EN 61300-3-6:2003

SLOVENSKI SIST EN 61300-3-6:2004

STANDARD
september 2004
Povezovalne naprave in pasivne komponente optičnih vlaken – Postopki
osnovnega preskušanja in merjenja – 3-6. del: Preiskovanje in meritve;
povratna izguba (IEC 61300-3-6:2003)*
Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures - Part 3-6: Examinations and measurements - Return loss
(IEC 61300-3-6:2003)
ICS 33.180.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61300-3-6
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2003
ICS 33.180.20 Supersedes EN 61300-3-6:1997 + A1:1998 + A2:1999

English version
Fibre optic interconnecting devices and passive components -
Basic test and measurement procedures
Part 3-6: Examinations and measurements -
Return loss
(IEC 61300-3-6:2003)
Dispositifs d'interconnexion  Lichtwellenleiter-Verbindungselemente
et composants passifs à fibres optiques - und passive Bauteile -
Méthodes fondamentales d'essais Grundlegende Prüf- und Messverfahren
et de mesures Teil 3-6: Untersuchungen und Messungen -
Partie 3-6: Examens et mesures - Rückflussdämpfung
Puissance réfléchie (IEC 61300-3-6:2003)
(CEI 61300-3-6:2003)
This European Standard was approved by CENELEC on 2003-03-01. 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, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

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

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61300-3-6:2003 E
Foreword
The text of document 86B/1778/FDIS, future edition 2 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 2003-03-01.

This European Standard supersedes EN 61300-3-6:1997 + A1:1998 + A2:1999.

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) 2003-12-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-03-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA normative and annex A is informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61300-3-6:2003 was approved by CENELEC as a
European Standard without any modification.
__________
- 3 - EN 61300-3-6:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
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 EN 61300-1 1997
and passive components - Basic test
and measurement procedures
Part 1: General and guidance
1) 2)
IEC 61300-3-1 - Part 3-1: Examinations and EN 61300-3-1 1997
measurements - Visual examination

1) 2)
IEC 61300-3-39 - Part 3-39: Examinations and EN 61300-3-39 1997
measurements - PC optical connector
reference plug selection
1)
Undated reference.
2)
Valid edition at date of issue.

INTERNATIONAL IEC
STANDARD
61300-3-6
Second edition
2003-02
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 – Puissance réfléchie
 IEC 2003  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale
T
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 61300-3-6  IEC:2003(E)
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 General description. 5
3.1 Method 1 . 6
3.2 Method 2 . 6
3.3 Method 3 . 6
3.4 Method 4 . 6
3.5 Selection of reference measurement method. 6
4 Apparatus and symbols . 7
4.1 Device under test (DUT). 7
4.2 Method 1: measurements with OCWR . 7
4.3 Method 2: measurements with OTDR . 9
4.4 Method 3: measurements with OLCR . 9
4.5 Method 4: measurements with OFDR .11
5 Procedure .12
5.1 Launch conditions .12
5.2 Pre-conditioning.13
5.3 DUT output port .13
5.4 Method 1: measurement with OCWR.13
5.5 Method 2: measurement with OTDR.17
5.6 Method 3: measurement with OLCR .20
5.7 Method 4: measurements with OFDR .20
6 Details to be specified.22
6.1 Return loss measurement with OCWR .22
6.2 Return loss measurement with OTDR.22
6.3 Return loss measurement with OLCR.23
6.4 Return loss measurement of with OFDR.23
6.5 Measurement procedure .24
Annex A (informative) Comparison of return loss detectable by four different methods .25
Figure 1 – Measurement set-up of return loss OCWR method. 7
Figure 2 – Measurement set-up of return loss with OTDR method . 9
Figure 3 – Measurement set-up of return loss with OLCR method .10
Figure 4 – Measurement set-up of return loss with OFDR method .11
Figure 5 – Measurement set-up of the system reflected power .14
Figure 6 – Measurement set-up of the branching device transfer coefficient .14
Figure 7 – Measurement set-up of the splitting ratio of the branching device .15
Figure 8 – Measurement set-up of return loss with an OCWR .15
Figure 9 – Typical OTDR trace of the response to a reflection.17
Figure A.1 – Comparison of detectable return loss, resolution and measurable distance
for four return loss measurement methods.25

61300-3-6  IEC:2003(E) – 3 –
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 IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61300-3-6 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 1997 and its
amendments 1 (1998) and 2 (1999). This edition constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/1778/FDIS 86B/1832/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.
IEC 61300 consists of the following parts, under the general title Fibre optic interconnecting
devices and passive components – Basic test and measurement procedures:
– Part 1: General and guidance
– Part 2: Tests
– Part 3: Examinations and measurements

– 4 – 61300-3-6  IEC:2003(E)
The committee has decided that the contents of this publication will remain unchanged until
2007. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

61300-3-6  IEC:2003(E) – 5 –
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). RL, as used in this standard, is the ratio of the power (P )
i
incident on, or entering, the DUT to the total power reflected (P ) by the DUT, expressed
r
in decibels:
 P 
r
RL = −10 ⋅log  (1)
 
P
 i 
Return loss is a positive number.
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
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 reflectometry (OLCR) (method 3);
− measurement with an optical frequency domain reflectometry (OFDR) (method 4).
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).

– 6 – 61300-3-6  IEC:2003(E)
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.
The OTDR measurement method is very suitable for field measurements where it is necessary
to measure RLs on long optical lines.
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:2003(E) – 7 –
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 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 T
BD
P P
a
ref.
D D
1 2
IEC  030/03
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 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 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;
C is the splitting ratio of the branching device;
– 8 – 61300-3-6  IEC:2003(E)
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 (D1, D2 and D3)
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 are linear. 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. Where a second source is used, the central wavelength and spectral width of S shall
be the same as S .
4.2.4 Temporary joint (TJ)
A temporary joint is a joint that is made to connect the DUT into the measurement circuit.
Examples of temporary joints are a connector, splice, vacuum chuck or micro-manipulator. The
loss of the TJ shall be stable and the TJ shall have a return loss of at least 10 dB greater than
the maximum return loss to be measured (see 5.4.4).
Where a return loss greater than 50 dB is to be measured, a fusion splice is advised in order to
guarantee the prescribed measurement precision.
4.2.5 Termination (T)
Fibre terminations marked T shall have a high return loss. Three types of terminations are
suggested:
− angled fibre ends: the value of the angle depends on the fibre type; however, it shall be
higher than 12°;
− the application of an index match material to the fibre end;
− attenuation in the fibre, for example, with a mandrel wrap (not applicable to multimode
fibre).
Where attenuation is used as a termination, it may be applied between components. For
example, the measurement of P in Figure 5 may be made by applying attenuation between
TJ and the DUT in Figure 8.
The fibre termination shall have a return loss of at least 20 dB greater than the maximum
return loss to be measured.
Where a return loss greater than 50 dB is to be measured, the “attenuation in the fibre”
termination technique is advised in order to guarantee the prescribed measurement precision.

61300-3-6  IEC:2003(E) – 9 –
4.3 Method 2: measurements with OTDR
The measurement set up for the RL measurement using an OTDR is shown in Figure 2. The
following is a list of the apparatus and components used in the measurement.
TJ
TJ
b
a
OTDR
DUT
L L
L
1 2 3
IEC  031/03
Figure 2 – Measurement set-up of return loss with OTDR method
4.3.1 Optical time domain reflectometer (OTDR)
An instrument able to measure the optical power backscattered along a fibre as a function of
time. With this instrument it is possible to measure several characteristics of an optical line
(attenuation, splice loss, splice location, fibre uniformity, breaks) by looking at the fibre from
only one end. The return loss from a discontinuity in the fibre is one of the parameters that can
be measured.
An attenuator at the OTDR receiver input may be required to reduce the optical power to a
level that does not saturate the OTDR receiver (see 5.5.4).
4.3.2 Fibre sections (L , L , and L
1 2 3)
Sections of fibre that are to be included in an OTDR measurement. Section L is required by
most OTDRs to provide separation between the OTDR and the events to be measured.
Sections L and L provide the space required for the OTDR to resolve the measurement of the
2 3
return loss of the DUT. The fibre between points “a” and “b” shall have the same backscatter
coefficient (see equation (15)).
Where the DUT is terminated with connectors, the connectors are part of the DUT, they shall
fall between sections L and L .
2 3
4.3.3 Temporary joints (TJ)
A temporary joint is a joint that is made to connect the DUT into the measurement circuit.
Examples of temporary joints are a connector, splice, vacuum chuck, or micromanipulator. The
temporary joints shall be out of the “a”-“b” zone. The loss of the TJ shall be stable and shall
have an RL sufficiently high that it does not affect the OTDR trace in the measurement zone.
In the case in which the temporary joints TJ or TJ fall between “a” and “b”, the absolute value
1 2
of the loss of these joints as measured by a one-way OTDR measurement shall be less than
0,10 H (see 5.5.4). To obtain this low H value, it may be necessary to work with several
different fibre combinations to match the backscatter characteristics of the pigtails attached to
the DUT.
4.4 Method 3: measurements with OLCR
The description of the apparatus shown in Figure 3 indicates only the principle of the method.
NOTE A practical measuring system needs to u
...