Keysight Technologies 81940A User manual

Keysight 81940A, 44A, 49A,
80A & 89A Compact Tunable
Laser Source Modules
User’s Guide

Notices
© Keysight Technologies 2002 - 2015
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Manual Part Number
81980-90A11
Edition
Edition 5, March 2015
Edition 4, April 2005
Edition 3, January 2005
Edition 2, July 2004
Edition 1, October 2003
Printed in Germany
Keysight Technologies, Deutschland
GmbH
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71034 Böblingen, Germany.
Subject Matter
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The hardware and/or software
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Safety Notices
CAUTION
A CAUTION notice denotes a
hazard. It calls attention to an
operating procedure, practice, or
the like that, if not correctly
performed or adhered to, could
result in damage to the product
or loss of important data. Do not
proceed beyond a CAUTION
notice until the indicated
conditions are fully understood
and met.
WARNING
A WARNING notice denotes a
hazard. It calls attention to an
operating procedure, practice,
or the like that, if not correctly
performed or adhered to, could
result in personal injury or
death. Do not proceed beyond a
WARNING notice until the
indicated conditions are fully
understood and met.

Keysight Technologies Sales and Service Offices
For more information about Keysight Technologies test and measurement
products, applications, services, and for a current sales office listing, viesit
our web site:
http://www.keysight.com/find/lightwave
You can also contact one of the following centers and ask for a test and
measurement sales representative.
United States: 1 800 829 4444
1 800 829 4433 (FAX)
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In This Guide...
Chapter 1, “Getting Started.
This chapter contains an introductory description of the modules and aims
to make the modules familiar to you.
Chapter 2, “Accessories.
This chapter contains details of the various modules and options available.
Chapter 3, “Specifications.
This chapter contains the full performance specifications for the modules.
Chapter 4, “Performance Tests.
This chapter contains full detailed instructions that enable you to run a
performance test on a High Power Optical Attenuator. Also included are
Test Report sheets to record the measurements taken during the
performance test.
Chapter 5, “Cleaning Information.
This appendix contains information as to how best clean your instrument,
along with some general safety instructions that you should follow when
cleaning your instrument.

Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 5
Table of Contents
Getting Started 11
Safety Considerations 12
Safety Symbols 12
Initial Inspection 13
Line Power Requirements 13
Operating Environment 13
Input/Output Signals 14
Storage and Shipment 14
Initial Safety Information for Tunable Laser Modules 15
Laser Safety Labels 16
Introduction 17
Typical Use Models 20
Optical Output 22
Polarization Maintaining Fiber 22
Angled and Straight Contact Connectors 23
Signal Input and Output 24
Accessories 25
Modules and Options 26
Modules 27
Options 27
Connector Interfaces 28
User’s Guides 29
Specifications 31
Definition of Terms 32
General Definitions 46
Compact Tunable Laser Module Specifications 47
Conditions 53
Supplementary Performance Characteristics 54
General 56

6Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5
Performance Tests 57
Required Test Equipment 58
Test Record 59
Performance Test Instructions 60
General test Setup 60
Wavelength Tests 61
Wavelength Meter Settings for all Wavelength Tests 61
Wavelength Accuracy 62
Absolute and Relative Wavelength Accuracy 62
Mode-Hop Free Tuning 66
Wavelength Repeatability 67
Power Tests 69
Maximum Output Power 69
Power Linearity 74
Power Flatness versus Wavelength 77
Power Stability 80
Signal-to-Source Spontaneous Emission Ratio 83
Optional Performance Tests 86
Signal-to-Total-Source Spontaneous Emission Ratio 86
Test Records 90
Test Record 91
Test Record 101
Test Record 111
Test Record 118
Test Record 128
Cleaning Information 139
Cleaning Instructions 140
Safety Precautions 140
Why is it important to clean optical devices ? 141
What do I need for proper cleaning? 142
Preserving Connectors 146
Cleaning Instrument Housings 146
Which Cleaning Procedure should I use? 147
How to clean connectors 148
How to clean connector interfaces 150

Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 7
How to clean bare fiber adapters 151
How to clean instruments with a fixed connector interface 152
Additional Cleaning Information 153
Other Cleaning Hints 154
Index 155

8Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5

Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 9
List of Figures
Figure 1 Class 1M Safety Label - 81980A, 81940A, 81944A, 81980A, 81949A 16
Figure 2 Keysight 81980A Compact Tunable Laser Modules 17
Figure 3 Keysight 81940A Compact Tunable Laser Modules 18
Figure 4 Keysight 81989A Compact Tunable Laser Modules 18
Figure 5 Keysight 81949A Compact Tunable Laser Modules 19
Figure 6 PMF Output Connector 22
Figure 7 Angled and Straight Contact Connector Symbols 23
Figure 8 Mainframes, Tunable Laser Modules, and Options 26
Figure 9 Maximum Output Power vs. Wavelength, Maximum Flat Output Power
vs. Wavelength 36
Figure 10 Circular traces on the Poincaré sphere used to calculate polarization
extinction ratio. 38
Figure 11 Power flatness vs. wavelength. 39
Figure 12 Power linearity. 39
Figure 13 Power stability. 40
Figure 14 Relative wavelength accuracy. 41
Figure 15 Signal to source spontaneous emission ratio. 43
Figure 16 Signal to total source spontaneous emission ratio. 44
Figure 17 Test Setup for Wavelength Tests 61
Figure 18 Absolute and Relative Wavelength Accuracy. 63
Figure 19 Mode-hop free Tuning Range. 66
Figure 20 Wavelength Repeatability. 67
Figure 21 Maximum Output Power. 69
Figure 22 Test Setup for Maximum Output Power Tests 70
Figure 23 Test Setup for Maximum Output Power Tests 71
Figure 24 Power Linearity 74
Figure 25 Test Setup for Power Linearity Tests 75
Figure 26 Power Flatness 77
Figure 27 Test Setup for Power Linearity Tests 78
Figure 28 Stability of Output Power vs Time 80
Figure 29 Test Setup for Power Stability Tests 81
Figure 30 Signal-to-source spontaneous emission ratio 83
Figure 31 Test Setup for Source Spontaneous Emission Test. 84
Figure 32 Total SSE Measurement. 86
Figure 33 Test Setup for Source Spontaneous Emission Test. 87

10 Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5

1
Getting Started
This chapter provides a general description of Keysight 81940A, 44A, 49A,
80A & 89A Tunable Laser Source Familys.
Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Line Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Operating Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Input/Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Initial Safety Information for Tunable Laser Modules . . . 15
Laser Safety Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
What is a Tunable Laser Source? . . . . . . . . . . . . . . . . . . . . . . . . .17
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Front Panels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Front Panel Controls and Indicators. . . . . . . . . . . . . . . . . . . . . . .19
Typical Use Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Optical Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Polarization Maintaining Fiber . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Angled and Straight Contact Connectors . . . . . . . . . . . . . . . . . . 23
Signal Input and Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Getting Started Safety Considerations
12 Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5
Safety Considerations
The following general safety precautions must be observed during all
phases of operation, service, and repair of this instrument. Failure to
comply with these precautions or with specific warnings elsewhere in this
manual violates safety standards of design, manufacture, and intended
use of the instrument. Keysight Technologies assumes no liability for the
customer’s failure to comply with these requirements.
Before operation, review the instrument and manual, including the red
safety page, for safety markings and instructions. You must follow these to
ensure safe operation and to maintain the instrument in safe condition.
Safety Symbols
The apparatus will be marked with this symbol when it is necessary for the
user to refer to the instruction manual in order to protect the apparatus
against damage.
Hazardous laser radiation.
The WARNING sign denotes a hazard. It calls attention to a
procedure, practice or the like, 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.
CAUTIONWARNING

Safety Considerations Getting Started
Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 13
Initial Inspection
Inspect the shipping container for damage. If there is damage to the
container or cushioning, keep them until you have checked the contents of
the shipment for completeness and verified the instrument both
mechanically and electrically.
The Performance Tests give procedures for checking the operation of the
instrument. If the contents are incomplete, mechanical damage or defect
is apparent, or if an instrument does not pass the operator’s checks, notify
the nearest Keysight Technologies Sales/Service Office.
Line Power Requirements
The Keysight 81980A, 81940A, 81944A, 81989A and 81949A Compact
Tunable Laser Source modules operate when installed in
Keysight 8163A/B Lightwave Multimeters, Keysight 8164A/B Lightwave
Measurement Systems, and Keysight 8166A/B Lightwave Multichannel
Systems.
Operating Environment
The safety information in your mainframe’s User’s Guide summarizes the
operating ranges for the Keysight 81980A, 81940A, 81944A, 81989A and
81949A Compact Tunable Laser Source modules. In order for these
modules to meet specifications, the operating environment must be within
the limits specified for your mainframe.
To avoid hazardous electrical shock, do not perform electrical
tests when there are signs of shipping damage to any portion of
the outer enclosure (covers, panels, etc.).
CAUTIONWARNING
You MUST return instruments with malfunctioning laser modules
to a Keysight Technologies Sales/Service Center for repair and
calibration.
CAUTIONWARNING

Getting Started Safety Considerations
14 Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5
Input/Output Signals
Storage and Shipment
A Keysight 81980A, 81940A, 81944A, 81989A or 81949A Compact Tunable
Laser Source module can be stored or shipped at temperatures between
- 40°C and + 70°C.
Protect the module from temperature extremes that may cause
condensation within it.
There is one BNC input connector on the front panel of a
Keysight 81980A, 81940A, 81944A, 81989A or 81949A Compact
Tunable Laser Source module.
An absolute maximum of ±6 V can be applied as an external voltage
to any BNC connector.
CAUTION

Initial Safety Information for Tunable Laser Modules Getting Started
Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 15
Initial Safety Information for
Tunable Laser Modules
The laser sources specified by this user guide are classified according to
IEC 60825-1 (2007).
The laser sources comply with 21 CFR 1040.10 except for deviations
pursuant to Laser Notice No. 50 dated 2007-June-24:
Keysight 81980A Keysight 81940A 81944A Keysight 81989A Keysight 81949A
Laser Type ECL-Laser
InGaAsP
ECL-Laser
InGaAsP
ECL-Laser
InGaAsP
ECL-Laser
InGaAsP
ECL-Laser
InGaAsP
Wavelength range 1465 nm-1575 nm 1520 nm-1630 nm 1525 nm-1620 nm 1465 nm-1575 nm 1520 nm-1630 nm
Max. CW output power* 30 mW 30 mW 30 mW 30 mW 30 mW
Beam waist diameter 9 µm 9 µm 9 µm 9 µm 9 µm
Numerical aperture 0.1 0.1 0.1 0.1 0.1
Laser Class according to
IEC 60825-1 (2007)
1M 1M 1M 1M 1M
Max. permissible CW
output power**
163 mW 163 mW 163 mW 163 mW 163 mW
* Max. CW output power is defined as the highest possible optical power that the laser source can produce at its output
connector.
** Max. permissible CW output power is the highest optical power that is permitted within the appropriate laser class.

Getting Started Laser Safety Labels
16 Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5
Laser Safety Labels
Laser class 1M label
A sheet of laser safety labels is included with the laser module as required.
In order to meet the requirements of IEC 60825-1 we recommend that you
stick the laser safety labels, in your language, onto a suitable location on
the outside of the instrument where they are clearly visible to anyone
using the instrument.
Figure 1Class 1M Safety Label - 81980A, 81940A, 81944A, 81980A, 81949A
Please pay attention to the following laser safety warning:
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.
The laser is enabled by pressing the ’active’ button close to the
optical output connector on the front panel of the module. The
laser is on when the green LED on the front panel of the instrument
is lit.
The use of optical instruments with this product will increase eye
hazard.
The laser module has a built-in safety circuitry which will disable
the optical output in the case of a fault condition
Refer servicing only to qualified and authorized personnel.
CAUTIONWARNING

Introduction Getting Started
Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5 17
Introduction
What is a Tunable Laser Source?
A Tunable Laser Source (TLS) is a laser source for which the wavelength
can be varied through a specified range. The Keysight Technologies range
of TLS modules also allow you to set the output power, and to choose
between continuous wave or modulated power.
The Keysight Technologies range of compact TLS modules are flexible
stimulus modules suitable for applications such as the testing of optical
amplifiers, DWDM components, and complete DWDM systems.
Installation
The Keysight 81940A, 44A, 49A, 80A & 89A Tunable Laser Source Familys
are front-loadable modules.
For a description of how to install your module, refer to “How to Fit and
Remove Modules” in the Installation and Maintenance chapter of your
mainframe’s User’s Guide.
Front Panels
Figure 2Keysight 81980A Compact Tunable Laser Modules
Angled Contact Connector
Keysight 81980A with
Straight Contact Connector
Keysight 81980A with

Getting Started Introduction
18 Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS modules, Edition 5
Figure 3Keysight 81940A Compact Tunable Laser Modules
Figure 4Keysight 81989A Compact Tunable Laser Modules
Angled Contact Connector
Keysight 81940A with
Straight Contact Connector
Keysight 81940A with
Angled Contact Connector
Keysight 81989A with
Straight Contact Connector
Keysight 81989A with