IEC 61977:2001

INTERNATIONAL IEC
STANDARD
QC 840000
First edition
2001-12
Fibre optic filters –
Generic specification
Filtres à fibres optiques –
Spécification générique
Reference number
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INTERNATIONAL IEC
STANDARD
QC 840000
First edition
2001-12
Fibre optic filters –
Generic specification
Filtres à fibres optiques –
Spécification générique
 IEC 2001  Copyright - all rights reserved
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 the publisher.
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Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
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International Electrotechnical Commission
For price, see current catalogue

– 2 – 61977  IEC:2001(E)
CONTENTS
FOREWORD.3

INTRODUCTION.4

1 Scope.5

2 Normative references .5

3 Definitions .6
4 Requirements .8
4.1 Classification.8
4.2 Documentation .11
4.3 Standardisation system .14
4.4 Design and construction .16
4.5 Quality.16
4.6 Performance requirements .16
4.7 Identification and marking.16
4.8 Packaging .17
4.9 Storage conditions.17
4.10 Safety.18
5 Quality assessment procedures.18
5.1 Primary stage of manufacture.18
5.2 Structurally similar components.18
5.3 Qualification approval procedures .18
5.4 Quality conformance inspection.20
5.5 Certified record of released lots.21
5.6 Delayed deliveries.22
5.7 Delivery release before completion of group B tests .22
5.8 Alternative test methods .22
5.9 Unchecked parameters.22
Table 1 – The IEC specification structure.12
Table 2 – Standards interlink matrix.16

Table 3 – Quality assurance options .16

61977  IEC:2001(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
FIBRE OPTIC FILTERS –
Generic specification
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61977 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/1603/FDIS 86B/1637/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.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
The QC number that appears on the front cover of this publication is the specification number
in the IEC Quality Assessment System for Electronic Components (IECQ).
The committee has decided that the contents of this publication will remain unchanged until
2008. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 4 – 61977  IEC:2001(E)
INTRODUCTION
This standard is divided into three elements.

The first element, made up of clauses 1 to 3, contains general information which pertains to
this standard.
The second element, consisting of clause 4, Requirements, contains all requirements which
should be met by fibre optic filters covered by this standard. Requirements for classification,

the IEC specification system, documentation, materials, workmanship, quality, performance,

identification, and packaging are covered.

The third element, composed of clause 5, Quality assessment procedures, contains all of the
procedures which must be followed for proper quality assessment of products covered by this
standard.
61977  IEC:2001(E) – 5 –
FIBRE OPTIC FILTERS –
Generic specification
1 Scope
IEC 61977 applies to the family of fibre optic filters. These components have all of the
following general features:
– they are passive for the reason that they contain no optoelectronic or other transducing
elements which can process the optical signal launched into the input port;
– they modify the spectral intensity distribution in order to select some wavelengths and
inhibit others;
– they are fixed, i.e. the modification of the spectral intensity distribution is fixed and can
not be tuned;
– they have a maximum of two ports for the transmission of optical power; the ports are
optical fibre or optical fibre connectors;
– they differ according to their characteristics. They can be divided into the following
categories:
• short-wave pass (only wavelengths lower than or equal to a specified value are
passed);
• long-wave pass (only wavelengths greater than or equal to a specified value are
passed);
• band-pass (only an optical window is allowed);
• notch (only an optical window is inhibited).
It is also possible to have a combination of the above categories.
This standard establishes uniform requirements for the following:
– optical, mechanical and environmental properties;
– measurement and test procedures for quality assessment.
2 Normative references
The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IECQ 001001:2000, IEC Quality Assessment System for Electronic Components (IECQ) –
Basic Rules
IECQ 001002 (all parts), IEC Quality Assessment System for Electronic Components (IECQ) –
Rules of Procedure
IEC 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050(731):1991, International Electrotechnical Vocabulary – Chapter 731: Optical fibre
communication
IEC 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 60617 (all parts), Graphical symbols for diagrams

– 6 – 61977  IEC:2001(E)
IEC 60695-2-2:1991, Fire hazard testing – Part 2: Test methods – Section 2: Needle-flame test

IEC 60825-1:1993, Safety of laser products – Part 1: Equipment classification, requirements

and user’s guide
IEC 61300 (all parts), Fibre optic interconnecting devices and passive components – Basic
test and measurement procedures

ISO 129:1985, Technical drawings – Dimensioning – General principles, definitions, methods

of execution and special indications

ISO 286-1:1988, ISO system of limits and fits – Part 1: Bases of tolerances, deviations and

fits
ISO 1101:1983, Technical drawings – Geometrical tolerancing – Tolerancing of form,
orientation, location and run-out – Generalities, definitions, symbols, indications on drawings
ISO 8601:2000, Data elements and interchange formats – Information interchange –
Representation of dates and times
3 Definitions
For the purposes of this standard the definitions given in IEC 60050(731) and the following
apply.
3.1
fibre optic filter
a passive component used in fibre optic transmission to modify the spectral intensity
distribution of a signal in order to pass some wavelengths and block some others
3.2
port
an optical fibre or optical fibre connector attached to a passive component for the entry and/or
exit of the optical power (input and/or output port)
3.3
unidirectional fibre optic filter
a fibre optic filter whose specified filtering action is in one direction only or requires
designation of its input and output ports
3.4
bidirectional fibre optic filter

a fibre optic filter in which each port may be used either as an input or output port
3.5
transmitting type fibre optic filter
a fibre optic filter in which the input and output ports are different
3.6
reflecting type fibre optic filter
a fibre optic filter in which the input and output ports are coincident
3.7
operating wavelength
a nominal wavelength λ , at which a fibre optic filter operates with the specified performances
h
61977  IEC:2001(E) – 7 –
3.8
operating wavelength range, bandpass

the specified range of wavelengths from λ to λ around the operating wavelength λ ,
hmin hmax h
within which a fibre optic filter operates with the specified performances

3.9
isolation wavelength
a nominal wavelength λ (where λ ≠ λ ), that is nominally suppressed by a fibre optic filter
k h k
3.10
isolation wavelength range, stopband

the specified range of wavelengths from λ to λ around the isolation wavelength λ ,
kmin kmax k
that are nominally suppressed by a fibre optic filter
3.11
attenuation
the reduction of optical power, when transmitted between the ports of a two-port fibre optic
filter expressed in decibels. It is defined as:
a = −10 log()P P
out in
where
P is the optical power launched into one of the two ports;
in
P is the optical power received from the other port.
out
The attenuation is a function of wavelength
3.12
transmittance
the percentage of optical power transmitted by the filter at the operating wavelength
3.13
return loss
the fraction of input power that is returned from a port of a fibre optic filter expressed in
decibels. It is defined as:
RL = −10 log()P P
refl in
where
P is the optical power launched into the port;
in
P is the optical power received back from the same port.
refl
The return loss is a function of wavelength
3.14
reflectance
the percentage of optical power reflected by the filter at the operating wavelength
3.15
X dB-bandwidth
a) for transmitting-type fibre optic filters: defined through the spectral dependence of the
attenuation as the minimum wavelength range about the operating wavelength λ within
h
which the variation of the attenuation is less than "X" dB; the minimum wavelength range
is determined considering the worst case shift due to temperature operating range and
polarisation;
– 8 – 61977  IEC:2001(E)
b) for reflecting-type fibre optic filters: defined through the spectral dependence of the return

loss as the minimum wavelength range about the operating wavelength λ within which
h
the variation of the return loss is less than "X" dB. The minimum wavelength range is

determined considering the worst case shift due to temperature operating range and

polarisation.
3.16
free spectral range
in the case of a periodic spectral response of a fibre optic filter, the difference between two

adjacent operating wavelengths

3.17
spectral ripple (flatness)
the maximum peak-to-peak variation in attenuation (for transmitting-type fibre optic filter) or
return loss (for reflecting-type fibre optic filter) over the bandpass
3.18
maximum slope of spectral ripple
the maximum value in module of the derivative of the attenuation (for transmitting-type fibre
optic filter) or return loss (for reflecting-type fibre optic filter) as a function of wavelength over
the bandpass
3.19
polarization dependent loss (PDL)
the maximum variation of attenuation over all the polarization states
3.20
polarization mode dispersion (PMD)
the maximum differential delay for all the polarization states of signals when they pass
through a filter
4 Requirements
The requirements for filters covered by this section are intended to aid in classifying a filter in
a detail specification.
4.1 Classification
Filters are classified either totally or in part by the following categories:
− type;
− style;
− variant;
− environmental category;
− assessment level;
− normative reference extensions.
An example of a typical filter classification is as follows:
Type Fixed
Style – Configuration C
– Fibre type: IEC type A1a
– SC connector
Variant Means of mounting
Assessment level A
61977  IEC:2001(E) – 9 –
4.1.1 Type
The optic filter type shall be defined by its intended function and optical performance. There

are several types of filters, for instance:

– low pass filter (LPF);
– band pass filter (BPF);
– high pass filter (HPF);
– "notch".
4.1.2 Style
The optic filter style shall be defined on the basis of the following elements:
– the input and output port configuration;
– the connector set type(s), if any.
The four different input and output configurations can be scheduled as follows:
Configuration A – a device containing integral fibre optic pigtails without connectors.
Filter
Configuration B – a device containing integral fibre optic pigtails, with a connector on each
pigtail.
Filter
Configuration C – a device containing fibre optic connectors as an integral part of the device
housing.
Filter
Configuration D – a device containing some combination of the interfacing features of the
preceding configurations.
4.1.3 Variant
The optic filter variant defines the feature that identifies the variety of structurally similar
components. Examples of feature variables which create variants are:
– cable type;
– fibre type;
– housing;
– orientation of ports;
– means of mounting.
– 10 – 61977  IEC:2001(E)
4.1.4 Environmental category
Various environmental categories are given in the blank detail specifications associated with

this document, these define the test sequences needed for quality assurance.

Detail specification writers may add tests and/or groups of tests to a particular environmental

category.
However, the detail specification writer shall not remove tests nor alter the sequence of an

environmental category standard.

When a detail specification writer adds tests to a specified category, the environmental
category shall be given a plus (+) designation.
Example:
– environmental category ii +
– environmental category v +
The blank detail specification for environmental category 99 is available for use where the
category standards are not suitable.
4.1.5 Assessment level
Assessment level defines the inspection levels and the acceptable quality level (AQL), of
groups A and B and the periodicity of inspection of groups C and D. Detail specifications shall
specify one or more assessment levels, each of which shall be designated by a capital letter.
The following are preferred levels:
Assessment level A:
– Group A inspection: inspection level II, QL = 4 %
– Group B inspection: inspection level II, AQL = 4 %
– Group C inspection: 24-month periods
– Group D inspection: 48-month periods
Assessment Level B:
– Group A inspection: inspection level II, AQL = 1 %
– Group B inspection: inspection level II, AQL = 1 %

– Group C inspection: 18-month periods
– Group D inspection: 36-month periods
Assessment level C:
– Group A inspection: inspection level II, AQL = 0,4 %
– Group B inspection: inspection level II, AQL = 0,4 %
– Group C inspection: 12-month periods
– Group D inspection: 24-month periods
One additional assessment level may be added in the detail specification. When this is done,
the capital letter X shall be used.

61977  IEC:2001(E) – 11 –
4.1.6 Normative reference extensions

Normative reference extensions are used to identify independent standards specifications or

other reference documents integrated 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 the International Telecommunication Union

(ITU), consistent with the scope statements of the relevant IEC specification series may be
used as an extension. Published documents produced by other regional standardisation
bodies such as the Telecommunications Industry Association (TIA), the European
Telecommunications Standards Institute (ETSI), Japanese Industrial Standards (JIS) etc, may
be referenced in a bibliography attached to the generic.
Some optical fibre filter configurations require special qualification provisions which shall not be
imposed universally. This accommodates individual component design configurations, specialised
field tooling, or specific application processes. In this case requirements are necessary to
guarantee 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, in descending order, shall be generic
over mandatory extension, over blank detail, over detail, over application specific extension.
The following is an example of an optical connector extension:
• Using IEC 61754-4 and IEC 61754-2 to partially define a future IEC 60874-XX
specification for a duplex type “SC/BFOC/2,5” hybrid connector adapter.
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 specialised locations.
Specialised field tooling may require an extension to implement specific ocular safety, elec-
trical shock or burn hazard avoidance requirements, or require isolation procedures to prevent
potential ignition of combustible gases.

4.2 Documentation
4.2.1 Symbols
Graphical and letter symbols shall, whenever possible, be taken from IEC 60027, IEC 60617
and IEC 61748 unless superseded by this specification.
4.2.2 Specification system
This specification is part of the IEC specification system. Subsidiary specifications shall
consist of blank detail specifications and detail specifications. This system is shown in table 1.
There are no sectional specifications for filters.

– 12 – 61977  IEC:2001(E)
Table 1 – The IEC specification structure

Specification level Examples of information to be included Applicable to

Assessment system rules
Inspection rules
Optical measurement methods
Sampling plans
Identification rule
Two or more component families
Marking standards
Basic
or sub-families
Dimensional standards
Terminology
Symbol
Preferred number series
SI units
Specific terminology
Specific symbols
Specific units
Preferred values
Generic Marking Component family
Quality assessment procedures
Selection of tests
Qualification approval and/or capability
approval procedures
Quality conformance test schedule
Groups of types having a
Inspection requirements
Blank detail
common test schedule
Information common to a number of types
Individual values
Specific information
Detail Individual type
Completed quality conformance test
schedules
4.2.2.1 Blank detail specification
The blank detail specification lists all of the parameters and features applicable to a filter
including the type, operating characteristics, housing configurations, test methods and
performance requirements. The blank detail specification is applicable to any filter design and
quality assessment requirement. The blank detail specification contains the preferred format
for stating the required information in the detail specification.
4.2.2.2 Detail specification
A specific fibre optic filter is described by a corresponding detail specification, which is
prepared by filling in the blanks of the detail specification.
Detail specifications shall specify the following as applicable:
– type (see 4.1.1);
– optic filter style (see 4.1.2);
– variant(s) (see 4.1.3);
– variant identification number(s
...