IEC 61978-1:2014

Fibre optic interconnecting devices and passive components - Fibre optic passive chromatic dispersion compensators - Part 1: Generic specification

IEC 61978-1:2014 applies to fibre optic passive chromatic dispersion compensators, all exhibiting the following features:
- they are optically passive;
- they have an optical input and an optical output for transmitting optical power;
- the ports are optical fibres or optical fibre connectors;
- they are wavelength sensitive;
- they may be polarization sensitive. This standard establishes uniform requirements for the passive chromatic dispersion compensator. This third edition cancels and replaces the second edition, published in 2009, and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- introduction of new terms and definitions;
- revision of classifications;
- addition of Annex E. Keywords: fibre optic passive chromatic dispersion compensators

Dispositifs d'interconnexion et composants passifs à fibres optiques - Compensateurs de dispersion chromatique passifs à fibres optiques - Partie 1: Spécification générique

IEC 61978-1:2014 s'applique aux compensateurs de dispersion chromatique passifs à fibres optiques présentant les caractéristiques suivantes:
- ils sont passifs au niveau optique;
- ils possèdent une entrée optique et une sortie optique pour la transmission de la puissance optique;
- les ports sont des fibres optiques ou des connecteurs de fibres optiques;
- ils sont sensibles aux longueurs d'onde;
- ils peuvent être sensibles à la polarisation. La présente norme établit des exigences uniformes pour les compensateurs de dispersion chromatique passifs. La présente troisième édition annule et remplace la deuxième édition publiée en 2009, dont elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- introduction de nouveaux termes et définitions;
- révision des classifications;
- ajout de l'Annexe E. Mots clés: compensateurs de dispersion chromatique passifs à fibres optiques

General Information

• Status: Published
• Publication Date: 22-May-2014
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86B - Fibre optic interconnecting devices and passive components
• Drafting Committee: WG 7 - TC 86/SC 86B/WG 7
• Current Stage: DELPUB - Deleted Publication
• Start Date: 15-Apr-2024
• Completion Date: 30-Dec-2022

Relations

• Revises: IEC 61978-1:2009 - Fibre optic interconnecting devices and passive components - Fibre optic passive chromatic dispersion compensators - Part 1: Generic specification
• Effective Date: 05-Sep-2023
• Revised: IEC 61978-1:2024 - Fibre optic interconnecting devices and passive components - Fibre optic passive chromatic dispersion compensators - Part 1: Generic specification
• Effective Date: 05-Sep-2023

Overview

IEC 61978-1:2014 - “Fibre optic interconnecting devices and passive components - Fibre optic passive chromatic dispersion compensators - Part 1: Generic specification” - defines uniform requirements for fibre optic passive chromatic dispersion compensators (PCDCs). This third edition (2014) is a technical revision that replaces the 2009 edition and introduces new terms and definitions, revised classifications, and the addition of Annex E describing technology-dependent characteristics.

The standard applies to two‑port, optically passive devices that have an optical input and output (ports are optical fibres or fibre connectors), are wavelength sensitive, and may be polarization sensitive. It provides a framework for specifying, testing and documenting passive dispersion compensators used in optical fibre systems.

Key Topics and Requirements

• Scope and definitions: clear terminology for ports, PCDC types and related component terms.
• Classification system: hierarchical classification by type, style and variant to standardize product descriptions.
• Design and construction: general requirements for materials, workmanship and safety considerations for passive components.
• Performance and testing:
  • Measurement of group delay, chromatic dispersion and phase ripple (referencing IEC 61300-3-38).
  • Performance and reliability expectations without prescribing proprietary technology limits.
• Documentation and specifications:
  • Three‑level specification structure (general, product, and test data).
  • Required drawings, test data sheets and instructions for use.
• Identification, marking and packaging: rules for component marking, variant identification numbers and packaging/storage conditions.
• Informative technology annexes:
  • Annex A: Dispersion compensating fibre (DCF) examples
  • Annex B: Fibre Bragg grating (FBG) examples
  • Annex C: Virtually imaged phased array (VIPA) examples
  • Annex D: Gires–Tournois (GT) etalon examples
  • Annex E: Technology-dependent characteristics of PCDCs

Practical Applications and Users

Who benefits from IEC 61978-1:

• Component manufacturers - to design, specify and declare passive dispersion compensators consistently for product lines (DCF modules, FBG modules, VIPA, GT etalon devices).
• System and network designers - to select components that meet measurable dispersion compensation requirements for DWDM, metro and long‑haul links.
• Test laboratories and QA teams - to follow standard test methods and produce compliant test data sheets.
• Procurement and compliance officers - to define supplier requirements and verify marking, packaging and documentation.

Typical applications include chromatic dispersion compensation in single‑mode fibre links for improved signal integrity in broadband and high‑data‑rate optical networks.

Related Standards (select)

• IEC 61300 series (fibre optic test & measurement procedures), notably IEC 61300-3-38
• IEC 60793-2-50 (single‑mode optical fibre product spec)
• IEC 60825 (laser safety)
• IEC TR 61930 (fibre optic graphical symbology)
• IEC Guide 102 (specification structures for quality assessment)
• ISO 8601 (data interchange: dates/times)

Keywords: fibre optic passive chromatic dispersion compensators, PCDC, chromatic dispersion compensation, fibre Bragg grating, dispersion compensating fibre, VIPA, Gires–Tournois etalon.

Standards Content (Sample)

IEC 61978-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
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inside
Fibre optic interconnecting devices and passive components – Fibre optic
passive chromatic dispersion compensators –
Part 1: Generic specification
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IEC 61978-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
colour
inside
Fibre optic interconnecting devices and passive components – Fibre optic

passive chromatic dispersion compensators –

Part 1: Generic specification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 33.180.01 ISBN 978-2-8322-1583-8

– 2 – IEC 61978-1:2014 © IEC 2014

CONTENTS
FOREWORD . 4

1 Scope . 6

2 Normative references . 6

3 Terms and definitions . 7

3.1 Basic terms . 7

3.2 Component terms . 7

3.3 Performance parameter . 8
4 Requirements . 10
4.1 General . 10
4.2 Classification . 10
4.2.1 General . 10
4.2.2 Type . 10
4.2.3 Style . 11
4.2.4 Variant . 12
4.2.5 Normative reference extensions . 12
4.3 Documentation . 13
4.3.1 Symbols . 13
4.3.2 Specification system . 13
4.3.3 Drawings . 14
4.3.4 Tests and measurements . 15
4.3.5 Test data sheets . 15
4.3.6 Instructions for use . 15
4.4 Standardization system . 15
4.4.1 Performance standards . 15
4.4.2 Reliability standards . 16
4.4.3 Interlinking . 16
4.5 Design and construction. 18
4.5.1 Materials . 18
4.5.2 Workmanship . 18
4.6 Performance . 18
4.7 Identification and marking . 18
4.7.1 General . 18

4.7.2 Variant identification number . 18
4.7.3 Component marking . 19
4.7.4 Package marking . 19
4.8 Packaging . 19
4.9 Storage conditions . 20
4.10 Safety . 20
Annex A (informative) Example of dispersion compensating fibre (DCF) technologies . 21
Annex B (informative) Example of fibre Bragg grating (FBG) technologies . 23
Annex C (informative) Example of virtually imaged phased array (VIPA) technologies . 25
Annex D (informative) Example of GT etalon technologies . 27
Annex E (informative) Technology dependent characteristics of PCDCs . 28
Bibliography . 29

Figure 1 – Standards currently under preparation . 17

Figure A.1 – Chromatic dispersion in a standard single-mode optical fibre (SMF) . 21

Figure A.2 – Calculated contour for different dispersion at the wavelength of 1,55 µm

(CD(λ:1,55 µm)) for a step index core fibre . 22

Figure A.3 – Examples of refractive index profile used in DCF . 22

Figure B.1 – Illustration of the use of a chirped fibre Bragg grating for chromatic

dispersion compensation . 23

Figure B.2 – Expanded view over 10 nm of the insertion loss spectrum of a multi-
channel FBG . 24

Figure C.1 – Structure of virtually imaged phased array (VIPA) . 25
Figure C.2 – Detailed light path and mechanism of generating chromatic dispersion . 26
Figure D.1 – Gires-Tournois etalon . 27

Table 1 – Types of passive chromatic dispersion compensators . 11
Table 2 – Three-level IEC specification structure . 13
Table 3 – Standards interlink matrix . 17
Table 4 – Quality assurance options . 18
Table E.1 – Summary of technology dependent characteristics of PCDCs . 28

– 4 – IEC 61978-1:2014 © IEC 2014

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
FIBRE OPTIC INTERCONNECTING DEVICES

AND PASSIVE COMPONENTS – FIBRE OPTIC PASSIVE

CHROMATIC DISPERSION COMPENSATORS –

Part 1: Generic specification
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 61978-1 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This third edition cancels and replaces the second edition, published in 2009, and constitutes
a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) introduction of new terms and definitions;
b) revision of classifications;
c) addition of Annex E.
The text of this standard is based on the following documents:

CDV Report on voting
86B/3639/CDV 86B/3710/RVC
Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 61978 series, published under the general title Fibre optic
interconnecting devices and passive components – Fibre optic passive chromatic dispersion
compensators, can be found on the IEC website.
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.
A bilingual version of this publication may be issued at a later date.

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 publication using a
colour printer.
– 6 – IEC 61978-1:2014 © IEC 2014

FIBRE OPTIC INTERCONNECTING DEVICES

AND PASSIVE COMPONENTS – FIBRE OPTIC PASSIVE

CHROMATIC DISPERSION COMPENSATORS –

Part 1: Generic specification
1 Scope
This part of IEC 61978 applies to fibre optic passive chromatic dispersion compensators, all
exhibiting the following features:
– they are optically passive;
– they have an optical input and an optical output for transmitting optical power;
– the ports are optical fibres or optical fibre connectors;
– they are wavelength sensitive;
– they may be polarization sensitive.
This standard establishes uniform requirements for the passive chromatic dispersion
compensator.
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 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050-731, International Electrotechnical Vocabulary – Chapter 731: Optical fibre
communication
IEC 60617 (all parts), Graphical symbols for diagrams
IEC 60695-11-5, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method –

Apparatus, confirmatory test arrangement and guidance
IEC 60793-2-50:2012, Optical fibres – Part 2-50: Product specifications – Sectional
specification for class B single-mode fibres
IEC 60825 (all parts), Safety of laser products
IEC 61300 (all parts), Fibre optic interconnecting devices and passive components – Basic
test and measurement procedures
IEC 61300-3-38, Fibre optic interconnecting devices and passive components – Basic test
and measurement procedures – Part 3-38: Examinations and measurements – Group delay,
chromatic dispersion and phase ripple
IEC TR 61930, Fibre optic graphical symbology

IEC Guide 102, Electronic components – Specification structures for quality assessment

(Qualification approval and capability approval)

ISO 129-1, Technical drawings – Indication of dimensions and tolerances – Part 1: General

principles
ISO 286-1, Geometrical product specifications (GPS) – ISO coding system for tolerances of

linear sizes – Part 1: Bases of tolerances and fits

ISO 1101, Geometrical Product Specifications (GPS) – Geometrical tolerancing – Tolerances

of form, orientation, location and run-out

ISO 8601, Data elements and interchange formats – Information interchange –
Representation of dates and times
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-731, as well
as the following definitions apply.
3.1 Basic terms
3.1.1
port
optical fibre or optical fibre connector attached to a passive component for the entry and/or
exit of optical power (input and/or output port)
3.2 Component terms
3.2.1
passive chromatic dispersion compensator
PCDC
two-port in-line passive device used to perform chromatic dispersion compensation
Note 1 to entry: PCDCs are commonly used to compensate the chromatic dispersion of an optical path by adding
the opposite sign chromatic dispersion.
Note 2 to entry: The typical optical paths comprise single-mode fibre, dispersion shifted fibre and/or non-zero
dispersion shifted fibre. PCDCs have either negative or positive chromatic dispersion values depending on the
chromatic dispersion sign of the optical path.
3.2.2
dispersion compensating fibre
DCF
speciality fibre to compensate for the chromatic dispersion of an optical path
3.2.3
passive DCF based dispersion compensator
PCDC which constitutes DCF; realised by having chromatic dispersion characteristics of
opposite sign to that of the optical path which are controlled the refractive index profile of the
fibre
3.2.4
fibre Bragg grating
FBG
fibre type optical device which has modulated refractive index profile in the core

– 8 – IEC 61978-1:2014 © IEC 2014

3.2.5
passive FBG based dispersion compensator

PCDC which constitutes a FBG; PCDC is realised by a chirped FBG which has gradually

changing refractive index along the fibre axis

3.2.6
virtually imaged phased array
VIPA
optical device having a glass plate with a highly reflective mirror

Note 1 to entry: A VIPA has the same functions as a grating.

3.2.7
passive VIPA based dispersion compensator
PCDC which consisting of a VIPA, focusing lens and 3-dimensional mirror
Note 1 to entry: PCDC produces both positive and negative chromatic dispersion by the movement of the 3-
dimensional mirror to compensate for the chromatic dispersion of an optical path.
3.2.8
etalon
optical cavity which consists of a pair of parallel reflective mirrors
3.2.9
Gires-Tournois etalon
GT etalon
etalon having a highly reflective mirror and a half mirror
Note 1 to entry: The GT etalon is sometimes called a GT interferometer.
3.2.10
passive GT etalon based dispersion compensator
PCDC which comprises a GT etalon
3.3 Performance parameter
3.3.1
chromatic dispersion compensation
process by which a specific amount of chromatic dispersion is removed in order to mitigate
the system impairment caused by unwanted dispersion
3.3.2
group delay
time by which a pulse is delayed by an optical device
Note 1 to entry: The group delay generally varies with the operating wavelength.
3.3.3
chromatic dispersion
derivative of group delay with respect to wavelength or frequency
Note 1 to entry: A typical unit is ps/nm or ps/GHz. The chromatic dispersion generally varies with the operating
wavelength.
Note 2 to entry: The units of ps/GHz are not commonly used; however, it is suitable for the evaluation of
transmission system influence.
3.3.4
dispersion slope
derivative of chromatic dispersion with respect to wavelength or frequency

Note 1 to entry: A typical unit is ps/nm2 or ps/GHz2.The unit of ps/GHz2 is not commonly used; however, it is

suitable for the evaluation of transmission system influence.

Note 2 to entry: The dispersion slope generally varies with the operating wavelength

3.3.5
operating wavelength
nominal wavelength λ at which a passive device operates with the specified performance

Note 1 to entry: Operating wavelength includes the wavelength to be nominally transmitted, attenuated and
isolated.
3.3.6
operating wavelength range
specified range of wavelengths including all operating wavelengths
Note 1 to entry: Operating wavelength range shall include all passbands when two or more the passbands are exist.
3.3.7
figure of merit
FoM
ratio of the dispersion to the insertion loss of a PCDC at a particular operating wavelength
3.3.8
passband
wavelength range within which a passive optical component is required to operate with optical
attenuation less than or equal to a specified optical attenuation value
Note 1 to entry: There may be one or more passbands for a PCDC.
3.3.9
passband ripple
maximum peak-to-peak variation of insertion loss in the passband
Note 1 to entry: The passband ripple of a PCDC is defined as the maximum passband ripple for all passbands.
3.3.10
group delay ripple
GDR
maximum peak-to-peak variation of the group delay approximated by a desired function of
wavelength (or frequency), typically a linear fit, within a channel wavelength (or frequency)
range
3.3.11
phase ripple
maximum peak-to-peak variation in measured phase spectrum when compared to a quadratic
fit within a channel wavelength (or frequency) range
Note 1 to entry: Phase ripple (unit: radian) is calculated as the product of a peak-to-peak group delay ripple
(unit: s) and a period of group delay ripple (unit: Hz). Refer to IEC 61300-3-38.
3.3.12
insertion loss
reduction in optical power between an input and output port of a passive component
expressed in decibels. It is defined as follows:
P
a
a=−10log
P
where
P is the optical power launched into the input port;
– 10 – IEC 61978-1:2014 © IEC 2014

P is the optical power received from the output port.
a
3.3.13
return loss
fraction of input power that is returned from a port of a passive component expressed in

decibels. It is defined as follows:

P
r
RL=−10log
P
where
P is the optical power launched into a port;
P is the optical power received back from the same port.
r
3.3.14
reflectance
ratio of the optical power returning back from a port to input power expressed in %
3.3.15
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of polarization (SOP) over
all the SOPs
3.3.16
wavelength dependent loss
WDL
maximum variation of the insertion loss over operating wavelength range
3.3.17
polarization mode dispersion
PMD
average delay of the travelling time between the two principal states of polarization (PSP),
when an optical signal passes through an passive optical component
4 Requirements
4.1 General
The requirements for PCDCs covered by this clause are intended to aid in classifying this
device in a relevant specification. Additional or more severe requirements may be imposed by

the relevant blank detail specification and by the detail specification.
4.2 Classification
4.2.1 General
PCDCs shall be classified as follows:
– type;
– style;
– variant;
– normative reference extensions.
4.2.2 Type
PCDCs can be categorized into different types, as follows:

– by operating technologies (DCF, FBG, VIPA, GT etalon and so on);

– by dispersion compensating performance (for example, wavelength dispersion

compensating, dispersion slope compensating);

– by operating wavelength range (for example, O-band, C-band, L-band);

– by categories of transmission fibre which PCDCs are applied (for example,

IEC 60793-2-50:2012, B1, B2, B4).

The application of PCDCs and the suitable operating mechanisms are summarized in Table 1.

Table 1 – Types of passive chromatic dispersion compensators

Applications Channel number Passbands Technologies
TDM (Time division Single channel Narrow Dispersion compensating
multiplexing) fibre (DCF)
Fibre Bragg grating (FBG)
GT etalon
WDM (Wavelength Single channel Narrow FBG
division multiplexing)
a
Multi-channel Narrow FBG
GT etalon
Virtually imaged phased
array (VIPA)
Wide DCF
a
Multi-channel PCDCs can be used for a single channel use.

4.2.3 Style
4.2.3.1 General
PCDC may be classified into styles based on the fibre type(s), the connector type(s), cable
type(s), housing shape, temperature control and the configuration. Style is not intended to
define material or design. The configurations of PCDC ports are classified as follows.
4.2.3.2 Configuration A
A device containing integral fibre optic pigtails, without connectors.

PCDC
Pigtail
IEC  1687/2000
4.2.3.3 Configuration B
A device containing integral fibre optic pigtails, with a connector on each pigtail.
Connector
PCDC
Pigtail
IEC  1688/2000
– 12 – IEC 61978-1:2014 © IEC 2014

4.2.3.4 Configuration C
A device containing fibre optic connectors as an integral part of the device housing.

Connector
PCDC
IEC  1689/2000
4.2.3.5 Configuration D
A device containing some combination of the interfacing features of the preceding
configurations.
4.2.4 Variant
The PCDC variant identifies those common features which encompass structurally similar
components.
Examples of features which define a variant include, but are not limited to, the following:
– fibre type;
– connector type.
4.2.5 Normative reference extensions
Normative reference extensions are used to identify integrated independent standards,
specifications or other reference documents into blank detail specifications.
Unless a specified exception is noted, additional requirements imposed by an extension are
mandatory. Usage is primarily intended to merge associated components to form hybrid
devices, or integrated functional application requirements that are dependent on technical
expertise other than fibre optics.
Published reference documents produced by ITU consistent with the scope statements of the
relevant IEC specification series may be used as an extension. Published documents
produced by other regional standardization bodies such as TIA, ETSI, JIS, etc., may be
referenced in a bibliography attached to the generic specification.
Some optical fibre splice configurations require special qualification provisions that shall not
be imposed universally. This accommodates individual component design configurations,
specialized field tooling, or specific application processes. In this case, requirements are

necessary to assure repeatable performance or adequate safety, and provide additional
guidance for complete product specification. These extensions are mandatory whenever used
to prepare, assemble or install an optical fibre splice either for field application usage or
preparation of qualification test specimens. The relevant specification shall clarify all
stipulations. However, design- and style-dependent extensions shall not be imposed universally.
In the event of conflicting requirements, precedence shall be given, in descending order, as
follows: generic over mandatory extension, over blank detail, over detail, over application
specific extension.
Examples of requirements for normative extensions are as follows:
a) some commercial or residential building applications may require direct reference to
specific safety codes and regulations or incorporate other spe
...

IEC 61978-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Fibre optic
passive chromatic dispersion compensators –
Part 1: Generic specification
Dispositifs d’interconnexion et composants passifs à fibres optiques –
Compensateurs de dispersion chromatique passifs à fibres optiques –
Partie 1: Spécification générique
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IEC 61978-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Fibre optic

passive chromatic dispersion compensators –

Part 1: Generic specification
Dispositifs d’interconnexion et composants passifs à fibres optiques –

Compensateurs de dispersion chromatique passifs à fibres optiques –

Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-3086-2

– 2 – IEC 61978-1:2014 © IEC 2014
CONTENTS
CONTENTS . 2
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
3.1 Basic terms . 7
3.2 Component terms . 7
3.3 Performance parameter . 8
4 Requirements . 10
4.1 General . 10
4.2 Classification . 10
4.2.1 General . 10
4.2.2 Type . 11
4.2.3 Style . 11
4.2.4 Variant . 12
4.2.5 Normative reference extensions . 12
4.3 Documentation . 13
4.3.1 Symbols . 13
4.3.2 Specification system . 13
4.3.3 Drawings . 14
4.3.4 Tests and measurements . 15
4.3.5 Test data sheets . 15
4.3.6 Instructions for use . 15
4.4 Standardization system . 15
4.4.1 Performance standards . 15
4.4.2 Reliability standards . 16
4.4.3 Interlinking . 16
4.5 Design and construction. 18
4.5.1 Materials . 18
4.5.2 Workmanship . 18
4.6 Performance . 18
4.7 Identification and marking . 18
4.7.1 General . 18
4.7.2 Variant identification number . 18
4.7.3 Component marking . 19
4.7.4 Package marking . 19
4.8 Packaging . 19
4.9 Storage conditions . 20
4.10 Safety . 20
Annex A (informative) Example of dispersion compensating fibre (DCF) technologies . 21
Annex B (informative) Example of fibre Bragg grating (FBG) technologies . 23
Annex C (informative) Example of virtually imaged phased array (VIPA) technologies . 25
Annex D (informative) Example of GT etalon technologies . 27
Annex E (informative) Technology dependent characteristics of PCDCs . 28
Bibliography . 29

Figure 1 – Standards currently under preparation . 17
Figure A.1 – Chromatic dispersion in a standard single-mode optical fibre (SMF) . 21
Figure A.2 – Calculated contour for different dispersion at the wavelength of 1,55 mm
(CD(λ:1,55 mm)) for a step index core fibre . 22
Figure A.3 – Examples of refractive index profile used in DCF . 22
Figure B.1 – Illustration of the use of a chirped fibre Bragg grating for chromatic
dispersion compensation . 23
Figure B.2 – Expanded view over 10 nm of the insertion loss spectrum of a multi-
channel FBG . 24
Figure C.1 – Structure of virtually imaged phased array (VIPA) . 25
Figure C.2 – Detailed light path and mechanism of generating chromatic dispersion . 26
Figure D.1 – Gires-Tournois etalon . 27

Table 1 – Types of passive chromatic dispersion compensators . 11
Table 2 – Three-level IEC specification structure . 13
Table 3 – Standards interlink matrix . 17
Table 4 – Quality assurance options . 18
Table E.1 – Summary of technology dependent characteristics of PCDCs . 28

– 4 – IEC 61978-1:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS – FIBRE OPTIC PASSIVE
CHROMATIC DISPERSION COMPENSATORS –

Part 1: Generic specification
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 61978-1 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This bilingual version (2016-01) corresponds to the English version, published in 2014-05.
This third edition cancels and replaces the second edition, published in 2009, and constitutes
a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) introduction of new terms and definitions;
b) revision of classifications;
c) addition of Annex E.
The text of this standard is based on the following documents:
CDV Report on voting
86B/3639/CDV 86B/3710/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61978 series, published under the general title Fibre optic
interconnecting devices and passive components – Fibre optic passive chromatic dispersion
compensators, can be found on the IEC website.
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 publication using a
colour printer.
– 6 – IEC 61978-1:2014 © IEC 2014
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS – FIBRE OPTIC PASSIVE
CHROMATIC DISPERSION COMPENSATORS –

Part 1: Generic specification
1 Scope
This part of IEC 61978 applies to fibre optic passive chromatic dispersion compensators, all
exhibiting the following features:
– they are optically passive;
– they have an optical input and an optical output for transmitting optical power;
– the ports are optical fibres or optical fibre connectors;
– they are wavelength sensitive;
– they may be polarization sensitive.
This standard establishes uniform requirements for the passive chromatic dispersion
compensator.
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 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050-731, International Electrotechnical Vocabulary – Chapter 731: Optical fibre
communication
IEC 60617 (all parts), Graphical symbols for diagrams
IEC 60695-11-5, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method –
Apparatus, confirmatory test arrangement and guidance
IEC 60793-2-50:2012, Optical fibres – Part 2-50: Product specifications – Sectional
specification for class B single-mode fibres
IEC 60825 (all parts), Safety of laser products
IEC 61300 (all parts), Fibre optic interconnecting devices and passive components – Basic
test and measurement procedures
IEC 61300-3-38, Fibre optic interconnecting devices and passive components – Basic test
and measurement procedures – Part 3-38: Examinations and measurements – Group delay,
chromatic dispersion and phase ripple
IEC TR 61930, Fibre optic graphical symbology

IEC Guide 102, Electronic components – Specification structures for quality assessment
(Qualification approval and capability approval)
ISO 129-1, Technical drawings – Indication of dimensions and tolerances – Part 1: General
principles
ISO 286-1, Geometrical product specifications (GPS) – ISO coding system for tolerances of
linear sizes – Part 1: Bases of tolerances and fits
ISO 1101, Geometrical Product Specifications (GPS) – Geometrical tolerancing – Tolerances
of form, orientation, location and run-out
ISO 8601, Data elements and interchange formats – Information interchange –
Representation of dates and times
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-731, as well
as the following definitions apply.
3.1 Basic terms
3.1.1
port
optical fibre or optical fibre connector attached to a passive component for the entry and/or
exit of optical power (input and/or output port)
3.2 Component terms
3.2.1
passive chromatic dispersion compensator
PCDC
two-port in-line passive device used to perform chromatic dispersion compensation
Note 1 to entry: PCDCs are commonly used to compensate the chromatic dispersion of an optical path by adding
the opposite sign chromatic dispersion.
Note 2 to entry: The typical optical paths comprise single-mode fibre, dispersion shifted fibre and/or non-zero
dispersion shifted fibre. PCDCs have either negative or positive chromatic dispersion values depending on the
chromatic dispersion sign of the optical path.
3.2.2
dispersion compensating fibre
DCF
speciality fibre to compensate for the chromatic dispersion of an optical path
3.2.3
passive DCF based dispersion compensator
PCDC which constitutes DCF; realised by having chromatic dispersion characteristics of
opposite sign to that of the optical path which are controlled the refractive index profile of the
fibre
3.2.4
fibre Bragg grating
FBG
fibre type optical device which has modulated refractive index profile in the core

– 8 – IEC 61978-1:2014 © IEC 2014
3.2.5
passive FBG based dispersion compensator
PCDC which constitutes a FBG; PCDC is realised by a chirped FBG which has gradually
changing refractive index along the fibre axis
3.2.6
virtually imaged phased array
VIPA
optical device having a glass plate with a highly reflective mirror
Note 1 to entry: A VIPA has the same functions as a grating.
3.2.7
passive VIPA based dispersion compensator
PCDC which consisting of a VIPA, focusing lens and 3-dimensional mirror
Note 1 to entry: PCDC produces both positive and negative chromatic dispersion by the movement of the 3-
dimensional mirror to compensate for the chromatic dispersion of an optical path.
3.2.8
etalon
optical cavity which consists of a pair of parallel reflective mirrors
3.2.9
Gires-Tournois etalon
GT etalon
etalon having a highly reflective mirror and a half mirror
Note 1 to entry: The GT etalon is sometimes called a GT interferometer.
3.2.10
passive GT etalon based dispersion compensator
PCDC which comprises a GT etalon
3.3 Performance parameter
3.3.1
chromatic dispersion compensation
process by which a specific amount of chromatic dispersion is removed in order to mitigate
the system impairment caused by unwanted dispersion
3.3.2
group delay
time by which a pulse is delayed by an optical device
Note 1 to entry: The group delay generally varies with the operating wavelength.
3.3.3
chromatic dispersion
derivative of group delay with respect to wavelength or frequency
Note 1 to entry: A typical unit is ps/nm or ps/GHz. The chromatic dispersion generally varies with the operating
wavelength.
Note 2 to entry: The units of ps/GHz are not commonly used; however, it is suitable for the evaluation of
transmission system influence.
3.3.4
dispersion slope
derivative of chromatic dispersion with respect to wavelength or frequency

Note 1 to entry: A typical unit is ps/nm2 or ps/GHz2.The unit of ps/GHz2 is not commonly used; however, it is
suitable for the evaluation of transmission system influence.
Note 2 to entry: The dispersion slope generally varies with the operating wavelength
3.3.5
operating wavelength
nominal wavelength λ at which a passive device operates with the specified performance
Note 1 to entry: Operating wavelength includes the wavelength to be nominally transmitted, attenuated and
isolated.
3.3.6
operating wavelength range
specified range of wavelengths including all operating wavelengths
Note 1 to entry: Operating wavelength range shall include all passbands when two or more the passbands are exist.
3.3.7
figure of merit
FoM
ratio of the dispersion to the insertion loss of a PCDC at a particular operating wavelength
3.3.8
passband
wavelength range within which a passive optical component is required to operate with optical
attenuation less than or equal to a specified optical attenuation value
Note 1 to entry: There may be one or more passbands for a PCDC.
3.3.9
passband ripple
maximum peak-to-peak variation of insertion loss in the passband
Note 1 to entry: The passband ripple of a PCDC is defined as the maximum passband ripple for all passbands.
3.3.10
group delay ripple
GDR
maximum peak-to-peak variation of the group delay approximated by a desired function of
wavelength (or frequency), typically a linear fit, within a channel wavelength (or frequency)
range
3.3.11
phase ripple
maximum peak-to-peak variation in measured phase spectrum when compared to a quadratic
fit within a channel wavelength (or frequency) range
Note 1 to entry: Phase ripple (unit: radian) is calculated as the product of a peak-to-peak group delay ripple
(unit: s) and a period of group delay ripple (unit: Hz). Refer to IEC 61300-3-38.

– 10 – IEC 61978-1:2014 © IEC 2014
3.3.12
insertion loss
reduction in optical power between an input and output port of a passive component
expressed in decibels. It is defined as follows:
P
a
a=−10log
P
where
P is the optical power launched into the input port;
P is the optical power received from the output port.
a
3.3.13
return loss
fraction of input power that is returned from a port of a passive component expressed in
decibels. It is defined as follows:
P
r
RL=−10log
P
where
P is the optical power launched into a port;
P is the optical power received back from the same port.
r
3.3.14
reflectance
ratio of the optical power returning back from a port to input power expressed in %
3.3.15
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of polarization (SOP) over
all the SOPs
3.3.16
wavelength dependent loss
WDL
maximum variation of the insertion loss over operating wavelength range
3.3.17
polarization mode dispersion
PMD
average delay of the travelling time between the two principal states of polarization (PSP),
when an optical signal passes through an passive optical component
4 Requirements
4.1 General
The requirements for PCDCs covered by this clause are intended to aid in classifying this
device in a relevant specification. Additional or more severe requirements may be imposed by
the relevant blank detail specification and by the detail specification.
4.2 Classification
4.2.1 General
PCDCs shall be classified as follows:

– type;
– style;
– variant;
– normative reference extensions.
4.2.2 Type
PCDCs can be categorized into different types, as follows:
– by operating technologies (DCF, FBG, VIPA, GT etalon and so on);
– by dispersion compensating performance (for example, wavelength dispersion
compensating, dispersion slope compensating);
– by operating wavelength range (for example, O-band, C-band, L-band);
– by categories of transmission fibre which PCDCs are applied (for example,
IEC 60793-2-50:2012, B1, B2, B4).
The application of PCDCs and the suitable operating mechanisms are summarized in Table 1.
Table 1 – Types of passive chromatic dispersion compensators
Applications Channel number Passbands Technologies
TDM (Time division Single channel Narrow Dispersion compensating
multiplexing) fibre (DCF)
Fibre Bragg grating (FBG)
GT etalon
WDM (Wavelength Single channel Narrow FBG
division multiplexing)
a
Multi-channel Narrow FBG
GT etalon
Virtually imaged phased
array (VIPA)
Wide DCF
a
Multi-channel PCDCs can be used for a single channel use.

4.2.3 Style
4.2.3.1 General
PCDC may be classified into styles based on the fibre type(s), the connector type(s), cable
type(s), housing shape, temperature control and the configuration. Style is not intended to
define material or design. The configurations of PCDC ports are classified as follows.
4.2.3.2 Configuration A
A device containing integral fibre optic pigtails, without connectors.

PCDC
Pigtail
IEC  1687/2000
4.2.3.3 Configuration B
A device containing integral fibre optic pigtails, with a connector on each pigtail.

– 12 – IEC 61978-1:2014 © IEC 2014
Connector
PCDC
Pigtail
IEC  1688/2000
4.2.3.4 Configuration C
A device containing fibre optic connectors as an integral part of the device housing.

Connecteur
PCDC
IEC  1689/2000
4.2.3.5 Configuration D
A device containing some combination of the interfacing features of the preceding
configurations.
4.2.4 Variant
The PCDC variant identifies those common features which encompass structurally similar
components.
Examples of features which define a variant include, but are not limited to, the following:
– fibre type;
– connector type.
4.2.5 Normative reference extensions
Normative reference extensions are used to identify integrated independent standards,
specifications or other reference documents into blank detail specifications.
Unless a specified exception is noted, additional requirements imposed by an extension are
mandatory. Usage is primarily intended to merge associated components to form hybrid
devices, or integrated functional application requirements that are dependent on technical
expertise other than fibre optics.
Published reference documents produced by ITU consistent with the scope statements of the
relevant IEC specification series may be used as an extension. Published documents
produced by other regional standardization bodies such as TIA, ETSI, JIS, etc., may be
referenced in a bibliography attached to the generic specification.
Some optical fibre splice configurations require special qualification provisions that shall not
be imposed universally. This accommodates individual component design configurations,
specialized field tooling, or specific application processes. In this case, requirements are
necessary to assure repeatable performance or adequate safety, and provide additional
guidance for complete product specification. These extensions are mandatory whenever used
to prepare, assemble or install an optical fibre splice either for field application usage or
preparation of qualification test specimens. The relevant specification shall clarify all
stipulations. However, design- and style-dependent extensions shall not be imposed universally.
In the event of conflicting requirements, precedence shall be given, in descending order, as
follows: generic over mandatory extension, over blank detail, over detail, over application
specific extension.
Examples of requirements for normative extensions are as follows:

a) some commercial or residential building applications may require direct reference to
specific safety codes and regulations or incorporate other specific material flammability or
toxicity requirements for specialized locations;
b) specialized field tooling may require an extension to implement specific ocular safety,
electrical shock or burn hazard avoidance requirements, or require isolation procedures to
prevent potential ignition of combustible gases.
4.3 Documentation
4.3.1 Symbols
Graphical and letter symbols shall, whenever possible, be taken from the IEC 60027 series,
IEC 60617 and IEC TR 61930.
4.3.2 Specification system
4.3.2.1 General
This specification is part of a three-level IEC specification system. Subsidiary specifications
shall consist of blank detail specifications and detail specifications. This system is shown in
Table 2. There are no sectional specifications for passive dispersion compensators.
Table 2 – Three-level IEC specification structure
Specification level Examples of information to be included Applicable to
Basic
Inspection rules Two or more component
families or subfamilies
Optical measuring methods
Environmental test methods
Sampling plans
Identification rule
Marking standards
Dimensional standards
Terminology standards
Symbol standards
Preferred number series
SI units
Generic Specific terminology Component family
Specific symbols
Specific units
Preferred values
Marking
Selection of tests
Blank detail Quality conformance test schedule Groups of types having a
common test schedule
Inspection requirements
Information common to a number of types
Detail Individual values Individual type
Specific information
Completed quality conformance test schedules

– 14 – IEC 61978-1:2014 © IEC 2014
4.3.2.2 Blank detail specifications
The blank detail specification lists all of the parameters and features applicable to a PCDC,
including the type, operating characteristics, housing configurations, test methods, and
performance requirements. The blank detail specification is applicable to any PCDC design
and quality assessment requirement. The blank detail specification contains the preferred
format for stating the required information in the detail specification.
Blank detail specifications are not, by themselves, a specification level. They are associated
with the generic specification.
Each blank detail specification shall be limited to one environmental category.
Each blank detail specification shall contain
– the minimum mandatory test schedules and performance requirements,
– one or more assessment levels,
– the preferred format for stating the required information in the detail specification,
– in case of hybrid components, including connectors, addition of appropriate entry fields to
show the reference normative document, document title and issue date.
4.3.2.3 Detail specifications
A specific PCDC is described by a corresponding detail specification, which is prepared by
filling in the blanks of the blank detail specification. Within the constraints imposed by this
generic specification, the blank detail specification may be filled in by any national committee
of the IEC, thereby defining a particular PCDC as an IEC standard.
Detail specifications shall specify the following, as applicable:
– type (see 4.2.2);
– style (see 4.2.3);
– variant(s) (see 4.2.4);
– part identification number for each variant (see 4.7.1);
– drawings, dimensions required (see 4.3.3);
– performance requirements (see 4.6).
4.3.3 Drawings
4.3.3.1 General
The drawings and dimensions given in detail specifications shall not restrict themselves to
details of construction, nor shall they be used as manufacturing drawings.
4.3.3.2 Projection system
Either first angle or third angle projection shall be used for the drawings in documents
covered by this specification. All drawings within a document shall use the same projection
system and the drawings shall state which system is used.
4.3.3.3 Dimensional system
All dimensions shall be given in accordance with ISO 129-1, ISO 286-1 and ISO 1101.
The metric system shall be used in all specifications.
Dimensions shall not contain more than five significant digits.

When units are converted, a note shall be added in each relevant specification and the
conversion between systems of units shall use a factor of 25,4 mm to 1 inch.
4.3.4 Tests and measurements
4.3.4.1 Test and measurement procedures
The test and measurement procedures for optical, mechanical, climatic and environmental
characteristics of passive dispersion compensators to be used shall be defined and selected
preferentially from the IEC 61300 series.
The size measurement method to be used shall be specified in the detail specification for
dimensions, which are specified within a total tolerance of 0,01 mm or less.
4.3.4.2 Reference components
Reference components for measurement purposes, if required, shall be specified in the
relevant specification.
4.3.4.3 Gauges
Gauges, if required, shall be specified in the relevant specification.
4.3.5 Test data sheets
Test data sheets shall be prepared for each test conducted as required by a relevant
specification. The data sheets shall be included in the qualification report and in the periodic
inspection report.
Data sheets shall contain the following information as a minimum:
– title of test and date;
– specimen description including the type of fibre, connector or other coupling device. The
description shall also include the variant identification number (see 4.7.2);
– test equipment used and date of latest calibration;
– all applicable test details;
– all measurement values and observations;
– sufficiently detailed documentation to provide traceable information for failure analysis.
4.3.6 Instructions for use
Instructions for use, when required, shall be given by the manufacturer and shall include
– assembly and connection instructions;
– cleaning method;
– safety aspects;
– additional information as necessary.
4.4 Standardization system
4.4.1 Performance standards
Performance standards contain a series of tests and measurements (which may or may not be
grouped into a specified schedule depending on the requirements of that standard) with
clearly defined conditions, severities, and “pass/fail” criteria. The tests are intended to be run
on a “once-off” basis to prove any product’s ability to satisfy the “performance standards”
requirement. Each performance standard has a different set of tests, and/or severities (and/or
groupings) and represents the requirements of a market sector, user group or system location.

– 16 – IEC 61978-1:2014 © IEC 2014
A product that has been shown to meet all the requirements of a performance standard can
be declared as complying with a performance standard but should then be controlled by a
quality assurance/quality conformance programme.
It is possible to define a key point of the test and measurements standards when these are
applied (particularly with regard to insertion loss and return loss) in conjunction with the
interface standards of inter product compatibility. This ensures conformance of each
individual product to this standard,
4.4.2 Reliability standards
Reliability standards are intended to ensure that a component can meet performance
specifications under stated conditions for a stated time period.
For each type of component, the following shall be identified (and appear in the standard):
• failure modes (ways in which a component can fail);
• failure mechanisms (causes of failure, which may be common to several components);
• failure effects (observable, general, mechanical or optical effects of failure).
These are all related to environmental and material aspects.
Initially, just after component manufacture, there is an “infant mortality phase” during which
many components would fail if they were deployed in the field. To avoid early field failure, all
components may be subjected to a screening process in the factory involving environmental
stresses that may be mechanical, thermal or humidity-related. This is to induce known failure
mechanisms in a controlled environmental situation to occur earlier than would normally be
seen in the unscreened population. For those components that survive (and are then sold),
there is a reduced failure rate, since these mechanisms have been eliminated.
Screening is an optional part of the manufacturing process, rather than a test method. It will
not affect the “useful life” of a component defined as the period during which it performs
according to specifications. Eventually other failure mechanisms appear, and the failure rate
increases beyond the defined threshold. At this point the useful life ends and the “wear-out
region” begins, and the component shall be replaced.
At the beginning of useful life, performance testing on a sampled population of components
may be applied by the supplier, by the manufacturer or by a third party. This is to ensure that
the component meets performance specifications over the range of intended environments at
this initial time. Reliability testing, on the other hand, is applied to ensure that the component
meets performance specifications for at least a specified minimum useful lifetime or specified
maximum failure rate. These tests are usually carried out by utilizing the performance testing,
but increasing duration and severity to accelerate the failure mechanisms.
A reliability theory relates component reliability testing to component parameters and to
lifetime or failure rate under testing. The theory then extrapolates these to lifetime or failure
rate under less stressful service conditions. The reliability specifications include values of the
component parameters needed to ensure the specified minimum lifetime or maximum failure
rate in service.
4.4.3 Interlinking
Standards currently under preparation are given in Figure 1. A large number of the test and
measurements standards already exist, and quality assurance qualification approval already
exists and has done so for many years. As previously mentioned, alternative methods of
quality assurance/quality conformance are being developed under the headings of capability
approval and technology approval which are covered in IEC Guide 102.

With regard to interface, performance and reliability standards, once all three of these
standards are in place, the matrix given in Table 3 demonstrates some of the other options
available for product standardization.
Pr
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