New Focus 1480 User Manual Download

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U S E R ’ S G U I D E

15-GHz & 25-GHz
Photodetectors

Models 1480 & 1481

Includes Model 1481-50

These photodetectors are sensitive to electrostatic

discharges and could be permanently damaged if

subjected even to small discharges. Ground your-

self adequately prior to handling these detectors or

making connections. A ground strap provides the

most effective grounding and minimizes the

likelihood of electrostatic damage.

NEW FOCUS, Inc.

2630 Walsh Ave.• Santa Clara, CA 95051-0905• USA
phone: (408) 980-8088 • Fax: (408) 980-8883
e-mail: [email protected] • www.newfocus.com

1480 FC Det revA.fm Page 1 Monday, March 13, 2000 2:55 PM

Summary of Contents for 1480

Page 1: ...y damaged if subjected even to small discharges Ground your self adequately prior to handling these detectors or making connections A ground strap provides the most effective grounding and minimizes the likelihood of electrostatic damage NEW FOCUS Inc 2630 Walsh Ave Santa Clara CA 95051 0905 USA phone 408 980 8088 Fax 408 980 8883 e mail contact newfocus com www newfocus com ...

Page 2: ...om the date of shipment This is in lieu of all other guarantees expressed or implied and does not cover incidental or consequential loss Copyright 2000 New Focus Inc All rights reserved The symbol and NEW FOCUS Inc are registered trademarks of NEW FOCUS Inc Document Number 151095 Rev A ...

Page 3: ...ng the Detector to the Optical Input 9 Characteristics 11 Photodetector Characteristics 11 Bias Monitor Characteristics 12 Responsivity 12 Troubleshooting 13 Testing the Photodiode 13 Checking the DC Offset Voltage 13 Basic Optical Test 13 Cleaning the Fiber Connector 14 Customer Service 17 Technical Support 17 Service 17 Appendix I Microwave Connectors 19 Appendix II Inside the Photodetector 20 ...

Page 4: ...4 Contents NEW FOCUS Inc ...

Page 5: ... photodiode bias circuit and battery are self contained eliminating the hassle of external power supplies and expensive bias networks and reducing the possibility of photodiode damage due to overvoltage The Models 1480 and 1481 use a GaAs PIN photodiode designed for high responsivity in the 780 870 nm wavelength range The high speed circuitry produces a clean impulse response making these models i...

Page 6: ...utions Prior to handling the detector or making connections be sure to ground yourself adequately even small electrostatic discharges could permanently damaged 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 cl...

Page 7: ...age 6 2 Remove the module from its case 3 Turn on power using the Off On switch If you are using the detector for the first time or you wish to check the battery and DC offset perform steps 4 5 and 6 4 Connect a voltmeter to the Bias Monitor SMA connector 5 Press the Batt Chk button The voltage should be at least 3 5 V 6 Release the Batt Chk button Without an optical input the voltage should be le...

Page 8: ...Chk button and observe the bias monitor output The photodiode bias voltage is momentarily applied to the Bias Monitor SMA connector A reading of 5 V on this connector is typical with a new battery the battery should be replaced when the voltage reaches 3 5 V 4 Release the Batt Chk button and observe the voltage level on the voltmeter Without an optical input this voltage is the DC offset plus dark...

Page 9: ...nector damage and signal distortion be sure that the cable and the instrument you intend to connect to the module have compatible connectors See Appendix I Microwave Connectors on page 19 for a list of compatible connectors Connecting the Detector to the Optical Input 1 Measure the peak power in the fiber prior to con nection to the module to be sure it is within the safe operating range see Photo...

Page 10: ...10 Operation NEW FOCUS Inc ...

Page 11: ...rsion Gain 10 V W 10 V W Responsivity 0 4 A W 0 4 A W Output Impedance 50 Ω 50 Ω Minimum NEP 45 pW 45 pW cw Saturation Power 5 mW 2 mW Detector Material Type GaAs PIN GaAs PIN Detector Diameter 65 µm 25 µm Input Fiber Core Diameter 50 version 62 5 µm multimode N A 9 µm single mode 50 µm multimode Power Requirements Internal 9 V battery Internal 9 V battery Optical Input Connector FC PC FC PC Elect...

Page 12: ...dicted responsivity of the Models 1480 and 1481 is shown below Figure 2 Responsivity vs wavelength for Models 1480 1481 Model 1480 1481 DC Gain 1 mV µA 1 mV µA DC Offset max 10 mV 10 mV Output Impedance 10 kΩ 10 kΩ Bandwidth 50 kHz 50 kHz 0 1 0 0 2 0 3 0 4 0 5 700 600 800 900 Wavelength nm Responsivity A W ...

Page 13: ... the DC Offset Voltage below Checking the DC Offset Voltage 1 With no light on the photodetector turn the detector on 2 Use a voltmeter to measure the Bias Monitor output voltage This voltage is the DC offset plus dark current 3 If the output is 10 mV then the detector is probably damaged and will need to be returned to New Focus If the output is 10 mV then perform the Basic Optical Test described...

Page 14: ...as monitor port is 1000 V A If the output voltage is low then the fiber connector may be dirty see Cleaning the Fiber Connector below If you suspect the unit is damaged contact New Focus to arrange for a repair see Customer Service on page 17 Cleaning the Fiber Connector The high speed photodetectors have an internal fiber connector and a fiber pigtail that brings the input light to the detector I...

Page 15: ...m and carefully slide the detector housing off Caution For steps 6 8 be extremely careful not to pull on the fiber The fiber is not designed to withstand excessive stress where it connects to the microwave housing 6 Carefully disconnect the fiber connector from the fiber receptacle attached to the front panel of the detector 7 The front surface of the fiber can be cleaned using acetone or alcohol ...

Page 16: ...16 Troubleshooting NEW FOCUS Inc ...

Page 17: ...sponse ask for Technical Support and know the model number for your receiver The model number is printed on the front panel of the receiver Phone 408 980 8088 Fax 408 980 8883 Support is also available by email Email techsupport newfocus com We typically respond to email within one business day Service In the event that your photodetector malfunctions or becomes damaged please contact New Focus fo...

Page 18: ...18 Customer Service NEW FOCUS Inc ...

Page 19: ...Even if you are not using an intervening cable performance can be degraded if an improper adapter is chosen for mating to the instrument Common SMA connectors for example are intended for use only to 18 GHz The following table lists a few connectors and the frequency ranges in which they may be used For more information request Application Note 1 Connector Frequency Range Compatibility BNC DC 2 GH...

Page 20: ... photodiode and amplifies the DC photocurrent for the monitor port The optical signal is brought from the front panel connector to the microwave housing with 9 cm fiber The fiber is protected by a sheet metal flange to prevent damage while changing the battery A simplified schematic is provided below Figure 3 Simplified schematic of the Models 1480 1481 photodetector modules V V V V V V V Microwav...

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