IEC TR 62349:2014

Guidance of measurement methods and test procedures - Basic tests for polarization-maintaining optical fibres

IEC TR 62349:2014(E) applies to polarization-maintaining (PM) optical fibres. The object of this report is to define test procedures to be used in establishing uniform requirements for the geometrical and transmission properties of PM fibres. This second edition cancels and replaces the first edition published in 2005. It constitutes a technical revision. In this edition, guidance of measurement methods and test procedures for dimensional characteristics, cut-off wavelength, mode field diameter and beat length of polarization-maintaining optical fibres have been added. Thus, the title of the technical report is changed to "Guidance of measurement methods and test procedures - Basic tests for polarization-maintaining optical fibres" from "Guidance for polarization crosstalk measurement of optical fibre". Keywords: polarization-maintaining (PM) optical fibres, geometrical and transmission properties

General Information

• Status: Withdrawn
• Publication Date: 04-Feb-2014
• Withdrawal Date: 29-Jun-2020
• ICS: 33.180.10 - Fibres and cables
• Technical Committee: SC 86A - Fibres and cables
• Drafting Committee: WG 1 - TC 86/SC 86A/WG 1
• Current Stage: WPUB - Publication withdrawn
• Start Date: 30-Jun-2020
• Completion Date: 30-Jun-2020

Relations

• Revises: IEC TR 62349:2005 - Guidance for polarization crosstalk measurement of optical fibre
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TR 62349 ®
Edition 2.0 2014-02
TECHNICAL
REPORT
colour
inside
Guidance of measurement methods and test procedures – Basic tests for
polarization-maintaining optical fibres

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing more than 30 000 terms and
Technical Specifications, Technical Reports and other definitions in English and French, with equivalent terms in 14
documents. Available for PC, Mac OS, Android Tablets and additional languages. Also known as the International
iPad. Electrotechnical Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a More than 55 000 electrotechnical terminology entries in
variety of criteria (reference number, text, technical English and French extracted from the Terms and Definitions
committee,…). It also gives information on projects, replaced clause of IEC publications issued since 2002. Some entries
and withdrawn publications. have been collected from earlier publications of IEC TC 37,

77, 86 and CISPR.
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Centre: [e-mail].
IEC TR 62349 ®
Edition 2.0 2014-02
TECHNICAL
REPORT
colour
inside
Guidance of measurement methods and test procedures – Basic tests for

polarization-maintaining optical fibres

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
T
ICS 33.180.10 ISBN 978-2-8322-1396-4

– 2 – TR 62349 © IEC:2014(E)
CONTENTS
FOREWORD . 4
1 Scope and object . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Testing conditions . 7
5 Guidance for dimensional characteristics measurement of polarization-maintaining
optical fibres . 7
5.1 Object . 7
5.2 Overview of method . 7
5.3 Reference test method . 8
6 Guidance for cut-off wavelength measurement of polarization-maintaining optical
fibres . 8
6.1 Object . 8
6.2 Overview of method . 8
7 Guidance for mode field diameter measurement of polarization-maintaining optical
fibres . 8
7.1 Object . 8
7.2 Overview of method . 8
8 Guidance for beat length measurement of polarization-maintaining optical fibres . 9
8.1 Object . 9
8.2 Overview of methods . 9
8.3 Reference test method . 9
8.4 Specimen . 9
8.5 Beat length measuring method . 9
8.5.1 Method A: Phase beat length measurement method . 9
8.5.2 Method B: Group beat length measurement method . 12
8.6 Results . 12
8.6.1 Information available with each measurement . 12
8.6.2 Information available upon request . 13
9 Guidance for polarization crosstalk measurement of polarization-maintaining
optical fibres . 13
9.1 Object . 13
9.2 Polarization crosstalk measuring method . 13
9.2.1 General . 13
9.2.2 Method A: Power ratio method . 13
9.2.3 Method B: In-line polarimetric method . 15
Annex A (informative) Cut-off wavelength of PM fibre and SM fibre – Profiles and bend

dependence of cut-off wavelength . 17
Annex B (informative) Difference of beat length by measurement method . 19
B.1 Modal birefringence and beat length . 19
B.2 Beat length defined by Method B . 19
Annex C (informative) Electromagnet for Faraday rotation . 22
Bibliography . 23

TR 62349 © IEC:2014(E) – 3 –
Figure 1 – Apparatus of beat length measurement – Method A . 10
Figure 2 – Example of measurement profile by electro magnet . 11
Figure 3 – Example of test apparatus for polarization crosstalk measurement (power
ratio method) . 14
Figure 4a – Front view of data arc and fitted circle . 16
Figure 4b – 90° – Rotated cutaway view defining the geometrical relationships . 16
Figure 4 – Poincaré sphere representations for Method B . 16
Figure A. 1 – Cut-off wavelength profiles of PM fibre and SM fibre . 17
Figure A. 2 – Cut-off wavelength profile of PM fibre with extra bending . 17
Figure C. 1 – A schematic of the electromagnet . 22

– 4 – TR 62349 © IEC:2014(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE OF MEASUREMENT METHODS AND TEST PROCEDURES –
BASIC TESTS FOR POLARIZATION-MAINTAINING OPTICAL FIBRES

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.
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/TR 62349, which is a technical report, has been prepared by subcommittee 86A: Fibres
and cables, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2005. It constitutes a
technical revision.
In this edition, guidance of measurement methods and test procedures for dimensional
characteristics, cut-off wavelength, mode field diameter and beat length of polarization-
maintaining optical fibres have been added. Thus, the title of the technical report is changed
to “Guidance of measurement methods and test procedures – Basic tests for polarization-
maintaining optical fibres” from “Guidance for polarization crosstalk measurement of optical
fibre”.
TR 62349 © IEC:2014(E) – 5 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86A/1488/DTR 86A/1507/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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.

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 publication using a colour printer.

– 6 – TR 62349 © IEC:2014(E)
GUIDANCE OF MEASUREMENT METHODS AND TEST PROCEDURES –
BASIC TESTS FOR POLARIZATION-MAINTAINING OPTICAL FIBRES

1 Scope and object
This technical report applies to polarization-maintaining (PM) optical fibres.
The object of this report is to define test procedures to be used in establishing uniform
requirements for the geometrical and transmission properties of PM fibres.
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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60793-1-20:2001, Optical fibres – Part 1-20: Measurement methods and test procedures
– Fibre geometry
IEC 60793-1-44, Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-
off wavelength
IEC 60793-1-45:2001, Optical fibres – Part 1-45: Measurement methods and test procedures
– Mode field diameter
IEC 60793-1-48, Optical fibres – Part 1-48: Measurement methods and test procedures –
Polarization mode dispersion
3 Terms and definitions
For the purposes of this document, the following ters and definitions apply.
NOTE IEC 60793-1-1[1] provides general definitions for testing.
3.1
polarization-maintaining optical fibre
PM fibre
optical fibre capable of transmitting, under external perturbations such as bending or lateral
X Y
pressure, both independently of or either of the polarization modes HE and HE whose
11 11
directions of electric field vector intersect orthogonally with each other and which have
different propagation constants
.
___________
Numbers in square brackets refer to the bibliography.

TR 62349 © IEC:2014(E) – 7 –
3.2
phase beat length
one cycle of the periodical coupled polarization state by the phase difference of two linear-
polarization modes intersecting orthogonally in the PM fibre
Note 1 to entry: Small beat length results in high polarization maintaining capability
3.3
group beat length
one cycle of the periodical coupled polarization state by the group delay difference of two
linear-polarization modes intersecting orthogonally in the PM fibre
Note 1 to entry: Small beat length results in high polarization maintaining capability.
3.4
polarization crosstalk
strength of coupling of the two polarization modes intersecting orthogonally with each other
within a polarization-maintaining optical fibre, representing the ratio in optical strength exiting
the fibre of one polarization mode launched at the input end to the optical power of the other
polarization mode exiting the fibre when only the former polarization mode is excited (see also
9.2.2.4.2)
4 Testing conditions
Unless otherwise specified, the test is conducted under the standard conditions specified in
IEC 60068-1. However, when it is difficult to make measurements in the standard conditions,
the test can be conducted in conditions other than the standard conditions provided that no
doubts will arise about judgments.
5 Guidance for dimensional characteristics measurement of polarization-
maintaining optical fibres
5.1 Object
Clause 5 describes measurement methods and test procedures for the dimensional
characteristics of uncoated PM optical fibres.
5.2 Overview of method
This technical report gives measurement methods for dimensional characteristics of PM fibre
which are given in terms of the following parameters:
• cladding diameter;
• cladding non-circularity;
• core concentricity error.
Two methods are described for measuring dimensional characteristics of PM fibre:
• Method A: Refracted near-field;
• Method B: Grey-scale technique of near-field light distribution.
Information pertaining to each individual method is given in Annexes A and C of IEC 60793-1-
20:2001. Only notes for PM fibre are described below.
For a general optical fibre, a circle-fitting is used to determine the core centre. However, as
for the PM fibre, in particular the elliptical core PM fibre, the core centre cannot be
determined if an ellipse-fitting is not used, because the fibre has an oval core.

– 8 – TR 62349 © IEC:2014(E)
5.3 Reference test method
Method B is the reference test method (RTM), which is the one used to settle disputes.
6 Guidance for cut-off wavelength measurement of polarization-maintaining
optical fibres
6.1 Object
Clause 6 describes a measurement method and a test procedure for the cut-off wavelength,
λ of PM fibres.
c
6.2 Overview of method
The measurement method in this technical report describes procedures for determining the
cut-off wavelength of a sample fibre in a short length, uncabled and primary coated condition
(λ ).
c
Information pertaining to each individual method is given in IEC 60793-1-44. Only notes for
PM fibre are described below.
As shown in Annex A, the cut-off wavelength of the PM fibre is measured paying attention to
excite a LP mode sufficiently and not to impose an extra, small bending more carefully than
the cut-off wavelength measurement of a single-mode (SM) optical fibre.
The recommended deployment configuration of the sample fibre is as defined for the fibre cut-
off wavelength in IEC 60793-1-44.
7 Guidance for mode field diameter measurement of polarization-maintaining
optical fibres
7.1 Object
Clause 7 describes measurement methods and test procedures for the mode field diameter
(MFD) of PM fibres.
7.2 Overview of method
Three methods are described for measuring the MFD of the PM fibre:
• Method A: direct far-field scan;
• Method B: variable aperture in the far field;
• Method C: near-field scan.
Information pertaining to each individual method is given in Annexes A, B and C of
IEC 60793-1-45:2001. Only notes for PM fibre are described below.
The MFD of the PM fibre is non-axisymmetric in principle. The MFD is measured in the same
directions by rotating the fibre around the axis properly. The azimuthal dependence of the
MFD of a stress induced PM fibre and an elliptical sheath PM fibre are relatively small. On the
other hand, the azimuthal dependence of the MFD of an elliptical core PM fibre is relatively
large. The MFD of a stress induced fibre and an elliptical sheath PM fibre may be measured
without rotating the fibre complying with the demand of a required accuracy of the customer
depending on the measurement method.

TR 62349 © IEC:2014(E) – 9 –
In Method A, the MFD of a stress induced PM fibre and an elliptical sheath PM fibre may be
measured without rotating the fibre complying with the demand of a required accuracy by the
customer.
In Method B, the MFD of a stress induced PM fibre and an elliptical sheath PM fibre may be
measured complying with the demand of a required accuracy of the customer. The MFD is
measured as an axisymmetric electromagnetic field in Method B. Therefore, the MFD of the
PM fibre cannot be measured in Method B. However, the MFD of a stress induced PM fibre
and an elliptical sheath PM fibre may be measured in Method B because of the relatively
small azimuthal dependence of the MFD. Method B cannot be used to measure the MFD of an
elliptical core PM fibre.
In Method C, a two-dimensional detector is used. The fibre is rotated around the axis properly
on measurement with a one dimensional detector.
8 Guidance for beat length measurement of polarization-maintaining optical
fibres
8.1 Object
Clause 8 describes measurement methods and test procedures for the beat length of PM
fibres.
8.2 Overview of methods
This technical report gives two methods for measuring the beat length of the PM fibre:
• Method A: Phase beat length measurement method (Direct
...

IEC TR 62349 ®
Edition 2.0 2014-02
TECHNICAL
REPORT
colour
inside
Guidance of measurement methods and test procedures – Basic tests for
polarization-maintaining optical fibres

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or

your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]

CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing more than 30 000 terms and
Technical Specifications, Technical Reports and other definitions in English and French, with equivalent terms in 14
documents. Available for PC, Mac OS, Android Tablets and additional languages. Also known as the International
iPad. Electrotechnical Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a More than 55 000 electrotechnical terminology entries in
variety of criteria (reference number, text, technical English and French extracted from the Terms and Definitions
committee,…). It also gives information on projects, replaced clause of IEC publications issued since 2002. Some entries
and withdrawn publications. have been collected from earlier publications of IEC TC 37,

77, 86 and CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TR 62349 ®
Edition 2.0 2014-02
TECHNICAL
REPORT
colour
inside
Guidance of measurement methods and test procedures – Basic tests for

polarization-maintaining optical fibres

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
T
ICS 33.180.10 ISBN 978-2-8322-1396-4

– 2 – TR 62349 © IEC:2014(E)
CONTENTS
FOREWORD . 4

1 Scope and object . 6

2 Normative references . 6

3 Terms and definitions . 6

4 Testing conditions . 7

5 Guidance for dimensional characteristics measurement of polarization-maintaining
optical fibres . 7
5.1 Object . 7
5.2 Overview of method . 7
5.3 Reference test method . 8
6 Guidance for cut-off wavelength measurement of polarization-maintaining optical
fibres . 8
6.1 Object . 8
6.2 Overview of method . 8
7 Guidance for mode field diameter measurement of polarization-maintaining optical
fibres . 8
7.1 Object . 8
7.2 Overview of method . 8
8 Guidance for beat length measurement of polarization-maintaining optical fibres . 9
8.1 Object . 9
8.2 Overview of methods . 9
8.3 Reference test method . 9
8.4 Specimen . 9
8.5 Beat length measuring method . 9
8.5.1 Method A: Phase beat length measurement method . 9
8.5.2 Method B: Group beat length measurement method . 12
8.6 Results . 12
8.6.1 Information available with each measurement . 12
8.6.2 Information available upon request . 13
9 Guidance for polarization crosstalk measurement of polarization-maintaining
optical fibres . 13

9.1 Object . 13
9.2 Polarization crosstalk measuring method . 13
9.2.1 General . 13
9.2.2 Method A: Power ratio method . 13
9.2.3 Method B: In-line polarimetric method . 15
Annex A (informative) Cut-off wavelength of PM fibre and SM fibre – Profiles and bend

dependence of cut-off wavelength . 17
Annex B (informative) Difference of beat length by measurement method . 19
B.1 Modal birefringence and beat length . 19
B.2 Beat length defined by Method B . 19
Annex C (informative) Electromagnet for Faraday rotation . 22
Bibliography . 23

TR 62349 © IEC:2014(E) – 3 –
Figure 1 – Apparatus of beat length measurement – Method A . 10

Figure 2 – Example of measurement profile by electro magnet . 11

Figure 3 – Example of test apparatus for polarization crosstalk measurement (power

ratio method) . 14

Figure 4a – Front view of data arc and fitted circle . 16

Figure 4b – 90° – Rotated cutaway view defining the geometrical relationships . 16

Figure 4 – Poincaré sphere representations for Method B . 16

Figure A. 1 – Cut-off wavelength profiles of PM fibre and SM fibre . 17

Figure A. 2 – Cut-off wavelength profile of PM fibre with extra bending . 17

Figure C. 1 – A schematic of the electromagnet . 22

– 4 – TR 62349 © IEC:2014(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
GUIDANCE OF MEASUREMENT METHODS AND TEST PROCEDURES –

BASIC TESTS FOR POLARIZATION-MAINTAINING OPTICAL FIBRES

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.
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/TR 62349, which is a technical report, has been prepared by subcommittee 86A: Fibres
and cables, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2005. It constitutes a
technical revision.
In this edition, guidance of measurement methods and test procedures for dimensional
characteristics, cut-off wavelength, mode field diameter and beat length of polarization-
maintaining optical fibres have been added. Thus, the title of the technical report is changed
to “Guidance of measurement methods and test procedures – Basic tests for polarization-
maintaining optical fibres” from “Guidance for polarization crosstalk measurement of optical
fibre”.
TR 62349 © IEC:2014(E) – 5 –
The text of this technical report is based on the following documents:

Enquiry draft Report on voting

86A/1488/DTR 86A/1507/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.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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.

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 publication using a colour printer.

– 6 – TR 62349 © IEC:2014(E)
GUIDANCE OF MEASUREMENT METHODS AND TEST PROCEDURES –

BASIC TESTS FOR POLARIZATION-MAINTAINING OPTICAL FIBRES

1 Scope and object
This technical report applies to polarization-maintaining (PM) optical fibres.

The object of this report is to define test procedures to be used in establishing uniform
requirements for the geometrical and transmission properties of PM fibres.
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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60793-1-20:2001, Optical fibres – Part 1-20: Measurement methods and test procedures
– Fibre geometry
IEC 60793-1-44, Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-
off wavelength
IEC 60793-1-45:2001, Optical fibres – Part 1-45: Measurement methods and test procedures
– Mode field diameter
IEC 60793-1-48, Optical fibres – Part 1-48: Measurement methods and test procedures –
Polarization mode dispersion
3 Terms and definitions
For the purposes of this document, the following ters and definitions apply.
NOTE IEC 60793-1-1[1] provides general definitions for testing.
3.1
polarization-maintaining optical fibre
PM fibre
optical fibre capable of transmitting, under external perturbations such as bending or lateral
X Y
pressure, both independently of or either of the polarization modes HE and HE whose
11 11
directions of electric field vector intersect orthogonally with each other and which have
different propagation constants
.
___________
Numbers in square brackets refer to the bibliography.

TR 62349 © IEC:2014(E) – 7 –
3.2
phase beat length
one cycle of the periodical coupled polarization state by the phase difference of two linear-

polarization modes intersecting orthogonally in the PM fibre

Note 1 to entry: Small beat length results in high polarization maintaining capability

3.3
group beat length
one cycle of the periodical coupled polarization state by the group delay difference of two

linear-polarization modes intersecting orthogonally in the PM fibre

Note 1 to entry: Small beat length results in high polarization maintaining capability.
3.4
polarization crosstalk
strength of coupling of the two polarization modes intersecting orthogonally with each other
within a polarization-maintaining optical fibre, representing the ratio in optical strength exiting
the fibre of one polarization mode launched at the input end to the optical power of the other
polarization mode exiting the fibre when only the former polarization mode is excited (see also
9.2.2.4.2)
4 Testing conditions
Unless otherwise specified, the test is conducted under the standard conditions specified in
IEC 60068-1. However, when it is difficult to make measurements in the standard conditions,
the test can be conducted in conditions other than the standard conditions provided that no
doubts will arise about judgments.
5 Guidance for dimensional characteristics measurement of polarization-
maintaining optical fibres
5.1 Object
Clause 5 describes measurement methods and test procedures for the dimensional
characteristics of uncoated PM optical fibres.
5.2 Overview of method
This technical report gives measurement methods for dimensional characteristics of PM fibre
which are given in terms of the following parameters:

• cladding diameter;
• cladding non-circularity;
• core concentricity error.
Two methods are described for measuring dimensional characteristics of PM fibre:
• Method A: Refracted near-field;
• Method B: Grey-scale technique of near-field light distribution.
Information pertaining to each individual method is given in Annexes A and C of IEC 60793-1-
20:2001. Only notes for PM fibre are described below.
For a general optical fibre, a circle-fitting is used to determine the core centre. However, as
for the PM fibre, in particular the elliptical core PM fibre, the core centre cannot be
determined if an ellipse-fitting is not used, because the fibre has an oval core.

– 8 – TR 62349 © IEC:2014(E)
5.3 Reference test method
Method B is the reference test method (RTM), which is the one used to settle disputes.

6 Guidance for cut-off wavelength measurement of polarization-maintaining

optical fibres
6.1 Object
Clause 6 describes a measurement method and a test procedure for the cut-off wavelength,

λ of PM fibres.
c
6.2 Overview of method
The measurement method in this technical report describes procedures for determining the
cut-off wavelength of a sample fibre in a short length, uncabled and primary coated condition
(λ ).
c
Information pertaining to each individual method is given in IEC 60793-1-44. Only notes for
PM fibre are described below.
As shown in Annex A, the cut-off wavelength of the PM fibre is measured paying attention to
excite a LP mode sufficiently and not to impose an extra, small bending more carefully than
the cut-off wavelength measurement of a single-mode (SM) optical fibre.
The recommended deployment configuration of the sample fibre is as defined for the fibre cut-
off wavelength in IEC 60793-1-44.
7 Guidance for mode field diameter measurement of polarization-maintaining
optical fibres
7.1 Object
Clause 7 describes measurement methods and test procedures for the mode field diameter
(MFD) of PM fibres.
7.2 Overview of method
Three methods are described for measuring the MFD of the PM fibre:
• Method A: direct far-field scan;
• Method B: variable aperture in the far field;
• Method C: near-field scan.
Information pertaining to each individual method is given in Annexes A, B and C of
IEC 60793-1-45:2001. Only notes for PM fibre are described below.
The MFD of the PM fibre is non-axisymmetric in principle. The MFD is measured in the same
directions by rotating the fibre around the axis properly. The azimuthal dependence of the
MFD of a stress induced PM fibre and an elliptical sheath PM fibre are relatively small. On the
other hand, the azimuthal dependence of the MFD of an elliptical core PM fibre is relatively
large. The MFD of a stress induced fibre and an elliptical sheath PM fibre may be measured
without rotating the fibre complying with the demand of a required accuracy of the customer
depending on the measurement method.

TR 62349 © IEC:2014(E) – 9 –
In Method A, the MFD of a stress induced PM fibre and an elliptical sheath PM fibre may be

measured without rotating the fibre complying with the demand of a required accuracy by the

customer.
In Method B, the MFD of a stress induced PM fibre and an elliptical sheath PM fibre may be

measured complying with the demand of a required accuracy of the customer. The MFD is

measured as an axisymmetric electromagnetic field in Method B. Therefore, the MFD of the

PM fibre cannot be measured in Method B. However, the MFD of a stress induced PM fibre

and an elliptical sheath PM fibre may be measured in Method B because of the relatively

small azimuthal dependence of the MFD. Method B cannot be used to measure the MFD of an
elliptical core PM fibre.
In Method C, a two-dimensional detector is used. The fibre is rotated around the axis properly
on measurement with a one dimensional detector.
8 Guidance for beat length measurement of polarization-maintaining optical
fibres
8.1 Object
Clause 8 describes measurement methods and test procedures for the beat length of PM
fibres.
8.2 Overview of methods
This technical report gives two methods for measuring the beat length of the PM fibre:
• Method A: Phase beat length measurement method (Direct measurement method);
• Method B: Group beat
...