IEC 61755-3-32:2015

Fibre optic interconnecting devices and passive components - Connector optical interfaces - Part 3-32: Connector parameters of non-dispersion shifted single mode physically contacting fibres - Angled thermoset epoxy rectangular ferrules

IEC 61755-3-32:2015 defines certain dimensional limits of an angled PC rectangular thermoset (TS) 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. Keywords: dimensional limits of an angled PC rectangular thermoset (TS) ferrule optical interface

Dispositifs d'interconnexion et composants passifs a fibres optiques - Interfaces optiques de connecteurs - Partie 3-32: Paramètres des connecteurs équipés de férules rectangulaires en époxy thermodurcissable, en contact physique avec angle, pour fibres unimodales à dispersion non décalée

L'IEC 61755-3-32:2015 définit un certain nombre de limites dimensionnelles des interfaces optiques à férules rectangulaires en époxy thermodurcissable (TS), PC avec angle afin de satisfaire aux exigences particulières d'une interconnexion fibre à fibre. Les férules réalisées dans le matériau spécifié dans la présente norme sont adaptées à une utilisation dans les catégories C, U, E et O définies dans l'IEC 61753-1. Les dimensions et les caractéristiques des interfaces des férules sont contenues dans la série IEC 61754 qui traite des interfaces de connecteurs pour fibres optiques. Mots clés: limites dimensionnelles des interfaces optiques à férules rectangulaires en époxy thermodurcissable (TS)

General Information

• Status: Published
• Publication Date: 11-Jun-2015
• ICS: 33.180.20 - Fibre optic interconnecting devices
• Technical Committee: SC 86B - Fibre optic interconnecting devices and passive components
• Current Stage: WPUB - Publication withdrawn
• Start Date: 29-Nov-2024
• Completion Date: 29-Nov-2024

Relations

• Replaces: IEC PAS 61755-3-32:2007 - Fibre optic connector optical interfaces - Part 3-32: Optical interface - 8 degrees angled-PC end-face thermoset rectangular ferrule, single mode fibres
• Effective Date: 05-Sep-2023

Overview

IEC 61755-3-32:2015 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the dimensional limits and key parameters of angled physically contacting (PC) rectangular thermoset epoxy ferrules used in fibre optic interconnecting devices. This standard focuses on non-dispersion shifted single mode fibres with physically contacting fibre interfaces and applies to ferrules made of thermoset (TS) epoxy material.

The standard ensures fibre-to-fibre interconnection meets reliable and consistent performance requirements, especially for connector categories C, U, E, and O as defined in IEC 61753-1. It complements fibre optic connector interface standards contained within the IEC 61754 series.

Key Topics

• Angled PC Rectangular Thermoset Ferrules: Defines precise dimensional limits for angled ferrule interfaces which facilitate physical contact between single mode fibre ends, minimizing back-reflection and insertion loss.

• Dimensional Parameters: Focuses on dimensions critical to the optical interface, including fibre hole locations, ferrule geometry, alignment pin tolerances, and end face angles.

• Alignment Factors Affecting Performance:

  • Lateral Offset: Deviations of fibre holes from designated positions, core concentricity, and guide hole clearances.
  • Angular Offset: Fibre hole angular misalignment and precision of alignment pin diameters.
  • Longitudinal Offset: Fibre protrusion, fibre array coplanarity, end face angles and radii, and the axial force applied during mating.

• Material Specifications: Specifies the use of thermoset epoxy material for ferrules, ensuring compatibility with specified connector categories and mechanical reliability.

• Performance Impact Considerations: The standard includes informative annexes analyzing worst-case attenuation scenarios, minus coplanarity effects, and force characteristics needed for physical fibre contact.

Applications

IEC 61755-3-32:2015 is applicable in the design, manufacturing, and quality assurance of fibre optic connectors used in telecommunication, data communications, and high-speed optical networks that utilize non-dispersion shifted single mode fibres. Key applications include:

• Multi-fibre Connectors: Particularly connectors with single rows of up to 12 fibres, where precise physical contact is essential to maintain low optical attenuation and signal integrity.

• High-Performance Optical Networks: Ensures connector interfaces optimize fibre alignment and reduce return losses, critical in long-haul and metropolitan networks.

• Component Standardization: Facilitates interoperability among manufacturers and promotes universal compatibility of optical interconnection devices.

• Quality Control: Provides manufacturers and test laboratories with defined measurement procedures for ferrule dimensional conformity based on IEC normative references.

Related Standards

• IEC 61754 Series: Defines various fibre optic connector interfaces, including dimensions and configurations relevant to ferrule geometry and mechanical features.

• IEC 61753-1: Categories and environmental requirements for performance classes of fibre optic interconnecting devices.

• IEC 61755-1: General guidance on optical interfaces for single mode non-dispersion shifted fibres.

• IEC 60793-2-50: Product specifications for class B single-mode optical fibres that underpin the fibre types used in such ferrules.

• IEC 61300 (Parts 3-30 and 3-52): Basic test and measurement procedures related to the examination of polish angle, fibre position, and alignment pin deformation constants.

By adhering to IEC 61755-3-32:2015, manufacturers and designers are equipped to produce angled thermoset epoxy rectangular ferrule connectors that meet stringent international requirements. This standard supports enhanced optical performance in fibre optic interconnections by ensuring critical alignment parameters remain within predefined dimensional limits.

---

Keywords: angled PC rectangular thermoset ferrule, fibre optic interconnecting devices, non-dispersion shifted single mode fibres, optical interface dimensions, fibre alignment, IEC 61755-3-32, connector optical interfaces, thermoset epoxy ferrules, fibre-to-fibre interconnection, optical connector standards.

Standards Content (Sample)

IEC 61755-3-32 ®
Edition 1.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Connector
optical interfaces –
Part 3-32: Connector parameters of non-dispersion shifted single mode
physically contacting fibres – Angled thermoset epoxy rectangular ferrules

Dispositifs d’interconnexion et composants passifs à fibres optiques –
Interfaces optiques de connecteurs –
Partie 3-32: Paramètres de connecteurs pour fibres unimodales à dispersion
non décalée, en contact physique – Férules rectangulaires avec angle en
époxy thermodurcissable
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IEC 61755-3-32 ®
Edition 1.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Connector

optical interfaces –
Part 3-32: Connector parameters of non-dispersion shifted single mode

physically contacting fibres – Angled thermoset epoxy rectangular ferrules

Dispositifs d’interconnexion et composants passifs à fibres optiques –

Interfaces optiques de connecteurs –

Partie 3-32: Paramètres de connecteurs pour fibres unimodales à dispersion

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

époxy thermodurcissable
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.20 ISBN 978-2-8322-2713-8

– 2 – IEC 61755-3-32:2015 © 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 . 12
Annex B (informative) Minus coplanarity . 14
Annex C (informative) Minimum normal force required to achieve physical contact . 15
Bibliography . 19

Figure 1 – Fibre numbering conventions . 7
Figure 2 – Interface dimensions related to lateral and angular offset . 7
Figure 3 – Alignment pin geometry . 8
Figure 4 – Interface dimensions related to longitudinal offset . 9
Figure A.1 – Monte Carlo simulation of Grade C performance for 12-fibre connectors . 12
Figure B.1 – Illustration of fibre line and minus coplanarity parameters . 14
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 . 16
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 . 16

Table 1 – Optical interface variant information . 7
Table 2 – Optical interface dimensions related to lateral and angular offset for optical
interface variant 2112 . 10
Table 3 – Optical interface end face geometry dimensions related to physical contact
for optical interface variant 2112 . 11
Table A.1 – Grade C single channel vs. multi-fibre connector performance . 13
Table C.1 – Parameter constants for 4-fibre optical interface variant K2 . 18
Table C.2 – Parameter constants for 8-fibre optical interface variant K3 . 18
Table C.3 – Parameter constants for 12-fibre optical interface variant K4 . 18

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

Part 3-32: Connector parameters of non-dispersion
shifted single mode physically contacting fibres –
Angled thermoset epoxy rectangular ferrules

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 61755-3-32 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This first edition cancels and replaces IEC PAS 61755-3-32 published in 2007. This edition
constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/3889/FDIS 86B/3915/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 61755-3-32:2015 © IEC 2015
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61755 series, 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 3-32: Connector parameters of non-dispersion
shifted single mode physically contacting fibres –
Angled thermoset epoxy rectangular ferrules

1 Scope
This part of IEC 61755 defines certain dimensional limits of an angled PC rectangular
thermoset (TS) 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, C for 8 degree angled PC rectangular ferrule, single
D
mode fibres
IEC 61754 (all parts), Fibre optic interconnection 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 61755-1, Fibre optic connector optical interfaces – Part 1: Optical interface for single
mode non dispersion shifted fibres – General and guidance

– 6 – IEC 61755-3-32:2015 © IEC 2015
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. End face
geometry limits associated with longitudinal offset are specified in Table 3.

Table 1 – Optical interface variant information
a
Nominal ferrule cross section
Number
b,c
Variant number
mm × mm of fibres
2112 12
2,45 × 6,4
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 and 2 for thermoset 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 in 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.
Key
2× ØD
ØA U V
Y
ØE U
C
X
Yi
V U
Xi
B
IEC
Figure 2 – Interface dimensions related to lateral and angular offset

– 8 – IEC 61755-3-32:2015 © IEC 2015
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 follows:
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
Y
RF
X
SX
RY
SY
M
CF
H
HA
RX
IEC
NOTE Just four fibres shown for simplicity.
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.
L
– 10 – IEC 61755-3-32:2015 © IEC 2015
Table 2 – Optical interface dimensions related to lateral
and angular offset for optical interface variant 2112
Parameter values Remarks
Grade B Grade C Grade D
Ref. Units
Minimum Maximum Minimum Maximum Minimum Maximum

a,b
A  – 0,002 0  mm Core position
B
4,598 4,602  mm Hole pitch
C
C  – 0,2  ° Fibre angle error
c
D
0,699 0 0,699 6  mm Diameter
d
E  – 0,012  mm Hole parallelism
G  – 200  nm RMS roughness
J  0,698 0 0,699 0  mm Diameter

K
– 0,000 5  mm Cylindricity
L  0,010 0,350  mm Recess Depth
M  1,4 1,5  Recess Width
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 C performance, the fibre hole true position
target shall be less than 0,001 6 mm for ferrules terminated to IEC 60793-2-50 compliant fibre 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 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.

Table 3 – Optical interface end face geometry dimensions related
to physical contact for optical interface variant 2112
Ref. Parameter values Remarks
Units
Minimum Maximum
0,30
a
CF – µm Minus coplanarity
SX
b
–0,15 0,15 ° Ferrule surface x-angle

c
SY 7,8 8,2 °
Ferrule surface y-angle
H
d
1 3,5 µm Fibre height
HA 0 0,5 µm Adjacent fibre height
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 – 13,9 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 3 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 3 above apply for thermoset (TS) ferrules with a Young’s modulus of
20 GPa to 25 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.

– 12 – IEC 61755-3-32:2015 © 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 C rectangular ferrules will yield
≤ 0,5 dB attenuation for > 97 % of all channels with a mean of ≤ 0,25 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 C 2 fibre ferrules is illustrated in Figure A.1. Based on the Monte Carlo
simulation, attenuation yield percentages for Grade B are given in Table A.1.
Attenuation  (dB)
IEC
Figure A.1 – Monte Carlo simulation of Grade C performance for 12-fibre connectors
Frequency
Cumulative  (%)
Table A.1 – Grade C single channel vs. multi-fibre connector performance
Attenuation Single channel 4 fibre 12 fibre
8 fibre cumulative
cumulative cumulative cumulative
%
dB % % %
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.
– 14 – IEC 61755-3-32:2015 © IEC 2015
Annex B
(informative)
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.
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.

– 16 – IEC 61755-3-32:2015 © IEC 2015
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
A function that fits this behaviour can be expressed as
− A ⋅CF −B ⋅CF
−n⋅ SX
q q − p⋅CF
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 tip
0 1 q 0 1 q
radius of curvature, RF, as defined by
f
q
−
RF
f (RF) = ( f − f ) ⋅ e + f (C.3)
1 0 0
The letter f given in Equation (C.3) represents any of the parameter constants. The resultant
function, when Equation (C.2) and Equation (C.3) are combined, is constructed such that
GL = 0 when CF = 0 and SX = 0. Furthermore, the function degenerates to the simple linear
form given in Equation (C.1) when RF approaches infinity.
There are 30 constants that define the relationship among GL, SX, CF, and RF. When fully
expanded the function takes the form of
(C.4)
For incorporation with end face inspection algorithms, this function can also be expressed
with Unicode text
The parameter constants are dependent on the optical interface variant and are summarized
in Tables C.1 to C.3. Thresholds for GL are provided in Table 5 to Table 7.

– 18 – IEC 61755-3-32:2015 © IEC 2015
Table C.1 – Parameter constants for 4-fibre optical interface variant K2
A A A B B B C D N p
0 1 q 0 1 q
f 2,334 1,049 0,000 20,930 0,000 0,402 2,470 12,402 0,000 4,296
f 0,000 0,000 4,907 84,717 84,717 139,916 0,000 18,072 19,663 27,813
f 6,676 8,306 0,000 0,393 0,000 12,201 3,575 2,135 0,000 7,108
q
Table C.2 – Parameter constants for 8-fibre optical interface variant K3
A A A B B B C D n p
0 1 q 0 1 q
f 3,117 –0,372 0,000 122,558 0,000 –0,439 2,109 15,227 0,000 6,253
f 0,000 0,000 4,779 151,602 151,602 –0,441 0,000 27,043 14,698 15,980
f 5,504 56,276 0,000 1,095 0,000 –4,844 10,334 2,216 0,000 7,994
q
Table C.3 – Parameter constants for 12-fibre optical interface variant K4
Anglais Français
A A A B B B C D n p
0 1 q 0 1 q
f 0,563 –0,313 0,000 120,677 0,000 0,000 3,452 20,367 0,000 4,874
f 0,000 0,000 10,082 148,540 148,540 2,481 0,000 36,545 69,299 8,685
f 110,476 78,066 0,000 3,129 0,000 0,000 11,688 1,800 0,000 5,860
q
Bibliography
IEC 61753-1, Fibre optic interconnecting devices and passive components performance
standard – Part 1: General and guidance for performance standards
IEC 61754-10:2005, Fibre optic connector interfaces – Part 10: Type Mini-MPO connector
family
IEC 61755-2-1, Fibre optic connector optical interfaces – Part 2-1: Optical interface single
mode non-angled physically contacting fibres

_____________
– 20 – IEC 61755-3-32:2015 © IEC 2015
SOMMAIRE
AVANT-PROPOS . 21
1 Domaine d'application . 23
2 Références normatives . 23
3 Description . 24
4 Paramètres d’interface . 24
Annexe A (informative) Pourcentage d'affaiblissement de connecteur théorique dans
le cas le plus défavorable . 30
Annexe B (informative) Coplanarité inférieure . 32
Annexe C (informative) Force normale minimale nécessaire pour obtenir le contact
physique . 33
Bibliographie . 38

Figure 1 – Conventions pour la numérotation des fibres . 25
Figure 2 – Dimensions des interfaces en fonction du décalage latéral et du décalage
angulaire . 26
Figure 3 – Géométrie de la broche d’alignement . 27
Figure 4 – Dimensions des interfaces en fonction du décalage longitudinal . 27
Figure A.1 – Simulation de Monte Carlo des performances de Classe C pour
connecteurs à 12 fibres . 31
Figure B.1 – Représentation des paramètres de ligne de fibre et de coplanarité
inférieure . 32
Figure C.1 – Limite géométrique (GL), nécessaire pour accoupler 12 fibres, en fonction
de l'angle absolu en X, SX pour différentes amplitudes de coplanarité inférieure et
de surfaces d'extrémité de fibres plates . 34
Figure C.2 – Limite géométrique (GL), nécessaire pour accoupler 12 fibres, en fonction
de l'angle absolu en X, SX pour différentes amplitudes de coplanarité inférieure et
de surfaces d'extrémité de fibres plates . 35

Tableau 1 – Informations sur les variantes des interfaces optiques . 25
Tableau 2 – Dimensions des interfaces optiques en fonction du décalage latéral et du
décalage angulaire pour la variante d'interface optique 2112 . 28
Tableau 3 – Dimensions géométriques d'extrémité des interfaces optiques en fonction
du contact physique pour la variante d'interface optique 2112 . 29
Tableau A.1 – Canal unique de Classe C / Performance de connecteur multifibres . 31
Tableau C.1 – Constantes de paramètres pour variante d'interface optique à 4 fibres
K2 . 36
Tableau C.2 – Constantes de paramètres pour variante d'interface optique à 8 fibres
K3 . 36
Tableau C.3 – Constantes de paramètres pour variante d'interface optique à 12 fibres
K4 . 37

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
DISPOSITIFS D’INTERCONNEXION ET
COMPOSANTS PASSIFS À FIBRES OPTIQUES –
INTERFACES OPTIQUES DE CONNECTEURS –

Partie 3-32: Paramètres de connecteurs pour fibres unimodales
à dispersion non décalée, en contact physique –
Férules rectangulaires avec angle en époxy thermodurcissable

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