Keysight Technologies 81610A User manual

Keysight 81610A/11A/12A/
13A/14A
Return Loss Module
User’s Guide

Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 3

4 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
Notices
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No part of this document may reproduced in (including
electronic storage and retrieval or translation into a foreign
language) without prior agreement and written consent from
Keysight Technologies Deutschland GmbH as governed by
United States and international copywright laws.
©Copyright 2000, 2015 by:
Keysight Technologies Deutschland GmbH
Herrenberger Str. 130
71034 Böblingen
Germany
Subject Matter
The material in this document is subject to change without
notice.
Keysight Technologies makes no warranty of any kind with
regard to this printed material, including, but not limited to, the
implied warranties of merchantability and fitness for a
particular purpose.
Keysight 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.
Printing History
New editions are complete revisions of the guide reflecting
alterations in the functionality of the instrument. Updates are
occasionally made to the guide between editions. The date on
the title page changes when an updated guide is published. To
find out the current revision of the guide, or to purchase an
updated guide, contact your Keysight Technologies
representative.
Control Serial Number: First Edition applies directly to all
instruments.
Warranty
This Keysight Technologies instrument product is warranted
against defects in material and workmanship for a period of one
year from date of shipment. During the warranty period,
Keysight 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 Keysight. Buyer shall prepay
shipping charges to Keysight and Keysight shall pay shipping
charges to return the product to Buyer. However, Buyer shall
pay all shipping charges, duties, and taxes for products returned
to Keysight from another country.
Keysight warrants that its software and firmware designated by
Keysight for use with an instrument will execute its
programming instructions when properly installed on that
instrument. Keysight does not warrant that the operation of the
instrument, software, or firmware will be uninterrupted or error
free.
Limitation of Warranty
The foregoing warranty shall not apply to defects resulting from
improper or inadequate maintenance by Buyer, Buyer-supplied
software or interfacing, unauthorized modification or misuse,
operation outside of the environmental specifications for the
product, or improper site preparation or maintenance.
No other warranty is expressed or implied. Keysight
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
remedies. Keysight Technologies shall not be liable for any
direct, indirect, special, incidental, or consequential damages
whether based on contract, tort, or any other legal theory.
Assistance
Product maintenance agreements and other customer assistance
agreements are available for Keysight Technologies products.
For any assistance contact your nearest Keysight Technologies
Sales and Service Office.
Certification
Keysight Technologies certifies that this product met its
published specifications at the time of shipment from the
factory.
Keysight 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
calibration facilities of other International Standards
Organization members.
ISO 9001 Certification
Produced to ISO 9001 international quality system standard as
part of our objective of continually increasing customer
satisfaction through improved process control.
Edition 6:
81610-90A15
February 2015
Edition 1:
81610-90014 E0900
September 2000
Edition 2:
81610-90014 E1000
October 2000
Edition 3:
81610-90014 E0201
February 2001
Edition 4:
81610-90014 E0401
April 2001
Edition 5:
81610-90A15
February 2002

Safety Symbols Safety Considerations
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 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.
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.
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.

Safety Considerations Line Power Requirements
6 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
Line Power Requirements
Keysight 81610A/13A Return Loss Modules operate when installed in the
Keysight 8163A/B Lightwave Multimeter, Keysight 8164A/B Lightwave
Measurement System, and Keysight 8166A/B Lightwave Multichannel System.
Operating Environment
The safety information in the Keysight 8163A/B Lightwave Multimeter,
Keysight 8164A/B Lightwave Measurement System, and Keysight 8166A/B
Lightwave Multichannel System User’s Guide summarizes the operating
ranges for Keysight 81610A/13A Return Loss Modules. In order for these
modules to meet specifications, the operating environment must be within the
limits specified for the Keysight 8163A/B Lightwave Multimeter,
Keysight 8164A/B Lightwave Measurement System, and Keysight 8166A/B
Lightwave Multichannel System.
Storage and Shipment
This 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.
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.).
You MUST return instruments with malfunctioning laser modules to a
Keysight Technologies Service Center for repair and calibration.

Initial Safety Information for Return Loss Modules Safety Considerations
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 7
Initial Safety Information for
Return Loss 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:
Table 1 Return Loss Modules Laser Safety
Information
Keysight 81613A
Laser type FP-Laser
InGaAsP
Wavelength (±15nm) 1550/1625 nm
Max. CW output power* <1.8mW
Beam waist diameter 9 µm
Numerical aperture 0.1
Laser Class according to IEC 60825-1 (2007) 1
Max. permissible CW output power 10 mW
* Max. CW output power is defined as the highest possible optical pow-
er that the laser source can prodcue at its output connector

Safety Considerations Initial Safety Information for Return Loss Modules
8 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
Laser Safety Labels
Laser class 1 label
Figure 1 Class 1 Safety Label - Keysight 81613A
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 source when there is no fiber attached to the optical
output connector.
• The laser is enabled by pressing the gray 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.

Environmental Information Safety Considerations
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 9
Environmental Information
This product complies with the WEEE Directive (2002/96/EC) marking
requirements. The affixed label indicates that you must not discard this
electrical/ electronic product in domestic household waste.
Product Category: With reference to the equipment types in the WEEE
Directive Annex I, this product is classed as a "Monitoring and Control
instrumentation" product.
Do not dispose in domestic household waste.
To return unwanted products, contact your local Keysight office, or see
http://about.keysight.com/en/companyinfo/environment/takeback.shtml for
more information.

Safety Considerations The Structure of this Manual
10 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
The Structure of this Manual
This manual is divided into two categories:
• Getting Started
This section gives an introduction to the Tunable Laser modules. and aims to
make these modules familiar to you:
–“Getting Started with Return Loss” on page 15.
• Additional Information
This is supporting information of a non-operational nature. this contains
information concerning accessories, specifications, and performance tests:
–“Accessories” on page 47,
–“Specifications” on page 49
–“Performance Tests” on page 59
Conventions used in this manual
• Hardkeys are indicated by italics, for example, Config, or Channel.
• Softkeys are indicated by normal text enclosed in square brackets, for
example, [Menu] or [Details].
• Parameters are indicated by italics enclosed by square brackets, for example,
[RLref], or [Para].
• Menu items are indicated by italics enclosed in brackets, for example,
<Terminated Calibration>, or <Continuous>.

Table of Contents
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 11
Table of Contents
Safety Considerations 5
Safety Symbols 5
Initial Inspection 5
Line Power Requirements 6
Operating Environment 6
Storage and Shipment 6
Initial Safety Information for Return Loss Modules 7
Laser Safety Labels 8
Environmental Information 9
The Structure of this Manual 10
Conventions used in this manual 10
Getting Started with Return Loss 15
The Return Loss Module 16
A Description of the Front Panel 18
Optical Output 18
What is Return Loss? 19
What is Insertion Loss? 20
How to Choose a Light Source 21
Calibration Measurements 22
Making a Return Loss Measurement 22
Setup 23
Calibrating the Return Loss Module 25
Calibration using the Keysight 81000BR Reference Reflector
26
Reflectance Calibration 26
Termination Calibration 28
Calibration using the Keysight 81610CC Reference Cable 29
Reflectance Calibration 29
Front Panel Delta Calibration 30
Termination Calibration using the Measurement Patchcord 32
How to Measure Return Loss 34
Viewing the Calibration Values 35

Table of Contents
12 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
A Background to Return Loss Measurement 38
Measuring the Reflected Power from a Component with
Known Reflection Factor 38
Measuring the Power Transmitted Through the Reflection
Reference 39
Measuring the Power when there are No Reflections 39
Measuring the Power Transmitted Through the Measurement
Patchcord 40
Measuring the Reflections from the DUT 40
Measuring the Power Transmitted Through the DUT 41
Calculating the Return Loss of the DUT 41
Calculating the Front Panel Delta 43
Calculating the Insertion Loss of the DUT 45
Accessories 47
Modules and Options 48
Specifications 49
Definition of Terms 50
Return Loss 50
Return loss of the reference cable 50
Dynamic Range 51
External Input Power Range 51
External Input Damage Power 51
Center Wavelength 51
Wavelength Range 51
Relative Uncertainty 51
Total Uncertainty 53
Plug & Play 53
Return Loss Module Specifications 54
Return Loss Module Specifications with Internal Source
56
Performance Tests 59
Equipment Required 60
Test Record 61
Test Failure 61

Table of Contents
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 13
Instrument Specification 61
Performance Test Instructions 62
Keysight 81610A: Relative Uncertainty of Return Loss and
Dynamic Range Test 62
Example for Keysight 81610A Return Loss module 66
Keysight 81610A/13A: Relative Uncertainty of Return Loss
and Dynamic Range 67
Calibrating the 81610CC Reference Cable 72
Cleaning Information 87
Safety Precautions 88
Why is it important to clean optical devices? 88
What do I need for proper cleaning? 89
Standard Cleaning Equipment 89
Dust and shutter caps 89
Isopropyl alcohol 90
Cotton swabs 90
Soft tissues 90
Pipe cleaner 91
Compressed air 91
Additional Cleaning Equipment 92
Microscope with a magnification range about 50X up to 300X 92
Ultrasonic bath 92
Warm water and liquid soap 92
Premoistened cleaning wipes 93
Polymer film 93
Infrared Sensor Card 93
Preserving Connectors 93
Cleaning Instrument Housings 94
Which Cleaning Procedure should I use ? 94
How to clean connectors 95
How to clean connector adapters 96
How to clean connector interfaces 97
How to clean bare fiber adapters 98
How to clean lenses 99
How to clean instruments with a fixed connector
interface 99
How to clean instruments with an optical glass plate 101

Table of Contents
14 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
How to clean instruments with a physical contact
interface 101
How to clean instruments with a recessed lens interface
102
How to clean optical devices which are sensitive to
mechanical stress and pressure 103
How to clean metal filters or attenuator gratings 104
Additional Cleaning Information 105
How to clean bare fiber ends 105
How to clean large area lenses and mirrors 105
Other Cleaning Hints 107

Getting Started with Return Loss
This chapter describes the use of use the Keysight 81610A Return Loss
module.
Here you will find:
• an introduction to the features of the module, its front panel, and connectors.
• a brief explanation of the terms Return Loss and Insertion Loss,
• a description of how to use the module to measure Return Loss and Insertion
Loss,
• a brief discussion of the theoretical background to Return Loss
measurements using Keysight 8161x series Return Loss modules.

Getting Started with Return Loss The Return Loss Module
16 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
The Return Loss Module
What is a Return Loss Module? Keysight 8161xA series Return Loss modules are compact modules for use
with the Keysight 8163B Lightwave Multimeter, the Keysight 8164B
Lightwave Measurement System, and the Keysight 8166B Lightwave
Multichannel System. They are used for making return loss measurements and,
in conjunction with a power meter module, insertion loss measurements.
A return loss module allows you to measure the light reflected and scattered as
light passes through an optical component. In many applications, these affects
are unwanted because thay can affect the emission characteristecs of any laser
in the system.
Keysight 81610A Return Loss
module
The Keysight 81610A Return Loss Module includes a power sensor, monitor
diode and two couplers in one module.
Figure 2 The Keysight 81610A Return Loss module
The Keysight 81610A series Return Loss module does not include an internal
laser source. It is used in conjunction with an appropriate external source to
perform return loss measurements on both WDM components and broadband
devices.
Mdut
Pdut
External Laser
Source
Output 9/125 μm
physical contact

The Return Loss Module Getting Started with Return Loss
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 17
Keysight 81613A
Return Loss modules
Keysight 81613A Return Loss module include a power sensor, monitor diode,
three couplers, and two internal laser source in one module. They are for use in
the Keysight 8163B Lightwave Multimeter, the Keysight 8164B Lightwave
Measurement System, and the Keysight 8166B Lightwave Multichannel
System for making return loss measurements.
Figure 3 The Contents of the Keysight 81613A Return Loss modules
All Keysight 8161x series Return Loss modules include a monitor diode to
compensate for power variation in the light source.
Mdut
Pdut
External Laser
Source
Output 9/125 μm
Internal Laser
Sources
physical contact

Getting Started with Return Loss The Return Loss Module
18 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
A Description of the Front Panel
Figure 4 Front Panel of Keysight 816010A/13A Return Loss Modules
Inserting the module The procedure for inserting a module into your mainframe is described in your
mainframe’s User’s Guide.
Optical Output
Keysight 8161x series Return Loss modules are equipped with angled (8°)
contact optical input and output connectors.
Figure 5 Angled Contact Connector Symbols
Figure 5 shows the symbol for angled contact connectors. This symbol is
colored green.
Angled Contact
Connector Symbol
• In order to obtain reliable return loss values connectors must be in good
condition.
Damage to connectors is not included in the warranty for the Keysight 8161x
series Return Loss modules

What is Return Loss? Getting Started with Return Loss
Keysight 81610A/11A/12A/13A/14A Return Loss Module, Edition 6 19
What is Return Loss?
When light passes through an optical component most of it travels in the
intended direction, but some light is reflected or scattered. In many applications
these reflections are unwanted, because they can affect the emission
characteristics of any laser in the system. In such applications, it is important to
measure the reflections for the components of the system.
The reflection factor for a component is a measure of how much light the
component reflects. It is a ratio of the power reflected by the device to the
power incident on the device. More normally we talk about the return loss of a
component. The return loss has units of dB. Return loss is given by:
Return loss can be measured in several ways. A typical setup using the
Keysight 81610A Return Loss module, where the DUT is a connector pair, is
described in Figure 6.
Figure 6 Return Loss Equipment
Return Loss dB() 10 Reflection Factor()dB()log–=
Return Loss dB() 10 Reflected Power
Incident Power
--------------------------------------------- dB()log–=
or
Mdut
Pdut Termination
Knot
DUT
External Laser
Source
patchcord
physical contact
Keysight 81113PC

Getting Started with Return Loss What is Insertion Loss?
20 Keysight 81610A/11A/12A/13A/14A Return Loss Module,
Edition 6
What is Insertion Loss?
Light that is absorbed, scattered, or reflected by a component also affects how
much light a component transmits.
The transmission factor for a component is a measure of how much light the
component transmits. It is a ratio of the power transmitted by the device to the
power incident on the device. More normally we talk about the Insertion Loss
of a component. The insertion loss has units of dB. Insertion Loss is given by:
Insertion Loss can be measured in several ways.
A typical setup using the Keysight 81610A Return Loss module, where the
DUT is a connector pair, is described in Figure 7
Figure 7 Measuring the Power transmitted through the Device Under Test
You can use Eil to calculate the insertion loss, see “Calculating the Insertion
Loss of the DUT” on page 45
Insertion Loss dB() 10 Transmission Factor()dB()log–=
Insertion Loss dB() 10 Transmitted Power
Incident Power
----------------------------------------------------



dB()log–=
or
Mil DUT
Power Meter
Eil
81610A
Reflectivity
RDUT
External Laser
Source
patchcord
physical contact
81113PC