EN 61300-3-6:2009

SLOVENSKI STANDARD
01-junij-2009
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Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-6: Examinations and measurements - Return loss
(IEC 61300-3-6:2008)
Lichtwellenleiter - Verbindungselemente und passive Bauteile - Grundlegende Prüf- und
Messverfahren - Teil 3-6: Untersuchungen und Messungen - Rückflussdämpfung (IEC
61300-3-6:2008)
Dispositifs d'interconnexion et composants passifs à fibres optiques - Méthodes
fondamentales d'essais et de mesures - Partie 3-6: Examens et mesures -
Affaiblissement de réflexion (CEI 61300-3-6:2008)
Ta slovenski standard je istoveten z: EN 61300-3-6:2009
ICS:
33.180.20 3RYH]RYDOQHQDSUDYH]D Fibre optic interconnecting
RSWLþQDYODNQD devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61300-3-6
NORME EUROPÉENNE
March 2009
EUROPÄISCHE NORM
ICS 33.180.20 Supersedes EN 61300-3-6:2003

English version
Fibre optic interconnecting devices and passive components -
Basic test and measurement procedures -
Part 3-6: Examinations and measurements -
Return loss
(IEC 61300-3-6:2008)
Dispositifs d'interconnexion  Lichtwellenleiter -
et composants passifs à fibres optiques - Verbindungselemente
Méthodes fondamentales d'essais und passive Bauteile -
et de mesures - Grundlegende Prüf- und Messverfahren -
Partie 3-6: Examens et mesures - Teil 3-6: Untersuchungen und Messungen -
Affaiblissement de réflexion Rückflussdämpfung
(CEI 61300-3-6:2008) (IEC 61300-3-6:2008)

This European Standard was approved by CENELEC on 2009-03-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: avenue Marnix 17, B - 1000 Brussels

© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61300-3-6:2009 E
Foreword
The text of document 86B/2762/FDIS, future edition 3 of IEC 61300-3-6, 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 was approved by CENELEC as EN 61300-3-6 on 2009-03-01.
This European Standard supersedes EN 61300-3-6:2003.
The changes with respect to EN 61300-3-6:2003 are to reconsider the constitution of this standard and
launch conditions for multimode fibres.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2009-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-03-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61300-3-6:2008 was approved by CENELEC as a European
Standard without any modification.
__________
– 3 – EN 61300-3-6:2009
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60793-2 Series Optical fibres - EN 60793-2 Series
Part 2: Product specifications

1) 2)
IEC 61300-1 - Fibre optic interconnecting devices and EN 61300-1 2003
passive components - Basic test and
measurement procedures -
Part 1: General and guidance
1) 2)
IEC 61300-3-1 - Fibre optic interconnecting devices and EN 61300-3-1 2005
passive components - Basic test and
measurement procedures -
Part 3-1: Examinations and measurements -
Visual examination
1) 2)
IEC 61300-3-39 - Fibre optic interconnecting devices and EN 61300-3-39 1997
passive components - Basic test and
measurement procedures -
Part 3-39: Examinations and measurements -
PC optical connector reference plug selection

1)
Undated reference.
2)
Valid edition at date of issue.

IEC 61300-3-6
Edition 3.0 2008-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures –
Part 3-6: Examinations and measurements – Return loss

Dispositifs d'interconnexion et composants passifs à fibres optiques –
Méthodes fondamentales d'essais et de mesures –
Partie 3-6: Examens et mesures – Affaiblissement de réflexion

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 33.180.20 ISBN 2-8318-1019-2
– 2 – 61300-3-6 © IEC:2008
CONTENTS
FOREWORD.5
1 Scope.7
2 Normative references.7
3 General description.7
3.1 Method 1 .8
3.2 Method 2 .8
3.3 Method 3 .8
3.4 Method 4 .8
3.5 Selection of reference measurement method .8
4 Apparatus and symbols.9
4.1 Device under test (DUT) .9
4.2 Method 1: measurements with OCWR.9
4.2.1 Branching device (BD) .10
4.2.2 Detector (D , D and D ) .10
1 2 3
4.2.3 Source (S and S ) .10
1 2
4.2.4 Temporary joint (TJ) .10
4.2.5 Termination (T).10
4.3 Method 2: measurements with OTDR.11
4.3.1 Optical time domain reflectometer (OTDR).11
4.3.2 Fibre sections (L , L , and L ).11
1 2 3
4.3.3 Temporary joints (TJ).11
4.4 Method 3: measurements with OLCR .11
4.4.1 Light source (S) .12
4.4.2 Branching device (BD) .12
4.4.3 Optical delay line (ODL) .12
4.4.4 Optical detector (D).12
4.4.5 Temporary joint (TJ) .12
4.4.6 Data processing unit .12
4.5 Method 4: measurements with an OFDR .13
4.5.1 RF network analyser .13
4.5.2 Optical heads – Source (S) and receiver (D) .13
4.5.3 Optical variable attenuator (A) (optional) .13
4.5.4 Optical amplifier (OA) (optional) .13
4.5.5 Isolator (I) (optional) .14
4.5.6 Branching device (BD) .14
4.5.7 Temporary joint (TJ) .14
4.5.8 Computer.14
5 Procedure.14
5.1 Launch conditions.14
5.2 Pre-conditioning .14
5.3 DUT output port.14
5.4 Method 1: measurement with OCWR .14
5.4.1 Definition of the OCWR measurement.14
5.4.2 Set-up characterization .15
5.4.3 Measurement procedure .17

61300-3-6 © IEC:2008 – 3 –
5.4.4 Accuracy considerations .18
5.5 Method 2: measurement with OTDR.18
5.5.1 Definition of the OTDR measurement.18
5.5.2 Evaluation of backscattering coefficient.19
5.5.3 Measurement procedure .20
5.5.4 Accuracy considerations .21
5.6 Method 3: measurement with OLCR.21
5.6.1 Calibration procedure.21
5.6.2 Measurement procedure .21
5.6.3 Accuracy considerations .22
5.7 Method 4: measurements with OFDR.22
5.7.1 Calibration procedure.22
5.7.2 Measurement procedure .22
5.7.3 Accuracy considerations .22
6 Details to be specified.23
6.1 Return loss measurement with OCWR .23
6.1.1 Reference components .23
6.1.2 Branching device .23
6.1.3 Detector.23
6.1.4 Source.24
6.1.5 Temporary joint.24
6.1.6 Termination .24
6.2 Return loss measurement with OTDR .24
6.2.1 Reference components .24
6.2.2 OTDR .24
6.2.3 L , L , and L .24
1 2 3
6.2.4 Fibre.24
6.3 Return loss measurement with OLCR.24
6.3.1 Reference components .24
6.3.2 Source.25
6.3.3 Branching device (BD) .25
6.4 Return loss measurement with OFDR .25
6.4.1 Reference components .25
6.4.2 Vector network analyser.25
6.4.3 Branching device .25
6.4.4 Source.25
6.4.5 Detector.25
6.4.6 Optical amplifier (optional) .26
6.4.7 Isolator (optional).26
6.4.8 Calibration .26
6.5 Measurement procedure .26
Annex A (informative)  Comparison of return loss detectable by four different methods .27

Figure 1 – Measurement set-up of return loss OCWR method.9
Figure 2 – Measurement set-up of return loss with OTDR method.11
Figure 3 – Measurement set-up of return loss with OLCR method .12
Figure 4 – Measurement set-up of return loss with OFDR method.13
Figure 5 – Measurement set-up of the system reflected power.15

– 4 – 61300-3-6 © IEC:2008
Figure 6 – Measurement set-up of the branching device transfer coefficient.16
Figure 7 – Measurement set-up of the splitting ratio of the branching device .16
Figure 8 – Measurement set-up of return loss with an OCWR .17
Figure 9 – Typical OTDR trace of the response to a reflection.19
Figure A.1 – Comparison of detectable return loss, resolution and measurable distance
for four return loss measurement methods .27

Table 1 – OTDR parameters for some pulse duration .20
Table 2 – Example of system data and relevant dynamic range.23

61300-3-6 © IEC:2008 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-6: Examinations and measurements –
Return loss
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 61300-3-6 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 2003. It constitutes a
technical revision. The changes with respect to the previous edition are to reconsider the
constitution of the document and launch conditions for multimode fibres.

– 6 – 61300-3-6 © IEC:2008
The text of this standard is based on the following documents:
FDIS Report on voting
86B/2762/FDIS 86B/2792/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 2.
A list of all parts of 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 publication will remain unchanged until the
maintenance result 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.
61300-3-6 © IEC:2008 – 7 –
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-6: Examinations and measurements –
Return loss
1 Scope
This part of IEC 61300 presents procedures for the measurement of the return loss (RL) of a
fibre optic device under test (DUT).
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.
IEC 60793-2 (all parts), Optical fibres – Product specifications
IEC 61300-1, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 1: General and guidance
IEC 61300-3-1, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-1: Examinations and measurements – Visual examination
IEC 61300-3-39, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-39: Examinations and measurements – PC optical connector
reference plug selection
3 General description
RL, as used in this standard, is the ratio of the power (P ) incident on, or entering, the DUT to
i
the total power reflected (P ) by the DUT, expressed in decibels:
r
⎛ ⎞
P
r
⎜ ⎟
RL = −10 × log (1)
⎜ ⎟
P
i
⎝ ⎠
Return loss is a positive number.
Four methods will be presented for measuring optical return loss:
− measurement with an optical continuous wave reflectometer (OCWR) (method 1);
− measurement with an optical time domain reflectometer (OTDR) (method 2);
− measurement with an optical low coherence reflectometer (OLCR) (method 3);
− measurement with an optical frequency domain reflectometer (OFDR) (method 4).

– 8 – 61300-3-6 © IEC:2008
These four measurement methods have different characteristics and different applications in
terms of spatial resolution and detectable RL (in Annex A, a comparison of return loss
detectable by the four different methods is reported).
3.1 Method 1
This technique is the nearest to the theoretical definition of return loss given by equation (1). It
measures directly the incident power and the reflected power. It is not affected by instrumental
data processing and it gives absolute measurement values, which are not relative to a
reference reflection (technique A). This method has some limiting factors: it cannot spatially
resolve two different reflections on the line and its dynamic range is limited by the
characteristics of the branching device and by the ability to suppress the reflections beyond the
one from the DUT.
3.2 Method 2
This method allows measurement of RL from reflection points on an optical line, with a spatial
resolution in the metre range and with a dynamic range of more than 75 dB (depending on the
pulse width) using an OTDR instrument.
3.3 Method 3
The purpose of this method is to measure reflection profiles of single-mode optical devices with
a micrometre spatial resolution and a high dynamic range (> 90 dB) by using optical low-
coherence interference.
The reflection profile is defined as a distribution of reflections at individual end-faces and/or
connected points in single-mode optical devices. When the reflection at a particular point is −R
(dB), the return loss at this point is given by R (dB). This method measures the reflection at a
point by detecting the power of a beat signal produced by optical interference between the
reflected light and the reference light. When a component with dispersed reflections is
analysed, each reflection can be identified and located, provided their separation is greater
than the spatial resolution of the measurement system.
3.4 Method 4
The purpose of this procedure is to measure the return loss of single-mode optical devices with
a spatial resolution in the centimetre range and high dynamic range (> 70 dB) by using optical
frequency domain reflectometry.
One of the prime benefits of this technique is the ability to spatially resolve the desired
reflection from undesired ones, such as all of the connectors or unterminated ports on the
DUT, without any dead zone. Moreover, the OFDR method is highly reliable and the apparatus
can be compact.
Measurement in the frequency domain is based on the ability to convert information in the time
domain by means of an inverse Fourier transform. In this way, with a source modulated from
some kHz to 1 GHz, it is possible to resolve two reflective points on an optical line separated
by some centimetres.
3.5 Selection of reference measurement method
Due to the different characteristics of these methods, and their different application fields, the
reference method depends on the type of DUT. For a component with RL ≤ 55 dB, the
reference is method 1, for a component with RL > 55 dB, the reference is method 2 using a
pulse duration less than 100 ns. In cases in which it is necessary to resolve more reflection
points separated by a distance of less than 5 m, the reference shall be method 3.

61300-3-6 © IEC:2008 – 9 –
4 Apparatus and symbols
4.1 Device under test (DUT)
Where the DUT is the mounted connector on one end of a component, the reference mating
plug shall be considered one-half of the DUT connection on the temporary joint (TJ) side and
have the same end-face finish and minimum performance as the connectors to be measured.
Where the DUT is an entire component assembly terminated with pigtails with or without
connectors, reference plugs with pigtails and, as required, reference adapters are to be added
to those ports with connector terminations so as to form complete connector assemblies with
pigtails. Reference mating plugs shall then be considered one-half of the TJ and have the
same end-face finish and minimum performance as the connectors to be measured. All unused
ports shall be terminated as stated in 4.2.5.
Unless otherwise specified, reference plugs shall meet the requirements of IEC 61300-3-39.
The reference adapters shall meet the appropriate IEC connector interface dimensions and
ensure a high degree of repeatability and reproducibility. It is recommended that the test
adapters be tested and visually inspected after every 100 matings and replaced after 500
matings.
4.2 Method 1: measurements with OCWR

TJ
S
DUT
1 T
BD
P P
a
ref
D D
1 2
IEC  2141/08
Figure 1 – Measurement set-up of return loss OCWR method
The circuit in Figure 1 is representative of, but is not the only circuit that may be used for
OCWR return loss measurement. The requirements are that the values measured satisfy the
following two conditions:
− P (power measured by the detector D ) shall be proportional to the power reflected from
a 1
the DUT, P , plus the reflected power originating in the measurement circuit outside of the
r
DUT, P :
P = C x P + P (mW) (2)
a 1 r 0
− P (power measured by the detector D ) shall be proportional to the power incident on
ref 2
the DUT, P :
i
P = C x P (mW) (3)
ref 2 i
where
P is the power reflected from the DUT (equation (1));
r
P is the power incident on the DUT (equation (1));
i
P is the system reflected power originating in the measurement circuit;
C is the branching device transfer coefficient;
– 10 – 61300-3-6 © IEC:2008
C is the splitting ratio of the branching device.
The following is a list of the apparatus and components used in the measurement of return loss
using an OCWR (see Figure 1).
4.2.1 Branching device (BD)
The splitting ratio of the BD shall be stable and be insensitive to polarization (< 0,1 dB). The
directivity shall be at least 10 dB higher than the maximum return loss to be measured (see
5.4.4).
4.2.2 Detector (D , D and D )
1 2 3
The detector used consists of an optical detector, the associated electronics, and a means of
connecting to an optic fibre. The optical connection may be a receptacle for an optical
connector, a fibre pigtail or a bare fibre adapter.
The detectors linearity needs to be specified and sufficient for the dynamic range of the
measurements to be undertaken. Since all of the measurements are differential, however, it is
not necessary that the calibration be absolute. Care shall be taken to suppress the reflected
power from the detector D during the measurement.
Where, during the sequence of measurements, a detector is disconnected and reconnected,
the coupling efficiency for the two measurements shall be maintained.
4.2.3 Source (S )
and S
1 2
The source consists of an optical emitter, associated drive electronics, an excitation unit, and a
fibre connector or fibre pigtail. A second source S may be used for calibration, as illustrated in
Figure 6. Wh
...