EN 60728-6:2003

SLOVENSKI SIST EN 60728-6:2004

STANDARD
september 2004
Kabelska omrežja za televizijske signale, zvokovne signale in interaktivne
storitve – 6. del: Optična oprema (IEC 60728-6:2003)
Cable networks for television signals, sound signals and interactive services - Part
6: Optical equipment (IEC 60728-6:2003)
ICS 33.060.40 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 60728-6
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2003

ICS 33.060.40;33.160.99 Supersedes EN 50083-6:1997

English version
Cable networks for television signals,
sound signals and interactive services
Part 6: Optical equipment
(IEC 60728-6:2003)
Réseaux de distribution par câbles  Kabelnetze für Fernsehsignale,
pour signaux de télévision, Tonsignale und interaktive Dienste
signaux de radiodiffusion sonore Teil 6: Optische Geräte
et services interactifs (IEC 60728-6:2003)
Partie 6: Matériels optiques
(CEI 60728-6:2003)
This European Standard was approved by CENELEC on 2003-10-01. 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, Lithuania, 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 60728-6:2003 E
Foreword
The text of document 100/680/FDIS, future edition 2 of IEC 60728-6, prepared by IEC TC 100, Audio,
video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and
was approved by CENELEC as EN 60728-6 on 2003-10-01.
This European Standard supersedes EN 50083-6:1997.
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) 2004-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-10-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA is normative and annexes A and B are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60728-6:2003 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 60793-2-50 NOTE Harmonized as EN 60793-2-50:2002 (not modified).
IEC 60825-1 NOTE Harmonized as EN 60825-1:1994 (not modified).
IEC 61290-1-1 NOTE Harmonized as EN 61290-1-1:1998 (not modified).
IEC 61290-1-2 NOTE Harmonized as EN 61290-1-2:1998 (not modified).
__________
- 3 - EN 60728-6:2003
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
1) 2)
IEC 60068-1 - Environmental testing EN 60068-1 1994
Part 1: General and guidance
IEC 60068-2 series Part 2: Tests EN 60068-2 series

1) 2)
IEC 60169-2 - Radio-frequency connectors HD 134.2 S2 1984
Part 2: Coaxial unmatched connector

1) 2)
IEC 60169-24 - Part 24: Radio-frequency coaxial EN 60169-24 1993
connectors with screw coupling,
typically for use in 75 ohm cable
distribution systems (Type F)
IEC 60417 2002 Graphical symbols for use on equipment- -
database
1) 2)
IEC 60529 - Degrees of protection provided by EN 60529 1991
enclosures (IP Code) + corr. May 1993

IEC 60617 series Graphical symbols for diagrams - -
database
1)
IEC 60728-1 - Cabled distribution systems for - -
television and sound signals
Part 1: Methods of measurement and
system performance
1)
IEC 60728-2 - Part 2: Electromagnetic compatibility for - -
equipment
1)
IEC 60728-3 - Part 3: Active coaxial wideband - -
distribution equipment
1)
Undated reference.
2)
Valid edition at date of issue.

Publication Year Title EN/HD Year
1) 2)
IEC 61280-2-2 - Fibre optic communication subsystem EN 61280-2-2 1999
basic test procedures
Part 2-2: Test procedures for digital
systems - Optical eye pattern,
waveform, and extinction ratio

1) 2)
IEC 61280-4-2 - Part 4-2: Fibre optic cable plant - EN 61280-4-2 1999
Single-mode fibre optic cable plant
attenuation
1)
IEC/TR 61282-4 - Fibre optic communication system - -
design guides
Part 4: Accomodation and utilization of
non-linear effects
1) 2)
IEC 61290-1-3 - Optical fibre amplifiers - Basic EN 61290-1-3 1998
specification
Part 1-3: Test methods for gain
parameters - Optical power meter

1) 2)
IEC 61290-3 - Part 3: Test methods for noise figure EN 61290-3 2000
parameters
1) 2)
IEC 61290-3-2 - Part 3-2: Test methods for noise figure EN 61290-3-2 2003
parameters - Electrical spectrum
analyzer method
IEC 61290-5 series Part 5: Test methods for reflectance EN 61290-5 series
parameters
1) 2)
IEC 61291-1 - Optical fibre amplifiers EN 61291-1 1998
Part 1: Generic specification
1)
IEC/TR3 61931 - Fibre optic - Terminology - -

IEC 80416 series Basic principles for graphical symbols EN 80416 series
for use on equipment
1)
ITU-G.692 - Optical interfaces for multichannel - -
systems with optical amplifiers

EN 300019-1-3 - Environmental Engineering (EE) - - -
Environmental conditions and
environmental tests for
telecommunications equipment
Part 1-3: Classification of environmental
conditions - Stationery use at
weatherprotected locations
INTERNATIONAL IEC
STANDARD 60728-6
Second edition
2003-07
Cable networks for television signals,
sound signals and interactive services –
Part 6:
Optical equipment
© 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 XA
International Electrotechnical Commission
ɆɟɠɞɭɧɚɪɨɞɧɚɹɗɥɟɤɬɪɨɬɟɯɧɢɱɟɫɤɚɹɄɨɦɢɫɫɢɹ
For price, see current catalogue

– 2 – 60728-6 ¤ IEC:2003(E)
CONTENTS
FOREWORD . 4
INTRODUCTION .6
1 Scope . 7
2 Normative references. 7
3 Terms, definitions, symbols and abbreviations. 8
4 Methods of measurement.17
4.1 General measurement requirements .17
4.2 Optical power.17
4.3 Loss, isolation, directivity and coupling ratio .18
4.4 Return loss .19
4.5 Saturation output power of an optical amplifier .20
4.6 Polarization dependent loss .21
4.7 Centroidal wavelength and spectral width under modulation.22
4.8 Linewidth and chirping of transmitters with single mode lasers.23
4.9 Optical modulation index .25
4.10 Reference output level of an optical receiver .26
4.11 Slope and flatness .27
4.12 Composite second order distortion (CSO) of optical transmitters .29
4.13 Composite triple beats (CTB) of optical transmitters .30
4.14 Composite crossmodulation of optical transmitters .31
4.15 Receiver intermodulation.33
4.16 CSO of optical amplifiers.36
4.17 CTB of optical amplifiers .36
4.18 Carrier-to-noise ratio.36
4.19 Method for combined measurement of relative intensity noise (RIN), optical
modulation index and equivalent input noise current .40
4.20 Noise figure of optical amplifiers .42
4.21 Influence of fibre.43
4.22 SBS threshold.43
5 Universal performance requirements and recommendations .44
5.1 Safety.44
5.2 Electromagnetic compatibility (EMC) .44
5.3 Environmental.44
5.4 Marking .45
6 Active equipment .45
6.1 Optical downlink transmitters .45
6.2 Optical uplink transmitters.47
6.3 Optical receivers .49
6.4 Optical amplifiers .51
7 Passive equipment.52
7.1 Connectors and splices .52
7.1.1 Data publication requirements .52
Annex A (informative) A simplified method of measurement for return loss.53
Annex B (informative) Product specification worksheets for optical amplifiers.55
Bibliography .58

60728-6 ¤ IEC:2003(E) – 3 –
Figure 1 – Measurement of optical power.18
Figure 2 – Measurement of optical loss, directivity and isolation.19
Figure 3 – Measurement of the optical return loss.20
Figure 4 – Optical saturation output power .21
Figure 5 – Measurement of the polarization dependent loss .21
Figure 6 – Measurement of central wavelength and spectral width under modulation .22
Figure 7 – Measurement of the chirping and the linewidth of transmitters .24
Figure 8 – Measurement of the optical modulation index .26
Figure 9 – Measurement of the reference output level of an optical receiver .27
Figure 10 – Measurement of the frequency range and flatness.28
Figure 11 – Evaluation of the slope.28
Figure 12 – Evaluating the flatness .29
Figure 13 – Device under test for measuring CSO of optical transmitters .30
Figure 14 – Device under test for measuring CTB of optical transmitters .31
Figure 15 – Arrangement for measuring composite crossmodulation of optical transmitters .32
Figure 16 – Arrangement of test equipment for measuring receiver intermodulation.35
Figure 17 – System with internal noise sources.36
Figure 18 – PIN diode receiver .37
Figure 19 – Optical transmission system under test .38
Figure 20 – Arrangement of test equipment for carrier-to-noise measurement .38
Figure 21 – Measurement set-up for determination of the noise parameters and the
optical modulation index .42
Figure 22 – Arrangement for measuring the SBS threshold .44
Figure 23 – Classification of uplink transmitters .48
Figure A.1 – Test set-up for calibration .53
Figure A.2 – Measurement of the optical power of the light source .54
Figure A.3 – Test set-up for device under test.54
Figure A.4 – Measurement of the optical power at port A.54
Table 1 – Noise correction factors C for different noise level differences D.40
n
Table 2 – Data publication requirements for optical downlink transmitters .46
Table 3 – Recommendations for optical downlink transmitters.46
Table 4 – Requirements for optical downlink transmitters.47
Table 5 – Data publication requirements for optical uplink transmitters.48
Table 6 – Recommendations for optical uplink transmitters .49
Table 7 – Requirements for optical uplink transmitters .49
Table 8 – Classification of optical receivers .50
Table 9 – Data publication requirements for optical receivers .50
Table 10 – Recommendations for optical receivers .50
Table 11 – Performance requirements for optical receivers .51
Table B.1 – Minimum list of relevant parameters of power amplifiers to be specified for
analogue applications .55
Table B.2 – Minimum list of relevant parameters of line amplifiers to be specified for
analogue applications .56
Table B.3 – Minimum list of relevant parameters of optically amplified transmitters
(OAT) to be specified for analogue applications .57

– 4 – 60728-6 ¤ IEC:2003(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
CABLE NETWORKS FOR TELEVISION SIGNALS,
SOUND SIGNALS AND INTERACTIVE SERVICES –
Part 6: Optical equipment
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, 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 60728-6 has been prepared by technical area 5: Cable networks for
television signals, sound signals and interactive services, of IEC technical committee 100:
Audio, video and multimedia systems and equipment.
This second edition cancels and replaces the first edition published in 2001 of which it
constitutes a technical revision.
The text of this standard is based on
FDIS Report on voting
100/680/FDIS 100/697/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.

60728-6 ¤ IEC:2003(E) – 5 –
The committee has decided that this publication remains valid until 2006. At this date, in
accordance with the committee’s decision, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 6 – 60728-6 ¤ IEC:2003(E)
INTRODUCTION
Standards of the IEC 60728 series deal with cable networks for television signals, sound
signals and interactive services including equipment, systems and installations:
• for headend-reception, processing and distribution of sound and television signals and their
associated data signals, and
• for processing, interfacing and transmitting all kinds of interactive multimedia signals using
all applicable transmission media.
They cover all kinds of networks that convey modulated RF carriers such as
• CATV-networks;
• MATV-networks and SMATV-networks;
• individual receiving networks;
and all kinds of equipment, systems and installations installed in such networks.
The scope of these standards extends from antennas and special signal source inputs to
headend or other interface points, to networks as a whole up through system outlets, or
terminal inputs where no system outlet exists.
The standardization of any user terminals (i.e. tuners, receivers, decoders, multimedia
terminals, etc.) is excluded.
60728-6 ¤ IEC:2003(E) – 7 –
CABLE NETWORKS FOR TELEVISION SIGNALS,
SOUND SIGNALS AND INTERACTIVE SERVICES –
Part 6: Optical equipment
1 Scope
This part of IEC 60728 lays down the measuring methods, performance requirements and data
publication requirements of optical equipment of cable networks for television signals, sound
signals and interactive services.
This standard
• applies to all optical transmitters, receivers, amplifiers, directional couplers, isolators,
multiplexing devices, connectors and splices used in cable networks;
• covers the frequency range 5 MHz to 3 000 MHz;
NOTE The upper limit of 3 000 MHz is an example, but not a strict value. The frequency range or ranges, over
which the equipment is specified, shall be published.
• identifies guaranteed performance requirements for certain parameters;
• lays down data publication requirements with guaranteed performance;
• describes methods of measurement for compliance testing.
All requirements and published data relate to minimum performance levels within the specified
frequency range and in well-matched conditions as might be applicable to cable networks for
television signals, sound signals and interactive services.
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 60068-1, Environmental testing. Part 1: General and guidance
IEC 60068-2, (all parts), Environmental testing – Part 2: Tests
IEC 60169-2, Radio-frequency connectors – Part 2: Coaxial unmatched connector
IEC 60169-24, Radio-frequency connectors – Part 24: Radio-frequency coaxial connectors with
screw coupling, typically for use in 75 ohm cable distribution systems (Type F)
*
IEC 60417-DB:2002 , Graphical symbols for use on equipment
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60617 (all parts) [DB]*, Graphical symbols for diagrams
___________
*
“DB” refers to the IEC on-line database.

– 8 – 60728-6 ¤ IEC:2003(E)
IEC 60728-1, Cabled distribution systems for television and sound signals – Part 1: Methods of
measurement and system performance
IEC 60728-2, Cabled distribution systems for television and sound signals – Part 2:
Electromagnetic compatibility of equipment
IEC 60728-3, Cabled distribution systems for television and sound signals – Part 3: Active
coaxial wideband distribution equipment
IEC 61280-2-2, Fibre optic communication subsystem basic test procedures – Part 2-2: Test
procedures for digital systems – Optical eye pattern, waveform, and extinction ratio
IEC 61280-4-2, Fibre optic communication subsystem basic test procedures – Part 4-2: Fibre
optic cable plant – Single-mode fibre optic cable plant attenuation
IEC 61282-4, Fibre optic communication system design guides – Part 4: Guideline to
accommodate and utilize nonlinear effects in single-mode fibre optic systems
IEC 61290-1-3, Optical fibre amplifiers – Basic specification – Part 1-3: Test methods for gain
parameters – Optical power meter
IEC 61290-3, Optical fibre amplifiers – Basic specification – Part 3-1: Test methods for noise
figure parameters
IEC 61290-3-2, Optical fibre amplifiers – Part 3-2: Test methods for noise figure parameters –
Electrical spectrum analyzer
IEC 61290-5, Optical fibre amplifiers – Basic specification – Part 5: Test methods for
reflectance parameters
IEC 61291-1, Optical fibre amplifiers – Part 1: Generic specification
IEC 61931, Fibre optics – Terminology
IEC 80416, Basic principles for graphical symbols for use on equipment
ITU G.692, Optical interfaces for multichannel systems with optical amplifiers
EN 300019-1-3, Environmental Engineering (EE); Environmental conditions and environmental
tests for telecommunications equipment; Part 1-3: Classification of environmental conditions;
Stationary use at weatherprotected locations
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the definitions given in IEC 60728-1, IEC 61931 and the
following terms and definitions apply.
3.1.1
optical transmitting unit; optical transmitter; Tx (abbreviation)
transmit fibre optic terminal device accepting at its input port an electrical signal and providing
at its output port an optical carrier modulated by that input signal
NOTE For the purposes of this standard, optical transmitters may have more than one input port accepting
electrical RF signals.
[IEC 61931, definition 2.9.6]
60728-6 ¤ IEC:2003(E) – 9 –
3.1.2
optical receiving unit; optical receiver; Rx (abbreviation)
receive fibre optic terminal device accepting at its input port a modulated optical carrier, and
providing at its output port the corresponding demodulated electrical signal (with the associated
clock, if digital)
NOTE For the purposes of this standard, optical receivers may have more than one output port providing electrical
RF signals.
[IEC 61931, definition 2.9.7]
3.1.3
optical amplifier
optical waveguide device containing a suitably pumped, active medium which is able to amplify
an optical signal
[IEC 61931, definition 2.7.75]
3.1.4
(optical) isolator
two port non-reciprocal optical device intended to suppress backward reflection, while having
minimum insertion loss in the forward direction, based on Faraday effect
NOTE 1 An isolator is commonly used to prevent return reflections along a transmission path.
NOTE 2 An isolator is generally polarization dependent; however fibre optic polarization independent isolators exist.
[IEC 61931, definition 2.6.30]
3.1.5
(optical (fibre)) splice
permanent, or semi permanent, joint whose purpose is to couple optical power between two
optical fibres
[IEV 731-05-05 modified]
[IEC 61931, definition 2.6.8]
3.1.6
fibre optic branching device; (optical) (fibre) branching device;
(optical) (fibre) coupler (deprecated)]
optical fibre device, possessing three or more optical ports, which shares optical power among
its ports in a predetermined fashion, at the same wavelength or wavelengths, without
wavelength conversion
NOTE The ports may be connected to fibres, sources, detectors, etc.
[IEC 61931, definition 2.6.21]
3.1.7
directional branching device; directional coupler (deprecated)
device which distributes an optical signal among the output ports in a predetermined fashion
only when light is launched into one preselected input port
[IEC 61931, definition 2.6.22]
NOTE For the purposes of this standard, directional coupler is the preferred term because this is also the term for
its electrical equivalent.
3.1.8
multiplexing device; WDM device
wavelength selective branching device (used in WDM transmission systems) in which optical
signals can be transferred between two predetermined ports, depending on the wavelength of
the signal
– 10 – 60728-6 ¤ IEC:2003(E)
[IEC 61931, definition 2.6.51]
3.1.9
reference output level of an optical receiver
offset x by which the electrical output level of an optical receiver can be calculated from the
optical input level at a modulation index of m = 0,05 using following equation:
(1)
U = 2 P + x dB(µV)
opt,RX
where
U
is the electrical output level in dB(µV)
P is the optical input level in dB(mW)
opt,RX
x is the reference output level in dB(µV)
3.1.10
optical modulation index
optical modulation index is defined as
φ -φ
h l
m =
(2)
+
φ φ
h l
where φ is the highest and φ is the lowest instantaneous optical power of the intensity
h l
modulated optical signal. This term is mainly used for analogue systems.
NOTE This definition does not apply to systems where the input signals are converted and transported as digital
baseband signals. In this case, the terms modulation depth or extinction ratio defined in 2.6.79 and 2.7.46 of
IEC 61931 must be used. A test procedure for extinction ratio is described in IEC 61280-2-2.
3.1.11
noise figure
decrease of the signal-to-noise ratio (SNR), at the output of an optical detector with unitary
quantum efficiency, due to the propagation of a shot noise-limited signal through the optical
amplifier (OFA), expressed in dB
[IEC 61291-1]
NOTE The noise figure of optical amplifiers depends on the optical input power and on the wavelength used.

60728-6 ¤ IEC:2003(E) – 11 –
3.1.12
relative intensity noise
RIN
ratio of the mean square of the intensity fluctuations in the optical power of a light source to the
−1
square of the mean of the optical output power. The RIN is usually expressed in dB(Hz )
resulting in negative values then
NOTE The value for the RIN can be calculated from the results of a carrier-to-noise measurement for the system
(see 4.18).
3.1.13
noise equivalent power
NEP
value of the radiant power at the input of an optical detector which produces at the output a
signal-to-noise ratio equal to one, for a given wavelength, modulation frequency and equivalent
noise bandwidth
[IEV 731-06-40]
[IEC 61931, definition 2.7.61]
NOTE The NEP can be calculated from the carrier-to-noise ratio C/N (see 4.18) of a receiver using:
− C /N
mP
20 (3)
NEP = 10
2B
where
m is the optical modulation index;
P is the received optical power;
B is the bandwidth.
The NEP shall be expressed in units of W/√Hz.
3.1.14
equivalent input noise current density
notional input noise current density which, when applied to the input of an ideal noiseless
device, would produce an output noise current density equal in value to that observed at the
output of the actual device under consideration
NOTE It can be calculated from the carrier-to-noise ratio C/N (see 4.18) of a device or system using:
C
=
I
r
1 (4)
C/N
Z
where
C is the power of the carrier at the input of the device or system;
Z is its input impedance.
The equivalent input noise current density shall be expressed in units of A/√Hz.
3.1.15
responsivity
ratio of an optical detector’s electrical output to its optical input at a given wavelength
[IEV 731-06-36 modified]
NOTE 1 The responsivity is generally expressed in amperes per watt or volts per watt of incident radiant power.
NOTE 2 Sensitivity is sometimes used as an imprecise synonym for responsivity.
NOTE 3 The wavelength interval around the given wavelength may be specified.
[IEC 61931, definition 2.7.56]

– 12 – 60728-6 ¤ IEC:2003(E)
3.1.16
chromatic dispersion; total dispersion (deprecated)
spreading of a light pulse per unit source spectrum width in an optical fibre caused by different
group velocities of the different wavelengths composing the source spectrum.
NOTE The chromatic dispersion may be due to the following contributions: material dispersion, waveguide
dispersion, profile dispersion.
[IEC 61931, definition 2.4.54]
3.1.17
wavelength
distance covered in a period by the wavefront of a harmonic plane wave.
[IEC 61931, definition 2.2.9]
NOTE The wavelength λ of light in vacuum is given by
c
λ =
(5)
f
where
c is the speed of light in vacuum (c ≈ 2,99792 × 10 m/s);
is the optical frequency.
f
Although the wavelength in dielectric material such as fibres is shorter than in vacuum, only the
wavelength of light in vacuum is used.
3.1.18
chirping
rapid change of the emission wavelengths of a directly intensity-modulated optical source as
a function of the intensity of the modulating signal
NOTE 1 Chirping should not be confused with long-term wavelength drift.
NOTE 2 Due to the fibre chromatic dispersion, using a single-mode laser, chirping can cause either degradation or
improvement of the total bandwidth.
[IEC 61931, definition 2.7.44]
3.1.19
polarization
orientation of the electric field vector of the electromagnetic radiation
[IEC 61931, definition 2.1.44]
3.1.20
linewidth
spectral bandwidth of an individual mode of a laser, defined as the difference between those
optical frequencies at which the amplitude reaches or first falls to half of the maximum
amplitude
3.1.21
coherence length
propagation distance over which propagating light may be considered to be coherent radiation
[IEV 731-01-17 modified]
NOTE The coherence length in a medium of refractive index n is approximately
λ /(n⋅∆λ)
60728-6 ¤ IEC:2003(E) – 13 –
where
λ is the central wavelength;
∆λ is the spectral linewidth of the source.
[IEC 61931, definition 2.1.67]
3.1.22
coherence time
time over which a propagating light may be considered to be coherent radiation
[IEV 731-01-18]
NOTE 1 The coherence time is equal to coherence length divided by the phase velocity of light in a medium.
NOTE 2 The coherence time is given approximately λ /(c⋅∆λ) where λ is the central wavelength, ∆λ is the
0 0
spectral linewidth and c is the velocity of light in vacuum.
[IEC 61931, definition 2.1.68]
3.1.23
well-cleaved
well-cleaved end of fibre has a clean plane front perpendicular to the axis of the fibre
3.1.24
amplified spontaneous emission
ASE
optical power associated to spontaneously emitted photons amplified by an active medium in
an optical amplifier
[IEC 61931, definition 2.7.87]
3.1.25
directivity
in a generic optical branching device, measure of the undesired transfer of a portion of optical
power from one input port, when all other ports are optically matched for zero reflection
[IEC 61931, definition 2.6.50]
3.1.26
central wavelength
the average of those wavelengths at which the amplitude of a light source reaches or last falls
to half of the maximum amplitude
3.1.27
spectral width
measure of the wavelength range of a spectrum or spectral characteristic
[IEV 731-06-24 modified]
[IEC 61931, definition 2.7.42]
3.1.28
(stimulated) Brillouin scattering
SBS
non-linear scattering of optical radiation characterized by a frequency shift as for the Raman
scattering, but accompanied by a lower frequency (acoustical) vibration of the medium lattice.
The light is scattered backward with respect to the incident radiation
NOTE In silica fibres the frequency shift is typically around 10 GHz.
[IEC 61931, definition 2.1.88]

– 14 – 60728-6 ¤ IEC:2003(E)
3.1.29
saturation output power (gain compression power)
optical power level associated with the output signal above which the gain is reduced by N dB
(typically N=3) with respect to the small-signal gain at the signal wavelength.
NOTE The wavelength at which the parameter is specified shall be stated.
[IEC 61291-1, definition 3.1.11]
3.1.30
optical return loss; return loss; ORL (abbreviation)
ratio, expressed in dB, of the total reflected power to the incident power from an optical fibre,
optical device, or optical system, and defined as:
P
r
−10lg
P
i
where
P is the reflected power;
r
P is the incident power.
i
NOTE 1 When referring to a reflected power from an individual component, reflectance is the preferred term.
[IEC 61931, definition 2.6.49]
NOTE 2 For the purposes of this standard, the term reflectance is used for optical amplifiers only. The term optical
return loss is used for ports of all other types of equipment.
NOTE 3 The term return loss is also used for electrical ports. The definition relates to electrical powers in this
case.
3.1.31
cladding mode
mode in which the electromagnetic field is confined in the cladding and the core by virtue of
there being a lower refractive index medium surrounding the outermost cladding
[IEV 731-03-60]
[IEC 61931, definition 2.4.10]
3.1.32
slope
gain or attenuation difference at two defined frequencies between any two ports of a device or
system
3.1.33
flatness
difference between the maximum and the minimum gain or attenuation reduced by the slope
within the specified modulation frequency range of a device or system
3.1.34
small-signal gain
gain of an optical amplifier operated in its linear region where this gain is independent from the
optical input power
NOTE This parameter can be given for a single wavelength or as a function of the wavelength.
3.1.35
polarization dependent loss
maximum change in insertion loss for all states of input polarization

60728-6 ¤ IEC:2003(E) – 15 –
3.1.36
centroidal wavelength
mean or average wavelength of an optical spectrum
3.2 Symbols
The following graphical symbols are used in the figures of this standard. These symbols are
either listed in IEC 60617 or based on symbols defined in IEC 60617.
O
E
Optical transmitter Optical receiver
[S00213] [S00213]
E
O
Optical amplifier Optical fibre
[S00127, S01239] [S01318]
Isolator Coupler
[S01175] [S00059, S01188]
Directional coupler Delay line
[S00059, S01193] [S00608]
τ
Polarisation control device Low-pass filter
[S001430, proposed] [S01248]
Bandpass filter Variable attenuator
[S01249] A [S01245]
G G
Pulse generator Sine-wave generator
[S01228] [S00899, S01403]
G Voltmeter
Bit pattern generator V
[S00059, S00913]
Ammeter Power meter
A P
[S00059, S00910] [S00059, S00910]
Selective voltmeter
Oscilloscope
[S00059, S00081,
[S00059, S00922] V
S00913, S01249]
Electrical spectrum analyzer Optical spectrum analyzer
P(f)
P(λ)
[S00059, S00910] [S00059, S00910]

– 16 – 60728-6 ¤ IEC:2003(E)
RF choke Resistor
[S00583] [S00555]
Capacitor DC power supply
[S00567] [S00206]
Amplifier Photodiode with fibre pigtail
[S01239] [S01327]
Ground
[S01410]
3.3 Abbreviations
The following abbreviations are used in this standard:
AC alternating current
AGC automatic gain control
ALC automatic level control
ASE amplified spontaneous emission
CATV community antenna television (network)
C/N carrier-to-noise ratio
CSO composite second order
CTB composite triple beat
CW continuous wave
DC direct current
EMC electromagnetic compatibility
IF intermediate frequency
MATV master antenna television (network)
MTBF mean time between failure
NEP noise equivalent power
NF noise figure
PDL polarization dependent loss
PRBS pseudo random bit sequence
RF radio frequency
RIN relative intensity noise
SMATV satellite master antenna television (network)
WDM wavelength division multiplexing
XM composite crossmodulation
60728-6 ¤ IEC:2003(E) – 17 –
4 Methods of measurement
4.1 General measurement requirements
For all methods of measurements described in this clause the following requirements shall be
considered.
4.1.1 Input specification
The following conditions shall be obtained from the device specification:
• supply voltage(s);
• control signal(s), if any, with correct impedance, level and frequency.
4.1.2 Measurement conditions
Unless otherwise specified, all measurement shall be carried out under following conditions:
• the ambient or reference point temperature shall be 25 °C ± 5 °C;
• the ambient humidity shall be in the range 40 % to 70 %;
• sufficient care shall be taken to ensure that optical reflection does not impair the accuracy
of the measurement;
• during measurement any control input signal(s) shall be held constant.
• test fibres shall have clean and unscratched ends in order to prevent losses of power and
reflections.
4.2 Optical power
4.2.1 Purpose
The purpose of this test method is to measure the total average optical power emanating from
the end of a test fibre. The test fibre and the coupling means shall be as specified by the
manufacturer. The optical power shall be expressed in dB(mW).
4.2.2 Equipment required
a) An optical power meter with a range suitable for the expected power. The detector system
of the power meter shall have a sufficiently large area to collect all the radiation from the
test fibre and a spectral sensitivity compatible with the light source. A minimum accuracy of
±10 % is recommended.
b) A length of fibre for connecting the light source to the power meter.
c) A cladding mode stripper if the fibre has no cladding mode stripping coating.
d) Test signal generator(s).
4.2.3 General measurement requirements
a) The transmitter shall be modulated with at least one modulation carrier at the specified
optical modulation index.
b) Cladding modes shall be stripped from the fibre by means of suitable cladding mode
stripping techniques.
...