EN IEC 61753-042-02:2026
(Main)Fibre optic interconnecting devices and passive components - Performance standard - Part 042-02: Plug-pigtail-style and plug-receptacle-style OTDR reflecting devices for category C - Controlled environments
General Information
- Abstract
This part of IEC 61753 contains the minimum initial performance, test and measurement requirements and severities for plug-pigtail style and plug-receptacle style OTDR reflecting devices to meet the requirements of category C-Controlled environments, as specified in Annex A of IEC 61753-1 [1]1. These devices are utilized for out-of-band OTDR testing of an optical fibre system.
Annex B provides information concerning these devices.
- Status
- Published
- Publication Date
- 13-Aug-2026
- Current Stage
- 6060 - Document made available - Publishing
- Start Date
- 14-Aug-2026
- Due Date
- 30-Jun-2026
- Completion Date
- 14-Aug-2026
Overview
EN IEC 61753-042-02:2026 is a European performance standard developed by the International Electrotechnical Commission (IEC) and adopted by CENELEC (CLC). This standard focuses on fibre optic interconnecting devices and passive components, specifically outlining the performance requirements for plug-pigtail-style and plug-receptacle-style OTDR reflecting devices. These devices are intended for operation within category C controlled environments, which typically include equipment rooms or similar settings with regulated temperature and humidity.
Designed to ensure compatibility, interoperability, and reliability, EN IEC 61753-042-02:2026 sets the minimum initial performance, testing, and measurement criteria for OTDR reflecting devices, supporting optical network testing and maintaining system integrity in broadband and telecommunication infrastructures.
Key Topics
Plug-Pigtail & Plug-Receptacle OTDR Reflecting Devices
The standard covers two main form factors:- Plug-pigtail-style: One end with a connector, the other end with an optical fibre tail.
- Plug-receptacle-style: Both ends feature standard connectors or ports.
Performance Testing in Controlled Environments
This standard addresses stringent performance requirements to be met in stable, indoor environments, mapped as Category C in IEC 61753-1.Optical Characteristics
- Attenuation (Insertion Loss)
- Wavelength Isolation (separation between passing and reflecting ranges)
- Return Loss (reflection properties at specific wavelengths)
- Polarization Dependent Loss (PDL)
- High optical power durability
- Mechanical robustness (shock, vibration, mating durability, tensile strength, temperature cycling, humidity tolerance)
Test Methods and Reporting
All specified tests must follow methods from the IEC 61300 series, ensuring consistent, repeatable, and auditable results.Device Structure
Examples of device internal structures include solutions based on chirped fibre Bragg grating (FBG) filters or thin-film filters (TFF), integrated into standard connector assemblies.
Applications
EN IEC 61753-042-02:2026 is highly relevant to manufacturers and operators of fibre optic networks, including:
Broadband and FTTH Networks
OTDR reflecting devices facilitate out-of-band Optical Time-Domain Reflectometer (OTDR) testing, enabling in-service monitoring of fibre optic links without disrupting active data transmission.Telecommunications Infrastructure
Widely used for maintenance and troubleshooting in access, metro, and core networks, these devices help quickly locate faults and characterize connection quality.Controlled Environment Installations
This standard focuses on device performance in controlled settings, ensuring reliability in equipment rooms and data centers where environmental conditions are regulated.Quality Assurance and Compliance
Ensures devices meet rigorous international standards for physical and optical performance, supporting procurement and deployment in global projects.
Related Standards
For full compliance and integration with optical networks, reference these important related standards:
IEC 61300 Series:
Basic test and measurement procedures for fibre optic components.IEC 61754 Series:
Interface standards for fibre optic connectors, ensuring device compatibility.IEC 61753-1:
General performance standard for all fibre optic interconnecting devices and passive components.IEC 60793-2-50:
Product specifications for single-mode optical fibres.IEC TS 62627-09:
Vocabulary for passive optical devices.IEC 62074-1:
Generic specification for fibre optic WDM devices.
Adopting EN IEC 61753-042-02:2026 in your projects ensures robust, consistent, and standards-compliant performance for OTDR reflecting devices, supporting effective network operation, maintenance, and troubleshooting in controlled environments.
Relations
- Effective Date
- 06-Feb-2024
- Effective Date
- 15-Sep-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
- Effective Date
- 28-Jul-2026
Get Certified
Connect with accredited certification bodies for this standard
ANCE
Mexican certification and testing association.
Intertek Slovenia
Intertek testing, inspection, and certification services in Slovenia.
LNE (Laboratoire National de Métrologie et d'Essais)
French national laboratory for metrology and testing.
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Frequently Asked Questions
EN IEC 61753-042-02:2026 is a standard published by CLC. Its full title is "Fibre optic interconnecting devices and passive components - Performance standard - Part 042-02: Plug-pigtail-style and plug-receptacle-style OTDR reflecting devices for category C - Controlled environments". This standard covers: This part of IEC 61753 contains the minimum initial performance, test and measurement requirements and severities for plug-pigtail style and plug-receptacle style OTDR reflecting devices to meet the requirements of category C-Controlled environments, as specified in Annex A of IEC 61753-1 [1]1. These devices are utilized for out-of-band OTDR testing of an optical fibre system. Annex B provides information concerning these devices.
This part of IEC 61753 contains the minimum initial performance, test and measurement requirements and severities for plug-pigtail style and plug-receptacle style OTDR reflecting devices to meet the requirements of category C-Controlled environments, as specified in Annex A of IEC 61753-1 [1]1. These devices are utilized for out-of-band OTDR testing of an optical fibre system. Annex B provides information concerning these devices.
EN IEC 61753-042-02:2026 is classified under the following ICS (International Classification for Standards) categories: 33.180.20 - Fibre optic interconnecting devices. The ICS classification helps identify the subject area and facilitates finding related standards.
EN IEC 61753-042-02:2026 has the following relationships with other standards: It is inter standard links to EN 61753-042-2:2014, EN IEC 61300-2-2:2026, EN IEC 61300-1:2022/A2:2026, EN IEC 61300-2-6:2024, EN 61300-2-2:2009, EN IEC 61300-2-5:2022, EN IEC 61300-1:2022, EN IEC 60793-2-50:2025, EN IEC 61300-2-4:2019, EN IEC 61300-2-1:2023, EN IEC 61300-2-18:2023, EN IEC 61300-1:2022/A1:2024, EN IEC 61300-2-14:2021, EN 61300-2-9:2017, EN 61300-2-17:2011. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN IEC 61753-042-02:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2026
Nadomešča:
SIST EN 61753-042-2:2015
Optični spojni elementi in pasivne komponente - Tehnični standard - 042-2. del:
Odsevne naprave OTDR vrste vtič-repek in vtič-vtičnica za kategorijo C -
Nadzorovana okolja (IEC 61753-042-02:2026)
Fibre optic interconnecting devices and passive components - Performance standard -
Part 042-02: Plug-pigtail-style and plug-receptacle-style OTDR reflecting devices for
category C - Controlled environments (IEC 61753-042-02:2026)
Lichtwellenleiter-Verbindungseinrichtungen und passive Bauelemente -
Betriebsverhalten – Teil 042-02: OTDR-Reflektorbauteile in Steckverbinder-Pigtail- und
Steckverbinder-Buchse-Bauform für die Kategorie C – Kontrollierte Umgebung (IEC
61753-042-02:2026)
Dispositifs d'interconnexion et composants passifs à fibres optiques - Norme de
performance - Partie 042-2: Dispositifs de réflexion pour OTDR de modèle à fiche-fibre
amorce et modèle à fiche-embase pour catégorie c - Environnements contrôlés (IEC
61753-042-02:2026)
Ta slovenski standard je istoveten z: EN IEC 61753-042-02:2026
ICS:
33.180.20 Povezovalne naprave za Fibre optic interconnecting
optična vlakna devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 61753-042-02
NORME EUROPÉENNE
EUROPÄISCHE NORM August 2026
ICS 33.180.20 Supersedes EN 61753-042-2:2014
English Version
Fibre optic interconnecting devices and passive components -
Performance standard - Part 042-02: Plug-pigtail-style and plug-
receptacle-style OTDR reflecting devices for category C -
Controlled environments
(IEC 61753-042-02:2026)
Dispositifs d'interconnexion et composants passifs Lichtwellenleiter-Verbindungseinrichtungen und passive
fibroniques - Norme de performance - Partie 042-02: Bauelemente - Betriebsverhalten - Teil 042-02: OTDR-
Dispositifs de réflexion pour OTDR de modèle à fiche-fibre Reflektorbauteile in Steckverbinder-Pigtail- und
amorce et modèle à fiche-embase pour catégorie C - Steckverbinder-Buchse-Bauform für die Kategorie C -
Environnements contrôlés Kontrollierte Umgebung
(IEC 61753-042-02:2026) (IEC 61753-042-02:2026)
This European Standard was approved by CENELEC on 2026-07-22. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61753-042-02:2026 E
European foreword
The text of document 86B/5220/FDIS, future edition 1 of IEC 61753-042-02, prepared by SC 86B
"Fibre optic interconnecting devices and passive components" of IEC/TC 86 "Fibre optics" was
submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN IEC 61753-042-
02:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-08-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2027-08-31
document have to be withdrawn
This document supersedes EN 61753-042-2:2014 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61753-042-02:2026 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 61753-1:2018 NOTE Approved as EN IEC 61753-1:2018 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60793-2-50 - Optical fibres - Part 2-50: Product EN IEC 60793-2-50 -
specifications - Sectional specification for
class B single-mode fibres
IEC 61300 series Fibre optic interconnecting devices and EN IEC 61300 series
passive components - Basic test and
measurement procedures
IEC 61300-1 - Fibre optic interconnecting devices and EN IEC 61300-1 -
passive components - Basic test and
measurement procedures - Part 1: General
and guidance
IEC 61300-2-1 - Fibre optic interconnecting devices and EN IEC 61300-2-1 -
passive components - Basic test and
measurement procedures - Part 2-1: Tests -
Vibration (sinusoidal)
IEC 61300-2-2 - Fibre optic interconnecting devices and EN 61300-2-2 -
passive components - Basic test and
measurement procedures - Part 2-2: Tests -
Mating durability
IEC 61300-2-4 - Fibre optic interconnecting devices and EN IEC 61300-2-4 -
passive components - Basic test and
measurement procedures - Part 2-4: Tests -
Fibre or cable retention
IEC 61300-2-5 - Fibre optic interconnecting devices and EN IEC 61300-2-5 -
passive components - Basic test and
measurement procedures - Part 2-5: Tests -
Torsion
IEC 61300-2-6 - Fibre optic interconnecting devices and EN IEC 61300-2-6 -
passive components - Basic test and
measurement procedures - Part 2-6: Tests -
Tensile strength of coupling mechanism
IEC 61300-2-9 - Fibre optic interconnecting devices and EN 61300-2-9 -
passive components - Basic test and
measurement procedures - Part 2-9: Tests -
Shock
Publication Year Title EN/HD Year
IEC 61300-2-14 - Fibre optic interconnecting devices and EN IEC 61300-2-14 -
passive components - Basic test and
measurement procedures - Part 2-14: Tests
- High optical power
IEC 61300-2-17 - Fibre optic interconnecting devices and EN 61300-2-17 -
passive components - Basic test and
measurement procedures - Part 2-17: Tests
- Cold
IEC 61300-2-18 - Fibre optic interconnecting devices and EN IEC 61300-2-18 -
passive components - Basic test and
measurement procedures - Part 2-18: Tests
- Dry heat
IEC 61753-042-02 ®
Edition 1.0 2026-06
INTERNATIONAL
STANDARD
Fibre optic interconnecting devices and passive components - Performance
standard -
Part 042-02: Plug-pigtail-style and plug-receptacle-style OTDR reflecting devices
for category C - Controlled environments
ICS 33.180.20 ISBN 978-2-8327-1310-5
IEC 61753-042-02:2026-06(en)
IEC 61753-042-02:2026 © IEC 2026
CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms, definitions and abbreviated terms . 5
3.1 Terms and definitions . 5
3.2 Abbreviated terms. 6
4 Test . 6
5 Test report . 6
6 Performance requirements . 6
6.1 Reference components. 6
6.2 Dimensions . 6
6.3 Sample size . 6
6.4 Test details and requirements . 7
Annex A (normative) Sample size . 14
Annex B (informative) General information of OTDR reflecting devices . 15
Bibliography . 16
Figure B.1 – Examples of structure of an OTDR reflecting device . 15
Figure B.2 – Examples of an OTDR reflecting device . 15
Table 1 – Test details and requirements for plug-pigtail style . 7
Table 2 – Test details and requirements for plug-receptacle style . 11
Table A.1 – Number of plug-pigtail style samples for each test . 14
Table A.2 – Number of plug-receptacle style samples for each test . 14
IEC 61753-042-02:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Fibre optic interconnecting devices and
passive components - Performance standard -
Part 042-02: Plug-pigtail-style and plug-receptacle-style OTDR reflecting
devices for category C - Controlled environments
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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61753-042-02 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 the first edition of IEC 61753-042-2, published in 2014,
and constitutes a technical revision.
This edition includes the following significant technical changes with respect to
IEC 61753-042-2:
a) harmonization of test requirements with the requirements specified in IEC 61753-1:2018
IEC 61753-042-02:2026 © IEC 2026
The text of this International Standard is based on the following documents:
Draft Report on voting
86B/5520/FDIS 86B/5242/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of IEC 61753 series, under the general title Fibre optic interconnecting devices
and passive components - Performance standard, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 61753-042-02:2026 © IEC 2026
1 Scope
This part of IEC 61753 contains the minimum initial performance, test and measurement
requirements and severities for plug-pigtail style and plug-receptacle style OTDR reflecting
devices to meet the requirements of category C-Controlled environments, as specified in
Annex A of IEC 61753-1 [1] . These devices are utilized for out-of-band OTDR testing of an
optical fibre system.
Annex B provides information concerning these devices.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60793-2-50, Optical fibres - Part 2-50: Product specifications - Sectional specification for
class B single-mode fibres
IEC 61300 (all parts), Fibre optic interconnecting devices and passive components - Basic test
and measurement procedures
IEC 61300-1, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 1: General and guidance
IEC 61300-2-1, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-1: Tests - Vibration (sinusoidal)
IEC 61300-2-2, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-2: Tests - Mating durability
IEC 61300-2-4, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-4: Tests–Fibre or cable retention
IEC 61300-2-5, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-5: Tests - Torsion
IEC 61300-2-6, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-6: Tests - Tensile strength of coupling mechanism
IEC 61300-2-9, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-9: Tests - Shock
IEC 61300-2-14, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-14: Tests - High optical power
IEC 61300-2-17, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-17: Tests - Cold
IEC 61300-2-18, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-18: Tests - Dry heat
___________
Numbers in square brackets refer to the Bibliography.
IEC 61753-042-02:2026 © IEC 2026
IEC 61300-2-19, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-19: Tests - Damp heat (steady state)
IEC 61300-2-22, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-22: Tests - Change of temperature
IEC 61300-2-42, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-42: Tests - Static side load for strain relief
IEC 61300-2-44, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 2-44: Tests - Flexing of the strain relief of fibre optic devices
IEC 61300-3-2, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-2: Examination and measurements - Polarization dependent
loss in a single-mode fibre optic device
IEC 61300-3-6, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-6: Examination and measurements - Return loss
IEC 61300-3-7, Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-7: Examination and measurements - Wavelength
dependence of attenuation and return loss of single mode components
IEC 62074-1, Fibre optic interconnecting devices and passive components - Fibre optic WDM
devices - Part 1: Generic specification
IEC TS 62627-09, Fibre optic interconnecting devices and passive components - Vocabulary
for passive optical devices
3 Terms, definitions and abbreviated terms
For the purposes of this document, the terms and definitions given in IEC 62074-1 and
IEC TS 62627-09 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Terms and definitions
3.1.1
OTDR reflecting device
optical filter that has two ports in which light in the signal wavelength ranges transmits from the
first port to the second port and OTDR light in the OTDR wavelength range launched into one
port is (partly) reflected back to that launch port
Note 1 to entry: It is used for out of band testing of optical fibre systems.
3.1.2
passband wavelength range
the wavelength ranges of 1 260 nm to 1 360 nm, 1 480 nm to 1 500 nm and 1 550 nm to
1 560 nm
SIST EN I
...