IEC 61755-3-31:2015

IEC 61755-3-31 ®
Edition 1.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Connector
optical interfaces –
Part 3-31: Connector parameters of non-dispersion shifted single mode
physically contacting fibres – Angled polyphenylene sulphide rectangular
ferrules
Dispositifs d’interconnexion et composants passifs à fibres optiques –
Interfaces optiques de connecteurs –
Partie 3-31: Paramètres de connecteurs pour fibres unimodales à dispersion
non décalée, en contact physique – Férules rectangulaires avec angle en
poly(sulfure de phénylène)
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 Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

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

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing more than 30 000 terms and
Technical Specifications, Technical Reports and other definitions in English and French, with equivalent terms in 15
documents. Available for PC, Mac OS, Android Tablets and additional languages. Also known as the International
iPad. Electrotechnical Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a More than 60 000 electrotechnical terminology entries in
variety of criteria (reference number, text, technical English and French extracted from the Terms and Definitions
committee,…). It also gives information on projects, replaced clause of IEC publications issued since 2002. Some entries
and withdrawn publications. have been collected from earlier publications of IEC TC 37,

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

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: csc@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 plus de 30 000 termes et définitions en
Spécifications techniques, Rapports techniques et autres
anglais et en français, ainsi que les termes équivalents dans
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
15 langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.

Recherche de publications IEC - www.iec.ch/searchpub
Glossaire IEC - std.iec.ch/glossary
La recherche avancée permet de trouver des publications IEC Plus de 60 000 entrées terminologiques électrotechniques, en
en utilisant différents critères (numéro de référence, texte, anglais et en français, extraites des articles Termes et
comité d’études,…). Elle donne aussi des informations sur les Définitions des publications IEC parues depuis 2002. Plus
projets et les publications remplacées ou retirées. certaines entrées antérieures extraites des publications des

CE 37, 77, 86 et 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
Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur cette
Disponible en ligne et aussi une fois par mois par email. publication ou si vous avez des questions contactez-nous:
csc@iec.ch.
IEC 61755-3-31 ®
Edition 1.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Connector

optical interfaces –
Part 3-31: Connector parameters of non-dispersion shifted single mode

physically contacting fibres – Angled polyphenylene sulphide rectangular

ferrules
Dispositifs d’interconnexion et composants passifs à fibres optiques –

Interfaces optiques de connecteurs –

Partie 3-31: Paramètres de connecteurs pour fibres unimodales à dispersion

non décalée, en contact physique – Férules rectangulaires avec angle en

poly(sulfure de phénylène)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.20 ISBN 978-2-8322-2712-1

– 2 – IEC 61755-3-31:2015  IEC 2015
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Description . 6
4 Interface parameters . 6
Annex A (informative) Theoretical worst-case connector attenuation yield percentage . 16
Annex B (normative) Minus coplanarity . 19
Annex C (informative) Minimum normal force required to achieve physical contact . 20
Bibliography . 25

Figure 1 – Fibre numbering conventions . 7
Figure 2 – Interface dimensions related to lateral and angular offset . 8
Figure 3 – Alignment pin geometry . 8
Figure 4 – Interface dimensions related to longitudinal offset . 9
Figure A.1 – Monte Carlo simulation of Grade B performance for 12-fibre connectors . 16
Figure B.1 – Illustration of fibre line and minus coplanarity parameters . 19
Figure C.1 – Geometry limit, GL, needed to mate 12 fibres, as a function of absolute X-
angle, SX for different magnitudes of minus coplanarity and flat fibre tips. 21
Figure C.2 – Geometry limit, GL, needed to mate 12 fibres, as a function of absolute
X-angle, SX for different magnitudes of minus coplanarity and 1 mm fibre tips. . 21

Table 1 – Optical interface variant information . 7
Table 2 – Optical interface dimensions related to lateral and angular offset for optical
interface variant 1002 . 10
Table 3 – Optical interface dimensions related to lateral and angular offset for optical
interface variants 1104, 1108, 1112 . 11
Table 4 – Optical interface end face geometry dimensions related to physical contact
for optical interface variant 1002 . 12
Table 5 – Optical interface end face geometry dimensions related to physical contact
for optical interface variant 1104 . 13
Table 6 – Optical interface end face geometry dimensions related to physical contact
for optical interface variant 1108 . 14
Table 7 – Optical interface end face geometry dimensions related to physical contact
for optical interface variant 1112 . 15
Table A.1 – Grade B single channel vs. multi-fibre connector performance . 17
Table A.2 – Grade C single channel vs. multi-fibre connector performance . 17
Table A.3 – Grade D single channel vs. multi-fibre connector performance . 17
Table C.1 – Parameter constants for 4-fibre optical interface variant 1104 . 23
Table C.2 – Parameter constants for 8-fibre optical interface variant 1108 . 24
Table C.3 – Parameter constants for 12-fibre optical interface variant 1112 . 24

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
CONNECTOR OPTICAL INTERFACES –

Part 3-31: Connector parameters of non-dispersion
shifted single mode physically contacting fibres –
Angled polyphenylene sulphide rectangular ferrules

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 61755-3-31 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/3888FDIS 86B/3914/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 4 – IEC 61755-3-31:2015  IEC 2015
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61755 series, published under the general title Fibre optic
interconnecting devices and passive components –Connector optical interfaces, can be found
on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
CONNECTOR OPTICAL INTERFACES –

Part 3-31: Connector parameters of non-dispersion
shifted single mode physically contacting fibres –
Angled polyphenylene sulphide rectangular ferrules

1 Scope
This part of IEC 61755 defines certain dimensional limits of an angled PC rectangular
polyphenylene sulphide (PPS) ferrule optical interface in order to meet specific requirements
for fibre-to-fibre interconnection. Ferrules made from the material specified in this standard
are suitable for use in categories C, U, E, and O as defined in IEC 61753-1.
Ferrule interface dimensions and features are contained in the IEC 61754 series, which deals
with fibre optic connector interfaces.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 61300-3-30, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-30: Examinations and measurements – Polish angle and
fibre position on single ferrule multifibre connectors
IEC 61300-3-52, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-52: Examinations and measurements – Guide hole and
alignment pin deformation constant, CD for 8 degree angled PC rectangular ferrule, single
mode fibres
IEC 61754 (all parts), Fibre optic interconnecting devices and passive components – Fibre
optic connector interfaces
IEC 61754-5:2005, Fibre optic connector interfaces – Part 5: Type MT connector family
IEC 61754-7:2008, Fibre optic interconnecting devices and passive components – Fibre optic
connector interfaces – Part 7: Type MPO connector family
IEC 61754-7-1:2014, Fibre optic interconnecting devices and passive components – Fibre
optic connector interfaces – Part 7-1: Type MPO connector family – One fibre row
IEC 61754-10:2005, Fibre optic connector interfaces – Part 10: Type Mini-MPO connector
family
IEC 61754-18:2001, Fibre optic connector interfaces – Part 18: Type MT-RJ connector family

– 6 – IEC 61755-3-31:2015  IEC 2015
IEC 61755-1, Fibre optic connector optical interfaces – Part 1: Optical interfaces for single
mode non-dispersion shifted fibres – General and guidance
3 Description
The performance of a single mode angled PC rectangular ferrule optical interface is
determined by the accuracy with which the optical datum targets of two mating ferrules are
aligned with each other. There are three conditions affecting the alignment of the optical
datum targets: lateral offset, angular offset, and longitudinal offset.
Parameters influencing the lateral and angular offset of the optical fibre axes include the
following:
– fibre hole deviation from designated location;
– fibre cladding diameter relative to fibre hole clearance;
– fibre hole angular misalignment;
– fibre core concentricity relative to the cladding diameter;
– alignment pin diameter relative to the guide hole clearance.
Parameters influencing the longitudinal offset of the optical fibre axes include the following:
– fibre protrusion;
– fibre array minus coplanarity;
– adjacent fibre height differential;
– end face angle in the x-axis;
– end face angle in the y-axis;
– end face radius in the x-axis;
– end face radius in the y-axis;
– fibre tip spherical radii;
– axial force on ferrule end face;
– ferrule and fibre material constants;
– frictional force of alignment pins in ferrule guide holes.
4 Interface parameters
This standard defines the dimensional limits of angled PC rectangular ferrules with a single
row of up to 12 fibres. The fibre centres are spaced with a nominal alignment pitch of 0,25 mm.
Interface variants, which identify nominal ferrule cross-sections and applicable fibre counts,
are given in Table 1. The fibre numbering conventions are illustrated in Figure 1.
Optical interface dimensions related to lateral and angular offset are defined in Figure 2 and
the alignment pin geometry is shown in Figure 3. The end face geometry parameters that
influence longitudinal offset are outlined in Figure 4.
The parameter values related to lateral and angular offset are given in Table 2 and Table 3.
End face geometry limits associated with longitudinal offset are specified in Table 4 to Table 7.

Table 1 – Optical interface variant information
Nominal ferrule
Variant Number
a
cross section
b,c
number of fibres
(mm´ mm)
1002 2,45´ 4,4 2
1104 2,45´ 6,4 4
1108 2,45´ 6,4 8
1112 2,45´ 6,4 12
a
Refer to the applicable IEC 61754 series fibre optic connector interface standard for
dimensional requirements.
b
The four digit variant code describes a combination of material type, nominal ferrule
cross-section, and number of fibres. The first digit defines 1 for PPS ferrule
materials; the second digit represents 2,45 mm´ 4,4 mm with 0 and 2,45 mm´ 6,4
mm with 1; and the last two digits designates the number of fibres.
c
All ferrule materials for rectangular type ferrules are intended to be intermateable,
in the lowest specified performance category as described within IEC 61755-1,
provided that the last three digits of the variant number are the same. It is also
possible to mate ferrules with different fibre counts, in which case all mating fibres
shall meet the designated performance category.
IEC
Figure 1 – Fibre numbering conventions
To provide optical fibre-to-fibre interconnection, mating ferrules have to be correctly keyed.
Refer to the applicable IEC 61754 series document to ensure correct key orientation.

– 8 – IEC 61755-3-31:2015  IEC 2015
Key
2× ØD
ØA U V
Y
ØE U
C
XX
Yi
V
U
Xi
B
IEC
Figure 2 – Interface dimensions related to lateral and angular offset
The optical interface coordinate system is established with an x-axis, which passes through
the guide hole centres and a perpendicular y-axis that passes through the midpoint of the line
connecting the guide hole centres.
The basic x-location, Xi, for each fibre core centre is defined as:
Xi = (2i – n – 1) 0,125
th
Where, i corresponds to the i fibre per the numbering conventions outlined in Figure 1 and n
is the total number of fibres in the array.
The basic y-location, Yi, for each fibre core centre is defined as:
D − D
o i
Yi=α + C
D
The basic alignment pin dimension, D , is 0,698 5 mm and the basic guide hole dimension, D ,
i o
is a nominal value based on the manufacturer designed average hole size. The constant, α,
relates to differences in guide pin pitch and varies between 0 and 1. The term C is a
D
deformation constant based on ferrule structure, material, and moulding condition. Typical
values C are between 0,3 µm and 0,6 µm. Refer to IEC 61300-3-52 for information on how to
D
measure and define Yi.
To ensure compatibility when mating rectangular ferrules with alternative Yi targets,
manufacturers of ferrules shall report their specified values for Yi, α, D , and C .
o D
Rz < G
ØJ
K
IEC
Figure 3 – Alignment pin geometry

Key
Region of interest
YY
SX
RF
SY
XX
RY
CF
HA
H
RX
Four fibres shown for simplicity

IEC
Figure 4 – Interface dimensions related to longitudinal offset
The optical interface coordinate system is established with an x-axis, which passes through
the guide hole centres, a perpendicular y-axis that passes through the midpoint of the line
connecting the guide hole centres, and an orthogonal z-axis pointing away from the ferrule.
All parameters are illustrated as positive values with respect to the defined coordinate system.
Concave ferrule radii are indicated by negative values.

– 10 – IEC 61755-3-31:2015  IEC 2015
Table 2 – Optical interface dimensions related to lateral
and angular offset for optical interface variant 1002
Parameter values
Grade B Grade C Grade D
Ref. Units Remarks
Minimum Maximum Minimum Maximum Minimum Maximum
a,b
A
- 0,001 6 - 0,002 4 - 0,003 4 mm Core position
B
2,598 2,602 2,598 2,602 2,598 2,602 mm Hole pitch

C - 0,2 - 0,2 - 0,2 Fibre angle error
°
c
D 0,699 0 0,699 6 0,699 0 0,700 0 0,699 0 0,700 0 mm Diameter
d
E - 0,012 - 0,012 - 0,012 mm Hole parallelism
G - 200 - 200 - 200 nm RMS roughness
J 0,698 4 0,698 6 0,698 0 0,699 0 0,698 0 0,699 0 mm Diameter
K - 0,000 5 - 0,000 5 - 0,000 5 mm Cylindricity
NOTE 1 The core location and tilt angle values specified in this standard have been calculated to ensure
that the attenuation values specified in IEC 61755-2-1 are met, under all circumstances, at the single
channel level. Refer to Annex A for the relationship between per channel and per connector loss statistics.
NOTE 2 Refer to Figure 2 and Figure 3 for dimensional references.
a
Variation in fibre core centre location, as controlled by true position tolerance ∅A, is composed of
several parameters including the fibre hole deviation, clearance between fibre cladding and hole, and
relative fibre core-to-cladding concentricity. Wherever possible, inspection of the core centre shall be
directly measured. Where this is not possible, due to inspection system capability or other constraints,
the relevant component features may be independently measured and superimposed to establish a
resultant fibre core location.
b
If the fibre core centre location is not directly measured for grade B performance, the fibre hole true
position target shall be less than 0,001 2 mm for ferrules terminated to optical fibres specified in
IEC 60793-2-50 with a fibre hole diameter ranging between 0,125 5 mm and 0,126 5 mm.
c
Each guide hole shall accept a gauge pin as shown in Figure 4 of IEC 61754-10:2005 and Figure 1c of
IEC 61754-18:2001 to a depth of 5,5 mm with a maximum force of 1,7 N. In addition, two guide holes
shall accept a gauge as shown in Figure 5 of IEC 61754-10:2005 and Figure 1d of IEC 61754-18:2001 to
a depth of 5,5 mm with a maximum force of 3,4 N.
d
Parallelism tolerance applies over a hole depth of 3,3 mm.

Table 3 – Optical interface dimensions related to lateral and
angular offset for optical interface variants 1104, 1108, 1112
Parameter values
Ref. Grade B Grade C Grade D Units Remarks
Minimum Maximum Minimum Maximum Minimum Maximum
a,b
A
- 0,001 6 - 0,002 4 - 0,003 4 mm Core position
B
4,598 4,602 4,598 4,602 4,597 4,603 mm Hole pitch

C - 0,2 - 0,2 - 0,2 Fibre angle error
°
c
D 0,699 0 0,699 6 0,699 0 0,700 0 0,699 0 0,700 0 mm Diameter
d
E - 0,012 - 0,012 - 0,012 mm Hole parallelism
G - 200 - 200 - 200 nm RMS roughness
J 0,698 4 0,698 6 0,698 0 0,699 0 0,698 0 0,699 0 mm Diameter
K - 0,000 5 - 0,000 5 - 0,000 5 mm Cylindricity
NOTE 1 The core location and tilt angle values specified in this standard have been calculated to ensure
that the attenuation values specified in IEC 61755-2-1 are met, under all circumstances, at the single
channel level. Refer to Annex A for the relationship between per channel and per connector loss statistics.
NOTE 2 Refer to Figure 2 and Figure 3 for dimensional references.
a
Variation in fibre core centre location, as controlled by true position tolerance ∅A, is composed of
several parameters including the fibre hole deviation, clearance between fibre cladding and hole, and
relative fibre core-to-cladding concentricity. Wherever possible, inspection of the core centre shall be
directly measured. Where this is not possible, due to inspection system capability or other constraints,
the relevant component features may be independently measured and superimposed to establish a
resultant fibre core true position.
b
If the fibre core centre location is not directly measured for grade B performance, the fibre hole true
position target shall be less than 0,0012 mm for ferrules terminated to optical fibres specified in
IEC 60793-2-50 with a fibre hole diameter ranging between 0,1255 mm and 0,1265 mm.
c
Each guide hole shall accept a gauge pin as shown in Figure 2 of IEC 61754-5:2005 and Figure 5 of
IEC 61754-7-1:2014 to a depth of 5,5 mm with a maximum force of 1,7 N. In addition, two guide holes
shall accept a gauge as shown in Figure 6 of IEC 61754-5:2005 and Figure 5 of IEC 61754-7:2008 to a
depth of 5,5 mm with a maximum force of 3,4 N.
d
Parallelism tolerance applies over a hole depth of 3,3 mm.

– 12 – IEC 61755-3-31:2015  IEC 2015
Table 4 – Optical interface end face geometry dimensions related
to physical contact for optical interface variant 1002
Parameter values
Ref. Units Remarks
Minimum Maximum
a
SX
-0,2 0,2 ° Ferrule surface x-angle

b
SY 7,8 8,2 ° Ferrule surface y-angle

c
H
1 3,5 µm Fibre height
HA 0 0,3 µm Adjacent fibre height differential
d
RF 1 - mm Fibre tip spherical radius
2 000 (convex)
RX - mm Ferrule surface x-radius
-10 000 (concave)
RY 5 - mm Ferrule surface y-radius
NOTE 1 End face parameter requirements apply to performance grades B, C, and D.
NOTE 2 Refer to Figure 4 for dimensional references.
NOTE 3 End face geometry to be measured in accordance with IEC 61300-3-30.
NOTE 4 The values in Table 4 above to be specified in the central surface region surrounding fibres of
0,900 mm wide and 0,675 mm high. Furthermore, the outside surface region is lower than the central
surface region of interest.
NOTE 5 The values in Table 4 above apply for polyphenylene sulphide (PPS) ferrules with a Young’s
modulus of 15 GPa to 20 GPa. Ferrule compression force: 7,8 N minimum and 11,8 N maximum.
a
X-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
b
Y-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
c
A positive value indicates a fibre protrusion.
d
Fibre tip spherical radii fitting region is defined within IEC 61300-3-30.

Table 5 – Optical interface end face geometry dimensions related
to physical contact for optical interface variant 1104
Parameter values
Ref. Units Remarks
Minimum Maximum
a
0,4
CF - µm Minus coplanarity
b
SX
-0,2 0,2 ° Ferrule surface x-angle

c
SY 7,8 8,2 ° Ferrule surface y-angle

d
H
1 3,5 µm Fibre height
HA 0 0,3 µm Adjacent fibre height differential
e
RF 1 - mm Fibre tip spherical radius
2 000 (convex)
RX - mm Ferrule surface x-radius
-10 000 (concave)
RY 5 - mm Ferrule surface y-radius
f
GL - 22,6 Geometry limit
NOTE 1 End face parameter requirements apply to performance grades B, C, and D.
NOTE 2 Refer to Figure 4 for dimensional references.
NOTE 3 End face geometry to be measured in accordance with IEC 61300-3-30.
NOTE 4 The values in Table 5 above to be specified in the central surface region surrounding fibres of
2,900 mm wide and 0,675 mm high. Furthermore, the outside surface region is lower than the central
surface region of interest.
NOTE 5 The values in Table 5 apply for polyphenylene sulphide (PPS) ferrules with a Young’s modulus of
15 GPa to 20 GPa. Ferrule compression force: 7,8 N minimum and 11,8 N maximum.
a
Refer to Annex B for a description of minus coplanarity.
b
X-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
c
Y-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
d
A positive value indicates a fibre protrusion.
e
Fibre tip spherical radii fitting region is defined within IEC 61300-3-30.
f
Refer to Annex C for a description of parameter GL.

– 14 – IEC 61755-3-31:2015  IEC 2015
Table 6 – Optical interface end face geometry dimensions related
to physical contact for optical interface variant 1108
Parameter values
Ref. Units Remarks
Minimum Maximum
a
0,4
CF - µm Minus coplanarity
b
SX
-0,15 0,15 ° Ferrule surface x-angle

c
SY 7,8 8,2 ° Ferrule surface y-angle

d
H
1 3,5 µm Fibre height
HA 0 0,3 µm Adjacent fibre height differential
e
RF 1 - mm Fibre tip spherical radius
2 000 (convex)
RX - mm Ferrule surface x-radius
-10 000 (concave)
RY 5 - mm Ferrule surface y-radius
f
GL - 17,9 Geometry limit
NOTE 1 End face parameter requirements apply to performance grades B, C, and D.
NOTE 2 Refer to Figure 4 for dimensional references.
NOTE 3 End face geometry to be measured in accordance with IEC 61300-3-30.
NOTE 4 The values in Table 6 above to be specified in the central surface region surrounding fibres of
2,900 mm wide and 0,675 mm high. Furthermore, the outside surface region is lower than the central
surface region of interest.
NOTE 5 The values in Table 6 above apply for polyphenylene sulphide (PPS) ferrules with a Young’s
modulus of 15GPa to 20 GPa. Ferrule compression force: 7,8 N minimum and 11,8 N maximum.
a
Refer to Annex B for a description of minus coplanarity.
b
X-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
c
Y-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
d
A positive value indicates a fibre protrusion.
e
Fibre tip spherical radii fitting region is defined within IEC 61300-3-30.
f
Refer to Annex C for a description of parameter GL.

Table 7 – Optical interface end face geometry dimensions related
to physical contact for optical interface variant 1112
Parameter values
Ref. Units Remarks
Minimum Maximum
a
0,4
CF - µm Minus Coplanarity
b
SX
-0,15 0,15 ° Ferrule surface x-angle

c
SY 7,8 8,2 ° Ferrule surface y-angle

d
H
1 3,5 µm Fibre height
HA 0 0,3 µm Adjacent fibre height differential
e
RF 1 - mm Fibre tip spherical radius
2 000 (convex)
RX - mm Ferrule surface x-radius
-10 000 (concave)
RY 5 - mm Ferrule surface y-radius
f
GL - 17,4 Geometry limit
NOTE 1 End face parameter requirements apply to performance grades B, C, and D.
NOTE 2 Refer to Figure 4 for dimensional references.
NOTE 3 End face geometry to be measured in accordance with IEC 61300-3-30.
NOTE 4 The values in Table 7 above to be specified in the central surface region surrounding fibres of
2,900 mm wide and 0,675 mm high. Furthermore, the outside surface region is lower than the central
surface region of interest.
NOTE 5 The values in Table 7 above apply for polyphenylene sulphide (PPS) ferrules with a Young’s
modulus of 15 GPa to 20 GPa. Ferrule compression force: 7,8 N minimum and 11,8 N maximum.
a
Refer to Annex B for a description of minus coplanarity.
b
X-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
c
Y-angle represents the slope of the ferrule surface as defined by a bi-parabolic fit in accordance with
IEC 61300-3-30.
d
A positive value indicates a fibre protrusion.
e
Fibre tip spherical radii fitting region is defined within IEC 61300-3-30.
f Refer to Annex C for a description of parameter GL.

– 16 – IEC 61755-3-31:2015  IEC 2015
Annex A
(informative)
Theoretical worst-case connector attenuation yield percentage
Rectangular ferrule connector core alignment specifications are defined at the single channel
level. A population of fibre links interconnected with Grade B rectangular ferrules will yield
≤ 0,25 dB attenuation for > 97% of all channels with a mean of ≤ 0,12 dB. The intra-connector
channel grouping of fully populated multi-fibre connectors results in the following theoretical,
worst-case connector attenuation yield percentage for a completely random core alignment
distribution:
n
Multi-fibre connector attenuation yield % = {single channel attenuation yield %} (A.1)
where n is the total number of populated fibres per ferrule.
A population of channels individually along with the theoretical worst case performance by
connector for Grade B 12 fibre ferrules is illustrated in Figure A.1. Based on the Monte Carlo
simulation, attenuation yield percentages for Grade B, C, and D are given in Tables A.1 to A.3.
IEC
Figure A.1 – Monte Carlo simulation of Grade B performance for 12-fibre connectors

Table A.1 – Grade B single channel vs. multi-fibre connector performance
Attenuation Single channel 4 fibre 8 fibre 12 fibre
(dB) cumulative % cumulative % cumulative % cumulative %
0,25 97,29 89,60 80,29 71,94
0,3 98,71 94,92 90,10 85,53
0,35 99,41 97,66 95,37 93,14
0,4 99,72 98,90 97,81 96,74
0,45 99,87 99,49 98,98 98,48
0,5 99,94 99,75 99,49 99,24
NOTE Mean = 0,07 dB
Table A.2 – Grade C single channel vs. multi-fibre connector performance
Attenuation Single channel 4 fibre 8 fibre 12 fibre
(dB) cumulative % cumulative % cumulative % cumulative %
0,5 97,18 89,19 79,55 70,95
0,55 98,08 92,54 85,63 79,24
0,6 98,66 94,75 89,77 85,05
0,65 99,06 96,29 92,72 89,29
0,7 99,37 97,50 95,07 92,70
0,75 99,57 98,29 96,61 94,96
0,8 99,69 98,77 97,55 96,34
0,85 99,79 99,16 98,33 97,51
0,9 99,85 99,40 98,81 98,21
0,95 99,90 99,60 99,20 98,81
1 99,93 99,72 99,44 99,16
NOTE Mean = 0,14 dB
Table A.3 – Grade D single channel vs. multi-fibre connector performance
Attenuation Single channel 4 fibre 8 fibre 12 fibre
(dB) cumulative % cumulative % cumulative % cumulative %
1 97,80 91,50 83,72 76,60
1,05 98,22 93,06 86,60 80,59
1,1 98,53 94,25 88,84 83,74
1,15 98,82 95,35 90,92 86,70
1,2 99,05 96,25 92,64 89,17
1,25 99,22 96,92 93,93 91,03
1,3 99,38 97,52 95,11 92,75
1,35 99,51 98,04 96,13 94,25
1,4 99,59 98,38 96,79 95,22
1,45 99,67 98,70 97,42 96,15
1,5 99,75 98,99 97,98 96,99
1,55 99,80 99,20 98,41 97,63
1,6 99,85 99,40 98,81 98,21
1,65 99,87 99,48 98,96 98,45
– 18 – IEC 61755-3-31:2015  IEC 2015
Attenuation Single channel 4 fibre 8 fibre 12 fibre
(dB) cumulative % cumulative % cumulative % cumulative %
1,7 99,90 99,60 99,20 98,81
1,75 99,92 99,68 99,36 99,04
1,8 99,94 99,76 99,52 99,28
NOTE Mean = 0,27 dB
Annex B
(normative)
Minus coplanarity
The fibre protrusion distribution for rectangular ferrules is characterized by a parameter
referred to as minus coplanarity. This metric represents the unilateral distance from a least
squares fit line through the array of protrusions, known as the fibre line, to the minimum
height fibre as illustrated in Figure B.1
Fibre tip
Z
Minus
Fibre line
coplanarity
GX
X
Ferrule
surface
IEC
Figure B.1 – Illustration of fibre line and minus coplanarity parameters
The fibre line, which provides a single characterization of the height distribution, takes the
form:
z(x) = tan(GX)⋅x + β (B.1)
The angle of the array, GX, denotes the x-slope angle. A measure of the average fibre height
at the x-origin of the coordinate system is given by the intercept of the fit, β.
Minus coplanarity, CF, can be defined as:
CF = max(z (x) – Z ) (B.2)
i i
Where, z (x) – Z represents the deviation of each fibre tip, i, from the fibre line. The physical
i i
significance of minus coplanarity is that it indicates the requisite axial displacement of the
fibre line needed to ensure physical contact across the fibre array under worst case mating
conditions.
– 20 – IEC 61755-3-31:2015  IEC 2015
Annex C
(informative)
Minimum normal force required to achieve physical contact
To establish limits of acceptance on end face geometry, a mathematical system model was
developed to estimate the minimum normal force required to achieve physical contact across
an array of mated fibres. This model takes into account various factors including:
– fibre tip compression and axial stiffness;
– elastic, foundational deflection of the ferrule structure;
– rotational stiffness of the system;
– frictional resistance between the alignment pins and holes;
– variation in end face geometry dimensions.
For a ferrule with a single row of fibres, there are three dominant end face dimensions that
influence the minimum mating force needed to assure physical contact:
– X-slope angle of the end face, SX;
– minus coplanarity of the fibre array, CF;
– fibre tip spherical radius of curvature, RF.
These parameters were systematically varied to determine their interrelationships with mating
force. As a result of the analysis, a geometry limit, GL, can be used to quantitatively assess
the acceptability of an end face. This term is a calculated merit function, which relates X-slope
angle, coplanarity, and fibre tip radii in comparison to the defined ferrule compression force.
For a specific end face condition, lower calculated values for GL indicate a better geometry.
For instance, GL is zero for interfaces with perfectly coplanar fibres and null X-slope angle. A
maximum allowable limit can therefore be placed on GL to serve as a bound for unacceptable
geometries. Furthermore, the magnitude of the limit may be different depending on the
number of fibres or the ferrule material type.
To develop the relationship between GL, CF, and SX, end faces with flat fibre tips (RF = ∞)
were initially studied as summarized in Figure C.1.

CF  (µm)
|SX|  (degrees)
IEC
Figure C.1 – Geometry limit, GL, needed to mate 12 fibres, as a function of absolute X-
angle, SX for different magnitudes of minus coplanarity and flat fibre tips
Inspection of the results indicates that the family of curves are linear with equal slopes and
constant offsets between their y-axis intercepts. This gives a functional relationship of the
form
GL(SX ,CF, RF=∞)= B⋅ SX + D⋅ CF (C.1)
When the fibre tips have finite radii of curvature, there is slight nonlinearity and the slopes of
the curves steepen with increasing CF. Additionally, the value of GL when SX= 0 is no
longer directly proportional to CF as illustrated in Figure C.2.
CF  (µm)
|SX|  (degrees)
IEC
Figure C.2 – Geometry limit, GL, needed to mate 12 fibres, as a function of absolute
X-angle, SX for different magnitudes of minus coplanarity and 1 mm fibre tips.
GL GL
– 22 – IEC 61755-3-31:2015  IEC 2015
A function that fits this behaviour can be expressed as
−A ⋅CF −n⋅ SX −B ⋅CF
− p⋅CF
q q
GL(SX,CF)= [(A − A )⋅ e + A ]⋅(e −1)+ [(B − B )⋅ e + B ]⋅ SX + C⋅(e −1)+
0 1 1 0 1 1
(C.2)
D⋅ CF
where the parameter constants, A , A , A , n, B , B , B , C, p, and D, are related to the fibre
0 1 q 0 1 q
tip radiu
...