IEC TR 61292-7:2011

Optical amplifiers - Part 7: Four wave mixing effect in optical amplifiers

IEC/TR 61292-7:2011(E) applies to optical amplifiers (OAs) using active fibres and waveguides, containing rare-earth dopants, currently commercially available. It provides guidance on crosstalk caused by the four-wave mixing (FWM) effect. The object of this technical report is to provide introductory information for understanding of the crosstalk issue raised by the FWM effect.

General Information

• Status: Published
• Publication Date: 23-Nov-2011
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.160.10 - Amplifiers
• ICS: 33.180.30 - Optic amplifiers
• Technical Committee: SC 86C - Fibre optic systems and active devices
• Drafting Committee: WG 3 - TC 86/SC 86C/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 29-Feb-2012
• Completion Date: 24-Nov-2011

Standards Content (Sample)

IEC/TR 61292-7 ®
Edition 1.0 2011-11
TECHNICAL
REPORT
Optical amplifiers –
Part 7: Four wave mixing effect in optical amplifiers

IEC/TR 61292-7:2011(E)
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IEC/TR 61292-7 ®
Edition 1.0 2011-11
TECHNICAL
REPORT
Optical amplifiers –
Part 7: Four wave mixing effect in optical amplifiers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
S
ICS 33.160.10; 33.180.30 ISBN 978-2-88912-803-7

– 2 – TR 61292-7 © IEC:2011(E)
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope and object . 6
2 Normative references . 6
3 Abbreviated terms . 6
4 FWM effect in EDFAs . 7
4.1 General . 7
4.2 Introduction of the FWM effect . 7
4.3 FWM crosstalk enhancement in EDFA . 8
Annex A (informative) A technique for measurement of four wave mixing effect in OAs . 10
Annex B (informative) Underestimation of FWM crosstalk by reduced number of WDM

inputs . 18
Bibliography . 21

Figure 1 – Example of generation of FWM light . 8
Figure 2 – Examples of EDFA with FWM effect . 9
Figure A.1 – Basic measurement set-up . 10
Figure A.2 – Measurement flow chart . 14
Figure A.3 – Calculation of crosstalk . 16
Figure B.1 – Total number of combinations and number of combinations without the
FWM channel that contribute to the FWM product generation for each channel number . 19
Figure B.2 – Total channel number dependence of the ratio of the number of the
combinations under the condition f = f over the total number of combinations . 19
F r
Figure B.3 – Calculated FWM signal power when all the signal channels are input and
excluding the channel that coincides with the FWM channel . 20
Figure B.4 – Dependence of the difference between the FWM signal powers for signals
with all the channels and without the FWM channel on the total channel number for
various EDF dispersion values . 20

Table A.1 – Recommended test conditions . 12

TR 61292-7 © IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL AMPLIFIERS –
Part 7: Four wave mixing effect in optical amplifiers

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 61292-7, which is a technical report, has been prepared by subcommittee 86C: Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86C/1029/DTR 86C/1036/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

– 4 – TR 61292-7 © IEC:2011(E)
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 61292 series, under the general title Optical amplifiers, can be found
on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

TR 61292-7 © IEC:2011(E) – 5 –
INTRODUCTION
The four-wave mixing (FWM) effect is known as one of the major restrictions in DWDM
transmission systems. Although observation, conditions for generation, and evaluation
methods have been reported in the literature, no international standards have been published
on this subject, and manufacturers and users evaluate this phenomenon using their own
techniques.
This technical report is dedicated to the subject of four-wave mixing (FWM) effects in optical
amplifiers. It provides an overview of the FWM effect and references information on test
methods. The technology of optical amplifiers is quite new and still emerging; hence
amendments and new editions to this technical report can be expected.

– 6 – TR 61292-7 © IEC:2011(E)
OPTICAL AMPLIFIERS –
Part 7: Four wave mixing effect in optical amplifiers

1 Scope and object
This part of IEC 61292, which is a technical report, applies to optical amplifiers (OAs) using
active fibres and waveguides, containing rare-earth dopants, currently commercially available.
It provides guidance on crosstalk caused by the four-wave mixing (FWM) effect. The object of
this technical report is to provide introductory information for understanding of the crosstalk
issue raised by the FWM effect. This report also presents a measurement method in Annex A.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61290-10-4: Optical amplifiers – Test methods – Part 10-4: Multichannel parameters –
Interpolated source subtraction method using an optical spectrum analyzer
NOTE A list of informative references is given in the Bibliography.
3 Abbreviated terms
ASE amplified spontaneous emission
AWG arrayed waveguide
CW continuous wave
DFB distributed feed-back (laser diode)
DOP degree of polarization
DWDM dense wavelength division multiplexing
ECL external cavity laser (diode)
EDF erbium-doped fibre
EDFA erbium-doped fibre amplifier
FWM four-wave mixing
MUX multiplexer
OA  optical amplifier
OFA optical fibre amplifier
O-MUX optical multiplexer
OSA optical spectrum analyzer
ROADM reconfigurable optical add/drop multiplexer
SPM self-phase modulation
VOA variable optical attenuator
WDM wavelength division multiplexing
WSS wavelength selective switch
XPM cross-phase modulation
TR 61292-7 © IEC:2011(E) – 7 –
4 FWM effect in EDFAs
4.1 General
The EDFA is a crucial element to configure photonic network systems based on WDM
transmission because the EDFA compensates for loss in node devices such as ROADMs and
WSSs, and expands capacity and distance which leads to large scale networks. Therefore the
EDFA is required to amplify many channels of dense WDM signals and is also required to
produce higher power for respective channels in order to compensate for loss in node devices
and transmission fibre. These demands have recently led to adverse deterioration of WDM
signals caused by the nonlinear effect in the EDF. Previously this nonlinear effect was not
thoroughly considered because the effect on signal deterioration was small.
As for the L-
...