IEC 60793-2-50:2025

IEC 60793-2-50 ®
Edition 7.0 2025-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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
ICS 33.180.10  ISBN 978-2-8327-0410-3

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– 2 – IEC 60793-2-50:2025 © IEC 2025
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 8
3 Terms, definitions, abbreviated terms and symbols . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms and symbols . 9
4 Specifications . 10
4.1 General . 10
4.2 Dimensional requirements . 10
4.3 Mechanical requirements . 11
4.4 Transmission requirements . 12
4.5 Environmental requirements . 14
4.5.1 General . 14
4.5.2 Optical environmental requirements – Attenuation . 14
4.5.3 Mechanical environmental requirements . 15
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 . 29
Annex E (normative) Family specification for category B-656 Wideband non-zero
dispersion shifted single-mode fibres . 30
E.1 General . 30
E.2 Dimensional requirements . 30
E.3 Mechanical requirements . 30
E.4 Transmission requirements . 31
E.4.1 General . 31
E.4.2 Chromatic dispersion coefficient for category B-656 fibres . 31
E.5 Environmental requirements . 32
Annex F (normative) Family specification for category B-657 Bending loss insensitive

single-mode fibres . 33
F.1 General . 33
F.2 Dimensional requirements . 33
F.3 Mechanical requirements . 34
F.4 Transmission requirements . 34
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 . 7
Table 2 – Dimensional attributes and measurement methods . 10
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 . 13
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 . 14
Table 10 – Attributes measured in environmental exposure tests . 14
Table 11 – Change in attenuation for environmental tests . 14
Table 12 – Coating strip force for environmental tests . 15
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

– 4 – IEC 60793-2-50:2025 © IEC 2025
Table A.2 – Dimensional requirements specific to category B-652.D fibres . 17
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 . 30
Table E.2 – Mechanical requirements specific to category B-656 fibres . 31
Table E.3 – Transmission requirements specific to category B-656 fibres . 31
Table F.1 – Dimensional requirements specific to category B-657 fibres . 34
Table F.2 – Mechanical requirements specific to category B-657 fibres . 34
Table F.3 – Transmission requirements specific to category B-657 fibres . 35
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
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60793-2-50 has been prepared by subcommittee 86A: Fibres and cables, of IEC technical
committee 86: Fibre optics. It is an International Standard.
This seventh edition cancels and replaces the sixth edition published in 2018. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The addition of a 200 µm coating nominal outer diameter option for B-654A, B, C fibres in
Annex C.
– 6 – IEC 60793-2-50:2025 © IEC 2025
The text of this International Standard is based on the following documents:
Draft Report on voting
86A/2494/FDIS 86A/2570/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
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 4;
• particular requirements applicable to individual fibre categories or specific applications,
which are defined in Annex A to Annex 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 specifications as well
as the names used to describe these fibre types 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
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
category Recommendation
B-652 Dispersion unshifted fibre G.652
Annex A B-652.B B1.1 G.652.B
Annex A B-652.D B1.3 G.652.D
B-653 Dispersion shifted fibre G.653
Annex B B-653.A B2_a G.653.A
Annex B B-653.B B2_b G.653.B
B-654 Cut-off shifted fibre G.654
Annex C B-654.A B1.2_a G.654.A
Annex C B-654.B B1.2_b G.654.B
Annex C B-654.C B1.2_c G.654.C
Annex C B-654.D N/A G.654.D
___________
This publication has been withdrawn.

– 8 – IEC 60793-2-50:2025 © IEC 2025
Annex Category Sub Description IEC 60793-2-50:2015 ITU-T
category Recommendation
Annex C B-654.E N/A G.654.E
Annex D B-655 Non-zero dispersion shifted fibre B4 G.655
Annex D B-655.C B4_c G.655.C
Annex D B-655.D B4_d G.655.D
Annex D B-655.E B4_e G.655.E
Annex E B-656 Wideband non-zero dispersion shifted B5 G.656
fibre
Annex F B-657 Bending loss insensitive fibre B6 G.657
Annex F B-657.A1 B6_a1 G.657.A1
Annex F B-657.A2 B6_a2 G.657.A2
Annex F B-657.B2 B6_b2 G.657.B2
Annex 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: Attenuation measurement methods
IEC 60793-1-42:2013, 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 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
3 Terms, definitions, abbreviated terms and symbols
3.1 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.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://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.
3.2 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
– 10 – IEC 60793-2-50:2025 © IEC 2025
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
4 Specifications
4.1 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 can be all glass, or glass and glass and hard polymeric composites.
4.2 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 can impact fibre connectivity such as ribbons, multi-fibre connectors, mechanical
splices, and fusion splice protectors; adjustments can be necessary to either connectivity tools or tighter
coating tolerances, or both.
b
Length requirements vary and should be agreed between supplier and customer.

4.3 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 60793-2-50:2025 © IEC 2025
Table 5 – Mechanical requirements common to all class B fibres
Attribute Unit Limit
a
Proof stress level GPa
≥ 0,69
b, c
N 1,0 ≤ F ≤ 5,0
Coating strip force (average)
ave
b, c
N 1,0 ≤ F ≤ 8,9
Coating strip force (peak)
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, 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 are agreed upon between supplier and customer or provided in the detailed specifications
provided in the 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.

4.4 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
IEC 60793-1-44
Cut-off wavelength
Mode field diameter IEC 60793-1-45
Change of optical attenuation 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 can be considered. As
reported in IEC 60793-1-40:— , the spectral attenuation model has been demonstrated on all class B fibres.
b
There are two ways to measure cut-off wavelength, leading to fibre cut-off wavelength λ and to cable cut-off
c
wavelength λ , respectively. The correlation of the measured values of λ and λ depends on the specific
cc c cc
fibre and cable design and the test conditions. While in general λ < λ , a general quantitative relationship
cc c
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 1 260 nm or for
cc
worst case length and bends by recommending a maximum fibre cut-off wavelength λ to be 1 260 nm.
c
Table 7 – Transmission, requirements common to all class B fibres
Attribute Unit Limit
a
Polarization mode dispersion (PMD) coefficient link design value (PMD )

Q
ps km
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 60794-1-1.

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

___________
Under preparation. Stage at the time of publication: IEC APUB 60793-1-40:2024.

– 14 – IEC 60793-2-50:2025 © IEC 2025
For category B-655 fibre, information for system design is given in Annex G.
4.5 Environmental requirements
4.5.1 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 can 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 attenuation 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

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.
4.5.2 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.

4.5.3 Mechanical environmental requirements
4.5.3.1 General
These tests are, in practice, the most severe requirements amongst the environments defined
in Table 9.
4.5.3.2 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
In case of alternative nominal primary coating diameters (see Table 2), associated alternative coating strip force
values shall be agreed between supplier and customer unless specified in the detailed product specifications or
provided in the annexes of this document.

4.5.3.3 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.

4.5.3.4 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 60793-2-50:2025 © IEC 2025
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,
accommodation of dispersion can be necessary 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 4.2
Cladding non-circularity % ≤ 1,0 ≤ 1,0 4.2
Core – cladding concentricity error µm ≤ 0,6 ≤ 0,6 4.2
a
µm 235 to 255 180 to 210 4.2
Primary coating diameter – uncoloured
a
µm 235 to 265 180 to 220 4.2
Primary coating diameter – coloured
Primary coating-cladding concentricity error µm ≤ 12,5 ≤ 10,0 4.2
Fibre length km See 4.2 See 4.2 4.2
a
Alternative nominal primary coating diameters may be used (see Table 2), to be agreed between supplier and
customer.
Table A.2 contains dimensional requirements specific to category B-652.D fibres.

Table A.2 – Dimensional requirements specific to category B-652.D fibres
Attribute Unit Limit Limit Reference
(250 µm coating) (200 µm coating)
Cladding diameter µm 125 ± 0,7 125 ± 0,7 4.2
Cladding non-circularity % ≤ 1,0 ≤ 1,0 4.2
Core – cladding concentricity error µm ≤ 0,6 ≤ 0,6 4.2
a
µm 235 to 255 180 to 210 4.2
Primary coating diameter – uncoloured
a
µm 235 to 265 180 to 220 4.2
Primary coating diameter – coloured
Primary coating-cladding concentricity error µm ≤ 12,5 ≤ 10,0 4.2
Fibre length km See 4.2 See 4.2 4.2
a
Alternative nominal primary coating diameters may be used (see Table 2), to be agreed between supplier and
customer.
A.3 Mechanical requirements
Table A.3 contains mechanical requirements specific to category B-652 fibres.
Table A.3 – Mechanical requirements specific
...