IEC 60793-2-40:2021

IEC 60793-2-40 ®
Edition 5.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibres –
Part 2-40: Product specifications – Sectional specification for category A4
multimode fibres
Fibres optiques –
Partie 2-40: Spécifications de produits – Spécification intermédiaire pour les
fibres multimodales de catégorie A4

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IEC 60793-2-40 ®
Edition 5.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibres –
Part 2-40: Product specifications – Sectional specification for category A4

multimode fibres
Fibres optiques –
Partie 2-40: Spécifications de produits – Spécification intermédiaire pour les

fibres multimodales de catégorie A4

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-9437-6

– 2 – IEC 60793-2-40:2021 © IEC 2021
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Specifications . 9
4.1 Dimensional requirements . 9
4.2 Mechanical requirements . 10
4.2.1 General . 10
4.2.2 Tensile load test . 10
4.3 Transmission requirements . 11
4.4 Environmental requirements . 12
4.4.1 General . 12
4.4.2 Mechanical environmental requirements . 13
4.4.3 Transmission environmental requirements . 13
Annex A (normative) Family specifications for subcategory A4a multimode fibres . 15
A.1 General . 15
A.2 Dimensional requirements . 15
A.3 Mechanical requirements . 15
A.4 Transmission requirements . 15
A.5 Environmental requirements . 16
Annex B (normative) Family specifications for subcategory A4b multimode fibres . 17
B.1 General . 17
B.2 Dimensional requirements . 17
B.3 Mechanical requirements . 17
B.4 Transmission requirements . 17
B.5 Environmental requirements . 18
Annex C (normative) Family specifications for subcategory A4c multimode fibres . 19
C.1 General . 19
C.2 Dimensional requirements . 19
C.3 Mechanical requirements . 19
C.4 Transmission requirements . 19
C.5 Environmental requirements . 20
Annex D (normative) Family specifications for subcategory A4d multimode fibres . 21
D.1 General . 21
D.2 Dimensional requirements . 21
D.3 Mechanical requirements . 21
D.4 Transmission requirements . 21
D.5 Environmental requirements . 22
Annex E (normative) Family specifications for subcategory A4e multimode fibres . 23
E.1 General . 23
E.2 Dimensional requirements . 23
E.3 Mechanical requirements . 23
E.4 Transmission requirements . 23
E.5 Environmental requirements . 24
Annex F (normative) Family specifications for subcategory A4f multimode fibres . 25

Annex G (normative) Family specifications for subcategory A4g multimode fibres . 26
G.1 General . 26
G.2 Dimensional requirements . 26
G.3 Mechanical requirements . 26
G.4 Transmission requirements . 26
G.5 Environmental requirements . 27
Annex H (normative) Family specifications for subcategory A4h multimode fibres . 28
H.1 General . 28
H.2 Dimensional requirements . 28
H.3 Mechanical requirements . 28
H.4 Transmission requirements . 28
H.5 Environmental requirements . 29
Annex I (normative) Family specifications for subcategory A4i multimode fibres . 30
I.1 General . 30
I.2 Dimensional requirements . 30
I.3 Mechanical requirements . 30
I.4 Transmission requirements . 30
I.5 Environmental requirements . 31
Annex J (normative) Mode scramblers for subcategory A4a to A4c fibres . 32
J.1 General . 32
J.2 Specification for mode scramblers . 32
Annex K (informative) Additional transmission requirements for subcategory A4a
multimode fibres for wavelengths below 650 nm . 33
K.1 General . 33
K.2 Transmission requirements . 33
Bibliography . 34

Figure 1 – Tensile load versus elongation for a plastic optical fibre . 11
Figure J.1 – Mode scrambler for category A4 fibre . 32

Table 1 – Characteristics and applications of category A4 fibres . 7
Table 2 – Dimensional attributes and measurement methods . 9
Table 3 – Requirements common to all category A4 fibres . 9
Table 4 – Additional attributes required in A4g through A4i family specifications . 9
Table 5 – Mechanical attributes and test methods . 10
Table 6 – Requirements common to category A4 fibres . 10
Table 7 – Additional attributes required in family specification for sub-category A4g
through A4i fibres . 10
Table 8 – Transmission attributes and measurement methods . 12
Table 9 – Attributes required in family specifications . 12
Table 10 – Environmental exposure tests . 13
Table 11 – Attributes measured . 13
Table 12 – Requirement for tensile strength . 13
Table 13 – Requirement for change in attenuation for A4a through A4e fibre . 14
Table 14 – Requirement for change in attenuation for A4g through A4i fibre . 14
Table A.1 – Dimensional requirements specific to A4a fibres . 15

– 4 – IEC 60793-2-40:2021 © IEC 2021
Table A.2 – Mechanical requirements specific to A4a fibres . 15
Table A.3 – Transmission requirements specific to A4a fibres . 16
Table B.1 – Dimensional requirements specific to A4b fibres . 17
Table B.2 – Mechanical requirements specific to A4b fibres . 17
Table B.3 – Transmission requirements specific to A4b fibres . 18
Table C.1 – Dimensional requirements specific to A4c fibres . 19
Table C.2 – Mechanical requirements specific to A4c fibres . 19
Table C.3 – Transmission requirements specific to A4c fibres . 20
Table D.1 – Dimensional requirements specific to A4d fibres . 21
Table D.2 – Mechanical requirements specific to A4d fibres . 21
Table D.3 – Transmission requirements specific to A4d fibres. 22
Table E.1 – Dimensional requirements specific to A4e fibres . 23
Table E.2 – Mechanical requirements specific to A4e fibres . 23
Table E.3 – Transmission requirements specific to A4e fibres . 24
Table G.1 – Dimensional requirements specific to A4g fibres . 26
Table G.2 – Mechanical requirements specific to A4g fibres . 26
Table G.3 – Transmission requirements specific to A4g fibres . 27
Table H.1 – Dimensional requirements specific to A4h fibres . 28
Table H.2 – Mechanical requirements specific to A4h fibres . 28
Table H.3 – Transmission requirements specific to A4h fibres. 29
Table I.1 – Dimensional requirements specific to A4i fibres . 30
Table I.2 – Mechanical requirements specific to A4i fibres . 30
Table I.3 – Transmission requirements specific to A4i fibres . 31
Table J.1 – Mode Scrambler parameters . 32
Table K.1 – Transmission requirements specific to A4a.2 fibre. 33

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 2-40: Product specifications –
Sectional specification for category A4 multimode 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
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6) All users should ensure that they have the latest edition of this publication.
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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) 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 60793-2-40 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This fifth edition cancels and replaces the fourth 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) revision of NA range of A4a.2;
b) addition of a new subcategory A4i;
c) deletion of the subcategory A4f and of Annex F.

– 6 – IEC 60793-2-40:2021 © IEC 2021
The text of this International Standard is based on the following documents:
CDV Report on voting
86A/1943/CDV 86A/1981/RVC
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 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.
OPTICAL FIBRES –
Part 2-40: Product specifications –
Sectional specification for category A4 multimode fibres

1 Scope
This part of IEC 60793 is applicable to category A4 optical multimode fibres and the related
subcategories A4a, A4b, A4c, A4d, A4e, A4g, A4h and A4i. These fibres have a plastic core
and plastic cladding and may have step-index, multi-step index or graded-index profiles. The
fibres are used in information transmission equipment and other applications employing similar
light transmitting techniques, and in fibre optic cables. Table 1 summarizes some of the salient
characteristics and applications of these fibres.
Table 1 – Characteristics and applications of category A4 fibres
Sub-category A4a A4b A4c A4d A4e A4f A4g A4h A4i
A4a.1 A4a.2
Core diameter
a a a a c
≥ 500 120 62,5 55
(µm)
Cladding
d
c
1 000 750 500 1 000 750 490
490 245
diameter (µm)
Numerical
aperture Na
ff c
0,50 0,53 0,50 0,50 0,30 0,25 0,190 0,190 0,24

e
Operating 650
b
c
wave-length(s) 650 650 650 650 850 850
1 300
(nm) 1 300
c
Applications Digital audio Industrial Sensor Digital Digital Data Data Industrial

interface, automobile, and audio- audio- trans- trans- data
industrial, sensor and sensor visual visual mission mission; trans-
data transmission interface interface primarily mission
and data and data used in
trans- trans- ribbon
mission mission structures
a
Typically 15 µm to 35 µm smaller than the cladding diameter.
b
Other potential wavelengths for A4a fibre are described in Annex K.
c
This sub-category is outdated and therefore no more specified.
d
Cladding diameters of 490 µm and 750 µm are also possible.
e
Na is numerical aperture measured by far field pattern method.
ff
In addition to the applications shown in Table 1, other applications for A4 fibres include, but are
not restricted to, the following: support for short reach, high bit-rate systems in telephony,
distribution and local networks, carrying data, voice and/or video services and on-premises
intrabuilding and interbuilding fibre installations, including local area networks (LANs), private
branch exchanges (PBXs), video, various multiplexing uses and miscellaneous related uses,
such as consumer electronics and industrial and mobile networks.
Three types of requirements apply to A4 fibres:
• general requirements, as defined in IEC 60793-2;
• specific requirements common to category A4 multimode fibres covered in this document
and which are given in Clause 4;

– 8 – IEC 60793-2-40:2021 © IEC 2021
• particular requirements applicable to individual fibre sub-categories and implementations or
specific applications which are defined in this document, in the normative family
specification annexes.
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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60793-1-20, Optical fibres – Part 1-20: Measurement methods and test procedures – Fibre
geometry
IEC 60793-1-22, Optical fibres – Part 1-22: Measurement methods and test procedures –
Length measurement
IEC 60793-1-40:2019, Optical fibres – Part 1-40: Attenuation measurement methods
IEC 60793-1-41, Optical fibres – Part 1-41: Measurement methods and test procedures –
Bandwidth
IEC 60793-1-42, Optical fibres – Part 1-42: Measurement methods and test procedures –
Chromatic dispersion
IEC 60793-1-43, Optical fibres – Part 1-43: Measurement methods and test procedures –
Numerical aperture measurement
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 60793-1-50, 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
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org
• ISO Online browsing platform: available at http://www.iso.org/obp

4 Specifications
4.1 Dimensional requirements
Relevant dimensional attributes and measurement methods are given in Table 2.
Requirements common to all category A4 fibres are indicated in Table 3.
Additional attributes that shall be specified in the family specifications for subcategories A4g
through A4i are given in Table 4.
Table 2 – Dimensional attributes and measurement methods
Attribute Measurement method
a
Cladding diameter
IEC 60793-1-20
a
Cladding non-circularity
IEC 60793-1-20
b
IEC 60793-1-20
Core diameter
Fibre length IEC 60793-1-22
Core-cladding concentricity error IEC 60793-1-20
Core non-circularity IEC 60793-1-20
a
Mechanical methods are also applicable to cladding diameter and cladding non-circularity measurements if
they provide the same measurement uncertainty.
b
Core diameter is specified at 650 nm ± 10 nm with a test specimen length of 2,0 m ± 0,2 m and a threshold
value k of 2,5 % (IEC 60793-1-20, method B) for A4 fibres.
CORE
Table 3 – Requirements common to all category A4 fibres
Attribute Unit Limit
a
Cladding diameter µm
b
Cladding non-circularity %
≤ 6
c
Core diameter µm
d
Fibre length km
a
The cladding diameter varies and is listed in the family specification.
b
Unless otherwise specified in the family specification.
c
For A4a, A4b, A4c and A4d fibre, the core diameter is typically 15 µm to 35 µm smaller than the cladding
diameter. For A4e, A4g, A4h and A4i fibre, the core diameter varies and is listed in the relevant family
specification (in the annexes to this document).
d
Length requirements vary and should be agreed between supplier and customer.

Table 4 – Additional attributes required in A4g through A4i family specifications
Attribute
Core non-circularity
Core-cladding concentricity error

– 10 – IEC 60793-2-40:2021 © IEC 2021
4.2 Mechanical requirements
4.2.1 General
Mechanical attributes, test methods, and requirements for buffered fibres can be found in
IEC 60794-2-41.
Relevant mechanical attributes and test methods are given in Table 5.
Requirements common to all category A4 fibres are indicated in Table 6.
Additional attributes that shall be specified in the family specifications for subcategories A4g
through A4i are given in Table 7.
Table 5 – Mechanical attributes and test methods
Attribute Test method
Tensile performance 4.2.2
Table 6 – Requirements common to category A4 fibres
Attribute Unit Limit
Elongation at yield peak % ≥ 4,0
a
Tensile load at yield peak N
a
Tensile load at yield peak varies and is listed in the
family specification (see annexes to this document).

Table 7 – Additional attributes required in family specification
for subcategory A4g through A4i fibres
Attribute
Tensile load to induce 4 % elongation

4.2.2 Tensile load test
4.2.2.1 Object
The purpose of this test is to characterize the ability of the fibre to support a load during handling.
Its purpose is to obtain values of the fibre's tensile strength.
The test shall be carried out at the standard test conditions in compliance with IEC 60068-1.
4.2.2.2 Definition of yield peak
Figure 1 shows a typical load versus elongation curve for a plastic optical fibre. The curve
exhibits an initial monotonic increase in tensile load with applied elongation that goes through
a load peak. The peak is followed by a decrease in load as the sample begins to undergo a
ductile, irreversible elongation. Localized necking and drawing of the sample may accompany
the process. This phenomenon is known as yielding and the peak is termed a yield peak.

Figure 1 – Tensile load versus elongation for a plastic optical fibre
4.2.2.3 Test apparatus
The length of the sample between two clamping devices shall be between 100 mm and 200 mm.
The tensile strength measuring apparatus shall be a device, for example a vertical tensile tester,
which provides relative motion to the test fibre. The apparatus shall be capable of imparting
constant motion without jerking the fibre under test. The apparatus shall have the ability to
simultaneously measure and record the resulting tensile force or load. To prevent fibre
breakage, the means used to secure the fibre ends at the clamping points shall not stress the
fibre excessively.
4.2.2.4 Procedure
The tensile speed shall be 100 mm/min ± 10 %. Yield strength and yield elongation are obtained
from the load-elongation curve described in 4.2.2.2. Unless otherwise specified, tensile load at
the yield peak and tensile load to induce 4 % elongation shall be recorded.
NOTE Elongation to breaking point is not applicable to category A4 fibres.
4.2.2.5 Requirements
The requirements are stated in the family specifications found in Annex A to Annex J. If the
fibre sample breaks at a clamping point, the test shall be regarded as invalid and another test
shall be carried out. The number of samples tested shall be sufficient to allow for a statistical
analysis.
4.3 Transmission requirements
Relevant transmission attributes and measurement methods are given in Table 8.
Additional attributes required in the family specifications are indicated in Table 9.

– 12 – IEC 60793-2-40:2021 © IEC 2021
Table 8 – Transmission attributes and measurement methods
Attribute Measurement method
a
IEC 60793-1-40
Attenuation
a
IEC 60793-1-41
Modal bandwidth
Modal bandwidth with RML IEC 60793-1-41
b,c,d
IEC 60793-1-43
Numerical aperture
Chromatic dispersion IEC 60793-1-42
Macrobending loss IEC 60793-1-47, method B
a
When measuring attenuation and modal bandwidth, the appropriate launching conditions should be applied
as specified in IEC 60793-1-40 and IEC 60793-1-41 or as stated in the family specification. Bandwidth is not
necessarily linear with regard to length. The value of bandwidth is referenced to 100 m of fibre.
b
Numerical aperture is specified at 650 nm ± 10 nm with a test specimen length of 2,0 m ± 0,2 m and a
threshold value k of 50 % for A4a to A4c and A4e fibres.
NA
c
Numerical aperture is specified at 650 nm ± 10 nm with a test specimen length of 2,0 m ± 0,2 m and by the
local minimums and related angles in the farfield intensity pattern for A4d fibres (IEC 60793-1-43,
Technique 4, inverse far-field measurement).
d
Numerical aperture is specified at 850 nm ± 10 nm with a test specimen length of 6,0 m ± 0,6 m and a
threshold value k of 5 % for A4g to A4i fibres.
NA
Table 9 – Attributes required in family specifications
Attribute
Attenuation
Modal bandwidth
Numerical aperture
Chromatic dispersion
Macrobending loss
4.4 Environmental requirements
4.4.1 General
Environmental exposure tests and measurement methods are documented in two forms:
• relevant environmental attributes, test methods and test conditions given in Table 10;
• measurements of a particular mechanical and transmission attribute that may change during
exposure to the environmental test listed in Table 11.

Table 10 – Environmental exposure tests
a b c
Environment
Test condition Test method Test condition
Damp heat IEC 60793-1-50 +75 °C, 85 % RH, 30 days
Dry heat IEC 60793-1-51 +85 °C, 30 days
A
Change of temperature IEC 60793-1-52 T :−40 °C, T :+85 °C
A B
Damp heat IEC 60793-1-50 +60 °C, 85 % RH, 30 days
Dry heat IEC 60793-1-51 +70 °C, 30 days
B
Change of temperature IEC 60793-1-52 T :−20 °C, T :+70 °C
A B
a
Test condition A or B should be agreed between supplier and customer.
b
Although these test methods do not specifically mention their applicability to A4 fibres, the test methods should
be used. The test specimen length shall be agreed between supplier and customer.
c
These test conditions supersede any that might be specified in the indicated test methods.

Table 11 – Attributes measured
Attribute Measurement method
Change in optical transmission IEC 60793-1-46
Tensile load 4.2.2
These tests are normally conducted periodically as type-tests for a fibre design. Unless
otherwise specified:
• the specimen shall be pre-conditioned by keeping it at standard atmospheric conditions for
at least 24 h, and
• the recovery period allowed between the completion of the environmental exposure and
measuring the attributes shall be as stated in the particular environmental test method.
Environmental exposure testing of subcategory A4a to A4e fibres are usually performed after
the fibres are buffered (refer to IEC 60794-2-41 for environmental requirements on buffered
fibres). Environmental exposure testing of unbuffered fibre is only required when the fibres are
sold in unbuffered form.
4.4.2 Mechanical environmental requirements
Tensile strength shall be verified according to Table 12 following removal of the fibre from the
environment but only after cooling down the specimen at standard atmospheric conditions.
Table 12 – Requirement for tensile strength
Environment Elongation at yield peak
Damp heat ≥ 4,0 %
4.4.3 Transmission environmental requirements
Change in attenuation from the initial value shall be less than the values in Table 13 and
Table 14. The requirements differ for the two groups of fibres because of their different
application environments.
– 14 – IEC 60793-2-40:2021 © IEC 2021
Table 13 – Requirement for change in attenuation for A4a through A4e fibre
Environment Attribute Unit Limits
Damp heat Attenuation increase at 650 nm dB/100 m ≤ 5
(includes attenuation due to
water absorption)
Dry heat Attenuation increase at 650 nm dB/100 m ≤ 2
Change of temperature Attenuation increase at 650 nm dB/100 m ≤ 2

Table 14 – Requirement for change in attenuation for A4g through A4i fibre
Environment Attribute Unit Limits
Damp heat Attenuation increase at 650 nm, dB/100 m ≤ 1,0
a
850 nm and/or 1 300 nm
(includes attenuation due to
water absorption)
Dry heat Attenuation increase at 650 nm, dB/100 m ≤ 0,5
850 nm and/or 1 300 nm
Change of temperature Attenuation increase at 650 nm, dB/100 m ≤ 0,5
850 nm and/or 1 300 nm
a
Because the effect of absorbed water can be significant at 1 300 nm, attenuation increase is specified only
after the sample has recovered for at least 24 h under standard room temperature atmospheric conditions.

Annex A
(normative)
Family specifications for subcategory A4a multimode fibres
A.1 General
The clauses and tables in this Annex A contain particular requirements applicable to
subcategory A4a fibres. Common requirements, from the main body text of this document and
repeated here for ease of reference, are noted by an entry in the "Reference" column.
Subcategory A4a fibre is a 1 000 µm cladding diameter step-index fibre.
A.2 Dimensional requirements
Table A.1 contains dimensional requirements specific to A4a fibres.
Table A.1 – Dimensional requirements specific to A4a fibres
Attribute Unit Limit Reference
Cladding diameter µm 1 000 ± 60 4.1
Cladding non-circularity % ≤ 6 4.1
Core diameter µm See 4.1 4.1
Table 2
Fibre length km See 4.1 4.1
A.3 Mechanical requirements
Table A.2 contains mechanical requirements specific to A4a fibres.
Table A.2 – Mechanical requirements specific to A4a fibres
Attribute Unit Limit Reference
Tensile load at yield peak N ≥ 56 4.2.2
Elongation at yield peak % ≥ 4,0 4.2.2

A.4 Transmission requirements
Table A.3 contains transmission requirements specific to A4a fibres.
Implementation A4a.1 corresponds to subcategory A4a fibre specified in the second edition of
this document, IEC 60793-2-40:2006. Implementation A4a.2 is a higher grade of subcategory
A4a fibre in terms of attenuation and bandwidth, to achieve longer distance transmission than
implementation A4a.1 (see Annex J for information about 520 nm transmission over A4a.2
fibres).
– 16 – IEC 60793-2-40:2021 © IEC 2021
Table A.3 – Transmission requirements specific to A4a fibres
Attribute Unit Limit Reference
A4a.1 A4a.2
a
Attenuation at 650 nm when using an
≤ 40 ≤ 40 4.3
dB/100 m
overfilled launch
a
Attenuation at 650 nm when using an ≤ 30 ≤ 18 4.3
dB/100 m
c
equilibrium mode distribution launch
b
Minimum modal bandwidth at 650 nm 10 – 4.3
MHz over 100 m
b
Minimum modal bandwidth at 650 nm – 40 4.3
MHz over 100 m
using RML
Numerical aperture Unitless 0,50 ± 0,53 ± 4.3
0,15 0,07
Table 8
Macrobending loss at 650 nm (10 turns dB ≤ 0,5 ≤ 0,5 4.3
around a 25 mm radius quarter circle)
a
The unit of 100 m is used because this is typical of the fibre length actually used. Attenuation values expressed
in dB/100 m can be approximately compared to values stated in dB/km by multiplying the dB/100 m values by
10.
b
The unit of MHz over 100 m is used because this is typical of the fibre length actually used. Bandwidth values
expressed in MHz over 100 m can be approximately compared to values stated in MHz∙km by dividing the
MHz over 100 m values by 10.
c
See Annex J.
A.5 Environmental requirements
The requirements of 4.4 shall be met.

Annex B
(normative)
Family specifications for subcategory A4b multimode fibres
B.1 General
The clauses and tables in this Annex B contain particular requirements applicable to
subcategory A4b fibres. Common requirements, from the main body text of this document and
repeated here for ease of reference, are noted by an entry in the "Reference" column.
Subcategory A4b fibre is a 750 µm cladding diameter step-index fibre.
B.2 Dimensional requirements
Table B.1 contains dimensional requirements specific to A4b fibres.
Table B.1 – Dimensional requirements specific to A4b fibres
Attribute Unit Limit Reference
Cladding diameter µm 750 ± 45 4.1
Cladding non-circularity % ≤ 6 4.1
Core diameter µm See 4.1 4.1
Table 2
Fibre length km See 4.1 4.1
B.3 Mechanical requirements
Table B.2 contains mechanical requirements specific to A4b fibres.
Table B.2 – Mechanical requirements specific to A4b fibres
Attribute Unit Limit Reference
Tensile load at yield peak N ≥ 32 4.2.2
Elongation at yield peak % ≥ 4,0 4.2.2

B.4 Transmission requirements
Table B.3 contains transmission requirements specific to A4b fibres.

– 18 – IEC 60793-2-40:2021 © IEC 2021
Table B.3 – Transmission requirements specific to A4b fibres
Attribute Unit Limit Reference
a
Attenuation at 650 nm when using an ≤ 40 4.3
dB/100 m
overfilled launch
a
Attenuation at 650 nm when using an ≤ 30 4.3
dB/100 m
c
equilibrium mode distribution launch
b
Minimum modal bandwidth at 650 nm 10 4.3
MHz over 100 m
Numerical aperture Unitless 0,50 ± 0,15 4.3
Table 8
Macrobending loss at 650 nm (10 turns dB ≤ 0,5 4.3
around a 25 mm radius quarter circle)
a
The unit of 100 m is used because this is typical of the fibre length actually used. Attenuation values expressed
in dB/100 m can be approximately compar
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