High-Speed Receivers High-Speed Detectors
Contents
1. Bias Monitor Bandwidth uis 20 Bias Monitor Output Ohm 10k Impedance Power 15 V 15 V 15 V Requirements 200 mA 200 mA 200 mA Gadis Anritsu K Anritsu K FC PC FC PC FC PC 62 5 um MM 50 um MM 10 35 10 35 10 35 50 Detector Type Output Connector Input Connector Input Fiber Operating Temperature min max Table 2 o O typ min al a EST NI 12 GHz DC coupled Photoreceivers Wavelength Range nm 780 870 500 1630 780 1630 Bandwidth 3 dB DC to DC to DC to ara typ 12 105 12 105 127 105 Low Frequency 10 Cutoff AC coupled Risetime 10 90 a 2 Bara EB 550 450 900 800 800 700 o la lam Maximum Safe UTE perse m L1 LL EL Bias Monitor Bandwidth Bias Monitor Output Power 15 V 15 V 15 V Requirements 200 mA 200 mA 200 mA Detector ype Gaas InGaAs InGaAs Output Connector Anisuk AmisuK Amitsuk Input Connector FC PC rec rc ec Input Fiber 62 5 um MM 50 um MM Temperature min max Table 3 22 and 38 GHz Photoreceivers Wavelength Range 630 865 800 865 630 1620 Bandwidth 3 dB GHz 29 90 29 90 38 35 typ min Low Frequency Cutoff Risetime 10 9096 2 typ max pW rt Hz ins Output Voltage Maximum Safe Input Output Impedance Bias Monitor Gain V mA Bias Monitor Bandwidth Bias Monitor Output Impedance Power Requirements Output Connector Input Connector Input Fiber Operati2. In looking at the frequency response of the DC coupled receivers a crossover region exists where the DC response rolls off and the AC response rises In this region near 25kHz the response is not flat Signals with significant energy in this region will be somewhat distorted A time domain example is seen in Figure 10 which shows the response for a long duration step input For most applications such as measurement of extinction ratios on gigabit per second waveforms the crossover will be insignificant 0 1 0 0 1 0 2 Output Volts 0 3 0 4 0 5 t 1 20 10 0 10 20 30 40 50 60 time us Figure 10 Example crossover behavior for DC coupled receivers 27 28
3. min Responsivity Saturation Power Maximum Safe Input utput Impedance ias Monitor Gain Bias Monitor Bandwidth Impedance Power Internal 9 V Internal 9 V Internal 9 V Requirements Battery Battery Battery Detector Type Output Connector Input Connector FC PC FC PC FC PC nput Fiber Operating Temperature C 10 35 10 35 10 35 min max Table 7 Lens dispersion limits wavelength range 2 At 1550 nm for InGaAs Models and 775nm for GaAs models For GaAs models response at 850nm will be similar 3 DC 50 GHz noise bandwidth is 42 GHz for each model 1 5 compression of impulse response 5 CW or average power with high speed modulation 8 Model 0901 recommended 22 Customer Service Technical Support Information and advice about the operaion of any New Focus product is availabe from our applications engineers For quickest response ask for Technical Support and know the model number and serial number for your product Hours 8 00 5 00 PST Monday through Friday excluding holidays Toll Free 1 877 835 9620 from the USA 8 Canada only Phone 408 980 4330 Support is also available by fax and email Fax 408 919 6083 Email techsupport newfocus com We typically respond to faxes and email within one business day Service In the event that your photoreceiver malfunctions or becomes damaged please contact New Focus for a return authorization number and instructions on ship
4. Off On Ba O Chk Bias Optical Input Monitor ics e Q fiber optic input connector FC power indicator LED bias monitor port output 1 mV pA Model 1474 A 35 GHz IR PhotorecAggr lo PWR Bias Optical Input Monitor K 1mV pA fiber optic input connector FC Figure 5 Side and back view Note that the battery operated modules will not have the power connector on the side Output K Connector 2 26 2 00 57 5 50 8 r Ko 458 50 8 40 3 iS NEW FOCUS XXXX 1 NG s 54 Power Connector 3 15 80 1 Handling Precautions CAUTION The detector is sensitive to electrostatic discharges and could be permanently damaged if subjected to even to small discharges Whenever handling make sure to follow these precautions Follow standard electrostatic discharge precautions including grounding yourself prior to handling the detector or making connections even small electrostatic discharges could permanently damage the detector A ground strap provides the most effective grounding and minimizes the likelihood of electrostatic damage Do not over torque the microwave K connector Excessive torque can damage connectors Make sure the optical connector is clean and undamaged before connecting it to the detector module Powering and Connecting the Photoreceiver Photodete
5. USER S GUIDE High Speed Receivers Models 1591 1592 1580 A 1544 A 1580 B 1544 B 1484 A and 1474 A High Speed Detectors Models 1480 S 1481 S 1414 1004 1014 1444 and 1024 1 New Focus A Newport Corporation Brand 3635 Peterson Way Santa Clara CA 95054 USA phone 408 980 5903 fax 408 987 3178 e mail techsupport newfocus com www newfocus com Warranty Newport Corporation guarantees its products to be free of defects for one year from the date of shipment This is in lieu of all other guarantees expressed or implied and does not cover incidental or consequential loss Information in this document is subject to change without notice Copyright 2001 1998 2013 Newport Corporation All rights reserved The New Focus logo and symbol are registered trademarks of Newport Corporation Document Number 90063253 Rev A Contents Operation Introduellop AA AA AE 5 Photoreceivers Amplified Photodiodes 5 Photodetectors Unamplified Photodiodes 6 Mechanical Optical Description aasa 7 Handling Precautions subia i n 9 Powering and Connecting the Photodector Photoreceiver 10 Connecting the Power Supply and Bias Monitor 10 Battery Check For Units with Internal Batteries 11 DC coupled Madules AA apta acea dac 11 Connecting the Optical Input to the Receiver 12 Troubleshooting Possible Problems and Solutions 13 Checking th
6. ay need to be repaired by New Focus It is possible the module will still operate well with a voltage only somewhat higher than 10 mV The user may wish to continue using the module and monitor this voltage to see if it degrades Basic Optical Test To quickly test your receiver run this simple optical test 1 Turn the receiver on 2 Using a voltmeter or oscilloscope measure the output voltage from the Bias Monitor on the front panel of the module With no light input the Bias Monitor voltage should be lt 10 mV Illuminate the photodetector 4 With the voltmeter or oscilloscope you should observe a DC output voltage If you know the optical power and wavelength you can calculate the expected output voltage Vout using the expression Vow E R G where P is the input optical power Watts R is the photodiode s responsivity A W found on the datasheet shipped with the unit and G is the Bias Monitor s transimpedance gain 1 V mA If the measured voltage is substantially less than expected the module may need to be returned to New Focus for repair Specifications 5 GHZz PhatoreckiVETS lansa 1591 1592 Table 1 12 GHz Optical Photoreceivers 1580 A 1544 A a Table 2 12 GHz DC coupled Photoreceivers 1580 B 1544 B Table 3 22 GHz Photoreceivers a Table 4 38 GHz Photoreceivers a Table 4 15 GHz Photodetectors a Table 5 25 GHz Photodetectors a Table 5 40 GHz Photodetectors La k
7. ctor Connecting the Power Supply and Bias Monitor 1 Prior to handling the detector ground yourself with a grounding strap to prevent electrostatic damage to the module Connect the power cable to your disabled power supply Two power cables were included with the receiver use the appropriate cable for your power supply Connecting to a New Focus 0901 power supply Using the appropriate cable connect one end of the cable to one of the power supply s 300 mA outputs and the other end to the module If the 300 mA outputs are in use the 300 mA banana plug output can also be used with the appropriate cable On older 0901 s the 100 mA banana plug output can provide enough current for certain models Check the current rating for your specific model in the Power Requirements section of the specifications table Connecting to another power supply Use the cable with the three pin power connector on one end and three banana plugs on the other end Be careful to connect the banana plugs to the power supply as follows connect the red plug to a 15 V source connect the black plug to a 15 V source connect the green plug to the common or ground of the two sources The 15 V sources must be able to provide at least the required current for your specific model Connect the three pin power connector to the module Microwave Connection and Set up A Connect the photoreceiver module s K connector to a test instrument or component that
8. e Dark Voltage rrr 14 Basic Optical ES rre 15 Characteristics opeciications ADS sided Ead aw ed a a FRE Ear de ER 16 Customer Service Technical Support spse R AKA KAKA KA e hh Eee Ee Ee Eh Ea 23 wl PAA 23 Appendices 1 Microwave Conne6tolSo esee ox seo e E EE ERE E ETE TES 24 2 Replacing the Battery ecuuuses rh ook e e 25 3 Difference between a time domain optimized detector and a frequency domain optimized detector 25 4 DC coupled Photoreceivers Crossover Region 27 Operation Introduction High speed and ultrahigh speed measurements of optical waveforms are easy with the New Focus photoreceiver photodetector modules These modules convert optical signals to electrical signals and can be used to provide every high speed high frequency instrument in your lab an optical input The small size of the modules allows you to connect them directly to your test instrument amplifier if needed or another high speed component This eliminates the need to follow the photoreceiver with coaxial cables which can distort time domain waveforms and attenuate CW microwave signals The optical signal is delivered to the photodiode in the module through a single mode or multimode optical fiber Photoreceivers Amplified Photodiodes For the photoreceiver models the photodiode is followed by a low noise linear high bandwidth amplifier This combines gain and low noise to reduce the input referred noise floor
9. en the module must be repaired by New Focus 2 Slow Response Verify that the power supply has sufficient voltage and current capability If the frequency or time domain response is slower than expected then most likely the photodiode or amplifier is damaged See Checking the Dark Voltage below A damaged photodiode must be replaced by New Focus If the dark voltage is okay then the problem is most likely a damaged amplifier and the module must be repaired by New Focus Severe mechanical shock may misalign the optics If the frequency response drops excessively from a low frequency up to several gigahertz or if the time response has a slow component then misalignment is a possibility and the module must be repaired by New Focus Little or No Response Verify that the power supply has sufficient voltage and current capability After ruling out a dirty or defective fiber and making sure there is no loss due mismatch of input fiber core diameter a damaged component is the most likely cause The module must be repaired by New Focus For assistance in troubleshooting or arranging for a repair please see the Customer Service section of this manual Checking the Dark Voltage db With no light entering the module turn on power to the detector Use a voltmeter to measure the Bias Monitor output voltage This voltage is the dark voltage If the dark voltage is 210 mV then the photodiode may be damaged and m
10. etector and a frequency domain optimized detector Circuitry in frequency domain optimized detectors is designed to produce a flat frequency response where the responsivity varies only slightly across the operating bandwidth Time domain optimized detectors in contrast produce clean ring free pulses By using Fourier transform methods you can show that clean ring free pulses result in a characteristic roll off in the frequency domain On the other hand a flat frequency response results in some controlled ringing in the impulse response 10 M 3 Response dB a o gt do S 40 Frequency Figure 7 Frequency Domain vs Time Domain A Detectors designed for flat frequency response have enhanced responsivities at high frequencies B Detectors that are optimized for clean ring free pulses show a characteristic drop off in 3 dB frequency response 25 0 6 Amplitude a u 0 4 Time Figure 8 Time Domain Optimized This is the impulse response of a detector that is optimized for the time domain You can see the characteristic frequency response in the figure above Po Amplitude a u es 9 z oo o 2 o Time Figure 9 Frequency Domain Optimized This is the impulse response of a detector that is optimized for a flat frequency response You can see the corresponding frequency response in figure above 26 Appendix 4 DC coupled Photoreceivers Crossover Region
11. g using the appropriate fiber In models with single mode fiber input the optical signal is delivered to the PIN photodiode through a O 1m 9 um core optical fiber For multimode input the signal is delivered through a B0 um or 62 5 um core graded index multimode fiber of the same length For 12 GHz models and faster an internal lens focuses the light onto the small high speed PIN photodiode There is no degradation in frequency response since the fiber is 0 1 m long In modules with a battery the fiber is protected by a sheet metal flange to prevent damage while replacing the battery New Focus offers several photodetectors and photoreceivers allowing you to match the wavelength bandwidth and fiber type of your application bias monitor port power indicator LED output 1 mV uA AC DC switch T Off On PWR Bias Optical Inpu Monito HJ eoe o fiber optic input connector FC Figure 2 Models 1580 A 1544 A 1544 A 50 1480 S 1481 S and 1481 5 50 Figure 3 Models 1414 1414 50 1004 1014 1024 1444 and 1444 50 Figure 4 Models 1484 A 1484 A 50 and 1474 A positive supply bias monitor port check output 1 mV uA power switch Off On Batt Cl hik Bias Optical Input Monitor 3 e fiber optic inpu connector FC battery check button bias monitor port output z1 mV uA power switch O a
12. has a 50 Ohm input impedance If necessary use a high frequency cable best performance is achieved without a cable B To avoid connector damage and signal distortion be sure that the cable and the instrument you intend to connect to the module have compatible connectors See Appendix Microwave Connectors After connecting to the supply enable or turn on the supply While the module can handle any power on sequence it is recommended that both positive and negative be turned on together If desired connect the Bias Monitor port to a voltmeter and observe the voltage level with no optical input This dark voltage should be lt 10 mV Changes from the dark level will be proportional to photocurrent and will provide a low frequency indication of signal strength If you are coupling light into a fiber use the voltmeter to monitor the photocurrent to help optimize the coupling Battery Check For Units with Internal Batteries Is 2 3 Turn on power using the Off On switch Connect a voltmeter to the Bias Monitor SMA connector Press the Batt Chk button The voltage should be 3 5 to 5 V 3 5 to 5 V for the 1004 detector When finished using the module turn off power to preserve battery life DC coupled Modules The 1591 1592 1580 B 1544 B and the 1544 B 50 have a front panel switch to select either the DC or AC coupled electrical output The DC coupled mode is indicated by a red light while the AC coupled
13. is Table 6 45 GHz Photodetectors a Table 6 18 ps Photodetectors L Table 7 12 ps Photodetector e7 Characteristics typical except as noted 5 GHz Photoreceivers Wavelength Range 450 870 950 1630 Bandwidth 3 dB DC GHz DC to 5 5 4 5 DC to 5 45 coupled typ min Low Frequency Cutoff AC coupled Risetime 10 9096 ps yw Conversion Gain typ min V W 600 500 1300 1100 NEP punta a7 Ouipat oe E Saturation Power Output Impedance 50 Bias Monitor Gain V mA Bias Monitor Bandwidth 1 Maximum Safe Input mw 1 8 1 1 2 5 5 50 15V 150 mA 15V 150 mA KA i 15 V 150 mA Detector Type Output Connector EE Anritsu K NN L Bias Monitor Output Impedance O Power Requirements Input Connector FC PC FC PC 62 5 um MM 62 5 um MM 10 35 10 35 nm kHz ps mW mW Ohm kHz hm Input Fiber Operating Temperature eC min max Table 1 12 GHz Fiber Optic Photoreceivers 1580 A 1544 A 1544 A 50 780 870 500 1630 780 1630 12 10 5 12 10 5 12 10 5 Low Frequency Risetime 10 90 p 32 32 4 27 a H 1552 G iain v W 5507 450 900 800 800 700 typ max 49 9 NEP pW rt Hz 2 Output Noise mVrms x N 72 Wavelength Range Bandwidth 3 dB 3 z Saturation Power 1 5 Maximum Safe 2 8 0 7 Input U ohm IT 3 Output Impedance Bias Monitor Gain
14. mode is indicated by a green light Connecting the Optical Input to the Receiver Be aware that if your fiber is multimode at the operation wavelength then excessive fiber length can lead to signal distortion If you have the multimode 50 model use 50 125 um graded index fiber If you have model 1591 1592 1580 A or 1580 B use 62 5 125 um graded index fiber Smaller core fibers including singlemode will also work well Before connecting to the photoreceiver verify the power in the fiber is within the safe operating range Make sure the fiber is clean and undamaged then connect the fiber optic cable to the module s input Troubleshooting Possible Problems and Solutions 1 Low Gain Verify that the power supply has sufficient voltage and current capability If your output signal is lower than expected a dirty input fiber may be causing the problem See Basic Optical Test below and verify that the input fiber is clean The photodiode can be damaged by electrostatic discharge or excessive optical power which leads to an increased dark voltage A damaged photodiode can result in excess leakage current lower responsivity or a slower frequency impulse response See Checking the Dark Voltage below A damaged photodiode must be replaced by New Focus Severe mechanical shock may misalign the optics and lower the responsivity See Basic Optical Test below If dirty fiber tips have been ruled out th
15. ng Temperature min max Table 4 FC PC FC PC FC PC sw om s 10 35 10 35 10 35 O 3 3 15 and 25 GHz Photodetectors Rese an ner oro nen pep po oo aa 400 870 400 400 870 750 870 500 1630 1630 360 1630 1630 ange Bandwidth Reine E 11 10 11 10 aes 17 15 14 12 ain Heme Saturation Power Maximum Safe Input Output Impedance Bias Monitor V Gain mA Bias Monitor Bandwidth Power Requirements Bias Monitor Output ng 15V 15V 15V Internal 9 V Internal 200 mA 200mA 200mA Battery 9 V Battery Detector Type InGaAs Impedance Output Connector Anritsu K Anritsu K AnritsuK Anritsu K Anritsu K basi FC PC FC PC FC PC FC PC FC PC Connector 2 5 um 50 um mer ar e SP 9 enm Operating 10 35 10 35 10 35 10 35 10 35 Temperature 20 min max Table 5 40 and 45 GHz Photodetectors mo HH H Joa Wavelength Range mm 400870 500 1690 Remos ps 93 9 nm ps 02 mw 5 mw 10 outputimpedance Taa 100 V mA kHz Ohm 2 F 2 0 5 100 k Bias Monitor Output Impedance Power Requirements Internal 9 V Internal 9 V i Battery Battery 5 5 1 O 5 2 io 5 3 1 Fee FORO Operating Temperature 10 35 10 35 min max Table 6 21 12 and 18 5 ps Photodetectors Wavelength Range d ps 165 185 165 185 11 19 esponse typ max i in2 Conversion Lana 17 15 14 12 1179 typ
16. of your system and maintains linearity at high output levels providing a high dynamic range The high output level also facilitates operation with logic circuits The high speed amplifier which follows the photodiode produces a clean impulse response with minimal ringing This is ideal for digital communication measurements Most receivers have a negative conversion gain due to the inverting amplifier used if you are using an oscilloscope and would like to see a positive output an inverting function can be used DC coupled For DC coupled receivers the DC coupling is achieved by summing the signal s DC component with the high speed 5 AC component at the output of an AC coupled high speed transimpedance amplifier The gain of the DC path is set equal to that of the AC path and temperature compensated so that extinction ratios may be accurately measured Photodetectors Unamplified Photodiodes Frequency Domain Optimized Applications that rely on transmitting signals at RF and microwave frequencies benefit from detectors with flat frequency responses and improved response at higher frequencies These applications include linear fiber optic transmission to and from remote antennas for communication satellites wireless cellular networks and cable television Since the time domain response is not critical in these applications the impulse response can have ringing In particular Models 1414 and 1014 detectors are frequency domain
17. optimized to provide especially flat frequency responses over wide bandwidths Time Domain Optimized If you need accurate reproduction of your signal in the time domain choose Model 1444 or 1024 time domain optimized detectors These models provide clean fast impulse responses with minimal ringing and are ideal for pulse measurements with digital high speed oscilloscopes Moreover they can be used in digital communications applications where spurious ringing can degrade eye diagrams and the bit error rate BER measurement of your system And because these detectors are internally terminated at 50 Q you won t have to worry about any reflections between the detector and filter for standardized BER testing with SDH and SONET filters Internal 9 V Battery Models 1414 1004 1014 1444 and 1024 combine an internal 9 V battery with the bias circuitry which make these self contained eliminating the need for an external power supply and reducing the possibility of photodiode damage due to overvoltage 6 Figure 1 Models 1591 1592 1580 B 1544 B and 1544 B 50 Mechanical Optical Description A gold plated microwave housing inside the module contains the high frequency circuitry This housing is bolted to a printed circuit board which regulates the bias for the high frequency components and amplifies the DC photocurrent for the monitor port The optical signal is brought from the front panel connector to the microwave housin
18. ping the unit back for evaluation and repair 23 Appendices Appendix 1 Microwave Connectors The performance you obtain when making high speed measurements depends in part on the instruments you use and how connections are made to the instruments Connect the male connector of the photoreceiver directly to the female connector of the instrument If you need to use an adapter make sure it is designed for your frequency range of interest The following table lists common connectors their upper frequency limit and mating compatibility If you use an intervening coaxial cable select a shorter cable to minimize loss and verify that its bandwidth rating is sufficient For more information please see the Optical Measurement section in the Application Notes selection guide on the Newport webpage In particular Application Note 1 Insights into High Speed Detectors and High Frequency Techniques Connector Type Frequency Limit GHz Compatibility BNC 4 SMA 18 or 26 b 3 5 mm K 3 5 mm 34 SMA K K 2 92 mm 40 SMA 3 5 2 4 mm 50 V V 1 85 mm 65 2 4 mm 24 Appendix 2 Replacing the Battery 1 Appendix 3 Turn off the module and remove the two screws on the back panel with a Phillips screwdriver Remove the back panel and replace the battery Replace the back panel Check the battery level as described above in the Battery Check section Difference between a time domain optimized d
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