EN 61280-4-4:2017

SLOVENSKI STANDARD
01-oktober-2017
1DGRPHãþD
SIST EN 61280-4-4:2006
3RVWRSNLSUHVNXãDQMDRSWLþQHJDNRPXQLNDFLMVNHJDSRGVLVWHPDGHO.DEHOVNH
REOLNHLQSRYH]DYH0HULWYHSRODUL]DFLMVNHUD]SUãLWYHYYJUDMHQLKSRYH]DYDK,(&

Fibre optic communication subsystem test procedures - Part 4-4: Cable plants and links
- Polarization mode dispersion measurement for installed links (IEC 61280-4-4:2017)
Prüfverfahren für Lichtwellenleiter-Kommunikationsuntersysteme - Teil 4-4: Kabelnetze
und Übertragungsstrecken - Messung der Polarisationsmodendispersion von installierten
Übertragungsstrecken (IEC 61280-4-4:2017)
Procédures d'essai des sous-systèmes de télécommunication à fibres optiques - Partie 4
-4: Installation de câbles et liens - Mesure de la dispersion de mode polarisation pour les
liaisons installées (IEC 61280-4-4:2017)
Ta slovenski standard je istoveten z: EN 61280-4-4:2017
ICS:
33.180.01 6LVWHPL]RSWLþQLPLYODNQLQD Fibre optic systems in
VSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61280-4-4

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2017
ICS 33.180.01 Supersedes EN 61280-4-4:2006
English Version
Fibre optic communication subsystem test procedures -
Part 4-4: Cable plants and links - Polarization mode dispersion
measurement for installed links
(IEC 61280-4-4:2017)
Procédures d'essai des sous-systèmes de Prüfverfahren für Lichtwellenleiter-
télécommunication à fibres optiques - Partie 4-4: Installation Kommunikationsuntersysteme - Teil 4-4: Kabelnetze und
de câbles et liens - Mesure de la dispersion de mode Übertragungsstrecken - Messung der
polarisation pour les liaisons installées Polarisationsmodendispersion von installierten
(IEC 61280-4-4:2017) Übertragungsstrecken
(IEC 61280-4-4:2017)
This European Standard was approved by CENELEC on 2017-04-11. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61280-4-4:2017 E
European foreword
The text of document 86C/1378/CDV, future edition 2 of IEC 61280-4-4, prepared by SC 86C “Fibre
optic systems and active devices” of IEC/TC 86 “Fibre optics" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN 61280-4-4:2017.

The following dates are fixed:
(dop) 2018-02-18
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2020-08-18
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61280-4-4:2006.

This edition includes the following significant technical changes with respect to the previous edition:

EN 61280-4-4:2006:
a) theory is removed and replaced with a reference to IEC/TR 61282-9;
b) a new method, wavelength scanning OTDR and SOP analysis (WSOSA), is added as
Annex G;
c) a brief description of each method is added to Clause 5;
d) Methods E and F are converted to informative Annexes E and F;
e) a new Clause (6) on measurement configurations is added;
f) a new Clause (7) on measurement considerations is added;
g) Clause 10 on procedure is expanded;
h) several of the apparatus diagrams are improved;
i) several clarifications about what is measured and what is calculated have been made in
Annex H.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 61280-4-4:2017 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

1)
IEC 60793-1-48:2003 NOTE Harmonized as EN 60793-1-48:2003 (not modified).
IEC 60793-1-48:2007 NOTE Harmonized as EN 60793-1-48:2007 (not modified).
IEC 60793-2-50 NOTE Harmonized as EN 60793-2-50.
IEC 61280-4-4:2006 NOTE Harmonized as EN 61280-4-4:2006 (not modified).
IEC 61290-11-1 NOTE Harmonized as EN 61290-11-1.
IEC 61290-11-2 NOTE Harmonized as EN 61290-11-2.
IEC 61300-3-32 NOTE Harmonized as EN 61300-3-32.

1)
Superseded by EN 60793-1-48:2007 (IEC 60793-1-48:2007).
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu
Publication Year Title EN/HD Year

IEC 60793-1-44 -  Optical fibres - EN 60793-1-44 -
Part 1-44: Measurement methods and test
procedures - Cut-off wavelength
IEC 61300-3-35 -  Fibre optic interconnecting devices and EN 61300-3-35 -
passive components - Basic test and
measurement procedures -
Part 3-35: Examinations and
measurements - Visual inspection of fibre
optic connectors and fibre-stub
transceivers
IEC/TR 61282-9 -  Fibre optic communication system design - -
guides -
Part 9: Guidance on polarization mode
dispersion measurements and theory
IEC/TR 62627-01 -  Fibre optic interconnecting devices and - -
passive components -
Part 01: Fibre optic connector cleaning
methods
IEC 61280-4-4 ®
Edition 2.0 2017-03
INTERNATIONAL
STANDARD
colour
inside
Fibre optic communication subsystem test procedures –

Part 4-4: Cable plants and links – Polarization mode dispersion measurement

for installed links
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.01 ISBN 978-2-8322-4077-9

– 2 – IEC 61280-4-4:2017  IEC 2017
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms, definitions, symbols and abbreviated terms . 10
3.1 Terms and definitions . 10
3.2 Symbols and abbreviated terms . 11
4 Background on PMD properties . 12
5 Measurement methods . 13
5.1 Methods of measuring PMD . 13
5.1.1 General . 13
5.1.2 Method A: Fixed analyzer with Fourier transformation (FA-FT) . 14
5.1.3 Method B: Stokes parameters evaluation (SPE) . 14
5.1.4 Method C: Interferometric . 15
5.1.5 Method D: Stokes parameter evaluation using back-reflected light . 15
5.1.6 Method E: Modulated phase-shift technique . 15
5.1.7 Method F: Polarization phase shift (PPS) . 15
5.1.8 Method G: Wavelength scanning OTDR and SOP Analysis (WSOSA) . 16
5.2 Document structure . 16
5.3 Reference test method . 16
6 Measurement configurations . 16
6.1 Passive cabling link . 16
6.2 Link including amplifiers . 17
6.3 Link including chromatic dispersion compensating modules . 17
6.3.1 General . 17
6.3.2 Grating based DCM . 17
6.4 Link including ROADMs . 17
6.4.1 General . 17
6.4.2 Multi-channel point to point configuration . 18
6.4.3 Single channel configuration . 18
7 Measurement considerations . 18
7.1 General . 18
7.2 Wavelength range . 18
7.3 PMD measurement range. 18
7.4 Measurement dynamic range . 19
7.5 Fibre movement . 19
7.6 Input and output SOP scrambling . 19
7.6.1 General . 19
7.6.2 Polarizers/scramblers . 19
7.6.3 The 9-states Mueller set . 20
7.6.4 Random scrambling . 20
7.7 Polarization dependent loss . 20
7.8 Amplifier considerations . 20
7.8.1 General . 20
7.8.2 Optical isolators . 20
7.8.3 Wavelength range . 20

IEC 61280-4-4:2017  IEC 2017 – 3 –
7.8.4 Power levels . 20
7.8.5 Amplified spontaneous emission (ASE) noise . 21
7.9 Considerations on location of equipment . 21
8 Apparatus . 21
8.1 General . 21
8.2 Light source and polarizers . 21
8.3 Input optics . 22
8.4 Cladding mode stripper . 22
8.5 High-order mode filter . 22
8.6 Output connection . 22
8.7 Output optics . 23
8.8 Detector . 23
8.9 Computer or test platform . 23
8.10 Means to reduce the effects of amplified spontaneous emission . 23
9 Sampling and specimens . 23
10 Procedure . 23
11 Calculation or interpretation of results . 24
12 Documentation . 24
12.1 Information required for each measurement . 24
12.2 Information to be available . 24
13 Specification information . 25
Annex A (normative) Fixed analyzer method . 26
A.1 Apparatus . 26
A.1.1 Block diagrams . 26
A.1.2 Light source . 28
A.1.3 Analyzer . 29
A.1.4 Optional polarization control at the input and output of the link under
test . 29
A.2 Procedure . 29
A.2.1 Wavelength range and increment . 29
A.2.2 Complete the scans . 30
A.3 Calculations – Fourier transform . 31
A.3.1 General . 31
A.3.2 Data pre-processing and Fourier transformation . 32
A.3.3 Transform data fitting. 32
A.3.4 Spectral range . 34
Annex B (normative) Stokes parameter evaluation method . 36
B.1 Apparatus . 36
B.1.1 Block diagrams . 36
B.1.2 Light source . 37
B.1.3 Polarimeter . 37
B.2 Procedure . 37
B.3 Calculations . 38
B.3.1 General . 38
B.3.2 Jones matrix eigenanalysis (JME) . 38
B.3.3 Poincaré sphere analysis (PSA) DGD calculation . 40
Annex C (normative) Interferometric method . 41
C.1 General . 41

– 4 – IEC 61280-4-4:2017  IEC 2017
C.2 Traditional analysis (TINTY) . 42
C.2.1 Apparatus . 42
C.2.2 Procedure . 43
C.2.3 Calculations . 44
C.3 General analysis (GINTY) . 45
C.3.1 Benefit . 45
C.3.2 Apparatus . 45
C.3.3 Procedure . 46
C.3.4 Calculations . 47
Annex D (informative) Stokes parameter evaluation method using back-reflected light. 49
D.1 Utility . 49
D.2 Apparatus . 49
D.2.1 Block diagram . 49
D.2.2 Directional coupler . 49
D.2.3 Angled connector . 49
D.2.4 Far-end termination . 49
D.3 Procedure . 50
D.4 Calculation and interpretation of results . 50
Annex E (informative) Modulation phase-shift method . 51
E.1 Apparatus . 51
E.1.1 Overview and block diagrams . 51
E.1.2 Light source(s). 52
E.1.3 Modulation . 53
E.1.4 Polarization control . 54
E.1.5 Input and output optics . 54
E.1.6 Optical detector and phase detection electronics . 55
E.1.7 Reference signal. 55
E.2 Procedure . 55
E.2.1 Modulation frequency . 55
E.2.2 Scan the wavelengths and measure DGD . 55
E.2.3 Calibration . 58
E.3 Calculations . 58
E.3.1 DGD calculations . 58
E.3.2 PMD calculation . 59
Annex F (informative) Polarization phase shift method . 60
F.1 Apparatus . 60
F.1.1 Block diagram . 60
F.1.2 Light source . 60
F.1.3 Modulation . 60
F.1.4 Polarization control . 61
F.1.5 Output optics . 61
F.1.6 Optical detectors . 61
F.1.7 Amplitude and phase comparator . 61
F.1.8 Reference signal. 62
F.2 Procedure . 62
F.2.1 Modulation frequency . 62
F.2.2 Wavelength increment . 62
F.2.3 Scanning wavelengths and measuring DGDs . 62
F.2.4 Calibration . 63

IEC 61280-4-4:2017  IEC 2017 – 5 –
F.3 Calculations . 63
F.3.1 Results overview . 63
F.3.2 DGD determination . 64
F.3.3 PMD calculation . 65
Annex G (normative) Wavelength scanning OTDR and SOP analysis (WSOSA) PMD
test method . 66
G.1 General . 66
G.2 Apparatus . 66
G.2.1 Block diagram . 66
G.2.2 Light source . 67
G.2.3 Launch polarization . 67
G.2.4 Polarization scrambling . 68
G.2.5 Input/output optics . 68
G.3 Specimen stability . 68
G.4 Procedure . 68
G.4.1 Set instrument parameters . 68
G.4.2 Action of the instrument after measurement initiation . 69
G.5 Calculations . 71
G.5.1 Power normalisation . 71
G.5.2 Transmission differences . 72
G.5.3 Mean-square transmission difference and round trip PMD . 73
G.5.4 Determination of PMD . 74
G.6 Procedures for measuring PMD on installed aerial links . 74
G.6.1 Instability compensation . 74
G.6.2 Approaches to reducing the effects of instabilities . 75
Annex H (informative) PMD determination by Method C . 77
H.1 General . 77
H.2 Traditional analysis . 77
H.3 General analysis . 79
Bibliography . 81

Figure 1 – Typical passive cabling link configuration . 16
Figure 2 – Example configuration of link including amplifiers . 17
Figure A.1 – Block diagrams for fixed analyzer . 28
Figure A.2 – Example of the R-function for the fixed analyzer method . 31
Figure A.3 – A chirped sine wave . 33
Figure A.4 – PMD by Fourier analysis . 34
Figure B.1 – Block diagram for Method B using a narrowband (tuneable laser) source . 36
Figure B.2 – Block diagram for Method B using a broadband (ASE) source . 36
Figure C.1 – Generic set-up for Method C (INTY). 41
Figure C.2 – Schematic diagram for Method C (TINTY) . 42
Figure C.3 – Typical data obtained by Method C (TINTY) . 44
Figure C.4 – Schematic diagram for Method C (GINTY) . 45
Figure C.5 – Typical random-mode-coupling data obtained by Method C (GINTY) . 47
Figure C.6 – Typical mixed-mode-coupling data obtained by Method C (GINTY) . 47
Figure D.1 – Layout for Method D . 49
Figure E.1 – Basic apparatus . 51

– 6 – IEC 61280-4-4:2017  IEC 2017
Figure E.2 – Apparatus layout for polarization modulation . 52
Figure E.3 – Mueller states on Poincaré sphere . 57
Figure E.4 – DGD versus wavelength . 58
Figure E.5 – DGD in histogram format . 58
Figure F.1 – Block diagram for Method F (polarization phase shift method) . 60
Figure F.2 – DGD versus wavelength for a random mode coupling device . 64
Figure G.1 – Illustration of the frequency domain and parameters for WSOSA . 66
Figure G.2 − Typical generic experimental implementation for WSOSA . 67
Figure G.3 – Typical power measurement results . 71
Figure G.4 − Typical s(ω) for random I/O-SOP . 72
Figure G.5 − Typical transmission difference for a frequency pair and I/O-SOP . 73
Figure G.6 − Example of 2-pulse implementation in presence of instabilities . 76

Table E.1 – Example of Mueller set . 57

IEC 61280-4-4:2017  IEC 2017 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 4-4: Cable plants and links – Polarization mode dispersion
measurement for installed links

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61280-4-4 has been prepared by subcommittee 86C: Fibre optic
systems and active devices, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2006. This second
edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) theory is removed and replaced with a reference to IEC TR 61282-9;
b) a new method, wavelength scanning OTDR and SOP analysis (WSOSA), is added as
Annex G;
c) a brief description of each method is added to Clause 5;
d) Methods E and F are converted to informative Annexes E and F;

– 8 – IEC 61280-4-4:2017  IEC 2017
e) a new Clause (6) on measurement configurations is added;
f) a new Clause (7) on measurement considerations is added;
g) Clause 10 on procedure is expanded;
h) several of the apparatus diagrams are improved;
i) several clarifications about what is measured and what is calculated have been made in
Annex H.
The text of this International Standard is based on the following documents:
CDV Report on voting
86C/1378/CDV 86C/1419/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61280 series, published under the general title Fibre optic
communication subsystem test procedures, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
IEC 61280-4-4:2017  IEC 2017 – 9 –
INTRODUCTION
Polarization mode dispersion (PMD) is a statistical parameter. The reproducibility of
measurements depends on the particular method, but is limited also by the PMD level of the
link and the accessible wavelength range. Gisin [1] derived a theoretical limit to this
reproducibility independent of the measurement method by assuming ideal measurement
conditions.
Originally, the principles of IEC 61280-4-4:2006 were closely aligned with those of
IEC 60793-1-48:2003 on optical fibre and optical fibre cable test method, which focuses on
aspects related to the measurement of factory lengths. However, IEC 60793-1-48:2007
removed some of the test methods that are no longer of interest to fibre and cable
manufacturers. These have been retained as informative Annexes D, E, and F in this
document, and a new test method G has been added.
This document also updates test methods A, B and C and adds more information applicable to
testing of installed cabling.
NOTE 1 Test methods for factory lengths of optical fibres and optical fibre cables are given in IEC 60793-1-48.
NOTE 2 Test methods for optical amplifiers (OAs) are given in IEC 61290-11-1 and IEC 61290-11-2.
NOTE 3 Test methods for passive optical components are given in IEC 61300-3-32.
NOTE 4 Guidelines for the calculation of PMD for links that include components such as dispersion compensators
or optical amplifiers are given in IEC TR 61282-3.
NOTE 5 Further general guidance on PMD measurements and background theory is contained in
IEC TR 61282-9.
___________
Figures in square brackets refer to the Bibliography.

– 10 – IEC 61280-4-4:2017  IEC 2017
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 4-4: Cable plants and links – Polarization mode dispersion
measurement for installed links

1 Scope
This part of IEC 61280 provides uniform methods of measuring polarization mode dispersion
(PMD) of single-mode installed links. An installed link is the optical path between transmitter
and receiver, or a portion of that optical path. These measurements can be used to assess
the suitability of a given link for high bit rate applications, or to provide insight on the
relationships of various related transmission attributes. This document focuses on the
measurement methods and requirements for measuring long lengths of installed cabling that
can also include other optical elements, such as splices, connectors, amplifiers, chromatic
dispersion compensating modules, dense wavelength division multiplexing or multiplexer
(DWDM) components, multiplexers, wavelength selective switches, re-configurable optical
add drop multiplexer (ROADMS).
This document focuses on the apparatus, procedures, and calculations needed to complete
measurements. IEC TR 61282-9 explains the theory behind the test methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60793-1-44, Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-
off wavelength
IEC 61300-3-35, Fibre optic interconnecting devices and passive components – Basic test
and measurement procedures – Part 3-35: Examinations and measurements – Visual
inspection of fibre optic connectors and fibre-stub transceivers
IEC TR 61282-9, Fibre optic communication system design guides – Part 9: Guidance on
polarization mode dispersion measurements and theory
IEC TR 62627-01, Fibre optic interconnecting devices and passive components – Part 01:
Fibre optic connector cleaning methods
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/

IEC 61280-4-4:2017  IEC 2017 – 11 –
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Symbols and abbreviated terms
c velocity of light in vacuum (299792458 m/s)
h coupling length (also called h-parameter)
L length of the link
t optical source coherence time (Method C)
c
δl wavelength increment (interval, spacing or step size)
δν optical frequency increment (interval, spacing or step size)
∆l optical source spectral width or linewidth (FWHM unless noted otherwise)
∆θ rotation angle on the Poincaré sphere
δτ differential arrival times of different polarization components
δτ maximum measurable δτ
max
δτ minimum δτ value that can be measured
min
∆τ differential group delay value
<∆τ> average DGD over a wavelength range or PMD value
average
2 1/2
<∆τ > RMS DGD over a wavelength range or PMD value
RMS
∆τ maximum ∆τ value that can be measured
max
∆ω angular frequency variation in Method B
l test wavelength used to measure PMD
l central wavelength of the light source
v optical light frequency
σ second moment of Fourier transform data
R
σ RMS width of the squared autocorrelation envelope
σ RMS width of the squared cross-correlation envelope
x
σ RMS width of interferogram
ε
ω angular optical frequency
ASE amplified spontaneous emission
DCF (chromatic) dispersion compensating fibre
DCM (chromatic) dispersion compensating module
DGD differential group delay
DOP degree of polarization
DUT device under test
DWDM dense wavelength division multiplexing or multiplexer
FA fixed analyzer
FA-FT fixed analyzer-Fourier transform (PMD test method)
FBG fibre Bragg grating
FET field effect transistor
FWHM full-wid
...