IEC 60793-2-70:2017

IEC 60793-2-70 ®
Edition 1.0 2017-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibres –
Part 2-70: Product specifications – Sectional specification for polarization-
maintaining fibres
Fibres optiques –
Partie 2-70: Spécifications de produits – Spécification intermédiaire pour
les fibres à maintien de polarisation

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IEC 60793-2-70 ®
Edition 1.0 2017-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibres –
Part 2-70: Product specifications – Sectional specification for polarization-

maintaining fibres
Fibres optiques –
Partie 2-70: Spécifications de produits – Spécification intermédiaire pour

les fibres à maintien de polarisation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-9364-5

– 2 – IEC 60793-2-70:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Specifications . 7
4.1 General . 7
4.2 Dimensional requirements . 7
4.3 Mechanical requirement . 8
4.4 Transmission requirements . 8
4.5 Environmental requirements . 9
Annex A (normative) Family specification for category D1 polarization-maintaining
fibres . 10
A.1 General . 10
A.2 Dimensional requirements . 10
A.3 Mechanical requirement . 10
A.4 Transmission requirements . 10
A.5 Environmental requirements . 11
Annex B (normative) Family specification for category D2 polarization-maintaining
fibres . 12
B.1 General . 12
B.2 Dimensional requirements . 12
B.3 Mechanical requirement . 12
B.4 Transmission requirements . 12
B.5 Environmental requirements . 13
Annex C (normative) Family specification for category D3 polarization-maintaining
fibres . 14
C.1 General . 14
C.2 Dimensional requirements . 14
C.3 Mechanical requirement . 14
C.4 Transmission requirements . 14
C.5 Environmental requirements . 15
Annex D (normative) Mode field diameter (MFD) measurement of PM fibre . 16
Annex E (informative) Cut-off wavelength of PM fibre and SM fibre . 17
Bibliography . 19

Figure E.1 – Cut-off wavelength profiles of PM fibre and SM fibre . 17
Figure E.2 – Cut-off wavelength profile of PM fibre with extra bending . 18

Table 1 – Categories of glass core/glass clad polarization-maintaining fibres . 6
Table 2 – Dimensional attributes and measurement methods . 8
Table 3 – Mechanical attribute and test method . 8
Table 4 – Transmission attributes and measurement methods . 9
Table 5 – Environmental exposure tests . 9
Table 6 – Attributes measured . 9
Table A.1 – Dimensional requirements specific to D1 fibres . 10

Table A.2 – Mechanical requirement specific to D1 fibres . 10
Table A.3 – Transmission requirements specific to D1 fibres . 11
Table A.4 – Environmental requirements specific to D1 fibres . 11
Table B.1 – Dimensional requirements specific to D2 fibres . 12
Table B.2 – Mechanical requirement specific to D2 fibres . 12
Table B.3 – Transmission requirements specific to D2 fibres . 13
Table B.4 – Environmental requirements specific to D2 fibres . 13
Table C.1 – Dimensional requirements specific to D3 fibres . 14
Table C.2 – Mechanical requirement specific to D3 fibres . 14
Table C.3 – Transmission requirements specific to D3 fibres . 15
Table C.4 – Environmental requirements specific to D3 fibres . 15

– 4 – IEC 60793-2-70:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 2-70: Product specifications –
Sectional specification for polarization-maintaining 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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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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
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
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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 60793-2-70 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
The text of this International Standard is based on the following documents:
CDV Report on voting
86A/1741/CDV 86A/1780/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.
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.
– 6 – IEC 60793-2-70:2017 © IEC 2017
OPTICAL FIBRES –
Part 2-70: Product specifications –
Sectional specification for polarization-maintaining fibres

1 Scope
This part of IEC 60793 is applicable to optical fibre types D1, D2, D3, as described in Table 1.
These fibres are polarization-maintaining fibre types, and are used or can be incorporated in
information transmission equipment and optical fibre cable. These fibres are available for use
in optical transport networks. Three types of requirements apply to these fibres:
– general requirements defined in IEC 60793-2;
– specific requirements common to the category D polarization-maintaining fibres covered in
this document and which are given in Clause 4;
– particular requirements applicable to individual fibre types or specific applications, which
are defined in Annexes A to C.
Table 1 – Categories of glass core/glass clad polarization-maintaining fibres
Category Type Description
D1 Polarization-maintaining fibre This category of polarization-maintaining fibre is
suitable for use at 980 nm optimised for polarization-maintaining ability in the
980 nm region. This fibre is used for erbium-doped
fibre amplifier.
D2 Polarization-maintaining fibre This category of polarization-maintaining fibre is
suitable for use at 1 310 nm optimised for polarization-maintaining ability and
connection property of category B fibres in the
1 310 nm region.
D3 Polarization-maintaining fibre This category of polarization-maintaining fibre is
suitable for use at 1 550 nm optimised for polarization-maintaining ability and
connection property of category B fibres in the
1 550 nm region.
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 60793-1-20:2014, 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 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –
Attenuation
IEC 60793-1-44:2011, 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 60793-1-46, Optical fibres – Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance
IEC 60793-1-52, Optical fibres – Part 1-52: Measurement methods and test procedures –
Change of temperature tests
IEC 60793-1-60 , Optical fibres – Part 1-60: Measurement methods and test procedures –
Beat length
IEC 60793-1-61 , Optical fibres – Part 1-61: Measurement methods and test procedures –
Polarization crosstalk
IEC 60793-2, Optical fibres – Part 2: Product specifications – General
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 General
The fibre shall consist of a glass core and glass cladding in accordance with the construction
of optical fibre category D – polarization-maintaining fibre – as given in IEC 60793-2.
The term "glass" usually refers to material consisting of non-metallic oxides.
4.2 Dimensional requirements
Relevant dimensional attributes and measurement methods are given in Table 2.
___________
Under preparation. Stage at the time of publication: IEC 60793-1-60:2017.
Under preparation. Stage at the time of publication: IEC 60793-1-61:2017.

– 8 – IEC 60793-2-70:2017 © IEC 2017
Table 2 – Dimensional attributes and measurement methods
Attributes Measurement methods
a
IEC 60793-1-20
Cladding diameter
a
IEC 60793-1-20
Cladding non-circularity
a
IEC 60793-1-20
Core-cladding concentricity error
Primary coating diameter IEC 60793-1-21
Primary coating-cladding concentricity error IEC 60793-1-21
Fibre length IEC 60793-1-22
a
The dimensional characteristics of polarization-maintaining (PM) fibre can be measured by method A:
refracted near-field or method B: transmitted near-field. Information pertaining to each individual method
appears respectively in Annexes A and B of IEC 60793-1-20:2014.
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. Method C is the reference test method (RTM), which shall be the one used
to settle disputes.
4.3 Mechanical requirement
The relevant mechanical attribute and test method are given in Table 3.
Table 3 – Mechanical attribute and test method
Attribute Test method
Proof test IEC 60793-1-30
4.4 Transmission requirements
The relevant transmission attributes and measurement methods are given in Table 4.

Table 4 – Transmission attributes and measurement methods
Attributes Measurement methods
a
Attenuation coefficient
IEC 60793-1-40
b
Mode field diameter (MFD)
IEC 60793-1-45
c
Beat length
IEC 60793-1-60
d
Polarization crosstalk IEC 60793-1-61
e
Cut-off wavelength IEC 60793-1-44
a
When measuring attenuation, the appropriate launching conditions should be applied. These may differ from
those prescribed in the measurement methods to which reference is made.
b
MFD of PM fibre can be measured by method A: direct far-field scan, method B: variable aperture in the far
field or method C: near-field scan of IEC 60793-1-45. Information pertaining to each individual method
appears respectively in Annexes A, B and C of IEC 60793-1-45:2001. Only information for PM fibre is shown
in Annex D.
c
Beat length of PM fibre is basically defined and measured by the phase beat length measurement methods
shown in IEC 60793-1-60. The phase beat length and group beat length are based on different definitions,
and will give different results depending on the type of PM fibre. If the correlation between both methods is
confirmed in advance, the group beat length measurement with the appropriate correlation factor can be
used as an alternative easy-to-use measurement method. Each definition (phase or group beat length) and

measurement method is not excluded if supplier and customer agree in advance.
d
Polarization crosstalk of PM fibre is basically defined and measured by method A of IEC 60793-1-61. The
crosstalk measured by method A is defined as an "averaged" crosstalk value over a measured wavelength
range. The crosstalk value obtained from method B of IEC 60793-1-61 shows the "worst case" crosstalk
value. Each definition (averaged, or the worst case crosstalk) and measurement method (method A or B) is

not excluded if supplier and customer agree in advance, however, they will give different results.
e
As shown in Annex E, the cut-off wavelength of the PM fibre should be measured paying attention to excite
an 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 shall follow the same condition as defined for fibre cut-off wavelength in IEC 60793-1-44.

4.5 Environmental requirements
Environmental exposure tests and measurement methods are documented in two forms:
– relevant environmental attributes and test methods are given in Table 5;
– measurements of particular transmission attributes that may change on the application of
the environment are listed in Table 6.
Table 5 – Environmental exposure tests
Attributes Test methods
Change of temperature tests IEC 60793-1-52

Table 6 – Attributes measured
Attributes Test methods
Change in optical transmission IEC 60793-1-46
Attenuation IEC 60793-1-40
Polarization crosstalk IEC 60793-1-61

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 the measurements of the attribute shall be as stated in the
particular environmental test method.

– 10 – IEC 60793-2-70:2017 © IEC 2017
Annex A
(normative)
Family specification for category D1
polarization-maintaining fibres
A.1 General
Category D1 polarization-maintaining fibres is suitable for 980 nm transmissions.
The following clauses and tables contain particular requirements applicable to D1 fibres.
Common requirements, repeated here for ease of reference from this document, are noted by
an entry in the "Reference" column.
A.2 Dimensional requirements
Table A.1 contains dimensional requirements specific to D1 fibres.
Table A.1 – Dimensional requirements specific to D1 fibres
Attributes Unit Limits Reference
Cladding diameter µm 125 ± 3 4.2
Cladding non-circularity % ≤ 2,0 4.2
Core concentricity error µm ≤ 0,8 4.2
a
µm
Primary coating diameter – uncoloured 245 ± 15 4.2
Primary coating-cladding concentricity error µm ≤ 12,5 4.2
b
Fibre length km 4.2
a
These limits are most commonly used in telecommunications cables. There are other applications, which use
other primary coating diameter, several of which are listed below. Alternative nominal primary coating
diameter and ranges (µm):
300 ± 20
400 ± 15
b
Length requirements vary and should be agreed between supplier and customer.

A.3 Mechanical requirement
Table A.2 contains the mechanical requirement specific to D1 fibres.
Table A.2 – Mechanical requirement specific to D1 fibres
Attribute Unit Limit Reference
a
Proof test level GPa ≥ 0,69 4.3
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 4.

A.4 Transmission requirements
Table A.3 contains transmission requirements specific to D1 fibres.

Table A.3 – Transmission requirements specific to D1 fibres
Attributes Unit Limits Reference
Attenuation coefficient at 980 nm dB/km ≤ 3,0 4.4
Nominal MFD range at 980 nm µm 6,6 4.4
MFD tolerance µm ±1,0 4.4
Beat length at 980 nm mm ≤ 3,3 4.4
a
Polarization crosstalk at 980 nm dB/100 m ≤ –25 4.4
Cut-off wavelength nm ≤ 970 4.4
a
The fibre configuration when measuring polarization crosstalk may be specified by agreement between
supplier and customer.
A.5 Environmental requirements
Table A.4 contains environmental requirements specific to D1 fibres.
Table A.4 – Environmental requirements specific to D1 fibres
Environment Attributes Unit Limits Reference
a
Change of temperature Attenuation at 980 nm dB/km 4.5
a
Change of temperature Polarization crosstalk at 980 nm dB/100 m 4.5
a
These requirements should be agreed between supplier and customer.

– 12 – IEC 60793-2-70:2017 © IEC 2017
Annex B
(normative)
Family specification for category D2
polarization-maintaining fibres
B.1 General
Category D2 polarization-maintaining fibres are suitable for 1 310 nm transmissions.
The following clauses and tables contain particular requirements applicable to D2 fibres.
Common requirements, repeated here for ease of reference from this document, are noted by
an entry in the "Reference" column.
B.2 Dimensional requirements
Table B.1 contains dimensional requirements specific to D2 fibres.
Table B.1 – Dimensional requirements specific to D2 fibres
Attributes Unit Limits Reference
Cladding diameter µm 125 ± 3 4.2
Cladding non-circularity % ≤ 2,0 4.2
Core concentricity error µm ≤ 0,8 4.2
a
µm
Primary coating diameter – uncoloured 245 ± 15 4.2
Primary coating-cladding concentricity error µm ≤ 12,5 4.2
b
Fibre length km 4.2
a
These limits are most commonly used in telecommunications cables. There are other applications, which use
other primary coating diameter, several of which are listed below. Alternative nominal primary coating
diameter and ranges (µm):
300 ± 20
400 ± 15
b
Length requirements vary and should be agreed between supplier and customer.

B.3 Mechanical requirement
Table B.2 contains mechanical requirement specific to D2 fibres.
Table B.2 – Mechanical requirement specific to D2 fibres
Attribute Unit Limit Reference
a
Proof test level GPa ≥ 0,69 4.3
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 4.

B.4 Transmission requirements
Table B.3 contains transmission requirements specific to D2 fibres.

Table B.3 – Transmission requirements specific to D2 fibres
Attributes Unit Limits Reference
Attenuation coefficient at 1 310 nm dB/km ≤ 2,0 3.4
a
Nominal MFD range at 1 310 nm µm 3.4
8,6 to 9,5
MFD tolerance µm ±1,0 3.4
Beat length at 1 310 nm mm ≤ 4,3 3.4
b
Polarization crosstalk at 1 310 nm dB/100 m 3.4
≤ –25
Cut-off wavelength nm ≤ 1 290 3.4
a
The value of the nominal MFD shall be agreed between supplier and customer from within the range given.
The tolerance shown is then applied around that nominal value.
b
The fibre configuration when measuring polarization crosstalk may be specified by agreement between
supplier and customer.
B.5 Environmental requirements
Table B.4 contains environmental requirements specific to D2 fibres.
Table B.4 – Environmental requirements specific to D2 fibres
Environment Attributes Unit Limits Reference
a
Change of temperature Attenuation at 1 310 nm dB/km 4.5
a
Change of temperature Polarization crosstalk at 1 310 nm dB/100 m 4.5
a
These requirements should be agreed between supplier and customer.

– 14 – IEC 60793-2-70:2017 © IEC 2017
Annex C
(normative)
Family specification for category D3
polarization-maintaining fibres
C.1 General
Category D3 polarization-maintaining fibres are suitable for 1 550 nm transmissions.
The following clauses and tables contain particular requirements applicable to D3 fibres.
Common requirements, repeated here for ease of reference from this document, are noted by
an entry in the "Reference" column.
C.2 Dimensional requirements
Table C.1 contains dimensional requirements specific to D3 fibres.
Table C.1 – Dimensional requirements specific to D3 fibres
Attributes Unit Limits Reference
Cladding diameter µm 125 ± 3 4.2
Cladding non-circularity % ≤ 2,0 4.2
Core concentricity error µm ≤ 1,0 4.2
a
µm
Primary coating diameter – uncoloured 245 ± 15 4.2
Primary coating-cladding concentricity error µm ≤ 12,5 4.2
b
Fibre length km 4.2
a
The above limits on primary coating diameter are most commonly used in telecommunications cables. There
are other applications, which use other primary coating diameter, several of which are listed below.
Alternative nominal primary coating diameter and ranges (µm):
300 ± 20
400 ± 15
b
Length requirements vary and should be agreed between supplier and customer.

C.3 Mechanical requirement
Table C.2 contains the mechanical requirement specific to D3 fibres.
Table C.2 – Mechanical requirement specific to D3 fibres
Attribute Unit Limit Reference
a
Proof test level GPa ≥ 0,69 4.3
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 4.

C.4 Transmission requirements
Table C.3 contains transmission requirements specific to D3 fibres.

Table C.3 – Transmission requirements specific to D3 fibres
Attributes Unit Limits Reference
Attenuation coefficient at 1 550 nm dB/km ≤ 2,0 4.4
Nominal MFD range at 1 550 nm µm 10,5 4.4
MFD tolerance µm ± 1,0 4.4
Beat length at 1 550 nm mm ≤ 5,2 4.4
a
Polarization crosstalk at 1 550 nm dB/100 m ≤ –25 4.4
Cut-off wavelength nm ≤ 1 530 4.4
a
The fibre configuration when measuring polarization crosstalk may be specified by agreement between
supplier and customer.
C.5 Environmental requirements
Table C.4 contains environmental requirements specific to D3 fibres.
Table C.4 – Environmental requirements specific to D3 fibres
Environment Attributes Unit Limits Reference
a
Change of temperature Attenuation at 1 550 nm dB/km 4.5
a
Change of temperature Polarization crosstalk at 1 550 nm dB/100 m 4.5
a
These requirements should be agreed between supplier and customer.

– 16 – IEC 60793-2-70:2017 © IEC 2017
Annex D
(normative)
Mode field diameter (MFD) measurement of PM fibre
NOTE As of the writing of this document, the scope of IEC 60793-1-45:2001 relating to test methods of mode field
diameter, does not cover categories D1, D2 and D3 fibres. When IEC 60793-1-45:2001 will be revised, it is
expected to include the category D fibres. When this revision is available, this annex will be superseded.
The MFD of a PM fibre can be measured by method A: direct far-field scan, method B:
variable aperture in the far field or method C: near-field scan of IEC 60793-1-45. Information
pertaining to each individual method appears respectively in Annexes A, B and C of
IEC 60793-1-45:2001.
Only information for PM fibres is described below.
The MFD of the PM fibre is non-axisymmetric in principle. The MFD shall be measured in the
same direction by rotating the fibre around the axis properly. The azimuthal dependence of
the MFD of a stress induced PM fibre and an elliptical jacket PM fibre is 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 jacket 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.
In method A, the MFD of a stress induced PM fibre and an elliptical jacket 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 jacket PM fibre may be
measured complying with demand of a required accuracy by the customer. The MFD is
measured as an axisymmetric electromagnetic field in method B. Therefore, the MFD of the
PM fibre should not be measured in method B. However, the MFD of a stress induced PM
fibre and an elliptical jacket PM fibre may be measured in method B because of relatively
small azimuthal dependence of the MFD. Method B should not be used to measure the MFD
of an elliptical core PM fibre.
In method C, a two-dimensional detector should be used. The fibre shall be rotated around
the axis properly on measurement with a one-dimensional detector.

Annex E
(informative)
Cut-off wavelength of PM fibre and SM fibre
NOTE As of the writing of this document, the scope of IEC 60793-1-44:2011 relating to test methods of cut-off
wavelength, does not cover categories D1, D2 and D3 fibres. When IEC 60793-1-44:2011 will be revised, it is
expected to include the category D fibres. When this revision is available, this annex will be superseded.
A refractive index of a core of a PM fibre varies according to the polarization mode, as well as
the cut-off wavelength.
The cut-off wavelength profile of PM fibre and SM fibre is shown in Figure E.1. Due to a
separation of the LP mode, the cut-off wavelength profile of the PM fibre typically has two
peaks of LP mode. Also, the cut-off wavelength profile results in a broader value than that
of the SM fibre.
SM fibre
PM fibre
900 1 000 1 100 1 200 1 300
Wavelength (nm)
IEC
Figure E.1 – Cut-off wavelength profiles
of PM fibre and SM fibre
Figure E.2 shows the cut-off wavelength profile of same PM fibre as Figure E.1 when there
are some extra bends on the measured fibre. The peak in the longer wavelength disappears
and the measured cut-off wavelength results in a smaller value.
Attenuation (dB)
– 18 – IEC 60793-2-70:2017 © IEC 2017
900 1 000 1 100 1 200 1 300
Wavelength (nm)
IEC
Figure E.2 – Cut-off wavelength profile of
PM fibre with extra bending
Due to a separation of the LP mode, even if a maximum attenuation of the LP mode is
11 11
equal to or greater than 2 dB as defined in IEC 60793-1-44, it is possible that the longer
wavelength side of the LP mode is not excited sufficiently. The longer wavelength side of
the LP mode of the PM fibre is sensitive to the bending relative to that of the SM fibre.
Therefore, the measurement requires special attention not to impose an extra small bending.
It is not enough only to take care of a maximum attenuation of the LP mode for the cut-off
wavelength measurement of the PM fibre. The LP mode separation is varied by a refractive
index difference between the x- and y-axis by birefringence such as stress induced fibre or
core non-circularity such as elliptical core fibre. If the cut-off wavelength profile is separated
into two peaks, the highest cut-off is the reported one.

Attenuation (dB)
Bibliography
IEC TR 62048:2014, Optical fibres – Reliability – Power law theory

___________
– 20 – IEC 60793-2-70:2017 © IEC 2017
SOMMAIRE
AVANT-PROPOS . 22
1 Domaine d’application . 24
2 Références normatives . 24
3 Termes et définitions . 25
4 Spécifications . 25
4.1 Généralités . 25
4.2 Exigences dimensionnelles . 25
4.3 Exigence mécanique . 26
4.4 Exigences de transmission . 26
4.5 Exigences environnementales . 27
Annexe A (normative) Spécification de famille pour les fibres à maintien de
polarisation de catégorie D1 . 29
A.1 Généralités . 29
A.2 Exigences dimensionnelles . 29
A.3 Exigence mécanique . 29
A.4 Exigences de transmission . 30
A.5 Exigences environnementales . 30
Annexe B (normative) Spécification de famille pour les fibres à maintien de
polarisation de catégorie D2 . 31
B.1 Généralités . 31
B.2 Exigences dimensionnelles . 31
B.3 Exigence mécanique . 31
B.4 Exigences de transmission . 32
B.5 Exigences environnementales . 32
Annexe C (normative) Spécification de famille pour les fibres à maintien de
polarisation de catégorie D3 . 33
C.1 Généralités . 33
C.2 Exigences dimensionnelles . 33
C.3 Exigence mécanique . 33
C.4 Exigences de transmission . 34
C.5 Exigences environnementales . 34
Annexe D (normative) Mesure du diamètre de champ de mode (MFD) d’une fibre PM. 35
Annexe E (informative) Longueur d’onde de coupure d’une fibre PM et d’une fibre SM . 36
Bibliographie . 38

Figure E.1 – Profils de longueur d’onde de coupure d’une fibre PM et d’une fibre SM . 36
Figure E.2 – Profil de longueur d’onde de coupure d’une fibre PM avec des courbures
supplémentaires . 37

Tableau 1 – Catégories de fibres à maintien de polarisation à cœur en verre/gaine en
verre . 24
Tableau 2 – Attributs dimensionn
...