EN IEC 61300-3-7:2021

Fibre optic interconnecting devices and passive components - Basic test and measurement procedures - Part 3-7: Examinations and measurements - Wavelength dependence of attenuation and return loss of single mode components

This part of IEC 61300-3 describes methods available to measure the wavelength dependence of attenuation and return loss of two port, single mode passive optical components. It is not, however, applicable to dense wavelength division multiplexing (DWDM) devices. Measurement methods of wavelength dependence of attenuation of DWDM devices are described in IEC 61300-3-29. There are two measurement cases described in this standard: a) Measurement of attenuation only; b) Measurement of attenuation and return loss at the same time.

Lichtwellenleiter - Verbindungselemente und passive Bauteile - Grundlegende Prüf- und Messverfahren - Teil 3-7: Untersuchungen und Messungen - Wellenlängenabhängigkeit von Dämpfung und Rückflussdämpfung von Einmodenbauteilen

Dispositifs d’interconnexion et composants passifs a fibres optiques - Méthodes fondamentales d'essais et de mesures - Partie 3-7: Examens et mesurages - Affaiblissement et affaiblissement de réflexion des composants unimodaux en fonction de la longueur d’onde

IEC 61300-3-7:2021 décrit les méthodes disponibles de mesure de l’affaiblissement et de l’affaiblissement de réflexion des composants optiques passifs unimodaux à deux ports en fonction de la longueur d'onde. Elle n’est toutefois pas applicable aux dispositifs de multiplexage par répartition en longueurs d'onde à forte densité (DWDM_dense wavelength division multiplexing). Les méthodes de mesure de l’affaiblissement des dispositifs DWDM en fonction de la longueur d'onde sont décrites dans l’IEC 61300-3-29. Le présent document décrit deux cas de mesure: a) mesurage de l’affaiblissement uniquement; b) mesurage simultané de l’affaiblissement et de l’affaiblissement de réflexion. Cette troisième édition annule et remplace la deuxième édition parue en 2009. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) réduction du nombre de méthodes alternatives proposées afin de les rendre conformes à la pratique industrielle; b) nouvel énoncé des équations relatives à la perte d’insertion et à l’affaiblissement de réflexion utilisant des formes logarithmiques plus courantes dans le secteur de l’industrie; c) recommandations supplémentaires concernant la création de terminaisons de fibres; d) analyse complémentaire de la caractérisation des sources optiques utilisées dans la présente norme; d) simplification des essais bidirectionnels; e) suppression de procédures de mesure distinctes par affaiblissement de réflexion uniquement.

Naprave za spajanje optičnih vlaken in pasivne komponente - Postopki osnovnega preskušanja in merjenja - 3-7. del: Preiskave in meritve - Odvisnost valovne dolžine od slabljenja in povratne izgube enorodovnih komponent (IEC 61300-3-7:2021)

General Information

• Status: Published
• Publication Date: 26-Aug-2021
• Withdrawal Date: 10-Aug-2022
• ICS: 33.180.20 - Fibre optic interconnecting devices
• Technical Committee: CLC/TC 86BXA - Fibre optic interconnect, passive and connectorised components
• Drafting Committee: IEC/SC 86B - IEC_SC_86B
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 27-Aug-2021
• Completion Date: 27-Aug-2021
• Ref Project: SIST EN IEC 61300-3-7:2021 - Fibre optic interconnecting devices and passive components - Basic test and measurement procedures - Part 3-7: Examinations and measurements - Wavelength dependence of attenuation and return loss of single mode components (IEC 61300-3-7:2021)

Relations

• Replaces: EN 61300-3-7:2012 - Fibre optic interconnecting devices and passive components - Basic test and measurement procedures - Part 3-7: Examinations and measurements - Wavelength dependence of attenuation and return loss of single mode components
• Effective Date: 31-Aug-2021
• Amended By: EN IEC 61300-3-7:2021/prA1:2024 - Fibre optic interconnecting devices and passive components - Basic test and measurement procedures - Part 3-7: Examinations and measurements - Wavelength dependence of attenuation and return loss of single mode components
• Effective Date: 02-Jul-2024

Overview

EN IEC 61300-3-7:2021 specifies standardized methods to measure the wavelength dependence of attenuation and return loss for two‑port, single‑mode passive optical components. Published by CLC/CENELEC and aligned with IEC 61300-3-7:2021, this test procedure standard defines measurement cases for (a) attenuation only and (b) attenuation and return loss simultaneously. It applies to general single‑mode components but is not applicable to DWDM devices (see IEC 61300-3-29 for DWDM measurement methods).

Key topics and technical requirements

• Measurement scope: Two-port single‑mode passive components (connectors, splices, simple passive assemblies).
• Measurement cases:
  • Attenuation vs wavelength (attenuation-only).
  • Attenuation and return loss vs wavelength (combined measurement).
• Accepted methods: Three principal source/detector approaches are defined:
  • Method A - Broadband light source (BBS) with spectral detection.
  • Method B - Tuneable narrowband light source (TNLS / TLS).
  • Method C - Set of discrete narrowband light sources (NLS).
• Required apparatus: Depolarizer, optical power meter or optical spectrum analyzer (TND/BBD detection options), branching device, terminations, temporary joint, test patch cords, reference plugs and adapters.
• Test procedure details: Reference measurements, system background, DUT mounting, wavelength sweep or discrete wavelength steps, and reporting of system parameters and uncertainties.
• Reporting: Detailed test conditions to be recorded - source type, detection method, depolarizer usage, reference adapters, termination values and full wavelength‑dependent results.

Practical applications

• Verifying spectral loss profiles of single‑mode connectors, passive splitters, filters and assemblies.
• Ensuring component performance across telecom wavelengths for manufacturers’ quality control and R&D.
• Acceptance and qualification testing in production and independent test labs.
• Supporting system designers and installers who need component attenuation and return‑loss behavior across wavelength for link budgeting and optical performance validation.

Who should use this standard

• Fibre optic component manufacturers (QA, R&D).
• Calibration and independent test laboratories.
• Network equipment vendors and system integrators assessing component compatibility.
• Standards and compliance engineers implementing test procedures for single‑mode passive components.

Related standards

• IEC 61300-3-29 (wavelength dependence for DWDM devices)
• IEC 60793-2-50 (single‑mode fibre specs)
• IEC 61755-2-4 / 61755-2-5 (connector reference interfaces)
• IEC 62074-1 (fibre optic WDM devices)

Keywords: EN IEC 61300-3-7:2021, wavelength dependence, attenuation, return loss, single mode components, fibre optic measurement procedures, broadband light source, tuneable laser, optical power meter, test methods.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2021
Nadomešča:
SIST EN 61300-3-7:2012
Naprave za spajanje optičnih vlaken in pasivne komponente - Postopki osnovnega
preskušanja in merjenja - 3-7. del: Preiskave in meritve - Odvisnost valovne
dolžine od slabljenja in povratne izgube enorodovnih komponent (IEC 61300-3-
7:2021)
Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-7: Examinations and measurements - Wavelength
dependence of attenuation and return loss of single mode components (IEC 61300-3-
7:2021)
Lichtwellenleiter - Verbindungselemente und passive Bauteile - Grundlegende Prüf- und
Messverfahren - Teil 3-7: Untersuchungen und Messungen - Wellenlängenabhängigkeit
von Dämpfung und Rückflussdämpfung von Einmodenbauteilen (IEC 61300-3-7:2021)
Dispositifs d’interconnexion et composants passifs a fibres optiques - Méthodes
fondamentales d'essais et de mesures - Partie 3-7: Examens et mesurages -
Affaiblissement et affaiblissement de réflexion des composants unimodaux en fonction
de la longueur d’onde (IEC 61300-3-7:2021)
Ta slovenski standard je istoveten z: EN IEC 61300-3-7:2021
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 61300-3-7

NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2021
ICS 33.180.20 Supersedes EN 61300-3-7:2012 and all of its
amendments and corrigenda (if any)
English Version
Fibre optic interconnecting devices and passive components -
Basic test and measurement procedures - Part 3-7:
Examinations and measurements - Wavelength dependence of
attenuation and return loss of single mode components
(IEC 61300-3-7:2021)
Dispositifs d'interconnexion et composants passifs a fibres Lichtwellenleiter - Verbindungselemente und passive
optiques - Méthodes fondamentales d'essais et de mesures Bauteile - Grundlegende Prüf- und Messverfahren - Teil 3-
- Partie 3-7: Examens et mesurages - Affaiblissement et 7: Untersuchungen und Messungen -
affaiblissement de réflexion des composants unimodaux en Wellenlängenabhängigkeit von Dämpfung und
fonction de la longueur d'onde Rückflussdämpfung von Einmodenbauteilen
(IEC 61300-3-7:2021) (IEC 61300-3-7:2021)
This European Standard was approved by CENELEC on 2021-08-11. 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,
Turkey 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
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61300-3-7:2021 E

European foreword
The text of document 86B/4337/CDV, future edition 3 of IEC 61300-3-7, 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 61300-3-7:2021.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022–08–11
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022–08–11
document have to be withdrawn
This document supersedes EN 61300-3-7:2012 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 61300-3-7:2021 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 61300-3-4 NOTE Harmonized as EN 61300-3-4
IEC 61300-3-6 NOTE Harmonized as EN 61300-3-6
IEC 61300-3-29 NOTE Harmonized as EN 61300-3-29
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.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-731 - International Electrotechnical Vocabulary - -
(IEV) - Part 731: Optical fibre
communication
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 61755-2-4 - Fibre optic interconnecting devices and EN 61755-2-4 -
passive components - Connector optical
interfaces - Part 2–4: Connection
parameters of non-dispersion shifted
single-mode physically contacting fibres -
Non-angled for reference connection
applications
IEC 61755-2-5 - Fibre optic interconnecting devices and EN 61755-2-5 -
passive components - Connector optical
interfaces - Part 2–5: Connection
parameters of non-dispersion shifted
single-mode physically contacting fibres -
Angled for reference connection
applications
IEC/TR 61931 - Fibre optic - Terminology - -
IEC 62074-1 - Fibre optic interconnecting devices and EN 62074-1 -
passive components - Fibre optic WDM
devices - Part 1: Generic specification

IEC 61300-3-7 ®
Edition 3.0 2021-07
INTERNATIONAL
STANDARD
Fibre optic interconnecting devices and passive components – Basic test and

measurement procedures –
Part 3-7: Examinations and measurements – Wavelength dependence of

attenuation and return loss of single mode components

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.20 ISBN 978-2-8322-9989-0

– 2 – IEC 61300-3-7:2021 © IEC 2021
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, abbreviated terms and quantity symbols . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
3.3 Quantity symbols . 9
4 General description . 9
4.1 General . 9
4.2 Light source and detector conditions . 9
4.3 General explanation of attenuation and return loss . 10
4.3.1 Attenuation . 10
4.3.2 Return loss . 10
4.4 Device under test (DUT) . 11
4.5 Measurement methods . 12
5 Apparatus . 12
5.1 General . 12
5.2 Optical source . 13
5.2.1 Method A – Broadband light source (BBS) . 13
5.2.2 Method B – Tuneable narrowband light source (TNLS) . 13
5.2.3 Method C – Set of multiple fixed narrowband light sources (NLS) . 13
5.3 Depolarizer . 13
5.4 Power detection systems . 14
5.4.1 Method A – Tuneable narrowband detection (TND) . 14
5.4.2 Method B and C – Broadband detection (BBD) . 14
5.5 Branching device (BD) . 15
5.6 Termination . 15
5.7 Temporary joint (TJ) . 15
5.8 Test patch cord . 15
5.9 Reference plugs (RP). 16
5.10 Reference adapters (RA) . 16
6 Procedure . 16
6.1 Method A – Broadband light source . 16
6.1.1 Method A1 – Attenuation only . 16
6.1.2 Method A2 – Attenuation and return loss . 17
6.2 Method B – Tuneable narrowband light source . 20
6.2.1 General . 20
6.2.2 Method B – Attenuation only . 21
6.2.3 Method B – Attenuation and return loss . 21
6.3 Method C – Set of multiple fixed narrowband light sources . 22
6.3.1 General . 22
6.3.2 Method C1 – Attenuation only . 22
6.3.3 Method C2 – Attenuation and return loss . 22
7 Test results . 23

IEC 61300-3-7:2021 © IEC 2021 – 3 –
8 Details to be reported . 23
8.1 General . 23
8.2 Total measurement system . 24
8.3 Source . 24
8.3.1 Broadband light source . 24
8.3.2 Tuneable or discrete narrowband light source . 24
8.3.3 Depolarizer . 24
8.4 Detection system . 24
8.4.1 Optical power meter. 24
8.4.2 Optical spectrum analyzer . 24
8.4.3 Branching device . 25
8.4.4 Termination . 25
8.4.5 Temporary joint . 25
8.4.6 Reference plug . 25
8.4.7 Reference adapter . 25
Annex A (informative) Types of passive optical components . 26
Annex B (informative) Typical light source characteristics . 27
B.1 General . 27
B.2 Broadband light source . 27
B.3 Tuneable laser source . 27
Annex C (informative) Terminations . 29
Bibliography . 31

Figure 1 – Generic explanation of attenuation and return loss . 11
Figure 2 – Method A1, attenuation-only, reference measurement set-up . 16
Figure 3 – Method A1, attenuation-only, DUT measurement set-up . 17
Figure 4 – Method A2, attenuation and return loss, reference branching device
measurement set-up . 18
Figure 5 – Method A2, attenuation and return loss, reference measurement set-up. 18
Figure 6 – Method A2, system background measurement set-up . 19
Figure 7 – Method A2, attenuation and return loss, DUT measurement set-up . 20
Figure 8 – Method B, tuneable narrowband light source with and without depolarizer . 21
Figure 9 – Method C, multiple fixed narrowband sources set-up . 22
Figure 10 – Example wavelength dependent attenuation plot . 23

Table 1 – Device under test categories . 11
Table 2 – Measurement methods . 12
Table 3 – Reference test methods . 12
Table 4 – Preferred OPM parameters . 15
Table 5 – Steps of method A1, attenuation only . 16
Table 6 – Steps of method A2, attenuation and return loss . 17
Table 7 – Steps of method B, attenuation only . 21
Table 8 – Steps of method B, attenuation and return loss . 21
Table 9 – Steps of method C, attenuation only . 22
Table 10 – Steps of method C2, attenuation and return loss . 22

– 4 – IEC 61300-3-7:2021 © IEC 2021
Table 11 – Example report for wavelength dependent attenuation and return loss . 23
Table A.1 – Functional summary of common passive optical components . 26
Table B.1 – Types of broadband light source (BBS) and main characteristics . 27
Table B.2 – Types of tuneable light source (TLS) and main characteristics . 28
Table C.1 – Impact on termination values on measured return loss . 29
Table C.2 – Impact on termination values on measured return loss uncertainty . 30

IEC 61300-3-7:2021 © IEC 2021 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-7: Examinations and measurements – Wavelength dependence
of attenuation and return loss of single mode components

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.
IEC 61300-3-7 has been prepared by subcommittee 86B: Fibre optic interconnecting devices
and passive components, of IEC technical committee 86: Fibre optics. It is an International
Standard.
This third edition cancels and replaces the second edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) reduction of the number of alternative methods proposed to bring in-line with industry
practice;
b) re-statement of the equations for insertion loss and return loss using logarithmic forms more
common in the industry;
c) additional recommendations with respect to the creation of fibre terminations;

– 6 – IEC 61300-3-7:2021 © IEC 2021
d) additional discussion on the characterization of the optical sources used in this document;
e) simplification of bi-directional testing;
f) removal of separate return loss only measurement procedures.
The text of this International Standard is based on the following documents:
Draft Report on voting
86B/4337/CDV 86B/4425A/RVC
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/standardsdev/publications.
A list of all parts in the IEC 61300 series, published under the general title Fibre optic
interconnecting devices and passive components – Basic test and measurement procedures,
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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC 61300-3-7:2021 © IEC 2021 – 7 –
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-7: Examinations and measurements – Wavelength dependence
of attenuation and return loss of single mode components

1 Scope
This part of IEC 61300-3 describes methods available to measure the wavelength dependence
of attenuation and return loss of two-port, single mode passive optical components. It is not,
however, applicable to dense wavelength division multiplexing (DWDM) devices. Measurement
methods of wavelength dependence of attenuation of DWDM devices are described in
IEC 61300-3-29.
There are two measurement cases described in this document:
a) measurement of attenuation only;
b) measurement of attenuation and return loss at the same time.
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 60050-731, International Electrotechnical Vocabulary (IEV) – Part 731: Optical fibre
communication (available at www.electropedia.org)
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 61755-2-4, Fibre optic interconnecting devices and passive components – Connector
optical interfaces – Part 2-4: Connection parameters of non-dispersion shifted single-mode
physically contacting fibres – Non-angled for reference connection applications
IEC 61755-2-5, Fibre optic interconnecting devices and passive components – Connector
optical interfaces – Part 2-5: Connection parameters of non-dispersion shifted single-mode
physically contacting fibres – Angled for reference connection applications
IEC TR 61931, Fibre optic – Terminology
IEC 62074-1, Fibre optic interconnecting devices and passive components – Fibre optic WDM
devices – Part 1: Generic specification
3 Terms, definitions, abbreviated terms and quantity symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-731, IEC TR
61931 and IEC 62074-1 apply.
– 8 – IEC 61300-3-7:2021 © IEC 2021
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp.
3.2 Abbreviated terms
APC angled physical contact
ASE amplified spontaneous emission
BBD broadband detector
BBS  broadband light source
BD  branching device
BPON broadband passive optical network
CC  coherent control
CWDM coarse wavelength division multiplexing
DFB distributed feedback
DOP degree of polarization
DUT device under test
DWDM dense wavelength division multiplexing
ECL  external cavity laser
EDFA erbium doped fibre amplifier
EDFL erbium doped fibre laser
EPON ethernet passive optical network
FBG fibre Bragg grating
FEC forward error correction
FP  Fabry-Perot
GPON gigabit Ethernet passive optical network
IR  infra-red
LD  laser diode
LED light emitting diode
NLS narrow band light source
OADM optical add drop multiplexer
OFA optical fibre amplifier
OPM optical power meter
OSA optical spectrum analyzer
PDL  polarization dependent loss
PON  passive optical network
RA  reference adapter
RBD reference branching device
RBW resolution bandwidth
RL  return loss
RP  reference plug
RTM reference test method
SLED super light emitting diode
SMSR side mode suppression ratio

IEC 61300-3-7:2021 © IEC 2021 – 9 –
SOP state of polarization
SSE source spontaneous emission
TJ  temporary joint
TLS tuneable laser source
TND tuneable narrow band detection
TNLS tuneable narrow band light source
UV  ultra violet
WDM wave division multiplexing
3.3 Quantity symbols
array of n (k = 1 to n) wavelengths to be measured, expressed in nm
λ
k
th
P (λ ) input optical power to the device under test (DUT) of the k wavelength to be
i k
measured, expressed in dBm
th
P (λ ) output optical power from the output port of the DUT of the k wavelength to be
t k
measured, expressed in dBm
P (λ ) output optical power at the input port of the DUT propagating away from the input
r k
th
port of the k wavelength to be measured, expressed in dBm
P ′(λ ) output optical power at the branching port of the reference branching device (RBD)
r k
th
propagating away from the input port of the RBD of the k wavelength to be
measured, expressed in dBm
th
A(λ ) attenuation of the DUT at k wavelength, expressed in dB
k
th
RL(λ ) return loss of the DUT at k wavelength, expressed in dB
k
th
RL*(λ ) calculated return loss of the DUT at k wavelength corrected for measurement
k
apparatus RL, expressed in dB
th
(λ ) return loss of the measurement apparatus at k wavelength, expressed in dB
RL
0 k
4 General description
4.1 General
Attenuation, A(λ ), is the relative decrease of transmitted optical power due to the insertion or
k
addition of a component within a fibre-optic system. Return loss, RL(λ ), is the relative optical
k
power reflected from a component inserted within a fibre-optic system. A(λ ) and RL(λ ) are
k k
expressed in decibels (dB) and are obtained by comparing the optical power incident on the
DUT with the optical powers transmitted or reflected at the ports of the DUT. These terms are
defined in IEC TR 61931.
4.2 Light source and detector conditions
A(λ ) and RL(λ ) are measured over a wavelength range defined by the DUT specifications. The
k k
spectral properties of the measurement system should be selected for the measurement of the
attenuation performance specification of the DUT. These properties should include:
• wavelength setting resolution (wavelength difference between two adjacent data points);
• wavelength setting uncertainty;
• 3 dB spectral bandwidth of the light source or the tuneable narrowband detector (TND);
• source spontaneous emission (SSE) noise floor relative to peak power for the light source;
• degree of polarization (DOP).

– 10 – IEC 61300-3-7:2021 © IEC 2021
The following performance guidelines shall be followed.
– The wavelength setting resolution shall be less than half the smallest resolvable attenuation
feature. For example, when the attenuation changes over 1 nm the wavelength resolution
shall be less than 0,5 nm.
– The 3 dB spectral bandwidth for the light source or the TND shall be less than half the
wavelength resolution of the measurement.
– When the DOP of the source is more than 5 %, the polarization dependence of the detection
system shall be considered as part of the total insertion loss uncertainty.
The impact of the source SSE noise floor on the uncertainty of the measurement depends
strongly on the wavelength dependence of the DUT. For CWDM components, this shall be
considered. The total ASE power over the measurement range limits the dynamic range of the
measurement.
Additional information can be found in Annex B.
4.3 General explanation of attenuation and return loss
4.3.1 Attenuation
), is the relative optical power reduction caused by the insertion of the DUT
Attenuation, A(λ
k
into an optical path and is illustrated in Figure 1. It is a function of wavelength. It is expressed
as shown in Formula (1):
A λ Pλ−P λ dB)
( ) ( ) ( ) (1)
k itkk
where
P (λ ) is the optical power, as a function of wavelength, incident on and measured at the input
i k
port of the DUT, expressed in dBm;
P (λ ) is the optical power, as a function of wavelength, transmitted through and measured at
t k
the output port of the DUT, expressed in dBm.
4.3.2 Return loss
Return loss, RL(λ ) is the optical power reflected by the DUT relative to the incident power. It is
k
a function of wavelength and is illustrated in Figure 1. It is expressed as shown in Formula (2):
RL λ Pλ−P λ  (dB)
( ) ( ) ( ) (2)
kkkir
where
P (λ ) is the optical power, as a function of wavelength, incident on and measured at the input
i k
port of the DUT, expressed in dBm;
P (λ ) is the optical power, as a function of wavelength, reflected by and measured from the
r k
input port of the DUT, expressed in dBm.
=
=
IEC 61300-3-7:2021 © IEC 2021 – 11 –

Figure 1 – Generic explanation of attenuation and return loss
4.4 Device under test (DUT)
The DUT may have more than two ports. Only two ports are relevant for attenuation testing
(input and output port) and only one is relevant for return loss testing (input port). It is not a
requirement to measure attenuation and return loss at the same time.
Eight two-port DUT configurations are described in Table 1. Port connections may consist of
bare fibre, connector plug, or receptacle. IEC 61300-3-4 describes multiple connection methods
in detail. This document focuses on type 4 and type 7. If a multiport DUT is to be measured,
all unused ports shall be terminated. For additional details, refer to Annex C.
A summary of the applicable DUT can be found in Annex A.
Table 1 – Device under test categories
Type Description DUT
Fibre to fibre
(component)
Fibre to fibre
2 (splice or field-mountable connector
set)
3 Fibre to plug
Plug to plug
(component)
Plug to plug
(patchcord)
Single plug
(pigtail)
Receptacle to receptacle
(component)
Receptacle to plug
(component)
Key
C: optical component
NOTE Type 1 can be measured using a temporary joint replacing optical
connectors.
– 12 – IEC 61300-3-7:2021 © IEC 2021
4.5 Measurement methods
The following measurement configurations are defined in Table 2. The applicable reference test
method (RTM) is shown in Table 3.
Table 2 – Measurement methods
Detection
Method Name Light source Example
system
A Broadband light source BBS TND BBS + DUT + OSA
Tuneable narrow band light
B TNLS BBD TLS + DUT + OPM
source
Set of multiple fixed narrow
C NLS BBD N x DFB-LD + DUT + OPM
band light sources
Table 3 – Reference test methods
Resolution bandwidth Wavelength band RTM Alternative
(RBW)
< 0,1 nm Any Method B Method A
≥ 0,1 nm C-band and L-band Method B Method A, method C
≥ 0,1 nm Not C-band and L-band Method A Method B, method C

a) Method A – Broadband light source (BBS)
In method A, a broadband light source (BBS) is used with a tuneable narrowband detector
(TND). A common implementation is to use an optical spectrum analyzer (OSA) for the TND.
In this implementation, the OSA controls the wavelength range, the measurement
wavelength and resolution bandwidth. The optical power and bandwidth of the BBS shall be
large enough to cover the attenuation of the DUT and the power measurement dynamic
range of the OSA.
b) Method B – Tuneable narrowband light source (TNLS)
In method B, a tuneable narrowband light source (TNLS) is used with a broadband detection
system (BBD). The most likely implementation of method B is the use of a tuneable laser
source (TLS) with an optical power meter (OPM). In this method, the TLS controls the
wavelength range, the measurement wavelength and resolution bandwidth. Given the
narrow linewidth and high DOP, care shall be taken to minimize the test system background
return loss. This will help to avoid coherent interference in the power measurement.
c) Method C – Set of multiple fixed narrowband light sources (NLS)
In method C, a set of narrowband light sources are used with a broadband detector (BBD).
This method is suitable for a DUT which has a small wavelength dependent loss and is
specified for operation over a wide wavelength range. A common implementation of
method C is the use of a set of fixed laser sources with an N x 1 optical branching device or
optical switch. The use of a switch prevents the need to turn off the light sources not in use.
This can reduce the time needed for laser power stabilization. An OPM is typically used as
the BBD.
5 Apparatus
5.1 General
All methods share a common basic setup:
• optical source;
• source depolarizer (optional);

IEC 61300-3-7:2021 © IEC 2021 – 13 –
• return path branching device (for RL measurement);
• temporary joint (TJ);
• fibre;
• reference plug (RP);
• reference adapter (RA);
• termination (for RL measurement);
• power detection system.
5.2 Optical source
5.2.1 Method A – Broadband light source (BBS)
A BBS is used for the source in method A. The BBS emits light over a continuous wavelength
range with various characteristics depending on its type. Examples of a BBS are a white light
source (i.e. tungsten lamp), a light emitting diode (LED), a super-luminescent LED (SLED) or
an optical fibre amplifier (OFA) without an input optical signal.
The wavelength range shall be wide enough to cover the entire specified DUT wavelength
operating range. The output power shall be high enough for A(λ ) and RL(λ ) to be measured.
k k
The spectral power density instability shall be smaller than ±0,05 dB as observed for at least
30 min.
5.2.2 Method B – Tuneable narrowband light source (TNLS)
A TNLS emits a narrow spectrum of light that can be spectrally tuned over the specified
wavelength range. There are various characteristics depending on its type. Examples of
applicable TNLS technologies are a BBS with a tuneable filter, an external cavity tuneable laser,
a tuneable DFB laser diode and a tuneable erbium-doped fibre laser. The wavelength accuracy
and spectral bandwidth shall be specified. Typical values are provided in Annex B.
5.2.3 Method C – Set of multiple fixed narrowband light sources (NLS)
Method C is based on a set of N discrete wavelengths. The wavelengths may be emitted by
sources such as a Fabry-Perot (FP) laser diode (LD) or distributed feedback (DFB) LD.
The set of NLS shall cover the specified wavelength range to be measured. When using a N × 1
fibre optic branching device or fibre optic switch, N is equal to the number of wavelengths to be
measured and NLS used.
When a TLS is used as the NLS, the requirement for a TLS is same as that for a NLS.
5.3 Depolarizer
The measurement results [A(λ ) and RL(λ )] shall be averaged as a function of the state of
k k
polarization (SOP). Sources based on lasers will be highly polarized (DOP is nearly equal to
100 %) while sources like LED and BBS will be highly depolarized (DOP is less than 5 %). For
sources with high DOP, a depolarizer will be required. The depolarizer shall reduce the DOP to
< 5 %.
There are two approaches for obtaining the polarization averaged value of A(λ ) and RL(λ ).
k k
• Direct approach: A depolarizer based on an active or passive device is connected at the
output port of the source in order to reduce its DOP. This allows direct measurement of the
averaged A(λ ) and RL(λ ). The averaging time of the power detection system shall be
k k
greater than 2 times the quoted de-polarization time.

– 14 – IEC 61300-3-7:2021 © IEC 2021
• Indirect approach: Measure A(λ ) and RL(λ ) as a function of the state of polarization (SOP)
k k
to obtain the average value of A(λ ) and RL(λ ) from the measurement results. This requires
k k
multiple measurements be made and recorded. In this case, the role of the depolarizer is
fulfilled by a polarization controller that either deterministically sets a chosen sequence of
SOP or randomly scans many SOP.
5.4 Power detection systems
5.4.1 Method A – Tuneable narrowband detection (TND)
The measurement system shall be stable within specified limits over the measuring time. For
measurements where the connection to the detector shall be separated between measurements,
the repeatability specification shall be less than 0,02 dB.
The TND (typically an OSA) measures the output optical power at a specified wavelength over
the wavelength range. Generally, an OSA has an optical filter function inside. The resolution
bandwidth (RBW) is typically specified at –3 dB or the full width at half the maximum. The RBW
shall be specified in accordance with the wavelength setting interval. In order to avoid false
interpretation of artefacts in the measurement, the optical rejection ratio shall be specified. An
example of such specification could be –20 dB at 0,1 nm away from the centre wavelength. If
a detailed assessment of the OSA RBW is required, the filter shape of the OSA should be
measured. This is typically achieved by measuring the envelope of a DFB known to have a
spectrum much narrower than the OSA RBW.
The power measurement range and sensitivity shall be high enough for A(λ ) and RL(λ ) to be
k k
measured in accordance with the DUT specification. The amplitude uncertainty due to
polarization dependence of the OSA shall be less than the desired uncertainty to be measured.
5.4.2 Method B and C – Broadband detection (BBD)
The broadband detection system (BBD) measures an integrated optical power over a wide range.
A typical BBD consists of an optical power sensor, a mechanism for coupling a fibre to it and
associated detection electronics. These devices are most commonly referred to as an OPM.
The performance of the measurement system shall be stable within specified limits over the
measuring time. For measurements where the connection to the detector shall be separated
between measurements, the repeatability specification shall be less than 0,02 dB. A detector
with a large sensitive area may be used to achieve this.
The power measurement range of the BBD shall cover the peak power of the light source and
intended attenuation of the DUT. The minimum detectable power is recommended to be more
than 10 dB smaller than the optical power to be measured. The amplitude uncertainty due to
polarization dependence of the OPM shall be less than the desired uncertainty to be measured.
The preferred OPM parameters are given in Table 4.

IEC 61300-3-7:2021 © IEC 2021 – 15 –
Table 4 – Preferred OPM parameters
Type Maximum nonlinearity Relative uncertainty
dB dB
±0,01
(attenuation ≤ 10 dB)
Single mode ≤ 0,02
±0,05
(10 dB < attenuation ≤ 60 dB)
In order to ensure that all light exiting the fibre is detected by the OPM, the sensitive area of the detector and the
relative position between it and the fibre should be compatible with the numerical aperture of the fibre.
NOTE Common sources of relative uncertainty are polarization dependence and interference with reflections from
...