 5 10 Performance Tests Test 5 Amplitude Accuracy and Linearity Table 5 21 Linearity Data Values Desired Power Power Meter Agilent 86120C dBm Attenuator Setting Reading Power Reading Linearity 5 11 Definition of Terms 6 3 Specifications NORMAL Update Mode 6 5 Specifications FAST Update Mode 6 8 Operating Specifications 6 11 Laser Safety Information 6 12 Compliance with Canadian EMC Requirements 6 13 Declaration of Conformity 6 14 Product Overview 6 15 Specificati
116. frequency correction is applied to the values To obtain the logarithmic dB result normalize the returned values by the largest value then take five times the logarithm of the normalized values Be prepared to process a large amount of data when this query is sent The amount of data returned depends on the measurement update state of the instrument which can be set using the CALCulate1 TRANsform FREQuency POINts command or the resolution argument of an instrument function Refer to Measurement Instruc tions on page 4 15 When NORMAL measurement update is specified over 250 kilobytes of data 15 047 values can be returned to the computer When FAST measurement update is specified over 125 kilobytes of data 7 525 val ues can be returned The following string is a typical example of the first few returned val ues 4 02646500E 001 6 78125100E 001 6 17986600E 001 4 26768200E 001 4 80245300E 00 1 3 10491300E 001 1 13409400E 001 5 07832500E 001 2 77746200E 001 3 89150500E 0 01 3 50217600E 001 7 34649800E 001 5 64983800E 000 Notice that only measurement values are returned to the computer There is no first value that indicates the number of values contained in the string as there is for example with the FETCh READ and MEASure commands Use the CALCulatel TRANsform FRE Quency POINTs command to query the number of points the CALCI DATA returns 4 26 Programming Commands CALCulate1 Subsystem When NORM
117. fset 0 dB last state Peak threshold 10 dB last state Peak excursion 15 dB last state Measurement speed normal last state 7 2 Reference Instrument Preset Conditions Table 5 22 Instrument Preset Conditions 2 of 2 iram Settings after Preset Settings after Power Key Pressed Turned On Device bandwidth narrowband last state Drift measurements off off Fabry Perot laser measurements off off Delta measurements A power off off A wavelength off off A wavelength and power off off reference signal position 1270 nm 1270 nm Signal to noise measurements measurement off off wavelength reference auto last state user wavelength not affected last state number of averages 100 last state GPIB address not affected last state Power bar display on last state a The term last state refers to the last setting that this parameter was in before the instrument power was turned off 7 3 Reference Menu Maps Menu Maps This section provides menu maps for the Agilent 86120C softkeys The maps show which softkeys are displayed after pressing a front panel key they show the relation ship between softkeys The softkeys in these maps are aligned vertically instead of horizontally as on the actual display This was done to conserve space and to make the maps easier to interpret 7 4 Reference Menu Maps Appl s Menu 4 AUTO USER USER WL gt EXIT RETURN RETURN S N S N AVG DRIFT
118. g paragraphs Damage to the equipment could result CAUTION This instrument has autoranging line voltage input Be sure the supply voltage is within the specified range T Verify that the line power meets the requirements shown in the following table Line Power Requirements Power max 70 W Voltage max 110 115 230 240 V Frequency 50 60 Hz 2 Connect the line power cord to the instrument s rear panel connector Getting Started Step 3 Connect a Printer Connect the other end of the line power cord to the power receptacle Various power cables are available to connect the Agilent 86120C to ac power outlets unique to specific geographic areas The cable appropri ate for the area to which the Agilent 86120C is originally shipped is included with the unit The cable shipped with the instrument also has a right angle connector so that the Agilent 86120C can be used while sitting on its rear feet You can order additional ac power cables for use in different geographic areas Refer to Power Cords on page 7 18 Step 3 Connect a Printer The Agilent 86120C can print hardcopies of measurement results on a printer The output is ASCII text If you don t have a printer continue with Step 4 Turn on the Agilent 86120C on page 1 7 Using a standard parallel printer cable connect the printer to the Agilent 86120C s rear panel PARALLEL PRINTER PORT connector 1 6 Getting Starte
119. gister so that even though it goes high it can never set the summary bit in the status byte high Use the SRE common command to set or query the mask for the Sta tus Byte Register The masks for the OPERation Status and QUEStionable Status registers are set and queried using the STATus subsystem s ENABle commands Use the ESE common command to set or query the mask for the Standard Event Status Register The CLS common command clears all event registers and all queues except the output queue If CLS is sent immediately following a pro gram message terminator the output queue is also cleared In addition the request for the OPC bit is also cleared For example suppose your application requires an interrupt whenever any type of error occurs The error related bits in the Standard Event Status Register are bits 2 through 5 The sum of the decimal weights of these bits is 60 Therefore you can enable any of these bits to generate the summary bit by sending the ESE 60 command Whenever an error occurs it sets one of these bits in the Standard Event Status Register Because the bits are all enabled a summary bit is generated to set bit 5 in the Status Byte Register If bit 5 ESB in the Status Byte Register is enabled via the SRE command an SRQ service request interrupt is sent to the external computer Standard Event Status Register bits that are not enabled still respond to their corresponding conditions that is they a
120. great dirt mag nets The oil or gel grabs and holds grit that is then ground into the end of the fiber Also some early gels were designed for use with the FC non contacting connectors using small glass spheres When used with contacting connectors these glass balls can scratch and pit the fiber If an index matching gel or oil must be used apply it to a freshly cleaned connector make the measurement and then immedi ately clean it off Never use a gel for longer term connections and never use it to improve a damaged connector The gel can mask the extent of damage and continued use of a damaged fiber can transfer damage to the instrument When inserting a fiber optic cable into a connector gently insert it in as straight a line as possible Tipping and inserting at an angle can scrape material off the inside of the connector or even break the inside sleeve of connectors made with ceramic material When inserting a fiber optic connector into a connector make sure that the fiber end does not touch the outside of the mating connector or adapter Avoid over tightening connections Unlike common electrical connections tighter is not better The pur pose of the connector is to bring two fiber ends together Once they touch tightening only causes a greater force to be applied to the deli cate fibers With connectors that have a convex fiber end the end can be pushed off axis resulting in misalignment and excessive return loss Many m
121. he computer Four basic measurement instructions are used CONFigure FETCh READ and MEASure Because the command trees for each of these four basic measurement instructions are identical only the MEASure tree is documented To perform a measurement append to the measurement instruction a POWer or LENGth function The POWer functions select power fre quency wavelength or wave number measurements When the SCALar command is used data for a single measurement value is returned When the ARRay command is used multiple data values are returned The MEASure measurement instruction always acquires new measure ment data In order to obtain both wavelength and power values from the same measurement data use two FETCh commands This is shown in the following program fragment OUTPUT 720 INIT CONT OFF OUTPUT 720 CONF ARR POW MAX OUTPUT 720 INIT IMM OUTPUT 720 FETC ARR POW ENTER 720 powers OUTPUT 720 FETC ARR POW WAV ENTER 720 wavelengths In the example above the data in the power and wavelength arrays are returned in the same order so that powers can be matched to wavelengths You can also send a MEASure command followed by a FETCh command 4 15 Programming Commands Measurement Instructions The commands in this subsystem have the following command hierar chy MEASure READ FETCh CONFigure ARRay SCALar POWer FREQuency WAVelength WNUMber 4 1
122. he laser power The noise floor is typically flat or white The actual level of the noise floor depends on the type of data format and the data rate PRBS modulation graph showing raised noise floor 2 35 CAUTION Making Measurements Measuring Total Power Greater than 10 dBm Measuring Total Power Greater than 10 dBm The maximum total power that can be measured by the Agilent 86120C is 10 dBm However with the addition of an external attenuator more power can be applied This may be necessary at the transmit end of a wavelength division multiplexed system where large signal levels are present By entering an amplitude offset equal to the amount of atten uation at the instrument s input accurate amplitude measurements are shown on the display Additional amplification can also be accounted for The maximum total input power that can be applied to the Agilent 86120C before damage occurs is 18 dBm The maximum total input power that can be measured is 10 dBm To measure total power exceeding 10 dBm Connect an optical attenuator between the front panel OPTICAL INPUT connector and the fiber optic cable The attenuator must reduce the total input power to the Agilent 86120C so that it is below 10 dBm Press Setup MORE CAL and then PWR OFS Notice that the PWR OFS annotation appears on the screen to indicate an offset is applied Use the softkey to select the digit that requires
123. hich is the last instrument function sent by a CONFigure command or MEASure query The returned string is in the short command form Use caution when using this query because if any instrument settings were changed since the last CONFigure command or MEASure query these changes may not be included in the returned string For example if the last CONFigure command was CONFigure SCALar POWer WAVelength 1300NM MAX a CONFigure query would return a string that is similar to the follow ing line POW WAV 1 3000006 6 0 01 The 1300NM and resolution values track the actual instrument settings and input signals Notice that the quotation marks are part of the returned string Return single or multiple measurement values You can specify whether FETCh READ or MEASure returns a single value SCALar or multiple values ARRay The following example specifies SCALar data which returns a single value MEASure SCALar POWer WAVelength MAX Programming Making Measurements ARRay and the SCPI standard According to the SCPI command reference the ARRay command causes an instru ment to take multiple measurements A size parameter indicates the number of measurements to take However the Agilent 86120C s ARRay command refers to the measurements performed for one measurement sweep this results in an array of measured signals Because the size parameter does not apply any size parameter sent will be ignored by the instrument
124. ifications and Regulatory Information Specifications NORMAL Update Mode Amplitude Calibration accuracy at calibration wavelengths Flatness 30 nm from any wavelength 0 5 dB at 1310 and 1550 nm 30 nm 1270 1600 nm characteristic 0 2 dB 1270 1650 nm characteristic 0 5 dB Linearity 1270 nm to 1600 nm lines above 30 dBm 0 3 dB Polarization dependence 1270 1600 nm 0 5 dB 1600 1650 nm characteristic 1 0 dB Display resolution 0 01 dB Sensitivity 1270 1600 nm single line input 40 dBm 1600 1650 nm single line input 30 dBm 1270 1650 nm multiple lines input characteristic 30 dB below total input power but not less than single line input sensitivity Selectivity Two lines input separated by 250 GHz characteristic Two lines input separated by 215 GHz characteristic Input Power Maximum displayed level sum of all lines Maximum safe input level sum of all lines Maximum Number of Laser Lines Input 25 dB 10 dB 10 dBm 18 dBm 200 6 6 Input Return Loss Specifications and Regulatory Information Specifications NORMAL Update Mode With straight contactconnectors With angled contact connectors Option 022 35 dB 50 dB Measurement Cycle Time Normal update mode characteristic 1 0 s 1 measurement per second Measurement Applications Signal to Noise Ratio characteristic chann
125. ing any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information POINts Queries the number of points in the data set CALCulate2 POINts Preset State unaffected RST State unaffected SCPI Compliance instrument specific Query Only This is the number of points that will be returned by the CALC2 DATA query For example if six laser lines are located 6 PTHReshold Sets the peak threshold limit used by the instrument to determine valid laser line peaks CALCulate2 PTHReshold lt integer gt MINimum MAXimum DEFault lt integer gt represents logarithmic units in dB Valid range is 0 to 40 Constant Value MINimum 0 dB MAXimum 40 dB 4 34 Attribute Summary Description Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem DEFault 10 dB Non sequential command Preset State 10 dB RST State 10 dB SCPI Compliance instrument specific A laser line is identified as a valid peak if its amplitude is above the maximum amplitude minus the peak threshold value The subtraction is done in dB units This setting works in conjunction with the peak excursion setting to determine which responses are located Refer to PEXCursion on page 4 33 Changing the peak threshold limit causes the instrument to reprocess the current set of data Refer also to Defini
126. ingle measurement mode Then pressing the Cont key will start a completely new measurement When measuring noise power the Agilent 86120C must account for the noise bandwidth used during the measurement Because noise band width varies with measurement bandwidth a wide bandwidth allows more noise to the Agilent 86120C s detector than a narrow bandwidth the Agilent 86120C normalizes all noise power measurements to a bandwidth of 0 1 nm The annotation 0 10 nm is displayed to show that the noise bandwidth is being normalized to a 0 1 nm bandwidth To measure signal to noise with averaging Press the front panel Preset key Press List by WL or List by Power Press Appl s and then S N AVG To change the number of averages press NUM AVG The default Preset value is 100 To stop the measurement at the current number of averages shown press the Single key Then press the Cont key to continue the present measurement When the measurement is complete the instrument will switch to the single measurement mode and stop To make a new measurement press the Cont key To exit press the EXIT softkey then press the Cont key for continuous measurement 2 30 Making Measurements Measuring Fabry Perot FP Lasers Measuring Fabry Perot FP Lasers The Agilent 86120C can perform several measurements on Fabry Perot lasers including FWHM and mode spacing The display shows the mea surement results in the selected wavelength
127. ion and use a WAI command at the end to save time However non sequential commands can also be a source of annoying errors Always use the OPC query or WAI command with the non sequential commands to ensure that your programs execute properly For example suppose that you wanted to set the elevation correction value and then send an INIT IMM command The following program ming fragment results in an error 213 Init ignored This occurs because the ELEVation command causes the recalculation of the data which is like sending the INIT IMM command When the actual INIT IMM is sent the error occurs because the command is already in progress OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 INIT IMM Use an OPC query to ensure that the ELEVation command has com pleted as shown in the following lines OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 0PC ENTER 720 Response OUTPUT 720 INIT IMM Or the WAI command could be used OUTPUT 720 INIT IMM OUTPUT 720 SENSe CORRection ELEVation 1000 OUTPUT 720 OUTPUT 720 INIT IMM 3 13 Programming Making Measurements Measure delta drift and signal to noise To select a measurement use one of the following STATe commands CALC3 DELT POW STAT delta power CALC3 DELT WAV STAT delta wavelength CALC3 DELT WPOW STAT delta power and wavelength CA
128. ion wavelengths Flatness 30 nm from any wavelength 0 5 dB at 1310 and 1550 nm 30 nm 1270 1600 nm characteristic 0 2 dB 1270 1650 nm characteristic 0 5 dB Linearity 1270 nm to 1600 nm lines above 30 dBm 0 3 dB Polarization dependence 1270 1600 nm 0 5 dB 1600 1650 nm characteristic 1 0 dB Display resolution 0 01 dB Sensitivity 1270 1600 nm single line input 40 dBm 1600 1650 nm single line input 30 dBm 1270 1650 nm multiple lines input characteristic 30 dB below total input power but not less than single line input sensitivity Selectivity Two lines input separated by 2100 GHz characteristic Two lines input separated by 230 GHz characteristic Input Power Maximum displayed level sum of all lines Maximum safe input level sum of all lines Maximum Number of Laser Lines Input 25 dB 10 dB 10 dBm 18 dBm 200 6 9 Specifications and Regulatory Information Specifications FAST Update Mode Input Return Loss With flat contacting connectors 35 dB With angled contacting connectors Option 022 50 dB Measurement Cycle Time Fast update mode characteristic 0 5 s 2 measurements per second Measurement Applications Signal to Noise Ratio characteristic channel spacing 2200 GHz gt 35 dB channel spacing 2100 GHz gt 27 dB Signal to Noise Ratio with Averaging modulated lasers characte
129. jacent signal If the next closest signal is lt 200 GHz approximately 1 6 nm at 1550 nm away from the signal of interest then the noise power is measured half way between the two channels and an equal distance to the other side of the signal of interest See points P and P in the following figure If the closest signal is more than 200 GHz from the signal of interest or if there is no other signals present then the noise power is mea sured at 100 GHz on either side of the signal of interest The two mea sured noise power levels are then averaged to estimate the noise power level at the signal wavelength The noise power measurements use linear interpolation to estimate the noise power level at the signal of interest s wavelength 2 26 User entered wavelength Noise bandwidth Making Measurements Measuring Signal to Noise Ratios Plaser line sun Automatic interpolation When the signal to noise user function is selected the Agilent 86120C uses only one wavelength to measure the noise power for all signals This wavelength is set by the user and all signals are compared to the noise level at this wavelength to determine their cor responding signal to noise ratios When measuring noise power the Agilent 86120C must account for the noise bandwidth used during the measurement Because noise band width varies with measurement bandwidth a wide bandwidth allows more noise to the Agilent 86120C s detec
130. kes the following error IF NOT POS Err_msg 0 THEN PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 Subend SUBEND Set_ese SUB Set ese COM Instrument 9 Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNidentity COM Instrument Mwm DIM Identity 50 Identity OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm Opc done OUTPUT GMwm IDN ENTER Mwm Identity RETURN Identity FNEND Cmd_opc SUB opc Set cmd COM Instrument OUTPUT Mwm Set_cmd OUTPUT Mwm OPC ENTER Mwm Opc_done SUBEND 3 40 Programming Example Programs Example 6 Increase a source s wavelength accuracy This example program uses the Agilent 86120C to increase the abso lute wavelength accuracy of Agilent 8167A 8168B and 8168C Tunable Laser Sources Essentially the Agilent 86120C s accuracy is transferred to the tunable laser source The absolute accuracy of the tunable laser source is increased from lt 0 1 nm to lt 0 003 nm which is the Agilent 86120C s absolute accuracy at 1550 nm In order to run this program the tunable laser source s firmware must support the automatic alignment command WAVEACT The program uses the following measurement algorithm Identify and initialize the Agilent 86120C and tunable laser source Ask user for desired wavelength Set wavelength of tunable laser source Turn tunable laser source s output
131. length Meter Identity is FNidentity ON TIMEOUT 7 5 CALL Err_mngmt md_opc RST TPUT Mwm MEAS ARR POW WAV TER Mwm USING K Nb_pt OCATE Current_wl 1 Nb_pt ER Mwm USING K Current_wl TPUT Mwm FETC ARR POW TER Mwm USING K Nb_pt LOCATE Current_pwr 1 Nb P ER Mwm USING K Current_pwr m signal to noise ratio Q md opc CALC3 SNR STAT ON Err_mngmt CALC3 SNR STAT ON Set first wavelength as noise reference Cmd_opce CALC3 SNR REF WAV MIN Err_mngmt CALC3 SNR REF WAV MIN Query number of data points OUTPUT Mwm CALC3 POIN ENTER Mwm USING K Nb_pt ALLOCATE Snr_pwr 1 Nb_pt Query signal to noise values OUTPUT Mwm CALC3 DATA POW ENTER Mwm Snr pwr OFF TIMEOUT 3 39 Programming Example Programs FOR 1 1 TO Nb pt PRINT USING 7A 2D 17A M4D 3D 25A S2D 2D 22A 2D 2D 3A Line 5E wavelength is Current_wl 1 1 0E 9 nm absolute level is Current pwr D dBm with a SNR of Snr pwr D dB NEXT I STOP Error msg PRINT The program is aborted due to ERRM END Err_mngmt SUB mngmt OPTIONAL Cmd_msg COM Instrument Mwmt DIM Err msg 255 INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwnm SYST ERR ENTER Mwm Err_msg IF NPAR gt 0 AND NOT POS Err_msg 0 THEN PRINT This command Cmd_msg ma
132. lly important in WDM systems because there is a direct relation between signal to noise and bit error rate The Agilent 86120C displays signal to noise measurements in the third column For example the selected signal in the following figure has a signal to noise ratio of 30 0 dB Signal to Noise Noise Bandwidth Auto Measurements Indicator Mode 15H5 H452nm i r3dBm 21 4 1548 066 6 06 25 curan eo UE 1549 668 H z2Y 3 OF 1551 279 4 92 2 WAC 1552 8M s 33 sena B M Signal to noise display During a signal to noise measurement the absolute power of the car rier in dBm is compared to the absolute power of the noise at the carrier wavelength See the following figure The noise power at the carrier must be determined by interpolation because the carrier in most cases can not or should not be turned off You can select one of two methods used to determine the wavelength where the noise is measured automatic interpolation or a user entered wavelength In the figure above notice that S N AUTO is displayed to indicate that automatic interpolation is selected 2 25 Automatic interpolation Making Measurements Measuring Signal to Noise Ratios Paser line Interpolated Noise value at noise value user entered using automatic wavelength mode peak Location of noise measurements When the signal to noise auto function is selected the Agilent 86120C first determines the proximity of any ad
133. lowing rules Power must be greater than the power established by the peak threshold limit Power must rise and then fall by at least the peak excursion value In addition the input wavelength range can be limited as described in this section Peak threshold The peak threshold limit is set by subtracting the peak threshold value limit from the power of the largest laser line So if the largest laser line is 2 dBm and the peak threshold value is 10 dB the peak threshold limit is 8 dBm 8 dBm 2 dBm 10 dB You can set the peak threshold value between 0 to 40 dB The peak threshold s default value is 10 dB This ensures that any modulated signals being measured are not confused with their AM sidebands For unmodulated lasers or Fabry Perot lasers it may be desirable to increase this threshold to look for responses that are more than 10 dB from the peak Peak threshold can be used to suppress spurious signals For example a laser that is amplitude modulated in the audio frequency range can cause spurious wavelengths to be displayed below and above the cor rect wavelength The power of these spurious wavelengths is below that of the correct wavelength These spurious signals can be elimi nated by decreasing Peak threshold from its Preset value 2 15 Peak excursion Examples of valid and invalid signals Making Measurements Defining Laser Line Peaks The peak excursion defines the rise and fall in amplitude that must
134. lt units for the lt real gt parameter are hertz Non sequential command Always use OPC query WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 38 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STARt WAVelength CALCulate2 WLIMit STARt WAVelength lt real gt MINimum MAXimum real is a wavenumber value that is within the following limits Constant Description MINimum 1270 nm MAXimum wavelength limit stop value Non sequential command Preset State 1270 nm RST State 1270 nm SCPI Compliance instrument specific This command sets the starting range for the wavelength limit The start wavelength value must be less than or equal to the stop wavelength value or the start wavelength will be clipped to the stop wavelength and a Data out of range error will be generated Setting the start wavelength is equivalent to setting the stop frequency wavenumber because of the inverse relationship of frequency to wavelength The default units for the real parameter are meters Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instr
135. lues are collected in fast update measurement mode the ability to resolve closely spaced signals is reduced Uncorrected data buffer frequency domain data 64K 8K Michelson Interferometer Resolution argument of FETCh READ or CALCulatel DATA INITiate MEASure continuous time domain or single data HeNE measurement 128K Reference acquisition Laser SENSe DATA flow 3 5 Programming Making Measurements After collecting the uncorrected data the Agilent 86120C searches the data for the first 200 peak responses For WLIMit OFF searching starts at 1650 nm and progresses towards 1270 nm For WLIMit ON searching starts at WLIMit START and progresses toward WLIMit STOP These peak values are then placed into the corrected data buffer Each peak value consists of an amplitude and wavelength measurement Amplitude and wavelength correction factors are applied to this data For a listing of the programming commands including a cross refer ence to front panel keys refer to the following tables Table 3 10 Programming Commands on page 3 43 Table 3 11 Keys Versus Commands on page 3 48 CALCulate2 WLIMit SENSe CORRection ELEVation PTHreshold MEDium PEXCursion OFFSet MAGNitude Corrected data buffer 100 pairs of election A and amplitude Display values DISPlay WINDow UNIT CALCulate2 DATA CONFigure POINts DISPlay MARKer PWAVerage CAL
136. measurements make sure that you enter the elevation from which you will be making measurements as described in Chapter 1 Getting Started The Agilent 86120C At a Glance Measurement accuracy it s up to you Fiber optic connectors are easily damaged when connected to dirty or damaged cables and accessories The Agilent 86120C s front panel INPUT connector is no exception When you use improper cleaning and handling techniques you risk expensive instrument repairs damaged cables and compromised measurements Before you connect any fiber optic cable to the Agilent 86120C refer to Cleaning Connections for Accurate Measurements on page 2 40 General Safety Considerations General Safety Considerations This product has been designed and tested in accordance with IEC 61010 1 and has been supplied in a safe condition The instruction documentation contains information and warnings which must be fol lowed by the user to ensure safe operation and to maintain the prod uct in a safe condition Laser Classification This product is classified according to IEC 60825 1 There is no output laser aperture The Agilent 86120C does not have an output laser aperture However light less than 1 nW escapes out of the front panel OPTICAL INPUT connector Operator maintenance or precautions are not necessary to maintain safety No controls adjustments or performance of procedures result in hazardous radiation expo
137. mmand Only If the display is in the Listby WL mode it will be changed to List by Ampl before the marker is moved MARKer MAXimum PREVious Moves the marker to the laser line that has the next higher power level DISPlay MARKer MAXimum PREVious Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only If the display is in the Listby WL mode it will be changed to List by Ampl before the marker is moved 4 77 Syntax Attribute Summary Description Syntax Attribute Summary Description Programming Commands DISPlay Subsystem MARKer MAXimum RIGHt Moves the marker right to the next laser line DISPlay MARKer MAXimum RIGHt Preset State marker set to maximum power laser line RST State marker set to maximum power laser line SCPI Compliance instrument specific Command Only Moves the marker from the current marker position to the next laser line having the following characteristic longer wavelength higher frequency higher wave number If the display is in the List by Ampl mode it will be changed to List by WL before the marker is moved WINDow GRAPhics STATe Turns on and off the display of the power bars DISPlay WINDow GRAPhics STATe ON OFF 1 0 Preset State on RST State on SCPI Compliance standard Specifying on displays the power bars in all modes ex
138. n above sea level and to select between measurements in air or vacuum You can also enter an amplitude offset The commands in this sub system have the following command hierarchy SENSe CORRection DEVice ELEVations MEDium OFFSet MAGNitude DATA 4 83 Syntax Attribute Summary Description Query Response Programming Commands SENSe Subsystem CORRection DEVice Selects the wavelength measurement algorithm SENSe CORRection DEVice NARRow BROad Constant Description NARRow Selects wavelength measurements for narrowband devices such as DFB lasers and modes of FP lasers BROad Selects wavelength measurements for broadband devices such as optical filters and LEDs Non sequential command Preset State NARRow RST sets this value to NARRow SCPI Compliance instrument specific The narrow bandwidth algorithm used for measuring lasers deter mines the wavelength based upon the peak The broad bandwidth algorithm used for LEDs filters and chirped lasers determines the wavelength based upon the center of mass of the power spectrum The peak excursion function is used to determine the value of the integration limits Care must be taken to ensure that the integration limits are above any noise This is especially true when measuring devices with sloping noise floors like an EDFA amplifier For more information on peak excursion refer to PEXCursion on page 4 33 Instrument sp
139. n page 3 12 for more information 4 105 Syntax Attribute Summary Programming Commands TRIGger Subsystem INITiate IMMediate Initiates a new measurement sequence INITiate I MMediate Non sequential command Preset State none SCPI Compliance standard Command Only Non sequential command Always use query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 106 Syntax Attribute Summary Programming Commands UNIT Subsystem UNIT Subsystem The only command provided in this subsystem is the POWer command as shown in the following command hierarchy UNIT POWer POWer Sets the power units to watts linear or dBm logarithmic UNITE POWer W DBM Preset State dBm RST State dBm SCPI Compliance standard 4 107 Programming Commands UNIT Subsystem 4 108 Test 1 Absolute Wavelength Accuracy 5 3 Test 2 Sensitivity 5 4 Test 3 Polarization Dependence 5 5 Test 4 Optical Input Return Loss 5 6 Test 5 Amplitude Accuracy and Linearity 5 9 Performance Tests Performance Tests Performance Tests Performance Tests The procedures in this chapter test the Agilent 86120C s performance using the specifications listed in Chapter
140. n Dependence Test 3 Polarization Dependence Polarization Dependence is verified using the following devices 1310 nm and 1550 nm DFB lasers Optical attenuator Agilent 11896A polarization controller Do not exceed 18 dBm source power The Agilent 86120C s input circuitry can be damaged when total input power exceeds 18 dBm Perform the following procedure first using the 1310 nm laser and then repeat the steps using the 1550 nm laser Turn on the lasers and allow them to warm up Set the polarization controller to a scan rate of 5 On the Agilent 86120C press the Preset key Connect the laser s optical output to the polarization controller s optical input Connect the polarization controller s optical output to the Agilent 86120C being tested Set the polarization controller to autoscan On the Agilent 86120C press Peak WL Appl s and then DRIFT Press MAX MIN so that both MAX and MIN in the softkey label are highlighted The display shows the total drift since the drift measurement was started Wait five minutes read the peak amplitude drift from the Agilent 86120C and compare with the specification listed in Chapter 6 Specifications and Regulatory Information 5 5 Description Procedure 10 11 12 Performance Tests Test 4 Optical Input Return Loss Test 4 Optical Input Return Loss Input return loss is verified using the following devices Agilent 8153A lightwave multimeter Agilen
141. nd fitness for a particular purpose Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material 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 will at its option either repair or replace products that prove to be defective For warranty service or repair this product must be returned to a service facility designated by Agi lent Buyer shall prepay shipping charges to Agilent and Agilent shall pay shipping charges to return the product to Buyer How ever Buyer shall pay all shipping charges duties and taxes for products returned to Agilent from another country Agilent warrants that its software and firmware designated by Agilent for use with an instrument will execute its programming instructions when properly installed on that instrument Agilent does not war rant that the operation of the instrument 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 misuse operation outside of the environ mental specifications for the
142. nd amplitude over time Drift is measured simultaneously for every laser line that is identified at the input The Agilent 86120C keeps track of each laser line s initial current minimum and maximum values and displays their differences relative to itself This allows the Agilent 86120C to be used for laser transmitter evaluation burn in or development In addition you can monitor system performance over time temperature or other condition The following display shows power and wavelength drift measured on five laser lines The DRIFT annotation item 1 tells you that drift mea surements are being performed The current relative drift values for wavelength and power are shown in items 2 and 3 respectively Item 4 indicates the absolute reference values for the laser line indi cated by the cursor The reference values are measured before the measurement starts H H 3dg DRIFT 4 868 H 16 EY WL 4 868 H 11 qQEE4 OF E A HAG 8 89 6 37 Wa 4 888 B 11 B oH drift 2 22 Making Measurements Measuring Laser Drift You can restart the drift measurement at any time by pressing the RESET softkey All minimum and maximum values are reset to the ref erence values and the Agilent 86120C begins to monitor drift from the current laser line values Move the cursor up and down the listing to see the reference wavelength and power of each laser line If measurement updating stops or the values
143. ng ARRay places the display in the List by Power or List by WL modes an array of data is returned to the computer 3 9 Programming Making Measurements A common programming error is to send the MEASure command when the instrument is in the continuous measurement acquisition mode Because MEASure contains an INIT IMM command which expects the single measurement acquisition mode an error is gener ated and the INIT command is ignored READ command The READ command works like the MEASure command except that it does not configure the instrument s settings You can use the CONFig ure command to configure the instrument for a particular measure ment without returning any data The MEASure and READ commands are identical to combining the fol lowing commands Command Equivalent Commands MEASure ABORt CONFigure READ READ ABORt INITiate IMMediate FETCh A common programming error is to send the READ command when the instrument is in the continuous measurement acquisition mode Because READ contains an INIT IMM command which expects the single measurement acquisition mode an error is generated and the INIT command is ignored FETCh command The FETCh command returns data from previously performed mea surements it does not initiate the collection of new data Because FETCh does not configure the instrument or acquire new input data you can use FETCh repeatedly on the same set of acquired data For example
144. ng Laser Line Peaks on page 2 15 The query response is the current value For example if the current value is set to 15 dB the following value is returned 15 Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information PWAVerage STATe Places the instrument in the power weighted average mode CALCulate2 PWAVerage STATe ON OFF 1 0 Preset State off RST State off When the state is on the CALC2 DATA POW query returns the total power and the CALC2 DATA WAV FREQ or WNUM query returns the power weighted average wavelength frequency or wave number val ues 4 35 Programming Commands CALCulate2 Subsystem Turning power weighted average mode on while making delta Fabry Perot or signal to noise measurements results in 221 Settings con flict error 4 36 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STATe Turns wavelength limiting on and off CALCulate2 WLIMit STATe ON OFF 1 0 Non sequential command Preset State on RST State on SCPI Compliance instrument specific When this function is on the Agilent 86120C has an input range from the WLIMit STARt to th
145. ngmt SUB mngmt OPTIONAL Cmd_msg COM Instrument Mwmt DIM Err msg 255 INTEGER Cme CLEAR Mwm REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwnm SYST ERR ENTER Mwm Err_msg IF gt 0 AND NOT POS Err_msg 0 THEN PRINT This command Cmd_msg makes the following error IF NOT POS Err_msg 0 THEN PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err msg 0 3 35 Programming Example Programs Subend SUBEND Set_ese SUB Set ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND Identity DEF FNidentity COM Instrument Mwm DIM Identity 50 Identity OUTPUT Mwm RST OUTPUT Mwm OPC 2 ENTER Mwm Opc_done OUTPUT Mwm IDN ENTER Mwm Identity RETURN Identity FNEND Cmd_opc SUB opc Set cmd COM Instrument 9 Mwm OUTPUT Mwm Set cmd OUTPUT Mwm OPC ENTER Mwm Opc_done SUBEND Tempo SUB Tempo Temp FOR I Temp TO 0 STEP 1 DISP Waiting for VALS D sec WAIT 1 NEXTI DISP SUBEND 3 36 Programming Example Programs Example 4 Measure WDM channel separation This program measures the line separations on a WDM system It mea sures separation delta between power and wavelength of each line using commands from the CALCulate3 subsystem Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm
146. nly the 200 longest wavelength lines are dis played Input Return Loss indicates the optical power reflected back to the user s fiber cable relative to the input power It is limited by the return loss of the front panel connector and assumes the user s connector is good Measurement cycle time refers to the cycle time when measuring wavelength and power of laser lines Specific advanced applications may require longer cycle times 6 4 Specifications and Regulatory Information Specifications NORMAL Update Mode Specifications NORMAL Update Mode Each laser line is assumed to have a linewidth including modulation side bands of less than 5 GHz All specifications apply when the instrument is in the following modes NORMAL update mode unless noted Refer to Measurement rate on page 2 13 Configured to measure narrowband devices Specifications do not apply when the instrument is configured to measure broadband devices Refer to Measuring broadband devices and chirped lasers on page 2 9 Wavelength Range 1270 1650 Absolute accuracy lines separated by 215 GHz 2 ppm 50 003 nm at 1550 nm and 1310 nm Differential accuracy characteristic 1 ppm Minimum resolvable separation characteristic 10 GHz 0 08 nm at 1550 nm 0 06 nm at 1300 nm Display resolution 0 001 nm a Signals of equal amplitude For lines that are separated by less than 30 GHz wavelength accuracy is reduced 6 5 Spec
147. nsition filter software which give you the ability to select the logic transitions which set bits in the OPERation Status and QUEStionable Status registers For example you can define the POWer bit of the QUEStionable Status register to report an event when the condition transitions from false to true This is a positive transition You can also specify a negative transition where the bit is set when the condition transitions from true to false Table 3 6 Bits in Operation Status Register Bit Definition 0 not used 1 SETTling indicating that the instrument is waiting for the motor to reach the proper position before beginning data acquisition 2 RANGing indicating the instrument is currently gain ranging 3 not used 4 MEASuring indicating that the instrument is making a measurement 5 through 8 not used 9 Processing indicating that the instrument is currently processing the data acquired 10 Hardcopy indicating that the instrument is currently printing the data to the parallel port 11 Averaging indicating that the instrument is in the process of averaging the noise for the signal to noise ratio calculation 12 through 16 not used 3 19 Programming Monitoring the Instrument Table 3 7 Bits in Questionable Status Register Bit Definition 0 1 and 2 not used 3 POWer indicating that the instrument is measuring too high of a power 3 through 8 not used 9 Maximum signals indicating that
148. nt Technologies instruments typically use a connector such as the Diamond HMS 10 which has concentric toler ances within a few tenths of a micron Agilent Technologies then uses a special universal adapter which allows other cable types to mate with this precision connector See Figure 2 4 2 41 Making Measurements Cleaning Connections for Accurate Measurements Figure 2 4 Universal adapters to Diamond HMS 10 The HMS 10 encases the fiber within a soft nickel silver Cu Ni Zn center which is surrounded by a tough tungsten carbide casing as shown in Figure 2 5 Staking Groove Fixing oper Secondary Staking Active Centering Tun gsten Carbide Hard Case 4 Nickel Silver Soft center 126 um Fiber Centered to about 0 2 microns Figure 2 5 Cross section of the Diamond HMS 10 connector The nickel silver allows an active centering process that permits the glass fiber to be moved to the desired position This process first stakes the soft nickel silver to fix the fiber in a near center location then uses a post active staking to shift the fiber into the desired posi tion within 0 2 um This process plus the keyed axis allows very pre cise core to core alignments This connector is found on most Agilent Technologies lightwave instruments 2 42 Making Measurements Cleaning Connections for Accurate Measurements The soft core while allowing precise cent
149. nt to its preset state 1 Press the Setup key 2 Press the WL LIM softkey 3 Press LIM OFF to remove the limits on wavelength range 1 10 Getting Started Returning the Instrument for Service Returning the Instrument for Service The instructions in this section show you how to properly return the instrument for repair or calibration Always call the Agilent Technolo gies Instrument Support Center first to initiate service before returning your instrument to a service office This ensures that the repair or calibration can be properly tracked and that your instrument will be returned to you as quickly as possible Call this number regardless of where you are located Refer to Agilent Technologies Service Offices on page 7 18 for a list of service offices Agilent Technologies Instrument Support Center 1 877 447 7278 If the instrument is still under warranty or is covered by an Agilent Technologies maintenance contract it will be repaired under the terms of the warranty or contract the warranty is at the front of this man ual If the instrument is no longer under warranty or is not covered by an Agilent Technologies maintenance plan Agilent Technologies will notify you of the cost of the repair after examining the unit When an instrument is returned to a Agilent Technologies service office for servicing it must be adequately packaged and have a com plete description of the failure symptoms attached When descri
150. o return the maximum power and frequency values measured CALCulate3 DRIF MAXimum STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the max imum power and frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 57 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt MINimum STATe Sets the drift calculation to return the minimum power and frequency values measured CALCulate3 DRIFt MINimum STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific Use the CALC3 DRIF PRES command to turn off all the drift states before turning on this state The CALC3 DATA query returns the min imum power or frequency Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 58
151. odes CALCulate3 FPERot PEAK WNUMber Queries the peak wavenumber of the selected modes CALCulate3 FPERot PEAK POWer Queries the peak power of the selected modes CALCulate3 FPERot FWHM WAVelength Queries full width half max wavelength of selected modes CALCulate3 FPERot FWHM FREQuency Queries full width half max frequency of selected modes CALCulate3 FPERot FWHM WNUMber Queries full width half max wavenumber of selected modes CALCulate3 FPERot MODE SPACing WAVelengt h Queries the mode spacing wavelength of the selected modes CALCulate3 FPERot MODE SPACing FREQuenc y Queries the mode spacing frequency of the selected modes CALCulate3 FPERot MODE SPACing WNUMbe r Queries the mode spacing wavenumber of the selected modes 3 45 Programming Lists of Commands Table 3 10 Programming Commands 4 of 5 Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command CALCulate3 FPERot POWer WAVelength Queries the power wavelength of the selected modes CALCulate3 FPERot POWer FREQuency Queries the power frequency of the selected modes CALCulate3 FPERot POWer WNUMber Queries the power wavenumber of the selected modes CALCulate3 FPERot SIGMa WAVelength Queries the sigma wavelength of the selected m
152. odes CALCulate3 FPERot SIGMa FREQuency Queries the sigma frequency of the selected modes CALCulate3 FPERot SIGMa WNUMber Queries the sigma wavenumber of the selected modes CALCulate3 POINts Queries the number of points in the data set CALCulate3 PRESet Turns off any CALCulate3 calculation that is on CALCulate3 SNR AUTO Selects the internal or externally entered frequency value for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence FREQuency Sets the frequency used for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence WAVelength Sets the wavelength used for the noise measurement reference in the SNR calculation CALCulate3 SNR REFerence WNUMber Sets the wave number used for the noise measurement reference in the SNR calculation CALCulate3 SNR STATe Turns the SNR calculation on and off DISPlay Subsystem DISPlay MARKer MAXimum Sets the marker to the signal with the largest power DISPlay MARKer MAXimum LEFT Moves marker to signal with the next lower wavelength or frequency DISPlay MARKer MAXimum NEXT Moves the marker to the signal with the closest power level just below the power level of the signal at the current marker position DISPlay MARKer MAXimum PREVious Moves the marker to the signal with the closest power level just above the power level of the signal at the current marker position DISPlay MARKer MAXimum R
153. ommands CALCulate3 Subsystem ASNR STATe Turns the average signal to noise ratio on or off CALCulate3 ASNR STATe ON OFF 110 Preset State off RST State off SCPI Compliance instrument specific This command turns the average signal to noise calculation on or off Only one of the CALCulate3 calculations ASNR DELTa DRIFt or SNR can be turned on at a time Turning on the ASNR calculation while another calculation is on will generate a Settings conflict error When the calculation is first turned on the lines measured in the cur rent measurement will be used as the reference values for the signal to noise ratio Subsequent measurements will average the noise values The signal values are not updated until the number of measurements used to average the noise is greater than or equal to the COUNt value Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 48 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DATA Queries the data resulting from delta drift and signal to noise mea surements CALCulate3 DATA POWer FREQuency WAVelength WNUMber Argument Description POWer Queries the array of laser lin
154. on Example Syntax Description Query Response Example Programming Commands Common Commands TRG The TRG trigger command is identical to the group execute trigger GET message or RUN command TRG This command acquires data according to the current settings This command cannot be issued as a query If a measurement is already in progress a trigger is ignored and an error is generated The following example starts the data acquisition according to the cur rent settings OUTPUT 720 TRG TST The TST test query starts a self test on the instrument TST The result of the test is placed in the output queue A zero indicates the test passed and a non zero value indicates the test failed The instrument will initiate a measurement and check for any hardware errors after the measurement is complete lt integer gt OUTPUT 720 TST ENTER 720 Result PRINT Result 4 13 Programming Commands Common Commands The WAI command prevents the instrument from executing any fur ther commands until the current command has finished executing Syntax WAI Description All pending operations are completed during the wait period This command cannot be issued as a query 4 14 Programming Commands Measurement Instructions Measurement Instructions Use the measurement instructions documented in this section to per form measurements and return the desired results to t
155. on Enter loop Measure wavelength Compare wavelength to desired wavelength Realign tunable laser source s wavelength Check if wavelength changed from last pass Repeat until delta wavelength 0 0015 nm or wavelength is stable 3 41 Programming Example Programs COM Current wl Diff wl Target wl Previous diff Diff diff Current_wl 0 Diff wl 0 Target wl 0 Previous diffzO Diff_diff 0 ASSIGN Tls TO 724 ASSIGN Mwm TO 720 Initialize instrument DIM Identity 50 Identity OUTPUT Tls CLS OUTPUT 15 10 ENTER TLS identity PRINT TLS IS A sidentity OUTPUT Mwm RST OUTPUT Mwm CLS OUTPUT Mwm IDN 2 ENTER Mwm ldentity PRINT MWM IS A identity Ask user for desired wavelength INPUT What wavelength nm do you wish to have Target wl Target wl Target wl 1 0E 9 PRINT the target wavelength is Target wl Set wavelength of tunable laser source OUTPUT GTls WAVE VAL Target wl OUTPUT Tls OUTP ON Enter realignment loop REPEAT OUTPUT Mwm MEAS SCAL POW WAV ENTER Mwm Current wl PRINT The current wavelength is WAL Current_wl Diff wIZPROUND ABS Target wl Current wl 16 PRINT Diff between target amp Current is or VALS Diff wl OUTPUT QTlIs WAVEACT VALS Current wl Diff diffZPROUND ABS Diff wl Previous diff 16 PRINT differential difference between two turn VALS Diff diff Previous diff Diff wl UNTIL Diff wl 1 5 1 0E
156. on Degree 2 CAUTION VENTILATION REQUIREMENTS When installing the product in a cabinet the convection into and out of the product must not be restricted The ambient temperature outside the cabinet must be less than the maximum operating temperature of the product 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 CAUTION Always use the three prong ac power cord supplied with this instrument Failure to ensure adequate earth grounding by not using this cord may cause instrument damage CAUTION Do not connect ac power until you have verified the line voltage is correct as described in Line Power Requirements on page 1 5 Damage to the equipment could result CAUTION This instrument has autoranging line voltage input Be sure the supply voltage is within the specified range viii Contents The Agilent 86120C At a Glance iii General Safety Considerations vi Getting Started Step 1 Inspect the Shipment 4 Step 2 Connect the Line Power Cable 5 Step 3 Connect a Printer 6 Step 4 Turn on the Agilent 86120C 7 Step 5 Enter Your Elevation 8 Step 6 Select Medium for Wavelength Values 9 Step 7 Turn Off Wavelength Limiting 10 Returning the Instrument for Service 11 Making Measurements Measuring Wavelength and Power 3 Changing the Units and Measurement Rate 12 Defining Laser Lin
157. one of these elements must be selected lt integer gt An ASCII string representing an integer This is defined by the IEEE 488 2 lt NR1 gt format lt real gt An ASCII string representing a real number This is defined by the IEEE 488 2 lt NR2 gt or lt NRf gt formats 4 2 Syntax Description Syntax Programming Commands Common Commands Common Commands Common commands are defined by the IEEE 488 2 standard They control generic device functions which could be common among many different types of instruments Common commands can be received and processed by the instrument whether they are sent over the GPIB as separate program messages or within other program messages CLS The CLS clear status command clears all the event status registers summarized in the status byte register CLS With the exception of the output queue all queues that are summa rized in the status byte register are emptied The error queue is also emptied Neither the event status enable register nor the service request enable register are affected by this command After the CLS command the instrument is left in the idle state The command does not alter the instrument setting OPC and OPC actions are cancelled This command cannot be issued as a query ESE The ESE event status enable command sets the bits in the event sta tus enable register and enables the corresponding bits in the event sta tus regist
158. ons and Regulatory Information Specifications and Regulatory Information Specifications and Regulatory Information Specifications and Regulatory Information This chapter lists specification and characteristics of the instrument The dis tinction between these terms is described as follows Specifications describe warranted performance over the temperature range 0 C to 55 C and relative humidity lt 95 unless otherwise noted All specifications apply after the instrument s temperature has been sta bilized after 15 minutes of continuous operation Characteristics provide useful information by giving functional but nonwarranted performance parameters Characteristics are printed in italics Calibration Cycle This instrument requires periodic verification of performance The instrument should have a complete verification of specifications once every two years 6 2 Wavelength Amplitude Specifications and Regulatory Information Definition of Terms Definition of Terms Range refers to the allowable wavelength range of the optical input signal Absolute accuracy indicates the maximum wavelength error over the allowed environmental conditions The wavelength accuracy is based on fundamental physical constants which are absolute standards not requiring traceability to artifacts kept at national standards laboratories Two He Ne gas lasers are used First there is an internal 632 991 nm vacuum 473 6127 THz re
159. ontinuous last state Wavelength calibration vacuum last state Elevation correction value not affected last state Wavelength units nm last state Amplitude units dBm last state Power offset 0 dB last state Peak threshold 10 dB last state Peak excursion 15 dB last state 4 100 Table 4 19 Instrument Conditions 2 of 2 Programming Commands SYSTem Subsystem Settings after Preset Settings after Power tei Key Pressed Turned On Measurement speed normal last state Measurement bandwidth narrowband narrowband Drift measurements off off Fabry Perot laser measurements off off Delta measurements A power off off A wavelength off off A wavelength and power off off reference signal position 1270 nm 1270 nm Signal to noise measurements measurement off off wavelength reference auto last state user wavelength not affected last state number of averages 100 last state GPIB address not affected last state Power bar display on last state a The term last state refers to the last setting that this parameter was in before the instrument power was turned off 4 101 Syntax Attribute Summary Description Programming Commands SYSTem Subsystem VERSion Queries the version of SCPI that the Agilent 86120C complies with SYSTem VERSion Preset State none RST State none SCPI Compliance standard Query Only The SCPI version used in the Agilent 86120C is 1995 0 Table 4 20 SCPI Version Numbers SCP
160. optical attenuator so that the power meter measures a power level of 0 dBm Enter the attenuator setting and the measured power level in the first row of Table 5 21 on page 5 11 Be sure to enter these values into the Attenuator Settings and Power Meter Readings columns Enter the measured power on the following line Pwr Change the attenuator in 1 dB steps as shown in Table 5 21 and enter the attenuator settings and power measurements After completing this step the first two columns of the table should be 5 9 10 11 12 13 14 15 16 17 18 19 20 21 Performance Tests Test 5 Amplitude Accuracy and Linearity completely filled in Disconnect the fiber optic cable from the optical power meter and connect it to the Agilent 86120C s OPTICAL INPUT connector Set the optical attenuator for the value that you recorded in Step 8 Place the polarization controller in the auto scan mode Press the Agilent 86120C s front panel Preset key Press List by Power Appl s and then DRIFT After two minutes stop the polarization controller s auto scan function Press the MAX MIN softkey so that MAX is highlighted Enter the maximum drift reading on the following line maximum drift Press the MAX MIN softkey so that MIN is highlighted Enter the minimum drift reading on the following line minimum drift Use the values recorded in Step 8 Step 16 and Step 17 to calculate the power correction o
161. ors and connection techniques more important than ever Damage to the con nectors on calibration and verification devices test ports cables and other devices can degrade measurement accuracy and damage instru ments Replacing a damaged connector can cost thousands of dollars not to mention lost time This expense can be avoided by observing the simple precautions presented in this book This book also contains a brief list of tips for caring for electrical connectors Choosing the Right Connector A critical but often overlooked factor in making a good lightwave mea surement is the selection of the fiber optic connector The differences in connector types are mainly in the mechanical assembly that holds the ferrule in position against another identical ferrule Connectors also vary in the polish curve and concentricity of the core within the cladding Mating one style of cable to another requires an adapter Agilent Technologies offers adapters for most instruments to allow testing with many different cables Figure 2 3 on page 2 41 shows the basic components of a typical connectors The system tolerance for reflection and insertion loss must be known when selecting a connector from the wide variety of currently available connectors Some items to consider when selecting a connector are How much insertion loss can be allowed Will the connector need to make multiple connections Some connectors are better than others and some are
162. outines are repeated in the examples The first five example programs contain several common subroutines These routines along with one function are described in the rest of this introduction The descriptions are listed in the general order that the subroutines are called in the programs Error_msg subroutine This function is found in examples 2 3 4 and 5 It displays an error message on the computer s screen explaining the reason that the pro gram s execution stopped Set_ese subroutine The subroutine sets the enable mask for the event status register to a value of 52 This allows bits 2 4 and 5 to be set whenever a query error QYE execution error EXE or command error CME respec tively occurs All this is accomplished using the ESE common com mand 3 28 Programming Example Programs The Err mngmt subroutine is used to actually read the value of the event status register Examples 1 through 5 call this subroutine FNIdentity function When this function is called it resets the instrument and queries the instrument s identification string which is displayed on the computer s screen by the calling function To accomplish this task the FNIdentity function uses the RST OPC and IDN common commands This function is called from Examples 1 through 5 Err mngmt subroutine This subroutine checks to make sure that no errors have set bits in the event status register and that there are no errors in the queu
163. per cleaning Material is smeared and ground into the end of the fiber causing light scattering and poor reflection Not only is the preci sion polish lost but this action can grind off the glass face and destroy the connector Figure 2 8 shows physical damage to the glass fiber end caused by either repeated connections made without removing loose particles or using improper cleaning tools When severe the damage of one con nector end can be transferred to another good connector endface that comes in contact with the damaged one Periodic checks of fiber ends and replacing connecting cables after many connections is a wise prac tice The cure for these problems is disciplined connector care as described in the following list and in Cleaning Connectors on page 2 47 2 43 Making Measurements Cleaning Connections for Accurate Measurements Use the following guidelines to achieve the best possible performance when making measurements on a fiber optic system Never use metal or sharp objects to clean a connector and never scrape the connector Avoid matching gel and oils 1 o Figure 2 6 Clean problem free fiber end and ferrule E 5 Pa Figure 2 7 Dirty fiber end and ferrule from poor cleaning 2 44 Making Measurements Cleaning Connections for Accurate Measurements IT n Figure 2 8 Damage from improper cleaning While these often work well on first insertion they are
164. product or improper site prepara tion or maintenance No other warranty is expressed or implied Agilent Technologies specifically disclaims the implied warranties of Merchantability and Fitness for a Particular Purpose Exclusive Remedies The remedies provided herein are Buyer s sole and exclusive reme dies Agilent Technologies shall not be liable for any direct indi rect special incidental or conse quential damages whether based on contract tort or any other legal theory Assistance Product maintenance agreements and other customer assistance agreements are available for Agi lent Technologies products For any assistance contact your near est Agilent Technologies Sales and Service Office Certification Agilent Technologies Inc certi fies that this product met its pub lished specifications at the time of shipment from the factory Agi lent Technologies further certifies that its calibration measurements are traceable to the United States National Institute of Standards and Technology NIST formerly the United States National Bureau of Standards NBS to the extent allowed by the Institutes s calibration facility and to the cali bration facilities of other Interna tional Standards Organization members ISO 9001 Certification Produced to ISO 9001 interna tional quality system standard as part of our objective of continu ally increasing customer satisfac tion through improved proc
165. ptical filters and chirped lasers use the Setup menu first to reconfigure the instrument When broadband devices are selected the display shows the BROAD annotation on the screen The measurement algorithm for broadband devices determines the wavelength based upon the center of mass of the power spectrum The peak excursion function is used to determine the value of the integra tion limits Care must be taken to ensure that the integration limits are above any noise This is especially true when measuring devices with sloping noise floors like an EDFA amplifier For more informa tion on peak excursion refer to Defining Laser Line Peaks on page 2 15 Instrument specifications apply when the Agilent 86120C is configured to measure narrowband devices Specifications do not apply when the instrument is configured to measure wideband devices To measure broadband devices Press the Setup key Press MORE twice and then the DEVICE softkey Press the BROAD softkey To return to measuring narrowband devices press NARROW 2 9 Making Measurements Measuring Wavelength and Power Graphical display of optical power spectrum A graphical display of optical power versus wavelength is shown from the start wavelength value to the stop wavelength value The start wavelength value is shown in the upper left corner of the graphical display and the stop wavelength value is shown in the upper right corner of the graphical display The
166. r additional informa tion on selecting measurements 4 60 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DRIFt STATe Turns on and off the drift measurement calculation CALCulate3 DRIFt STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When the drift mode is first turned on the current list of laser lines is placed into the reference All subsequent measurements take the new data subtract the reference data and display the differences in wave lengths and powers The CALC3 DATA query returns the power and frequency of the cur rent measurement minus the power and frequency of the reference Note Only one STATe command can be turned on at any one time Attempting to turn more than one state on at a time results in a 221 Settings Conflict error Refer to Measure delta drift and signal to noise on page 3 14 for additional informa tion on selecting measurements 4 61 Syntax Attribute Summary Description Syntax Example Query Response Programming Commands CALCulate3 Subsystem FPERot STATE Turns on and off the Fabry Perot measurement mode CALCulate3 FPERot STATE ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When the state is ON the Agilent 86120C measures characteristics of the Fabry Perot laser modes
167. r for information on application and cleaning procedures Table 2 2 Cleaning Accessories Item Agilent Part Number Any commercially available denatured alcohol Cotton swabs 5080 5400 Table 2 3 Dust Caps Provided with Lightwave Instruments Item Agilent Part Number FC PC dust cap 08154 44102 DIN dust cap 08154 44103 HMS10 dust cap 08154 44101 To clean a non lensed connector 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 Apply pure isopropyl alcohol to a clean lint free cotton swab or lens paper Cotton swabs can be used as long as no cotton fibers remain on the fiber end after cleaning Clean the ferrules and other parts of the connector while avoiding the end of the fiber Apply isopropyl alcohol to a new clean lint free cotton swab or lens 2 48 CAUTION Making Measurements Cleaning Connections for Accurate Measurements paper Clean the fiber end with the swab or lens paper Do not scrub during this initial cleaning because grit can be caught in the swab and become a gouging element Immediately dry the fiber end with a clean dry lint free cotton swab or lens paper Blow across the connector end face from a distance of 6 to 8 inches using filtered dry compressed air Aim the compressed air at a shallow angle to the fiber end face Nitrogen gas or compressed dust remover can also be u
168. re set if the corre sponding event occurs However because they are not enabled they do not generate a summary bit to the Status Byte Register 3 21 Programming Monitoring the Instrument Queues There are two queues in the instrument the output queue and the error queue The values in the output queue and the error queue can be queried Output queue The output queue stores the instrument responses that are generated by certain commands and queries that you send to the instrument The output queue generates the Message Available summary bit when the output queue contains one or more bytes This summary bit sets the MAV bit bit 4 in the Status Byte Register The method used to read the Output Queue depends upon the programming language and envi ronment For example with HP BASIC the output queue may be read using the ENTER statement Error queue As errors are detected they are placed in an error queue Instrument specific errors are indicated by positive values General errors have negative values You can clear the error queue by reading its contents sending the CLS command or by cycling the instrument s power The error queue is first in first out If the error queue overflows the last error in the queue is replaced with error 350 Queue overflow Any time the queue overflows the least recent errors remain in the queue and the most recent error is discarded The length of the instrument s error queue is 30
169. requency data corresponds to an optical frequency of 236 0620 THz 1269 974 nm For example a laser line peak located at the 1500th returned value has an optical fre quency of frequency 181 6879 THz 1 499 7 226756 GHz 192 5208 THz or 1557 195 nm in vacuum If your program is aborted or interrupted after sending this query the Agilent 86120C continues to process the data but does not place it in the output buffer Because of the amount of data processed the instrument will not respond to any new commands in its input buffer for up to 20 seconds 4 2 Programming Commands CALCulate1 Subsystem This query will generate a Settings conflict error if the instrument is in the signal to noise average application 4 28 Syntax Attribute Summary Description Programming Commands CALCulate1 Subsystem TRANsform FREQuency POINts Sets the size of the fast Fourier transform FFT performed by the instrument CALCulate1 TRANsform FREQuency POINts lt integer gt MINimum MAXimum integer Sets FFT size Must be either 15 047 or 7 525 Other values result in an error Constant Description MINimum 7 525 MAXimum 15 047 Non sequential command Preset State array size set to 15 047 RST State 15 047 SCPI Compliance instrument specific A NORMAL updated display corresponds to an FFT size of 15 047 A FAST updated display corresponds to an FFT size of 7 525 These val ues are a su
170. ristic channel spacing 200 GHz gt 35 dB with 100 averages channel spacing 2100 GHz gt 27 dB with 100 averages a 0 1 nm noise bandwidth lines above 25 dBm Specifications and Regulatory Information Operating Specifications Operating Specifications Operating Specifications Use Power Voltage Frequency Altitude Operating temperature Maximum relative humidity Weight Dimensions H x W x D indoor 70 W max 100 115 230 240 V 50 60 Hz Up to 2000 m 6600 ft 0 C to 55 C 80 for temperatures up to 31 C decreasing linearly to 50 relative humidity at 40 C 8 5 kg 19 Ib 140 x 340 x 465 mm 5 5 x 13 4 x 18 3 in Laser Safety Specifications and Regulatory Information Laser Safety Information Laser Safety Information The light sources specified by this user guide are classified according to IEC 60825 1 2001 The light sources comply with 21 CFR 1040 10 except for deviations pursuant to Laser Notice No 50 dated 2001 July 26 Laser type LED Wavelength 1200 1650nm Max CW output power 1nW Beam waist diameter 10 um Numeric aperture 0 1 Laser class according to IEC 60825 1 2001 1 Max permissible CW output power 10 mw Max CW output power means the highest possible optical CW power that the laser source can produce at its output Max permissible CW output power is the highest optical power that is permitted within
171. rk Refer to the examples for this command MAXimum The highest wavelength signal MINimum The lowest wavelength signal DEFault The current marker position 4 21 resolution Constants Examples Query Response Programming Commands Measurement Instructions MAXimum 0 01 resolution fast update MINimum 0 001 resolution normal DEFault Current resolution CONF ARR POW WAV DEF MAX FETC ARR POW WAV DEF MIN READ ARR POW WAV MEAS ARR POW WAV CONF SCAL POW WAV 1300NM MAX FETC SCAL POW WAV 1300NM MIN READ SCAL POW WAV 1300NM MEAS SCAL POW WAV 1300NM The following line is an example of a returned string when MEAS SCAL POW WAV MAX is sent 1 5529258E 006 If six laser lines are located and MEAS ARR POW WAV is sent the following string could be returned Notice that the first returned num ber indicates the number of laser line values returned in the query 6 1 54488100E 006 1 54648400E 006 1 54809000E 006 1 54969900E 006 1 55131100E 006 1 55292600E 006 4 22 Syntax Description expected value Constants Programming Commands Measurement Instructions MEASure ARRay SCALar POWer WNUMber Returns a wave number value POWerWNUMber lt expected_value gt lt resolution gt Used With lt expected_value gt lt resolution gt SCALar optional optional ARRay ignored optional a Although ignored this argument must be present if the resol
172. ry Response Example Programming Commands Common Commands ESR The ESR event status register query returns the value of the event status register ESR When you read the standard event status register the value returned is the total of the bit weights of all of the bits that are set to one at the time you read the byte The following table shows each bit in the event status register and its bit weight The register is cleared when it is read Table 4 14 Standard Event Status Register Bit Bit Weight Condition 7 128 PON Power On 6 64 Not Used 5 32 Command Error 4 16 EXE Execution Error 3 8 DDE Device Dependent Error 2 4 QYE Query Error 1 2 Not Used 0 1 OPC Operation Complete integer ranges from 0 to 255 OUTPUT 720 ESR ENTER 720 Event PRINT Event 4 5 Syntax Description Query Response Example Programming Commands Common Commands IDN The IDN identification number query returns a string value which identifies the instrument type and firmware version IDN An IDN query must be the last query in a program message Any queries after the IDN query in a program message are ignored The maximum length of the identification string is 50 bytes The following identification string is returned The third entry is the instrument s serial number The last entry in the string is the firmware version number this value may vary be
173. sages Error Messages In this section you ll find all the error messages that the Agilent 86120 can display on its screen Table 5 23 on page 7 11 lists all instrument specific errors Table 5 24 on page 7 14 lists general SCPI errors Table 5 23 Instrument Specific Error Messages 1 of 3 Error Number Error Message 1 BAD CHECKSUM FROM MOTOR 2 MOTOR COMMUNICATION PROBLEM 3 MOTOR NOT MOVING 4 MOTOR INDEX PULSE NOT FOUND 5 MOTOR CHIP SET INIT FAILED 6 MOTOR COMMUTATION FAILURE 7 MOTOR NOT SETTLED 8 MOTOR DID NOT STOP 9 MOTOR MOTION ERROR 10 MOTOR POSITION LIMIT FAILED 11 MOTOR POSITION WRAP FAILED 12 POWER LEVEL TOO HIGH 13 DATA DOWNLOAD PROBLEM 14 DATA ACQUISITION PROBLEM 15 MAX NUMBER OF SIGNALS FOUND 16 MOTOR INTERRUPT RECEIVED Reference Error Messages Table 5 23 Instrument Specific Error Messages 2 of 3 Error Number Error Message 17 ROM BYTE UNERASED 18 ROM WRITE OPERATION FAILED 19 ROM DEFECTIVE 20 ROM DATA INVALID 21 ROM VERSION INCOMPATIBLE 22 ROM POLLING LIMITED OUT 23 INPUT OUT OF RANGE 24 BAD CAL ROM DATA 25 BAD CAL ROM DATA 26 BAD CAL ROM DATA 27 BAD CAL ROM DATA 28 BAD CAL ROM DATA 29 BAD CAL ROM DATA 30 NVSRAM WRITE OPERATION FAILED 31 SOFTWARE INITIALIZATION FAIL 32 HARDWARE INITIALIZATION FAIL 33 INITIALIZATION TIMEOUT 34 BATTERY FAILED 36 TOO MANY ERRORS 37 FUNCTION NOT YET IMPLEMENTED 38 PRINTER OFF LINE 39 PRINTER OUT OF PAPER 40 PRINTER ERROR DET
174. sed Do not shake tip or invert compressed air canisters because this releases particles in the can into the air Refer to instructions provided on the compressed air canister As soon as the connector is dry connect or cover it for later use If the performance after the initial cleaning seems poor try cleaning the connector again Often a second cleaning will restore proper per formance The second cleaning should be more arduous with a scrub bing action To clean an adapter The fiber optic input and output connectors on many Agilent Technol ogies instruments employ a universal adapter such as those shown in the following picture These adapters allow you to connect the instru ment to different types of fiber optic cables Rk Figure 2 9 Universal adapters 1 Apply isopropyl alcohol to a clean foam swab Cotton swabs can be used as long as no cotton fibers remain after clean ing The foam swabs listed in this section s introduction are small enough to fit into adapters 2 49 Making Measurements Cleaning Connections for Accurate Measurements Although foam swabs can leave filmy deposits these deposits are very thin and the risk of other contamination buildup on the inside of adapt ers greatly outweighs the risk of contamination by foam swabs Clean the adapter with the foam swab Dry the inside of the adapter with a clean dry foam swab Blow through the adapter using filtered dry compressed air
175. ses the automatic interpolation method to determine the wavelengths where the noise is measured See Measuring Signal to Noise Ratios for a description of automatic interpolation There is no user entered wavelength selection in signal to noise with averaging During a signal to noise with averaging measurement the display indi cates S N A xx where A indicates averaging and xx is the number of 2 29 Noise bandwidth affects measurement A UO N me Making Measurements Measuring Signal to Noise Ratios with Averaging averages taken so far The maximum number of averages is 900 the minimum number of averages is 10 and the default Preset value is 100 averages A measurement with 100 averages takes about 2 minutes to complete When the measurement is complete the instrument switches to single measurement mode Then pressing the Cont key will start a completely new measurement During a measurement and before the number of averages has been reached pressing the Single key will stop the measurement Then pressing the Cont key will con tinue with the current measurement While making a signal to noise with averaging measurement the num ber of averages can be changed As long as the new number of aver ages is greater than the number of averages taken so far the measurement continues If the new number of averages selected is less than the number of averages taken so far the measurement stops and the instrument switches to s
176. set 36 specifications 6 9 annotation asterisk 4 14 1 nm 27 30 AVERAGE 7 BROAD 9 BY PWR 6 BY WL 6 DRIFT 22 4 4 PWR OFS 36 Remote 3 S N AUTO 25 S N USER 25 STD AIR 37 VAC 37 Appl s key 23 28 31 menu map 5 ARRay programming command 15 ASNR CLEar programming command 46 COUNt programming command 47 asterisk 4 14 attenuation See external attenuation audio modulation effects of 15 34 AUTO programming command 69 softkey 28 AVERAGE annotation 7 average wavelength iii 7 Avg WL key 7 8 B BAR OFF softkey 11 BAR ON softkey 11 bit error rate 25 block diagram 5 BROAD annotation 9 BROAD softkey 9 broadband devices measuring 9 programming command 84 broadband mode 9 5 8 BY PWR annotation 6 BY WL annotation 6 C cabinet cleaning vii 2 CAL softkey 8 CALCulate1 subsystem 25 CALCulate2 subsystem 31 CALCulate3 subsystem 14 34 37 39 44 calibration accuracy 3 cycle 2 elevation 8 measurements 37 medium for light 9 care of cabinet vii 2 of fiber optics v case sensitivity 24 channel spacing 19 characteristics 5 chirped lasers 9 classification product vii classification laser vi 12 cleaning adapters 49 cabinet vii 2 fiber optic connections 40 48 non lensed connectors 48 CLEAR softkey 23 Index 1 Index CLS 21 3 CM 1 softkey 13 Cmd opc subroutine 29 colon 25 commands combining 24 common
177. sion value can range from 1 to 30 dB The default value is 15 dB Press RETURN Press PK THLD and then enter the peak threshold value The peak threshold value can range from 0 to 40 dB Setting this value to 0 dB ensures that only the peak wavelength is identified The default value is 10 dB Pressing the green PRESET key changes the peak excursion and peak threshold values to their default settings It also turns wavelength range limiting on Turning the Agilent 86120C s power off and then on does not change these settings If too many lines are identified If the following message is displayed too many laser lines have been identified E15 MAX NUMBER OF SIGNALS FOUND The maximum number of laser lines that the instrument can measure is 200 If this message appears decrease the peak threshold value increase the peak excursion value or decrease the wavelength range of operation with the WL LIM START WL and STOP WL functions 2 17 Making Measurements Measuring Laser Separation Measuring Laser Separation It is often important to measure the wavelength and power separation between multiple laser lines This is especially true in wavelength divi sion multiplexed WDM systems where channel spacing must be adhered to The Agilent 86120C can display the wavelength and ampli tude of any laser line relative to another In fact the following types of relative measurements can be made compared to the referen
178. ss A product Typographical Conventions The following conventions are used in this book Key type for keys or text located on the keyboard or instrument Softkey type for key names that are displayed on the instrument s screen Display type for words or charac ters displayed on the computer s screen or instrument s display User type for words or characters that you type or enter Emphasis type for words or char acters that emphasize some point orthat are used as place holders for text that you type Second Edition 86120 90C03 August 2004 First Edition 86120 90035 February 2000 CAUTION The Agilent 86120C At a Glance The Agilent 86120C At a Glance The Agilent 86120C Multi Wavelength Meter measures the wavelength and optical power of laser light in the 1270 1650 wavelength range Because the Agilent 86120C simultaneously measures multiple laser lines you can characterize wavelength division multiplexed WDM systems and the multiple lines of Fabry Perot lasers NOTE The front panel OPTICAL INPUT connector uses a single mode input fiber For Option 022 instruments the front panel OPTICAL INPUT connector is an angled physical contact interface Characterize laser lines easily With the Agilent 86120C you can quickly and easily measure any of the following parameters Measure up to 200 laser lines simultaneously Wavelengths and powers Average wavelength Total optical power
179. stopping wavelength for the wavelength limit CALCulate2 WLIMit STOP WNUMber Sets the stopping wavenumber for the wavelength limit CALCulate3 Subsystem CALCulate3 ASNR CLEar Resets and restarts the signal to noise ratio averaging CALCulate3 ASNR COUNt Sets the number of measurements to average the signal to noise ratio CALCulate3 ASNR STATe Turns signal to noise ratio averaging mode on and off CALCulate3 DATA Queries the data resulting from delta drift and signal to S noise measurements CALCulate3 DELTa POWer STATe Turns the delta power measurement mode on and off CALCulate3 D ELTa REFerence FREQuency Selects the signal to be used as the reference for the DELTa calculations CALCulate3 D ELTa REFerence POWer Queries the power level of the reference signal 3 44 Table 3 10 Programming Commands 3 of 5 Programming Lists of Commands Command Description Code Codes S indicates a standard SCPI command indicates an instrument specific command CALCulate3 DELTa REFerence WAVelength Selects the signal to be used as the reference for the DELTa calculations CALCulate3 D ELTa REFerence WNUMber Selects the signal to be used as the reference for the DELTa calculations CALCulate3 D ELTa WAVelength S TATe Turns the delta wavelength measurement mode on and off CALCulate3 D
180. strument 3 input connector iii 40 power definition of 4 INPUT connector v inspecting instrument 4 installing 2 instrument addressing over GPIB 3 default state 2 front view 15 preset conditions 100 2 rear view 15 returning for service 11 state when turned on 100 2 integration limits 9 L laser aperture vi classification vi 12 drift iii 22 23 line separation iii 18 linewidth 2 modulated 34 tuning power 4 Laser safety 12 LEFT programming command 76 LIM OFF softkey 10 LIM ON softkey 10 LINE key 7 linearity 4 6 9 line power cable 5 cables 18 initial state 100 2 requirements 5 Index 3 Index specifications 11 linewidth 2 List by Power menu map 6 mode 9 softkey 6 23 List by WL key 6 menu map 7 mode 9 softkey 6 23 LOCAL softkey 3 long form commands 23 lowercase letters 24 M M annotation 4 MAGNitude programming command 87 MAX NUMBER OF SIGNALS FOUND 17 maximum power input iv MAXimum programming command 76 MAX MIN softkey 23 MEASure measurement instruction 30 32 15 measurement accuracy 3 air in 37 AM modulation 15 34 audio modulation effects of 15 34 average wavelength 7 calibration 37 channel separation 20 channel spacing 19 continuous acquisition 14 cycle time 4 7 10 definition of peaks 15 elevation effects of 37 Fabry Perot lasers 31 flatness 21 via GPIB 5 instructions 23 15 laser
181. surement The query returns the current wavelength of the reference laser line The default units for the lt real gt parameter are meters 4 52 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa REFerence WNUMber Selects the reference laser line for delta calculations CALCulate3 DELTa REFerence WNUMber real MINimum MAXimum real is a wave number value that is within the following limits Constant Description MINimum 6 060 cm 1650 nm MAXimum 7 824 cm 1270 nm Preset State 7 824 cm 1270 nm RST State 7 824 cm 1270 nm SCPI Compliance instrument specific The reference will be the laser line at the wave number closest to the wave number entered Subsequent measurements will use the wave number closest to the reference wave number used for the previous measurement The query returns the current wave number of the reference laser line The default units for the real parameter are ml 4 53 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa WAVelength STATe Turns the delta wavelength measurement mode on and off CALCulate3 DELTa WAVelength STATe ON OFF 1 0 Preset State off RST State off SCPI Compliance instrument specific When on the wavelength of the reference laser line is subtracted from the wavelength values of all laser lines except the reference
182. t 81553SM 1550 nm Fabry Perot laser SM 9 125 um source module Agilent 81534A return loss module Standard instruments flat contacting connectors Turn the source module s output off Connect a single mode patchcord between the source module s optical output and the return loss module s INPUT SOURCE connector Set the return loss module s wavelength to 1550 nm and select an average time of 1 second Locate an HMS 10 HRL to FC PC patchcord Connect the HMS 10 HRL end of the patchcord to the return loss module s OUTPUT connector Terminate the other end of the cable Zero the return loss module Turn on the source module Remove the termination from the cable and leave the cable s free end uncovered The return loss module measures the reflection reference 14 6 dB return loss of the patchcord s FC PC connector in air Make a low reflection termination in the HMS 10 HRL to FC PC patchcord Do this by wrapping the cable 6 times around a 5 mm diameter mandrel The return loss module measures the termination parameter Connect the HMS 10 HRL to FC PC patchcord to the Agilent 86120C s front panel OPTICAL INPUT connector The lightwave multimeter measures the return loss Compare this measurement with the specification listed in Chapter 6 Specifications 5 6 Procedure 10 11 12 13 Performance Tests Test 4 Optical Input Return Loss and Regulatory Information Option 022 instruments angled conta
183. t MODE SPACing Queries the mode spacing data of the selected modes CALCulate3 FPERot MODE SPACing WAVelength FREQuency WNUMber Argument Description WAVelength Returns the mode spacing wavelength of the selected modes FREQuency Returns the mode spacing frequency of the selected modes WNUMber Returns the mode spacing wavenumber of the selected modes WAVelength 3 18277200E 010 FREQuency 4 02787400E 011 WNUMber 1 34356200E 001 Preset State not affected RST State not affected SCPI Compliance instrument specific Query only 4 64 Syntax Example Query Response Attribute Summary Programming Commands CALCulate3 Subsystem FPERot PEAK Queries the peak data of the selected modes CALCulate3 FPERot PEAK WAVelength FREQuency WNUMber POWer DBM WATTs Argument Description WAVelength Returns the peak wavelength of the selected modes FREQuency Returns the peak frequency of the selected modes WNUMber Returns the peak wavenumber of the selected modes POWer Returns the peak amplitude of the selected modes in dBm or watts WAVelength 1 54073400 006 FREQuency 1 94577600E 014 WNUMber 6 49041000E 003 POWer 9 09446600E 4 000 dBm 1 23183800E 004 watts Preset State not affected RST State not affected SCPI Compliance instrument specific Query only 4 65 Syntax Example Query Response Attribute Summary Programming Commands CALCulat
184. tal power Press the Avg WL key Limiting the wavelength measurement range The wavelength range of measurement can be limited with the wave length limit function Both start and stop wavelengths can be chosen The units of wavelength start and stop are the same as the currently selected wavelength units If wavelength units are later changed the start and stop wavelength units will change accordingly Note that a start wavelength limit in nm will become a stop wavelength limit if THz or cm is chosen See To change the units of measure on page 2 12 The graphical display uses the start and stop wavelength values to plot the power spectrum whether the wavelength limit function is on or off Preset turns wavelength limiting on Only responses that are within the boundaries of the chosen start and stop wavelength limits are mea sured This includes Peak WL List by WL and List by Power modes To limit the wavelength range Press the Setup key Press the WL LIM softkey Press the STARTWL softkey to adjust the start wavelength value Press the STOP WL softkey to adjust the stop wavelength value 2 8 Making Measurements Measuring Wavelength and Power Measuring broadband devices and chirped lasers When first turned on or the green Preset key is pressed the Agilent 86120C is configured to measure narrowband devices such as DFB lasers and modes of FP lasers If you plan to measure broadband devices such as LEDs o
185. tall the instrument so that the LINE switch is readily identifiable and is easily reached by the operator The LINE switch or the detachable power cord is the instrument disconnecting device It disconnects the mains circuits from the mains supply before other parts of the instrument Alternately an externally installed switch or circuit breaker which is really identifiable and is easily reached by the operator may be used as a disconnecting device Install the instrument according to the enclosure protection provided This instrument does not protect against the ingress of water This instrument protects against finger access to hazardous parts within the enclosure 12 Getting Started Getting Started Measurement accuracy it s up to you Fiber optic connectors are easily damaged when connected to dirty or damaged cables and accessories The Agilent 86120C s front panel INPUT connector is no exception When you use improper cleaning and handling techniques you risk expensive instrument repairs damaged cables and compromised measurements Before you connect any fiber optic cable to the Agilent 86120C refer to Cleaning Connections for Accurate Measurements on page 2 40 Getting Started Step 1 Inspect the Shipment Step 1 Inspect the Shipment 1 Verify that all system components ordered have arrived by comparing the shipping forms to the original purchase order Inspect all shipping containers If your
186. te none RST State none SCPI Compliance standard Changes in the state of a condition register bit causes the associated OPERation Status or QUEStionable Status event register bit to be set This command allows you to select a positive bit transition to trigger an event to be recognized A positive transition is defined to occur whenever the selected bit changes states from a 0 to a 1 You can enter any value from 0 to 65535 When queried the largest value that can be returned is 32767 This is because the most significant register bit cannot be set true OUTPUT 720 STATUS OPER PTRansition 16 4 95 Syntax Attribute Summary Description Example Programming Commands STATus Subsystem PRESet Presets the enable registers and the PTRansition and NTRansition fil ters STATus PRESet Preset State none RST State none SCPI Compliance standard Command Only The PRESet command is defined by SCPI to affect the enable register If you want to clear all event registers and queues use the CLS com mand Table 4 18 Preset Values Status Node Preset Value Operation enable register 0 Questionable enable register 0 PTRansition filters 32767 NTRansition filters 0 OUTPUT 720 STATUS PRESET 4 96 Programming Commands SYSTem Subsystem SYSTem Subsystem The commands in this subsystem have the following command hierar chy SYSTem ERRor HELP HEADers PRESet VERSion
187. tes how many of the following digits convey the byte count The next digits give the actual byte count For example in the listing below 4387 bytes are indicated in the file Each command in the listing is separated by a linefeed character The following is an example of the first few lines and last few lines returned in the string The term nquery indicates that a command cannot be sent as a query The term qonly indicates that a command can only be sent as a query 44387 ABORt nquery CALCulate DATA gonly CALCulate TRANsform FREQuency POINts CALCulate1 DATA gonly CALCulate1 TRANsform FREQuency POINts CALCulate2 DATA gonly IDN gonly OPC RCL nquery RST nquery SAV nquery SRE STB gonly TRG nquery TST qonly WAl nquery 4 99 Programming Commands SYSTem Subsystem PRESet Performs the equivalent of pressing the front panel PRESET key Syntax SYSTem PRESet Attribute Preset State none Summary RST State none SCPI Compliance standard Command Only Description The instrument state is set according to the settings shown in the fol lowing table Table 4 19 Instrument Conditions 1 of 2 item Settings after Preset Settings after Power Key Pressed Turned On Display mode single wavelength last state Wavelength range limiting on last state Start wavelength 1270 nm last state Stop wavelength 1650 nm last state Graphical display off off Measurement acquisition c
188. th This is shown in the following example OUTPUT 720 CALCulate1 POINts ENTER 720 Length OUTPUT 720 CALCulate1 DATA ENTER 720 Result Data can be corrected for elevation and vacuum Normally the Agilent 86120C provides measurement values calculated for conditions in air at sea level Use the SENSe CORRection ELEVa tion command to compensate for air dispersion Altitudes up to 5000 meters can be entered Use the SENSe CORRection MEDium command to switch to readings in a vacuum Amplitude units The default amplitude units are dBm If you need measurements in watts use the UNIT POWer command When the Agilent 86120C is turned on the amplitude units are automatically set to the units used before the instrument was last turned off 3 15 Programming Monitoring the Instrument Monitoring the Instrument Almost every program that you write will need to monitor the Agilent 86120C for its operating status This includes querying execu tion or command errors and determining whether or not measure ments have been completed Several status registers and queues are provided to accomplish these tasks In this section you ll learn how to enable and read these registers In addition to the information in this section you should review the com mands documented in Common Commands on page 4 3 and STATus Subsystem on page 4 90 Programming Monitoring the Instrument Status registers The Agilent 86120C
189. the and softkeys to change the value Press RETURN While the signal to noise measurements are displayed you can press PEAK anytime to select the signal with the highest power 2 28 Making Measurements Measuring Signal to Noise Ratios with Averaging Measuring Signal to Noise Ratios with Averaging When the lasers being measured are modulated especially with repeti tive data formats such as SONET or PRBS the noise floor is raised Averaging reduces the noise floor and allows an improvement of greater than 10 dB in a signal to noise measurement In general aver aging will decrease the noise floor caused by modulation until the true optical noise level is reached The displayed signal to noise will improve with each average until the true optical noise level is reached and then the displayed signal to noise will remain approximately con stant If however the true signal to noise is below the instrument sensitivity of approximately 40 dB in a 0 1 nm noise bandwidth it will not be measured Averaging can also improve the accuracy of measuring signal to noise of unmodulated lasers 1545 4 58nm i8 81dBm 31 746 1548 868 6 06 36 roin By WE 1549 663 4 4 26 37 8 s 1551 281 4 34 37 8 ec 1552 894 8 22 E 8 M Signal to noise with averaging display Averaging is performed on the noise not on the wavelength or power of the laser signals The signal to noise with averaging measurement u
190. the current response to be lost This also generates an error in the error queue The output of the instrument may be numeric or character data depending on what is queried Refer to the specific commands for the formats and types of data returned from queries You can send multiple queries to the instrument within a single pro gram message but you must also read them back within a single pro gram message This can be accomplished by either reading them back into a string variable or into multiple numeric variables When you read the result of multiple queries into string variables each response is separated by a semicolon 3 27 Programming Example Programs Example Programs The following example programs are provided in this section Example 1 Measure a DFB laser 3 30 Example 2 Measure WDM channels 3 32 Example 3 Measure WDM channel drift 3 34 Example 4 Measure WDM channel separation 3 37 Example 5 Measure signal to noise ratio of each WDM channel 3 39 Example 6 Increase a source s wavelength accuracy 3 41 These programs are provided to give you examples of using Agilent 86120C remote programming commands in typical applications They are not meant to teach general programming techniques or pro vide ready to use solutions They should allow you to see how mea surements are performed and how to return data to the computer All of the examples are written in the HP BASIC programming lan guage Many subr
191. the following books Hewlett Packard Company Tutorial Description of Hewlett Packard Interface Bus 1987 Hewlett Packard Company SCPI Standard Commands for Program mable Instruments 1995 International Institute of Electrical and Electronics Engineers IEEE Standard 488 1 1987 IEEE Standard Digital Interface for Programma ble Instrumentation New York NY 1987 International Institute of Electrical and Electronics Engineers EEE Standard 488 2 1957 IEEE Standard Codes Formats Protocols and Common commands For Use with ANSI IEEE Std 4858 1 1957 New York NY 1987 Types of commands The Agilent 86120C responds to three types of commands Common commands Measurement instructions Subsystem commands All of these commands are documented in Chapter 4 Programming Commands HP is a registered trademark of Hewlett Packard Company 3 2 Programming Addressing and Initializing the Instrument Addressing and Initializing the Instrument The Agilent 86120C s GPIB address is configured at the factory to a value of 20 You must set the output and input functions of your pro gramming language to send the commands to this address You can change the GPIB address from the front panel as described in To change the GPIB address on page 3 4 Remote mode and front panel lockout Whenever the instrument is controlled by a computer the Remote message is displayed on the instrument s screen and the sof
192. the instrument has found the maximum number of signals 10 Drift Reference indicating that the number of reference signals is different from the current number of input signals 11 Delta Reference indicating that there is no delta reference signal 12 through 13 not used 14 Command Warning indicating that the instrument has received some extra unexpected parameters for one of the measurement functions 15 not used Standard Event Status register The Standard Event Status Register monitors the following instrument status events OPC Operation Complete RQC Request Control QYE Query Error DDE Device Dependent Error EXE Execution Error CME Command Error URQ User Request PON Power On When one of these events occur the event sets the corresponding bit in the register If the bits are enabled in the Standard Event Status Enable Register the bits set in this register generate a summary bit to set bit 5 ESB in the Status Byte Register The contents of the Standard Event Status Register can be read and the register cleared by sending the ESR query The value returned is the total bit weights of all of the bits that are set at the present time 3 20 Programming Monitoring the Instrument Enabling register bits with masks Several masks are available which you can use to enable or disable individual bits in each register For example you can disable the Hard copy bit in the OPERation Status Re
193. thin the following limits Constant Description MINimum 181 6924 THz MAXimum 236 0571 THz Preset State 236 0571 THz 1270 nm RST State 236 0571 THz 1270 nm SCPI Compliance instrument specific The reference will be the laser line at the frequency closest to the fre quency entered Subsequent measurements will use the frequency clos est to the reference frequency used for the previous measurement The query returns the reference laser line s frequency The default units for the real parameter are Hz DELTa REFerence POWer Queries the reference laser line s power level CALCulate3 DELTa REFerence POWer Preset State not affected RST State not affected SCPI Compliance instrument specific Query Only 4 51 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem DELTa REFerence WAVelength Selects the reference laser line for DELTa calculations CALCulate3 DELTa REFerence WAVelength real MINimum MAXimum real is a wavelength value that is within the following limits Constant Description MINimum 1270 nm MAXimum 1650 nm Preset State 1270 nm 236 0571 THz RST State 1270 nm 236 0571 THz laser line SCPI Compliance instrument specific The reference will be the laser line at the wavelength closest to the wavelength entered Subsequent measurements will use the wavelength closest to the reference wavelength used for the previous mea
194. tkey menu is blanked except for the LOCAL softkey This softkey can be pressed by the user to restore front panel control of the instrument You can specify a local lockout mode that prevents the LOCAL softkey from being displayed If the instrument is in local lockout mode all the softkeys may be blanked For example if the instrument is first placed in local lockout mode and then placed in remote mode no softkeys are displayed Consult the documentation for your programming environment to determine which commands are used to put an instrument in the remote and local lockout modes These are not Agilent 86120C com mands they control GPIB control lines and do not send any characters to the Agilent 86120C Initialize the instrument at start of every program It is good practice to initialize the instrument at the start of every program This ensures that the bus and all appropriate interfaces are in a known state HP BASIC provides a CLEAR command which clears the interface buffer and also resets the instrument s parser The parser is the program that reads the instructions that you send Whenever the instrument is under remote programming control it should be in the single measurement acquisition mode This is auto matically accomplished when the RST common command is used The RST command initializes the instrument to a preset state CLEAR 720 OUTPUT 720 RST 3 3 Programming Addressing and Initializing the Instrument
195. to the computer When FAST mea surement update is specified over 1 100 kilobytes of data 2 5 values can be returned The floating point values are scaled from 1 000 to 1 999756 1 4095 4096 Amplitude values are not calibrated The input laser line s generate an interference pattern on the photo detector as a function of the Michelson interferometer optical path delay The time domain data is sampled at uniform optical path delay increments of the reference laser wavelength or 0 632991 microns When NORMAL measurement update is selected the first data value is sampled at 41 48 mm optical path delay and the last value is sam pled at 41 48 mm optical path delay When FAST measurement update is selected the first data value is sampled at 20 74 mm optical path delay and the last value is sampled at 20 74 mm optical path delay The data value that corresponds to zero optical path delay is approxi mately but not exactly located in the center of the time domain data If your program is aborted or interrupted after sending this query the Agilent 86120C continues to process the data but does not place it in the output buffer Because of the amount of data processed the instrument will not respond to any new commands in its input buffer for 30 or 40 seconds 4 88 Query Response Programming Commands SENSe Subsystem The following string shows an example of the first few measurements returned by this query 1 51367200E
196. tor than a narrow bandwidth the Agilent 86120C normalizes all noise power measurements to a bandwidth of 0 1 nm The annotation 0 1 nm is displayed to show that the noise bandwidth is being normalized to a 0 1 nm bandwidth Repetitive data formats The Agilent 86120C signal to noise application works best when the laser being tested is not modulated or modulated with non repetitive data formats With repetitive data formats such as PRBS data and SONET formats there is signifi cant low frequency amplitude modulation of the laser This modulation raises the noise floor of the Agilent 86120C significantly The signal to noise measured can be limited to about 15 dB while measuring lasers modulated by repetitive data for mats For improved performance when the laser is modulated with repetitive data formats use the Signal to Noise with Averaging application 2 21 A N m Making Measurements Measuring Signal to Noise Ratios To measure signal to noise Press the front panel Preset key Press List by WL or List by Power Press Appl s and then S N To select the wavelength reference for measuring the noise do the following steps a Press WL REF and press AUTO to let the instrument interpolate the wavelength or press USER to select the last wavelength manually entered b If you chose USER you can specify the wavelength by pressing USER WL Use the softkey to select the digit that requires editing Use
197. ts can be sent directly to a printer Simply connect a compatible printer to the rear panel PARALLEL PRINTER PORT con nector The output is ASCII text An example of a compatible printer is Hewlett Packard s LaserJet series printer Be sure to use a parallel printer cable to connect the printer The printer output is not a copy of the display Rather it is a listing of all signals present at the input up to 200 The measurement values printed depend on the settings of the instrument when the Print key is pressed The following is an example of a typical printout Agilent 86120C SER US39400020 Firmware Ver 1 000 List By Wavelength 8 Lines Power Offset 0 0 dB Vacuum Elevation 0 Meters Update Normal Peak Excursion 15 dB Peak Threshold 10 dB Device Narrow Input Wavelength Power 1280 384nm 16 97dBm 1281 473 13 14 1282 569 13 92 1283 651 13 34 1284 752 11 69 1285 840 8 11 1286 944 10 38 1288 034 14 65 To create hardcopy 1 Connect the printer to the Agilent 86120C s rear panel PARALLEL PRINTER PORT connector Press Print You can use the ABORT and CONT softkey to stop and restart a print job that is in progress 1 Hewlett Packard and LaserJet are registered trademarks of Hewlett Packard Company 2 39 Making Measurements Cleaning Connections for Accurate Measurements Cleaning Connections for Accurate Measurements Today advances in measurement capabilities make connect
198. ts for the lt real gt parameter are inverse meters The stop wavenumber value must be less than or equal to the start wavenumber value or the stop wavenumber will be clipped to the start wavenumber and a Data out of range error will be generated Non sequential command Always use an query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 43 Programming Commands CALCulate3 Subsystem CALCulate3 Subsystem Use the CALCulate3 commands to perform delta drift signal to noise and Fabry Perot measurements The commands in this subsystem have the following command hierarchy CALCulate3 ASNR CLEar COUNE STATe DATA DELTa POWer STATe PRESet REFerence FREQuency POWer WAVelength WNUMber WAVelength STATe WPOWer STATe DRIFt DIFFerence STATe MAXimum STATe MINimum STATe PRESet REFerence RESet STATe STATe 4 44 Programming Commands CALCulate3 Subsystem FPERot STATE FWHM WAVelength FREQuency WNUMber MEA WAVelength FREQuency WNUMber MODE WAVelength FREQuency WNUMber PEAK WAVelength FREQuency WNUMber POWer POWer WAVelength FREQuency WNUMber SIGMa WAVelength FREQ
199. ts wavelength values in standard air VACuum Selects wavelength values in a vacuum Preset State VAC RST State VAC SCPI Compliance instrument specific Standard air is defined to have the following characteristics Barometric pressure 760 torr Temperature 15 Relative hwmidity 0 4 86 Syntax Attribute Summary Query Response Programming Commands SENSe Subsystem CORRection OFFSet MAGNitude Enters an offset for amplitude values SENSe CORRection OFFSet MAGNitude lt real gt MINimum MAXimum real is the logarithmic units in dB Constant Description MINimum 40 0 dB MAXimum 40 0 dB Preset State 0 0 RST State 0 0 SCPI Compliance standard The query form returns the current offset setting as shown in the fol lowing example 5 00000000E 000 4 87 Syntax Attribute Summary Description Programming Commands SENSe Subsystem DATA Queries the time domain samples of the input laser line SENSe DATA Preset State none SCPI Compliance instrument specific Query Only Be prepared to process a large amount of data when this query is sent The amount of data returned depends on the measurement update state of the instrument which is set using the resolution argu ment of an instrument function Refer to Measurement Instructions on page 4 15 When NORMAL measurement update is specified over 2 200 kilobytes of data 2 values can be returned
200. tween instruments Agilent 86120C USaaaabbbb 1 000 DIM Id 50 OUTPUT 720 IDN ENTER 720 ld PRINT 19 4 6 Syntax Description Query Response Example Syntax Description Programming Commands Common Commands OPC The OPC operation complete command sets the operation complete bit in the event status register when all pending device operations have finished OPC OPC The OPC query places an ASCII 1 in the output queue when all pending device operations have finished This command is useful when the computer is sending commands to other instruments The computer can poll the event status register to check when the Agilent 86120C has completed the operation Use the OPC query to ensure all operations have completed before continuing the program By following a command with an OPC query and an ENTER statement the program will pause until the response ASCII 1 is returned by the instrument Be sure the computer s timeout limit is at least two seconds since some of the Agilent 86120C commands take approximately one second to complete OUTPUT 720 0PC ENTER 720 0p RCL This command recalls a saved instrument state RCL lt integer gt lt integer gt range is 1 to 4 For a description of an instrument state see SAV command 4 7 Syntax Description Programming Commands Common Commands RST The RST reset command returns the Agil
201. u can combine commands from the same subsystem provided that they are both on the same level in the subsystem s hierarchy Simply separate the commands with a semi colon For example the follow ing two lines OUTPUT 720 CALC2 PEXC 12 OUTPUT 720 CALC2 PTHR 20 can be combined into one line OUTPUT 720 CALC2 PEXC 12 PTHR 20 The semicolon separates the two functions 3 24 Programming Reviewing SCPI Syntax Rules Combine commands from different subsystems You can send commands and program queries from different sub systems on the same line Simply precede the new subsystem by a semicolon followed by a colon In the following example the colon and semicolon pair before DISP allows you to send a command from another subsystem OUTPUT 720 CALC2 PEXC 12 DISP WIND GRAP STAT OFF Sending common commands If a subsystem has been selected and a common command is received by the instrument the instrument remains in the selected subsystem For example if the program message DISPLAY MARK MAX LEFT CLS DISP MARK MAX RIGH is received by the instrument the Display subsystem remains selected If some other type of command is received within a program message you must reenter the original subsystem after the command Adding parameters to a command Many commands have parameters that specify an option Use a space character to separate the parameter from the command as shown in the following line OUTPUT
202. uency WNUMber POINts PRESet SNR AUTO REFerence FREQuency WAVelength WNUMber STATe 4 45 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem ASNR CLEar Clears the number of measurements used in the average signal to noise calculation CALCulate3 ASNR CLEar Preset State not affected RST State not affected SCPI Compliance instrument specific This command clears the number of measurements used in the average signal to noise calculation The current measurement is used as the new reference for the average signal to noise calculation 4 46 Syntax Attribute Summary Description Programming Commands CALCulate3 Subsystem ASNR COUNt Sets the number of measurements to be used for the average signal to noise calculation CALCulate3 ASNR COUNt lt integer gt MINimum MAXimum integer is a value that is within the following limits Constant Description MINimum 10 MAXimum 900 Preset State 100 RST State 100 SCPI Compliance instrument specific This command sets the number of measurements to be used for the average signal to noise calculation If this count is changed while the average signal calculation is on and the new count is less than the number of measurements already taken the instrument will go into single measurement mode 4 47 Syntax Attribute Summary Description Programming C
203. ument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 39 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STARCWNUMber Sets the starting wavenumber for the wavelength limit range CALCulate2 WLIMit STAREWNUMber lt real gt MINimum MAXimum lt real gt is a wavenumber value that is within the following limits Constant Description MINimum 6060 cm 1650 nm MAXimum wavelength limit stop value Non sequential command Preset State 6 060606E5 m RST State 6 060606 5 m SCPI Compliance instrument specific This command sets the starting range for the wavelength limit The default units for the real parameter value are mt The start wave number value must be less than or equal to the stop wavenumber value or the start wavenumber will be clipped to the stop wavenumber and a Data out of range error will be generated Non sequential command Always use OPC query or a WAI command to ensure that this command has the time to complete before sending any more commands to the instrument Refer to Always force the Agilent 86120C to wait for non sequential commands on page 3 12 for more information 4 40 Syntax Attribute Summary Description Programming Commands CALCulate2 Subsystem WLIMit STOP FREQuency Sets the stopping frequency for th
204. ution argument is specified When used with a SCALar command a single value is returned The display is placed in the single wavelength mode and the marker is placed on the signal having a wave number that is closest to the expected value parameter Default units for expected value parameter are in m When used with an ARRay command an array of wave number is returned The display is placed in the list by wavelength mode The resolution parameter sets the resolution of the measurement It is a unitless number whose value will be limited to either 0 01 or 0 001 whichever is closer Returned values are in inverse meters Displayed units are inverse centimeters Power units are not affected CONFigure command When this function is used with the CONFigure command the query question mark character must not be included in the string However the FETCh READ and MEASure command are queries and require the question mark Refer to the examples for this command MAXimum The laser line having the largest wave number MINimum The laser line having the smallest wave number DEFault The current marker position 4 23 resolution Constants Examples Query Response Programming Commands Measurement Instructions MAXimum 0 01 resolution fast update MINimum 0 001 resolution normal DEFault Current resolution CONF ARR POW WNUM DEF MAX FETC ARR POW WNUM DEF MIN READ ARR POW WNUM
205. ve to a milliwatt MW for milliwatts UW for microwatts Measurement rate Under normal operation the Agilent 86120C makes a measurement and displays the results about once every second It is in this normal update mode that maximum accuracy and wavelength resolution are achieved However should a faster update be desired for example when real time feedback is required to tune a laser to its designated channel the Agilent 86120C can be set to update approximately two times per second This reduces both wavelength resolution and accu racy but can be beneficial in some applications The instrument resolution in NORMAL update mode is 7 GHz 0 06 nm at 1550 nm This resolution is useful when measuring closely spaced laser lines carrying data at up to 5 Gb s rates The instrument resolution in FAST update mode is 14 GHz 0 12 nm at 1550 nm This resolution is useful when measuring laser lines carry ing data at up to 10 Gb s rates NOTE When measuring laser lines carrying data at 10 Gb s in NORMAL update mode the instrument resolution is less than the modulation bandwidth of the laser lines In this case the displayed power of the laser lines will be less than the actual power by approximately 1 dB This power offset can be calculated by comparing the displayed power to that measured by a power meter Then the power offset can be entered by pressing Setup MORE CAL PWR OFS to display the correct power 2 13
206. very poor for making repeated connections What is the reflection tolerance Can the system take reflection degra dation 2 40 Making Measurements Cleaning Connections for Accurate Measurements s an instrument grade connector with a precision core alignment re quired s repeatability tolerance for reflection and loss important Do your specifications take repeatability uncertainty into account Will a connector degrade the return loss too much or will a fusion splice be required For example many DFB lasers cannot operate with reflections from connectors Often as much as 90 dB isolation is needed Connecting Body and Ferrule 2 5 mm Mechanical Retainer Fiber 125 um actual fiber s diameter is smaller than a human hair Alignment Key Figure 2 3 Basic components of a connector Over the last few years the FC PC style connector has emerged as the most popular connector for fiber optic applications While not the highest performing connector it represents a good compromise between performance reliability and cost If properly maintained and cleaned this connector can withstand many repeated connections However many instrument specifications require tighter tolerances than most connectors including the FC PC style can deliver These instruments cannot tolerate connectors with the large non concentrici ties of the fiber common with ceramic style ferrules When tighter alignment is required Agile
207. vity Sensitivity is verified using the following devices Optical power meter Optical attenuator 1310 nm and 1550 nm lasers gt 20 dBm output power Do not exceed 18 dBm source power The Agilent 86120C s input circuitry can be damaged when total input power exceeds 18 dBm Perform the following procedure first using the 1310 nm laser and then repeat the steps using the 1550 nm laser Connect the laser s output to the optical attenuator s input Connect the optical attenuator s output to the optical power meter Adjust the attenuator for a reading of 0 dBm on the power meter Record the attenuator s setting Attenuation at 0 dBm Adjust the attenuator for a reading of 35 dBm on the power meter Record the attenuator s setting Attenuation at 35 dBm Disconnect the fiber optic cable at the power meter s input and connect the cable to the Agilent 86120C being tested Reset the optical attenuator to the setting recorded in Step 3 Read the power and wavelength measured on the Agilent 86120C and compare them to the specifications listed in Chapter 6 Specifications and Regulatory Information Reset the optical attenuator to the setting recorded in Step 4 Read the power and wavelength measured on the Agilent 86120C and compare them to the specifications listed in Chapter 6 Specifications and Regulatory Information 5 4 Description CAUTION Procedure Performance Tests Test 3 Polarizatio
208. wavelength measurements switching between vacuum and standard air will not affect the measurement results This is because the frequency of an optical signal does not change in different mediums only the wavelength changes a Definition of standard air Standard air is defined to have the following characteristics Barometric pressure 1013 mbar Temperature 15 C Relative humidity 0 2 37 amp WO N m Making Measurements Calibrating Measurements To enter the elevation Press the Setup key Press the MORE softkey Press the CAL softkey Press ELEV Use the and softkeys to enter the elevation in meters Entries jump in 500 meter steps from 0 m to 5000 m In order for the Agilent 86120C to meet its published specifications the elevation value selected with the softkeys must be within 250 meters of the actual elevation Press RETURN to complete the entry Converting feet to meters If you know your elevation in feet you can convert this value to meters by using the following equation Lm To select the medium for light Press the Setup key Press the MORE softkey Press the CAL softkey and make the following selection Press VACUUM for wavelengths in a vacuum Press STD AIR for wavelengths in standard air Press RETURN to complete the entry 2 38 Making Measurements Printing Measurement Results Printing Measurement Results Measurement resul
209. y it can be queried as needed Refer to the introduction to this section for a description of each sub routine that is contained in this program COM Instrument Mwm ASSIGN Mwm TO 720 Set ese PRINT USING 37A 33A Multi Wavelength Meter Identity is FNidentity OUTPUT GMwm INIT CONT OFF ON TIMEOUT 7 5 CALL Err_mngmt OUTPUT Mwm MEAS SCAL POW WAV ENTER Mwm Current_wl OUTPUT Mwm FETC SCAL POW ENTER Mwm Current OFF TIMEOUT PRINT USING 20A 4D 3D 3A 19A M2D 2D 4A The wavelength is Current_wl 1 0E 9 nm with a power of Current pwr dBm END Err mngmt SUB Err_mngmt COM Instrument Mwm DIM Err msg 255 INTEGER Cme CLEAR 7 REPEAT OUTPUT Mwm ESR ENTER Mwm Cme OUTPUT Mwm SYST ERR ENTER Mwm Err_msg PRINT Err msg UNTIL NOT BIT Cme 2 AND NOT BIT Cme 4 AND NOT BIT Cme 5 AND POS Err_msg 0 Subend SUBEND Set_ese SUB Set_ese COM Instrument Mwm OUTPUT Mwm ESE IVAL 00110100 2 SUBEND 3 30 Programming Example Programs Identity DEF FNidentity COM Instrument MwmV DIM Identity 50 Identity OUTPUT Mwm RST OUTPUT GMwm OPC ENTER Mwm Opc_done OUTPUT Mwm IDN ENTER Mwm Identity RETURN Identity FNEND 3 31 Programming Example Programs Example 2 Measure WDM channels This program measures the multiple laser lines of a WDM system It measures both the power and wavelengths of each lin

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