IEC 60793-2-50:2018

IEC 60793-2-50 ®
Edition 6.0 2018-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibres –
Part 2-50: Product specifications – Sectional specification for class B single-
mode fibres
Fibres optiques –
Partie 2-50: Spécifications de produits – Spécification intermédiaire pour les
fibres unimodales de classe B
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.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
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 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. 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: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Catalogue IEC - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
Application autonome pour consulter tous les renseignements
Le premier dictionnaire en ligne de termes électroniques et
bibliographiques sur les Normes internationales,
électriques. Il contient 21 000 termes et définitions en anglais
Spécifications techniques, Rapports techniques et autres
et en français, ainsi que les termes équivalents dans 16
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.

Recherche de publications IEC -
Glossaire IEC - std.iec.ch/glossary
webstore.iec.ch/advsearchform
67 000 entrées terminologiques électrotechniques, en anglais
La recherche avancée permet de trouver des publications IEC et en français, extraites des articles Termes et Définitions des
en utilisant différents critères (numéro de référence, texte, publications IEC parues depuis 2002. Plus certaines entrées
comité d’études,…). Elle donne aussi des informations sur les antérieures extraites des publications des CE 37, 77, 86 et
projets et les publications remplacées ou retirées. CISPR de l'IEC.

IEC Just Published - webstore.iec.ch/justpublished Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications IEC. Just Si vous désirez nous donner des commentaires sur cette
Published détaille les nouvelles publications parues. publication ou si vous avez des questions contactez-nous:
Disponible en ligne et aussi une fois par mois par email. sales@iec.ch.

IEC 60793-2-50 ®
Edition 6.0 2018-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibres –
Part 2-50: Product specifications – Sectional specification for class B single-

mode fibres
Fibres optiques –
Partie 2-50: Spécifications de produits – Spécification intermédiaire pour les

fibres unimodales de classe B
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-6280-1

– 2 – IEC 60793-2-50:2018 © IEC 2018
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 9
4 Abbreviated terms and symbols . 10
5 Specifications . 10
5.1 General . 10
5.2 Dimensional requirements . 10
5.3 Mechanical requirements . 11
5.4 Transmission requirements . 12
5.5 Environmental requirements . 13
5.5.1 General . 13
5.5.2 Optical environmental requirements – Attenuation . 14
5.5.3 Mechanical environmental requirements . 14
Annex A (normative) Family specification for category B-652 Dispersion unshifted
single-mode fibres . 16
A.1 General . 16
A.2 Dimensional requirements . 16
A.3 Mechanical requirements . 17
A.4 Transmission requirements . 17
A.5 Hydrogen ageing for sub-category B-652.D . 19
A.6 Environmental requirements . 19
Annex B (normative) Family specification for category B-653 Dispersion shifted
single-mode fibres . 20
B.1 General . 20
B.2 Dimensional requirements . 20
B.3 Transmission requirements . 21
B.3.1 General . 21
B.3.2 Chromatic dispersion coefficient requirement for sub-category B-653.A
fibres . 21
B.3.3 Chromatic dispersion coefficient requirement for sub-category B-653.B
fibres . 22
B.4 Environmental requirements . 22
Annex C (normative) Family specification for category B-654 cut-off shifted single-
mode fibres . 23
C.1 General . 23
C.2 Dimensional requirements . 23
C.3 Mechanical requirements . 23
C.4 Chromatic dispersion parameters for B-654.E fibres . 25
C.5 Environmental requirements . 25
Annex D (normative) Family specification for category B-655 non-zero dispersion
shifted single-mode fibres . 26
D.1 General . 26
D.2 Dimensional requirements . 26
D.3 Mechanical requirements . 26
D.4 Transmission requirements . 27
D.4.1 General . 27

D.4.2 Chromatic dispersion coefficient limits for sub-category B-655.C fibres. 27
D.4.3 Chromatic dispersion coefficient limits for sub-category B-655.D fibres. 28
D.4.4 Chromatic dispersion coefficient limits for sub-category B-655.E fibres . 28
D.5 Environmental requirements . 28
Annex E (normative) Family specification for category B-656 Wideband non-zero

dispersion shifted single-mode fibres . 29
E.1 General . 29
E.2 Dimensional requirements . 29
E.3 Mechanical requirements . 29
E.4 Transmission requirements . 30
E.4.1 General . 30
E.4.2 Chromatic dispersion coefficient for category B-656 fibres . 30
E.5 Environmental requirements . 31
Annex F (normative) Family specification for category B-657 Bending loss insensitive
single-mode fibres . 32
F.1 General . 32
F.2 Dimensional requirements . 32
F.3 Mechanical requirements . 33
F.4 Transmission requirements . 33
F.5 Environmental requirements . 35
Annex G (informative) System design information for category B-655 non-zero
disperion shifted single-mode fibres . 36
G.1 General . 36
G.2 One standard deviation limits for sub-category B-655.D fibres . 36
G.3 One standard deviation limits for sub-category B-655.E fibres. 37
Bibliography . 39

Figure G.1 – Sub-category B-655.D chromatic dispersion coefficient limits . 37
Figure G.2 – Sub-category B-655.E chromatic dispersion coefficient limits . 38

Table 1 – Map of IEC designation to ITU-T Recommendations and IEC 60793-2-

50:2015 designation. 8
Table 2 – Dimensional attributes and measurement methods . 11
Table 3 – Dimensional requirements common to all category B fibres . 11
Table 4 – Mechanical attributes and test methods . 11
Table 5 – Mechanical requirements common to all class B fibres . 12
Table 6 – Transmission attributes and measurement methods . 12
Table 7 – Transmission, requirements common to all class B fibres . 13
Table 8 – Additional transmission attributes required in the family specifications . 13
Table 9 – Environmental exposure tests . 13
Table 10 – Attributes measured in environmental exposure tests . 13
Table 11 – Change in attenuation for environmental tests . 14
Table 12 – Coating strip force for environmental tests . 14
Table 13 – Tensile strength for environmental tests . 15
Table 14 – Stress corrosion susceptibility for environmental tests . 15
Table A.1 – Dimensional requirements specific to category B-652.B fibres. 16
Table A.2 – Dimensional requirements specific to category B-652.D fibres . 17

– 4 – IEC 60793-2-50:2018 © IEC 2018
Table A.3 – Mechanical requirements specific to category B-652 fibres . 17
Table A.4 – Transmission requirements specific to sub-category B-652.B fibres . 18
Table A.5 – Transmission requirements specific to sub-category B-652.D Fibres . 18
Table A.6 – Chromatic dispersion properties for sub-category B-652.D fibres . 19
Table B.1 – Dimensional requirements specific to category B-653 fibres . 20
Table B.2 – Mechanical requirements specific to category B-653 fibres . 21
Table B.3 – Transmission requirements specific to category B-653 fibres . 21
Table C.1 – Dimensional requirements specific to category B-654 fibres . 23
Table C.2 – Mechanical requirements specific to category B-654 fibres . 24
Table C.3 – Transmission requirements specific to category B-654 fibres . 24
Table D.1 – Dimensional requirements specific to category B-655 fibres . 26
Table D.2 – Mechanical requirements specific to category B-655 fibres . 27
Table D.3 – Transmission requirements specific to category B-655 fibres . 27
Table E.1 – Dimensional requirements specific to category B-656 fibres . 29
Table E.2 – Mechanical requirements specific to category B-656 fibres . 30
Table E.3 – Transmission requirements specific to category B-656 fibres . 30
Table F.1 – Dimensional requirements specific to category B-657 fibres . 33
Table F.2 – Mechanical requirements specific to category B-657 fibres . 33
Table F.3 – Transmission requirements specific to category B-657 fibres . 34
Table G.1 – Examples for λ = 1 530 nm and λ = 1 565 nm . 36
min max
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 2-50: Product specifications –
Sectional specification for class B single-mode 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.
International Standard IEC 60793-2-50 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
The sixth edition cancels and replaces the fifth edition published in 2015. This edition
constitutes a technical revision. This edition includes the following significant technical
changes with respect to the previous edition:
a) Introduction of a revised naming convention which better matches with those found in
ITU-T Recommendations G.652, G.653, G.654, G.655, G.656, and G.657. These changes
are outlined in the scope of this document along with a cross reference table for the new
names. Annexes have been rearranged to improve clarity based on the new naming;
b) Further details on the requirements for 200 micron coated single-mode fibre;
c) Harmonization with the following ITU-T Recommendations published in November 2016:
G.652, G.654, G.657 including revised chromatic dispersion specifications, new categories
and new application spaces for these fibre categories;

– 6 – IEC 60793-2-50:2018 © IEC 2018
d) Descriptions of fibre types have been added to the titles of Annexes A to F.
The text of this International Standard is based on the following documents:
FDIS Report on voting
86A/1884/FDIS 86A/1898/RVD
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 60793 series, published under the general title Optical fibres, 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.
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.
OPTICAL FIBRES –
Part 2-50: Product specifications –
Sectional specification for class B single-mode fibres

1 Scope
This part of IEC 60793 is applicable to optical fibre categories B-652, B-653, B-654, B-655,
B-656 and B-657. A map illustrating the connection of IEC designations to ITU-T designations
is shown in Table 1. These fibres are used or can be incorporated in information transmission
equipment and optical fibre cables.
Three types of requirements apply to these fibres:
• general requirements, as defined in IEC 60793-2;
• specific requirements common to the class B single-mode fibres covered in this document
and which are given in Clause 5;
• particular requirements applicable to individual fibre categories or specific applications,
which are defined in Annexes A to F.
For some fibre categories (shown in the relevant family specifications), there are sub-
categories that are distinguished on the basis of difference in transmission attribute
specifications. The designations for these sub-categories are documented in the individual
family specifications.
Table 1 shows a map from the IEC designations to the ITU-T recommendations. The table
also provides the normative annex in this document that contains the detailed specification as
well as the name used to describe this fibre type in IEC 60793-2-50:2015. The ITU-T
recommendations as well as the IEC categories/sub-categories within each recommendation
are given. In some cases, as for Recommendation G.652, a given IEC designation maps to
multiple categories in the ITU-T because the ITU-T categories are distinguished by cabled
fibre attribute (PMD ) performance which are not distinguished in the IEC fibre specifications.
Q
– 8 – IEC 60793-2-50:2018 © IEC 2018
Table 1 – Map of IEC designation to ITU-T Recommendations and
IEC 60793-2-50:2015 designation
Annex Category Sub Description IEC 60793-2-50:2015 ITU-T Rec
Category
B-652 Dispersion unshifted fibre G.652
A B-652.B B1.1 G.652.B
A B-652.D B1.3 G.652.D
B-653 Dispersion shifted fibre G.653
B B-653.A B2_a G.653.A
B B-653.B B2_b G.653.B
B-654 Cut-off shifted fibre G.654
C B-654.A B1.2_a G.654.A
C B-654.B B1.2_b G.654.B
C B-654.C B1.2_c G.654.C
C B-654.D N/A G.654.D
C B-654.E N/A G.654.E
C B-655 Non-zero dispersion shifted fibre B4 G.655
D B-655.C B4_c G.655.C
D B-655.D B4_d G.655.D
D B-655.E B4_e G.655.E
E B-656 Wideband non-zero dispersion shifted B5 G.656
fibre
F B-657 Bending loss insensitive fibre B6 G.657
F B-657.A1 B6_a1 G.657.A1
F B-657.A2 B6_a2 G.657.A2
F B-657.B2 B6_b2 G.657.B2
F B-657.B3 B6_b3 G.657.B3
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 (all parts), Optical fibres
IEC 60793-1-20, Optical fibres – Part 1-20: Measurement methods and test procedures –
Fibre geometry
IEC 60793-1-21, Optical fibres – Part 1-21: Measurement methods and test procedures –
Coating geometry
IEC 60793-1-22, Optical fibres – Part 1-22: Measurement methods and test procedures –
Length measurement
IEC 60793-1-30, Optical fibres – Part 1-30: Measurement methods and test procedures –
Fibre proof test
IEC 60793-1-31, Optical fibres – Part 1-31: Measurement methods and test procedures –
Tensile strength
IEC 60793-1-32, Optical fibres – Part 1-32: Measurement methods and test procedures –
Coating strippability
IEC 60793-1-33, Optical fibres – Part 1-33: Measurement methods and test procedures –
Stress corrosion susceptibility
IEC 60793-1-34, Optical fibres – Part 1-34: Measurement methods and test procedures –
Fibre curl
IEC 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –
Attenuation
IEC 60793-1-42, Optical fibres – Part 1-42: Measurement methods and test procedures –
Chromatic dispersion
IEC 60793-1-44, Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-
off wavelength
IEC 60793-1-45, Optical fibres – Part 1-45: Measurement methods and test procedures –
Mode field diameter
IEC 60793-1-46,
Optical fibres – Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance
IEC 60793-1-47, Optical fibres – Part 1-47: Measurement methods and test procedures –
Macrobending loss
IEC 60793-1-48, Optical fibres – Part 1-48: Measurement methods and test procedures –
Polarization mode dispersion
IEC 60793-1-50, Optical fibres – Part 1-50: Measurement methods and test procedures –
Damp heat (steady state) tests
IEC 60793-1-51, Optical fibres – Part 1-51: Measurement methods and test procedures – Dry
heat (steady state) tests
IEC 60793-1-52, Optical fibres – Part 1-52: Measurement methods and test procedures –
Change of temperature tests
IEC 60793-1-53, Optical fibres – Part 1-53: Measurement methods and test procedures –
Water immersion tests
IEC 60793-2, Optical fibres – Part 2: Product specifications – General
IEC 60794-2, Optical fibre cables – Part 2: Indoor cables – Sectional specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60793-2 and the
IEC 60793-1 series apply.
– 10 – IEC 60793-2-50:2018 © IEC 2018
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE General definitions for fibres are provided in IEC 60793-2. The definitions of the specified attributes are
contained in the relevant test methods standard of the IEC 60793-1 series, while general definitions for testing are
provided in IEC 60793-1-1.
4 Abbreviated terms and symbols
For the purposes of this document, the following abbreviated terms and symbols apply:
F Average strip force
avg
F Peak strip force
peak
λ Zero dispersion wavelength
λ Fibre cut-off wavelength
c
λ Cable cut-off wavelength
cc
MFD Mode field diameter
n Stress corrosion parameter – dynamic
d
PMD Polarization mode dispersion
PMD PMD link design value
Q
5 Specifications
5.1 General
The fibre shall consist of a glass core and glass cladding in accordance with the construction
of optical fibre class B – single-mode fibre – as given in IEC 60793-2.
The term “glass” usually refers to material consisting of non-metallic oxides. The composition
of some fibres may be all glass, or glass and glass/hard polymeric composites.
5.2 Dimensional requirements
Relevant dimensional attributes and measurement methods are given in Table 2.
Requirements common to all categories of class B single-mode fibres are given in Table 3.
Cladding diameter, cladding non-circularity, and core – cladding concentricity error shall be
specified in the family specifications

Table 2 – Dimensional attributes and measurement methods
Attribute Measurement method
Cladding diameter IEC 60793-1-20
Cladding non-circularity IEC 60793-1-20
Core – cladding concentricity error IEC 60793-1-20
Primary coating diameter IEC 60793-1-21
Primary coating non-circularity IEC 60793-1-21
Primary coating-cladding concentricity error IEC 60793-1-21
Fibre length IEC 60793-1-22
Table 3 – Dimensional requirements common to all category B fibres
Attribute Unit Limit
a
Primary coating diameter – uncoloured µm 235 to 255
a
Primary coating diameter – coloured µm 235 to 265
Primary coating-cladding concentricity error
µm ≤ 12,5
b
Fibre length km
a
The above limits on primary coating diameter are most commonly used in telecommunications cables. There
are other applications, such as fibre for use within optical sub-systems, pigtails, or specialty applications
such as for submarines cables or for compact FTTH cables, which use other primary coating diameters,
several of which are listed below.
180 µm to 210 µm uncoloured; 180 µm to 220 µm coloured
400 µm ± 40 µm
500 µm ± 50 µm
700 µm ± 70 µm
900 µm ± 90 µm
Alternative coating diameters may impact fibre connectivity such as ribbons, multi-fibre connectors,
mechanical splices, and fusion splice protectors; they may also need adjustments to connectivity tools and/
or tighter coating tolerances.
b
Length requirements vary and should be agreed between supplier and customer.

5.3 Mechanical requirements
Relevant mechanical attributes and test methods are given in Table 4. The relationship
between some of these attributes and mechanical reliability are described in IEC TR 62048
and ITU-T G.Sup.59.
Requirements common to all categories of class B single-mode fibres are given in Table 5.
Table 4 – Mechanical attributes and test methods
Attribute Test method
Proof test IEC 60793-1-30
Tensile strength IEC 60793-1-31
Coating strippability IEC 60793-1-32
Stress corrosion susceptibility IEC 60793-1-33
Fibre curl IEC 60793-1-34
– 12 – IEC 60793-2-50:2018 © IEC 2018
Table 5 – Mechanical requirements common to all class B fibres
Attribute Unit Limit
a
Proof stress level GPa ≥ 0,69
b, c
Coating strip force (average) N
1,0 ≤ F ≤ 5,0
ave
b, c
Coating strip force (peak) N 1,0 ≤ F ≤ 8,9

peak
d
Fibre curl radius m ≥ 2
Tensile strength (median) for 0,5 m specimen length GPa
≥ 3,8
Stress corrosion susceptibility parameter, n –
≥ 18
d
a
The proof test value of 0,69 GPa equals about 1 % strain or about 8,8 N force. For the relation between
these different units, see IEC TR 62048:2014, clause 8.4.
b
Either average strip force or peak strip force, which are defined in the test procedure, may be specified with
agreement between supplier and customer.
c
In case of alternative nominal primary coating diameters (see Table 2), associated alternative coating strip
force values need to be agreed between supplier and customer or provided in the detailed specifications
provided in Annexes of this document.
d
Depending on splicing methods, a minimum of 4 m may be specified for fibre intended to be used in some
cable constructions – such as ribbon cable.

5.4 Transmission requirements
Relevant transmission attributes and measurement methods are given in Table 6.
Requirements common to all categories of class B single-mode fibres are shown in Table 7.
Requirements that shall be specified in the family specifications are listed in Table 8.
Table 6 – Transmission attributes and measurement methods
Attribute Measurement method
a
Attenuation coefficient IEC 60793-1-40
Chromatic dispersion IEC 60793-1-42
b
Cut-off wavelength IEC 60793-1-44
Mode field diameter IEC 60793-1-45
Change of optical transmission IEC 60793-1-46
Macrobending loss IEC 60793-1-47
Polarization mode dispersion IEC 60793-1-48
The indicated maximum attenuation values apply to cabled and uncabled optical fibres. Tighter specifications for
the fibre may be requested to account for added attenuation in the cabling process; for the maximum cabled
attenuation values, reference is made to IEC 60794-2, which can be used in conjunction with this document.
a
The attenuation coefficient at various wavelengths can be calculated using the measured values at a few
wavelengths using a spectral model such as that given in IEC 60793-1-40. For example, the attenuation at
1 480 nm can be calculated and used for design of systems that employ remote pumping of optical
amplifiers. When using Method C, OTDR, additional guidance information in IEC TR 62316 shall be taken
into account. As reported in IEC 60793-1-40:20xx, the spectral attenuation model has been demonstrated on
all class B fibres.
b
λ and to cable cut-
There are two ways to measure cut-off wavelength, leading to: fibre cut-off wavelength
c
off wavelength λ , respectively. The correlation of the measured values of λ and λ depends on the
cc c cc
specific fibre and cable design and the test conditions. While in general λ < λ a general quantitative
cc c
relationship cannot be easily established, the importance of ensuring single-mode transmission in the
minimum cable length between joints at the minimum operating wavelength is paramount. This may be
performed by recommending the maximum cable cut-off wavelength λ of a cabled single-mode fibre to be
cc
1 260 nm or for worst case length and bends by recommending a maximum fibre cut-off wavelength λ to
c
be 1 260 nm.
Table 7 – Transmission, requirements common to all class B fibres
Attribute Unit Limit
a
Polarization mode dispersion (PMD) coefficient link
ps km
design value (PMD )
Q
a
A maximum value of PMD on uncabled fibre shall be agreed between supplier and customer to satisfy the
Q
primary requirement of cable PMD, given in IEC 60794-3.

Table 8 – Additional transmission attributes required in the family specifications
Attribute
Attenuation coefficient and wavelengths
Chromatic dispersion characteristics
Nominal mode field diameter (MFD) range and wavelength
Mode field diameter tolerance
Cable cut-off wavelength, λ
cc
Macrobending loss including: wavelength, mandrel size, and number of turns
Cladding diameter
Cladding non-circularity
Core – cladding concentricity error

For category B-655 fibre, information for system design is given in Annex G.
5.5 Environmental requirements
5.5.1 General
Environmental exposure tests and measurement methods are documented in two forms:
• relevant environmental attributes and test methods are given in Table 9;
• measurements of a particular mechanical or transmission attributes that may change on
the application of the environment are listed in Table 10.
Table 9 – Environmental exposure tests
Attribute Test method
Damp heat tests IEC 60793-1-50
Dry heat tests IEC 60793-1-51
Change of temperature tests IEC 60793-1-52
Water immersion tests IEC 60793-1-53

Table 10 – Attributes measured in environmental exposure tests
Attribute Test method
Change in optical transmission IEC 60793-1-46
Attenuation IEC 60793-1-40
Coating strip force IEC 60793-1-32
Tensile strength IEC 60793-1-31
Stress corrosion susceptibility IEC 60793-1-33

– 14 – IEC 60793-2-50:2018 © IEC 2018
These tests are normally conducted periodically as type-tests for a fibre and coating design.
Unless otherwise indicated, the recovery period allowed between the completion of the
environmental exposure and performing the attribute measurements shall be as stated in the
particular environmental test method.
5.5.2 Optical environmental requirements – Attenuation
Change in attenuation from the initial value shall be less than the values in Table 11.
Attenuation shall be measured periodically during the entire exposure to each environment
and after removal.
Table 11 – Change in attenuation for environmental tests
Environment Wavelength Maximum attenuation increase
nm dB/km
Damp heat 1 550, 1 625 ≤ 0,05
Dry heat 1 550, 1 625
≤ 0,05
Change of temperature 1 550, 1 625 ≤ 0,05
Water immersion 1 550, 1 625 ≤ 0,05
NOTE Attenuation changes at wavelengths lower than the test wavelength are smaller than the attenuation
change at the test wavelength.

5.5.3 Mechanical environmental requirements
5.5.3.1 General
These tests are, in practice, the most severe requirements amongst the environments defined
in Table 9.
5.5.3.2 Coating strip force
The attributes given in Table 12 shall be verified following removal of the fibre from the
particular environment.
Table 12 – Coating strip force for environmental tests
Environment Average strip force Peak strip force
N N
Damp heat 1,0 ≤ F ≤ 5,0 1,0 ≤ F ≤ 8,9
avg peak
Water immersion
1,0 ≤ F ≤ 5,0 1,0 ≤ F ≤ 8,9
avg peak
NOTE In case of alternative nominal primary coating diameters (see Table 2), associated alternative coating
strip force values need to be agreed between supplier and customer unless specified in the detailed product
specifications or provided in the annexes of this document.

5.5.3.3 Tensile strength
The attributes given in Table 13 shall be verified following removal of the fibre from the
environment indicated.
Table 13 – Tensile strength for environmental tests
Environment Median tensile strength (GPa), 15 percentile of the tensile
specimen length: 0,5 m strength distribution (GPa),
specimen length: 0,5 m
Damp heat
≥ 3,03 ≥ 2,76
NOTE These requirements do not apply to hermetically coated fibre. (A hermetic coating is a protective layer
that completely segregates the glass fibre from moisture, thereby ensuring a high level of stress corrosion
resistance. Typical hermetic coating is a carbon layer of several microns thickness applied on the glass
surface.)
5.5.3.4 Stress corrosion susceptibility
The attribute given in Table 14 shall be verified following removal of the fibre from the
environment indicated.
Table 14 – Stress corrosion susceptibility for environmental tests
Environment Stress corrosion susceptibility parameter, n
d
Damp heat
≥ 18
NOTE This requirement does not apply to hermetically coated fibre (see definition for hermetic coating in
Table 13).
– 16 – IEC 60793-2-50:2018 © IEC 2018
Annex A
(normative)
Family specification for category B-652 Dispersion
unshifted single-mode fibres
A.1 General
This dispersion unshifted single-mode fibre is optimized for use in the 1 310 nm region but
can be used in the 1 550 nm and 1 625 nm regions. Depending on link length and bit rates,
dispersion may need accommodation in the 1 550 nm and 1 625 nm regions.
The clauses and tables in Annex A contain particular requirements applicable to category
B-652 fibres. Common requirements, repeated here for ease of reference from the sectional
specification, are noted by an entry in the “Reference” column. Relevant notes from the
SS"
"
sectional specification are not repeated but indicated with a superscript .
A.2 Dimensional requirements
Table A.1 contains dimensional requirements specific to category B-652.B fibres.
Table A.1 – Dimensional requirements specific to category B-652.B fibres
Attribute Unit Limit Limit Reference
(250 µm coating) (200 µm coating)
Cladding diameter µm 125 ± 1 125 ± 1 5.2
Cladding non-circularity % 5.2
≤ 1,0 ≤ 1,0
Core – cladding concentricity µm ≤ 0,6 ≤ 0,6 5.2
error
Primary coating diameter – 235 to 255 180 to 210 5.2
µm
a
uncoloured
Primary coating diameter – 235 to 265 180 to 220 5.2
µm
a
coloured
Primary coating-cladding 5.2
µm ≤ 12,5 ≤ 10,0
concentricity error
Fibre length
...