IEC 61290-1-2:2026

IEC 61290-1-2 ®
Edition 3.0 2026-02
INTERNATIONAL
STANDARD
REDLINE VERSION
Optical amplifiers - Test methods -
Part 1-2: Power and gain parameters - Electrical spectrum analyzer method
ICS 33.180.30 ISBN 978-2-8327-1054-8
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CONTENTS
FOREWORD . 2
INTRODUCTION .
1 Scope . 4
2 Normative references . 5
3 Terms, definitions, abbreviated terms, and symbol . 5
3.1 Terms and definitions. 5
3.2 Abbreviated terms . 5
3.3 Symbols . 5
4 Apparatus . 5
5 Test sample . 8
6 Procedures . 9
7 Calculation . 12
8 Test results . 13
Bibliography . 16

Figure 1 – Typical arrangement of the electrical spectrum analyzer test apparatus for
measurement of average optical input signal power, electrical input signal power, and
electrical output signal power . 6
Figure 2 – Typical behaviour variation of gain as a function of input signal power . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Optical amplifiers - Test methods -
Part 1-2: power and gain parameters -
Electrical spectrum analyzer method

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
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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
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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
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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
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 61290-1-2:2005. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 61290-1-2 has been prepared by subcommittee 86C: Fibre optic systems, sensing and
active devices, of IEC technical committee 86: Fibre optics. It is an International Standard.
This third edition cancels and replaces the second edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) addition of information on the applicability of this document to the scope;
b) harmonization of the scope with the IEC 61290-1 series;
c) addition of safety recommendations to Clause 4 and Clause 5;
d) correction of an error in Clause 7, item e);
e) replacement of the term "wavelength measurement accuracy" with "wavelength accuracy".
The text of this International Standard is based on the following documents:
Draft Report on voting
86C/1973/CDV 86C/1991/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/publications.
A list of all parts in the IEC 61290 series, published under the general title Optical amplifiers -
Test methods, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
This International Standard is devoted to the subject of optical amplifiers. The technology of
optical amplifiers is still rapidly evolving, hence amendments and new editions to this standard
can be expected.
Each abbreviation introduced in this International Standard is explained in the text at least the
first time it appears. However, for an easier understanding of the whole text, a list of all
abbreviations used in this International Standard is given in Clause 3.
1 Scope
This part of IEC 61290 applies to all commercially available optical amplifiers (OAs) and
optically amplified sub-systems. It applies to OAs using optically pumped fibres (OFAs based
on either rare-earth doped fibres or on the Raman effect), semiconductors (SOAs), and planar
optical waveguides (POWAs). This document does not apply to polarization-maintaining optical
amplifiers.
NOTE The applicability of the test methods described in the present standard to distributed Raman amplifiers is for
further study.
This document defines uniform requirements for accurate and reliable measurements, by means
of the electrical spectrum analyzer test method, of the following OA parameters, as defined in
IEC 61291-1, Clause 3:
a) nominal output signal power;
b) gain;
c) reverse gain;
d) maximum gain;
e) polarization-dependent gain.
f) large-signal output stability;
g) saturation output power;
h) maximum input signal power;
i) maximum output signal power;
j) input power range;
k) output power range;
l) maximum total output power.
In addition, this test method provides a means for measuring the following parameters:
– maximum gain wavelength;
– gain wavelength band.
NOTE All numerical values followed by (‡) are suggested values for which the measurement is assured. Other
values may be acceptable, but should be verified.
This document specifically covers single-channel amplifiers. For multichannel amplifiers, the
IEC 61290-10 series applies.
NOTE 1 The applicability of the test methods described in this document to distributed Raman amplifiers is for
further study.
NOTE 2 A test method for polarization-maintaining optical amplifiers is for further study.

See Bibliography.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60793-1-40, Optical fibres - Part 1-40: Measurement methods and test procedures -
Attenuation
IEC 61291-1:2005, Optical amplifiers - Part 1: Generic specification
3 Terms, definitions, abbreviated terms, and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61291-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.2 Abbreviated terms
ASE amplified spontaneous emission
DBR distributed Bragg reflector (laser diode)
DFB distributed feedback (laser diode)
ECL external cavity laser (diode)
LED light emitting diode
OA optical amplifier
OFA optical fibre amplifier
POWA planar optical waveguide amplifier
SOA semiconductor optical amplifier
3.3 Symbols
(‡) indicates a suggested value for which a measurement is assured.
4 Apparatus
A diagram of the measurement set-up is given in Figure 1.

A first edition of IEC 61291-1 was published in 1998 under the title Optical fibre amplifiers – Part 1: Generic
specification.
a) Average optical input signal power

b) Electrical input signal power

c) Electrical output signal power

Key
J1, J2 Optical connectors
Figure 1 – Typical arrangement of the electrical spectrum analyzer test apparatus for
measurement of average optical input signal power, electrical input signal power, and
electrical output signal power
The test equipment items with their required characteristics listed in a) to k) in this clause, is
needed shall be used.
a) Optical source: the optical source shall be either at a fixed wavelength or wavelength
tuneable.
1) Fixed-wavelength optical source: the optical source shall generate light with a
wavelength and optical power specified in the relevant detail specification. The optical
source shall emit modulated light with the full width at half maximum of the spectrum
narrower than 1 nm (‡), unless otherwise specified in the relevant detail specification. A
distributed feedback (DFB) laser, a distributed Bragg reflector (DBR) laser, an external
cavity laser (ECL) diode and, or a light-emitting diode (LED) with a narrow-band filter
are applicable can be used as the optical source, for example. The suppression ratio for
of the side modes for the DFB laser, the DBR laser or, and the ECL shall be higher than
30 dB (‡). The output power fluctuation shall be less than 0,05 dB (‡), which may be
better attainable with can require the insertion of an optical isolator at the output port of
the optical source. Spectral broadening at the foot of the lasing spectrum shall should
be minimal for laser sources.
2) Wavelength-tuneable optical source: this optical source shall be able to generate
wavelength-tuneable light within the wavelength range specified in the relevant detail
specification. Its optical power shall be specified in the relevant detail specification. The
optical source shall emit modulated light with the full width at half maximum of the
spectrum narrower than 1 nm (‡), unless otherwise specified in the relevant detail
specification. An ECL or a LED with a narrow bandpass optical filter is applicable can
be used as the optical source, for example. The suppression ratio of side modes for the
ECL shall be higher than 30 dB (‡). The output power fluctuation shall be less than
0,05 dB, which may be better attainable with can require the insertion of an optical
isolator at the output port of the optical source. Spectral broadening at the foot of the
lasing spectrum shall should be minimal for the ECL.
NOTE The use of a LED should be limited to small-signal gain measurements.
NOTE 1 The regime of small-signal gain is the range of input signal power sufficiently small so that the OA
under test operates in the linear region. This regime can be found by plotting the signal gain G versus the
averaged input optical signal power [see Formula (3)]. The linear region is the range of input optical signal
powers where the gain is nearly independent of input optical signal power (see Figure 2). An averaged input
optical signal power between −30 dBm and −40 dBm is generally well within this range. In the saturated
region, the signal power is large enough to well suppress the ASE.

Figure 2 – Typical behaviour variation of gain as a function of input signal power
b) Optical power meter: it shall have a measurement accuracy better uncertainty less than
±0,2 dB, irrespective of the state of polarization, within the operational wavelength
bandwidth of the OA. The optical power meter shall have a dynamic range that exceeds the
measured gain is required (e.g. 40 dB).
c) Electrical spectrum analyzer: the spectral-power-measurement error shall be better than
within ±0,5 dB (optical). The linearity shall be better than within ±0,2 dB (optical).
d) Optical isolator: optical isolators may be used to bracket at the input and output ports of the
OA. The polarization-dependent loss variation of the isolator shall be better less than 0,2 dB
(‡). Optical isolation shall be better higher than 40 dB (‡). The reflectance from this device
shall be smaller less than −40 dB (‡) at each port.
e) Variable optical attenuator: the attenuation range and stability shall be over 40 dB (‡) and
better than within ±0,1 dB (‡), respectively. The reflectance from this device shall be smaller
less than –40 dB (‡) at each port.
f) Polarization controller: this device shall be able to provide as input signal light all possible
states of polarization (e.g. linear, elliptical and circular). For example, the polarization
controller may can consist of a linear polarizer followed by an all-fibre-type polarization
controller, or of a linear polarizer followed by a quarter-wave plate rotatable by minimum of
90° and a half-wave plate rotatable by minimum of 180°. The loss variation of the
polarization controller shall be less than 0,2 dB (‡). The reflectance from this device shall
be smaller less than −40 dB (‡) at each port. The use of a polarization controller is
considered optional, except for the measurement of polarization-dependent gain, but may
also can be necessary to achieve the desired accuracy of other power and gain parameters
for OA devices exhibiting significant polarization-dependent gain.
g) Optical fibre jumpers: the mode field diameter of the optical fibre jumpers used should be
as close as possible to that of fibres used as input and output ports of the OA. The
reflectance from this device shall be smaller less than −40 dB (‡) at each port, and the
length of the jumper shall be shorter than 2 m.
h) Optical connectors (J1 and J2 in Figure 1): the connection loss repeatability shall be better
than within ±0,2 dB.
i) Optical detector: this device shall be highly polarization insensitive and have a linearity
better than within ±0,2 dB. To minimize the saturation effects due to high DC levels, the
optical detector output shall be AC coupled. The maximum safe input power of the optical
detector should be sufficiently large to ensure safe testing of the OA.
NOTE In order to minimize the saturation effects due to high d.c. levels, the optical detector output shall be
a.c. coupled.
NOTE 2 The maximum safe input power to the optical detector can be effectively increased by adding an optical
attenuator with very low polarization sensitivity in front of the optical detector and using it as an integral part of
the optical detector.
j) Signal generator: the signal generator shall generate a sinusoidal wave at a frequency
higher than several hundreds of kilohertz with a linearity better than within ±1,5 dB.
NOTE 3 For small-signal gain measurements an optical chopping system could can be used alternatively.
k) Optical coupler: the polarization dependence of the branching ratio of the coupler shall
should be minimal. Change of the state of polarization of the input light shall should be
negligible. Any free port of the coupler shall be properly terminated in such a way as to
decrease the reflectance below to less than −40 dB (‡).
5 Test sample
The sample type and test parameters shall be confirmed prior to the test.
The OA shall operate at nominal operating conditions. If the OA is likely to cause laser
oscillations due to unwanted reflections, optical isolators should be used to bracket at the input
and output ports of the OA under test. This will minimize the signal instability and the
measurement inaccuracy uncertainty.
For measurements of parameters a) to l) d) of Clause 1 except e), care shall be taken in
maintaining, the state of polarization of the input light shall be maintained during the
measurement. Changes in the polarization state of the input light may can result in input optical
power changes because of the slight polarization dependency expected from all the optical
components used, this leading to measurement errors slight polarization dependence of the
optical components used in the amplifier. This polarization dependence can lead to
measurement errors.
For safety reasons, the optical signal power should be reduced by adjusting the optical source
or variable optical attenuator each time a connector is inserted or removed during the
measurement. Other protective measures are described in IEC 60825-1 and IEC 60825-2.
6 Procedures
The related measurement procedure is as follows a) to h).
a) Nominal output signal power: the nominal output signal power is the minimum output signal
optical power that is obtained at the input signal optical power specified in the relevant detail
specification under the nominal operating conditions specified in the relevant detail
specification.
To find this minimum value, input and output signal power levels shall be continuously
monitored for a given duration of time, and in presence of changes in the state of polarization
and other instabilities, as specified in the relevant detail specification. The measurement
procedures described below in steps 1) to 10) shall be followed, with reference to Figure 1.
1) Set the optical source at the test wavelength specified in the relevant detail specification.
2) Measure the branching ratio of the optical coupler through the signal power levels exiting
the two output ports, with an optical power meter.
3) Measure the loss, L , of the optical fibre jumper between the OA and the optical detector
j
[see Figure 1c)] by the insertion loss technique described in IEC 60793-1-40, Method B.
4) Set the signal generator in a way that the light emitted by the optical source is intensity
modulated at the frequency specified in the detail specification. The modulation
frequency shall be higher than several hundreds of kilohertz (e.g. 1 MHz) to avoid
waveform distortion due to slow gain response, unless otherwise specified. The
modulation depth shall be unchanged during the measurement.
5) For measuring optical powers with the electrical spectrum analyzer, the following
calibration procedure (of the electrical spectrum analyzer) is needed, the electrical
spectrum analyzer shall be calibrated as follows using an optical power meter:
i) for calibration, set the time-averaged optical power P using an optical power meter
cal
[see Figure 1a)], as specified in the relevant detail specification;
ii) measure the AC component of the input signal electrical power P with the optical
e,cal
detector and the electrical spectrum analyzer.
Keep the modulation depth unchanged during the measurement. The time-averaged
optical signal power P shall be derived from the AC component of the corresponding
signal electrical power P (measured with the electrical spectrum analyzer) using
e
Formula (1).
P= P PP
(1)
cal e e,cal
6) Set the optical source and the variable optical attenuator in such a way as to provide,
at the input port of the OA, the time-averaged input optical signal power specified P
in
in the relevant detail specification. Record the time-averaged optical power P
o
measured with an optical power meter at the other (second) output port of the optical
coupler, as shown in Figure 1a).
7) Keep the time-averaged optical signal power P at the OA input constant during the
in
following measurements, by monitoring the second output port of the coupler and, if
necessary, setting the variable optical attenuator in such a way that the time-averaged
optical power P exiting the second output port of the optical coupler remains constant.
o
8) Set the polarization controller at a given state of polarization as specified in the
relevant detail specification, and monitor, by means of the electrical spectrum
analyzer, the (time-averaged) optical signal power at the output of the OA for the
specified period of time, recording the minimum value.
9) Change the state of polarization of the input signal by means of the polarization
controller, trying to minimize the output optical signal power measure with the electrical
spectrum analyzer, and repeat step 8).
10) Repeat step 9) for the different states of polarization indicated in the relevant detail
specification, and finally take the absolute minimum output optical signal power
recorded in the various conditions: P .
out-min
NOTE 1 Optical connectors J1 and J2 should not be removed during the measurement
to avoid additional measurement errors uncertainty due to reconnection.
NOTE 2 The polarization controller should be operated as specified in the relevant
detail specifications. A possible way, when using a linear polarizer followed by a
quarter-wave rotatable plate, is the following When using a linear polarizer followed by
a rotatable quarter-wave plate and a rotatable half-wave plate, the polarization
controller can be operated as follows:
i) the linear polarizer is adjusted so that the OA output power is maximized;
ii) the quarter-wave plate is then rotated by at least 90° in small steps;
iii) at each step of the quarter-wave plate, the half-wave plate is rotated by at least
180° in small steps.
b) Gain: as in a), but this method permits determination of the gain, by measuring the
modulated electrical power, S and S , corresponding to the OA input and output signal
in out
powers, respectively, at the signal wavelength. The method, using a modulated input signal
and an electrical spectrum analyzer, permits discrimination of the output signal from the
amplified spontaneous emission (ASE) because the ASE is free of modulation at the
specified frequency. Thus, after filtering out the DC power component, the electrical output
power at the modulation frequency is considered free of the ASE. The measurement
procedures described below in steps 1) to 5) shall be followed.
1) Set the signal generator in such a way that the light emitted by the optical source is
intensity modulated at the frequency specified in the detail specification. The modulation
frequency shall be higher than several hundreds of kilohertz (e.g. 1 MHz) to avoid
waveform distortion due to slow gain response, unless otherwise specified.
2) Set the optical source to the test wavelength specified in the relevant detail specification.
3) Measure the time-averaged input optical signal power with the optical power meter, as
shown in Figure 1a), for calibration reference. Set the optical source and the variable
optical attenuator in a way to provide, at the input port of the OA, the time-averaged
input optical signal power specified in the relevant detail specification.
4) Measure the electrical power, S , corresponding to the specified time-averaged input
in
optical signal power at the modulation frequency by means of the optical detector and
the electrical spectrum analyzer, as shown in Figure 1b).
5) Measure the electrical power, S , corresponding to the OA output optical signal at the
out
modulation frequency by means of the optical detector and the electrical spectrum
analyzer, as shown in Figure 1c).
NOTE Optical connectors J1 and J2 should not be removed during the measurement to avoid measurement

error due to reconnection.
c) Reverse gain: as in b), but with the OA operating with the input port used as output port and
vice-versa.
d) Maximum gain: as in b), but using a wavelength-tuneable optical source. Repeat steps 1) to
5) at different wavelengths to cover the wavelength range specified in the relevant detail
specification, and replace step 2) with the following step 2):
2) Set the wavelength-tuneable optical source at a test wavelength within the specified
wavelength range.
NOTE 1 The wavelength should be changed by steps smaller than 1 nm (‡) around the
wavelength where the ASE spectral profile, observed (e.g. with an optical spectrum analyzer
or a monochromator) without the input signal, takes its maximum value, unless otherwise
specified.
NOTE 2 A wavelength measurement accuracy of ±0,01 nm, around 1 550 nm, is attainable can be attained with
commercially available wavelength meters based on interference-fringes counting techniques. Some tuneable
external-cavity laser-diode instruments provide a wavelength measurement accuracy of ±0,2 nm or better.
e) Maximum gain wavelength: as in d).
f) Maximum gain variation with temperature: Under consideration.
f) Gain wavelength band: as in d).
g) Gain variation: as in d).
i) Gain stability: Under consideration.
h) Polarization-dependent gain: as in b), but using a polarization controller between the
variable optical attenuator and the connector J1 (see Figure 1); repeat steps 1) to 5) at
different states of polarization as specified in the relevant detail specification, and replace
step 2) with the following step 2):
2) Set the optical source to the test wavelength specified in the relevant detail specification.
Set the polarization controller at a given state of polarization as specified in the relevant
detail specification.
NOTE 1 The state of polarization of the input signal should be changed after each
measurement of S and S by means of the polarization controller, so that substantially
in out
all the states of polarization, in principle, are successively launched into the input port
of the OA under test.
NOTE 2 The polarization controller should be operated as specified in the relevant detail
specifications. A possible way, When using a linear polarizer followed by a quarter-wave
rotatable plate, is the following When using a linear polarizer followed by a rotatable
quarter-wave plate and a rotatable half-wave plate, the polarization controller can be
operated as follows:
i) the linear polarizer should be is adjusted so that the OA output power is maximized;
ii) the quarter-wave plate is then rotated by at least 90° in small steps;
iii) at each step of the quarter-wave plate, the half-wave plate is rotated by at least 180°
in small steps.
Another possible way is Alternatively, the polarization controller can be operated to select
four known and specified states of polarization to allow matrix calculation of the resulting
polarization-dependent gain.
NOTE 3 A short optical jumper at the OA input, kept as straight or and stable as possible,
should be used, in order to minimize the change of the state of polarization induced in it the
jumper by possible stress and anisotropy.
NOTE 4 The polarization-dependent loss of the optical connector should be less than 0,2 dB
(‡).
k) Large-signal output stability: under consideration.
l) Saturation output power: under consideration.
m) Maximum input signal power: under consideration.
n) Maximum output signal power: under consideration.
o) Input power range: under consideration.
p) Output power range: under consideration.
q) Maximum total output power: under consideration.
7 Calculation
Calculation is carried out as follows described below in steps a) to h).
a) Nominal output signal power: the nominal output signal power P (in dBm) shall be calculated
using Formula (2).
P = 10 log (P ) + L (dBm)
out-min j
P 10 log PL+
( )
(2)
10 out-min j
where
P is the recorded absolute minimum value of output optical signal power (in mW);
out-min
L is the insertion of the optical fibre jumper placed between the OA and the optical
j
detector (in dB).
NOTE 1 The measurement error uncertainty can be better than ±0,5 dB (‡), depending mainly on the accuracy
of the electrical spectrum analyzer accuracy.
b) Gain:
The gain G at the signal wavelength shall be calculated as:
S (with el. mod .) − S (without el. mod.)
out out
G = (linear units)
S (with el. mod .) − S (without el. mod .)
in in
or
S (with el. mod .) − S (without el. mod.)
out out
G = 5 log  (dB)
S (with el. mod .) − S (without el. mod .)
in in
NOTE 1 The small-signal regime is the range of input signal power sufficiently small so that the OA under test
operates in the linear regime. This regime can be established by plotting G versus the averaged input optical
signal power. The linear regime demands averaged input optical signal power to be in the range where the gain
is quite independent from it (see Figure 2). An averaged input optical signal power ranging from –30 dBm to –

40 dBm is generally well within this range. In the saturated regime, the signal power is large enough to well
suppress the ASE.
NOTE 2 The measurement error can be better than ±0,4 dB (‡), depending mainly on the optical detector and
electrical spectrum analyzer linearities.
the gain G at the signal wavelength shall be calculated either in linear units using Formula
(3) or in units of dB using Formula (4).
SS−
out-m out-0
G=
(3)
S − S
in-m in-0
SS−
out-m out-0
G= 5 log
 (4)
S − S
in-m in-0
where
S is the modulated electrical power measured by the electrical spectrum analyzer at
out-m
the OA output, expressed in mW;
=
S is the modulated electrical power measured by the electrical spectrum analyzer at
in-m
the OA input, expressed in mW;
S is the electrical power measured by the electrical spectrum analyzer at the OA
out-0
output without intensity modulation of the optical source, expressed in mW;
S is the electrical power measured by the electrical spectrum analyzer at the OA input
in-0
without intensity modulation of the optical source, expressed in mW.
NOTE 2 The measurement uncertainty can be better than ±0,4 dB (‡), depending mainly on the linearity of the
optical detector and the linearity of the electrical spectrum analyzer.
c) Reverse gain: as in b).
d) Maximum gain: calculate the gain values at the different wavelengths, as in b). The
maximum gain shall be given by the highest of all these gain values.
e) Maximum gain wavelength: calculate the maximum gain as in d). The maximum gain
wavelength shall be that wavelength at which the maximum small-signal gain occurs.
f) Maximum gain variation with temperature: Under consideration.
f) Gain wavelength band: calculate the maximum gain as in d). Identify those wavelengths at
which the gain is N dB below the maximum gain. The gain wavelength band shall be given
by the wavelength interval(s), comprised between those wavelengths, within which the gain
is between the maximum gain value and a value N dB below the maximum gain.
NOTE 3 A value of N = 3 is typically applied.
g) Gain variation: calculate the maximum gain as in d). Calculate the minimum gain as the
lowest of all gain values within the specified measurement wavelength range. The gain
variation shall be the difference between the maximum and the minimum gain values.
i) Gain stability: Under consideration.
h) Polarization-dependent gain: calculate the gain values at the different states of polarization,
as in b). Identify the maximum gain, G , and the minimum gain, G , as the highest and
max min
the lowest of all these gain values, respectively. The polarization-dependent gain ∆G ,
p
expressed in dB, is calculated using Formula (5).
ΔGG− G
(5)
p max min
where
G is the maximum gain, expressed in dB;
max
G is the minimum gain, expressed in dB.
min
NOTE 4 G is defined as the same as G in b). G is defined as G in which P is replaced by P .
min max out-min out-max
NOTE 5 ∆G does not necessarily indicate the possible maximum variation of the polarization dependency.
p
This is because the attenuation through the OA under test is maximum only when each input state of polarization
simultaneously yields maximum attenuation in each component in the OA under test.
NOTE 6 The measurement error can be within ±0,4 dB (‡), depending mainly on thepolarization dependency
of the optical detector.
k) Large-signal output stability: under consideration.
l) Saturation output power: under consideration.
m) Maximum input signal power: under consideration.
n) Maximum output signal power: under consideration.
o) Input power range: under consideration.
p) Output power range: under consideration.
q) Maximum total output power: under consideration.
=
8 Test results
The following test results shall be presented recorded.
a) Nominal output signal power:
the following details shall be presented recorded:
1) arrangement of the test set-up;
2) spectral linewidth (full width at half maximum) of the optical source;
3) indication of the optical pump power and possibly driving current of pump lasers for
OFAs and injection current for SOAs (if applicable);
4) operating temperature (if required);
5) time-averaged input signal optical power P ;
in
6) resolution bandwidth of the electrical spectrum analyzer;
7) wavelength of the measurement;
8) nominal output signal power levels;
9) change in the state of polarization given to the input signal light.
b) Gain: the details 1) - 7) from a) shall be presented recorded in addition to:
8) gain.
NOTE 1 Parameters Details 5) and 8) can be replaced with the gain versus the averaged input signal optical
power curve.
c) Reverse gain: the details 1) to 7), previously listed for the gain, shall be presented recorded
and, in addition:
89) reverse gain.
NOTE 2 Parameters Details 5) and 8) can be replaced with the reverse small-signal gain versus the averaged
input signal optical power curve.
d) Maximum gain: the details 1) to 7), previously listed for the gain, shall be presented recorded
and, in addition to:
8) wavelength range of the measurement;
9) wavelength measurement accuracy;
10) maximum gain.
NOTE 3 Parameters Details 5) and 10) can be replaced with the maximum gain versus the averaged input
signal optical power curve.
e) Maximum gain wavelength: the details 1) to 7), previously listed for the gain, shall be
presented recorded and, in addition to:
8) wavelength range of the measurement;
9) wavelength measurement accuracy;
10) maximum gain wavelength.
NOTE 4 Parameters Details 8) and 10) can be replaced with the gain versus input signal wavelength curve.
f) Maximum gain variation with temperature: Under consideration.
f) Gain wavelength band: The details 1) to 7), previously listed for the gain, shall be presented
recorded and, in addition to:
8) wavelength range of the measurement;
9) wavelength measurement accuracy;
10) gain wavelength band;
11) the value of N chosen for the determination of the wavelength bandwidth.
NOTE 5 Parameters Details 8) and 10) and 11) can be replaced with the gain versus input signal wavelength
curve.
g) Gain variation: The details 1) to 7), previously listed for the gain, shall be presented
recorded and, in addition:
8) wavelength range of the measurement;
9) wavelength measurement accuracy;
10) gain variation.
NOTE 6 Parameters Details 8) and 10) can be replaced with the gain versus input signal wavelength curve.
i) Gain stability: Under consideration.
h) Polarization-dependent gain: The details 1) to 8), previously listed for the gain, shall be
presented recorded and, in addition:
9) polarization dependency of the optical detector;
10) the maximum and minimum gain, G and G ;
max min
11) polarization-dependent gain;
12) change in the state of polarization given to the input signal light.
k) Large-signal output stability: under consideration.
l) Saturation output power: under consideration.
m) Maximum input signal power: under consideration.
n) Maximum output signal power: under consideration.
o) Input power range: under consideration.
p) Output power range: under consideration.
q) Maximum total output power: under consideration.

Bibliography
IEC 60793-1-1, Optical fibres – Part 1-1: Measurement methods and test procedures – General
and guidance
IEC 60825-1, Safety of laser products - Part 1: Equipment classification and requirements and
user's guide
IEC 60825-2, Safety of laser products - Part 2: Safety of optical fibre communication systems
(OFCS)
IEC 60874-1, Connectors for optical fibres and cables – Part 1: Generic specification
IEC 61931, Fibre optic – Terminology
IEC 61290 (all parts), Optical amplifiers - Test methods
IEC 61290-10 (all parts), Optical amplifiers - Test methods - Part 10: Multichannel parameters
IEC 61290-10-1, Optical amplifiers – Test methods – Part 10-1: Multichannel parameters –
Pulse method using an optical switch and optical spectrum analyzer
IEC 61290-10-2, Optical amplifiers – Test methods – Part 10-2: Multichannel parameters –
Pulse method using a gated optical spectrum analyzer
IEC 61290-10-3, Optical amplifiers – Test methods – Part 10-3: Multichannel parameters –
Probe methods
___________
IEC 61290-1-2 ®
Edition 3.0 2026-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
...

IEC 61290-1-2 ®
Edition 3.0 2026-02
NORME
INTERNATIONALE
Amplificateurs optiques - Méthodes d'essai -
Partie 1-2: Paramètres de puissance et de gain - Méthode de l'analyseur de
spectre électrique
ICS 33.180.30  ISBN 978-2-8327-0943-6

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SOMMAIRE
AVANT-PROPOS . 2
1 Domaine d'application . 4
2 Références normatives . 4
3 Termes, définitions, abréviations et symboles . 5
3.1 Termes et définitions . 5
3.2 Abréviations . 5
3.3 Symboles . 5
4 Matériel . 5
5 Échantillon d'essai . 8
6 Procédure . 8
7 Calcul . 11
8 Résultats des tests . 13
Bibliographie . 15

Figure 1 – Disposition typique de l'appareil d'essai de l'analyseur de spectre électrique
pour la mesure de la puissance moyenne du signal d'entrée optique, de la puissance
du signal d'entrée électrique et de la puissance du signal de sortie électrique . 6
Figure 2 – Variation typique du gain en fonction de la puissance du signal d'entrée . 7

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
Amplificateurs optiques - Méthodes d'essai -
Partie 1-2 : paramètres de puissance et de gain -
Méthode de l'analyseur de spectre électrique

AVANT-PROPOS
1) La Commission Electrotechnique Internationale (IEC) est une organisation mondiale de normalisation composée
de l'ensemble des comités électrotechniques nationaux (Comités nationaux de l'IEC). L'IEC a pour objet de
favoriser la coopération internationale pour toutes les questions de normalisation dans les domaines de
l'électricité et de l'électronique. À cet effet, l'IEC – entre autres activités – publie des Normes internationales,
des Spécifications techniques, des Rapports techniques, des Spécifications accessibles au public (PAS) et des
Guides (ci-après dénommés "Publication(s) de l'IEC"). Leur élaboration est confiée à des comités d'études, aux
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2) Les décisions ou accords officiels de l'IEC concernant les questions techniques représentent, dans la mesure du
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référencées est obligatoire pour une application correcte de la présente publication.
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ou de plusieurs brevets. L'IEC ne prend pas position quant à la preuve, à la validité et à l'applicabilité de tout
droit de brevet revendiqué à cet égard. À la date de publication du présent document, l'IEC n'avait pas reçu
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L'IEC ne saurait être tenue pour responsable de ne pas avoir identifié de tels droits de propriété et averti de leur
existence.
L'IEC 61290-1-2 a été établie par le sous-comité 86C: Systèmes et dispositifs actifs et de
détection à fibres optiques, du comité d'études 86 de l'IEC: Fibres optiques. Il s'agit d'une
Norme internationale.
Cette troisième édition annule et remplace la deuxième édition parue en 2005. Cette édition
constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition
précédente:
a) ajout d'informations sur l'applicabilité du présent document au domaine d'application;
b) harmonisation du domaine d'application avec la série IEC 61290-1;
c) ajout de recommandations de sécurité à l'Article 4 et à l'Article 5;
d) correction d'une erreur de l'Article7, point e);
e) remplacement du terme "précision de mesure de longueur d'onde" par "précision de
longueur d'onde".
Le texte de cette Norme internationale est issu des documents suivants:
Projet Rapport de vote
86C/1973/CDV 86C/1991/RVC
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant
abouti à son approbation.
La langue employée pour l'élaboration de cette Norme internationale est l'anglais.
Ce document a été rédigé selon les Directives ISO/IEC, Partie 2, il a été développé selon les
Directives ISO/IEC, Partie 1 et les Directives ISO/IEC, Supplément IEC, disponibles sous
www.iec.ch/members_experts/refdocs. Les principaux types de documents développés par
l'IEC sont décrits plus en détail sous www.iec.ch/publications.
Une liste de toutes les parties de la série IEC 61290, publiées sous le titre général
Amplificateurs optiques - Méthodes d'essai, peut être consultée sur le site web de l'IEC.
Le comité a décidé que le contenu de ce document ne sera pas modifié avant la date de stabilité
indiquée sur le site web de l'IEC sous webstore.iec.ch dans les données relatives au document
spécifique. À cette date, le document sera
– reconduit,
– supprimé, ou
– amendé.
1 Domaine d'application
La présente partie de l'IEC 61290 s'applique à tous les amplificateurs optiques (OA) disponibles
dans le commerce et aux sous-systèmes amplifiés optiquement. Elle s'applique aux OA utilisant
des fibres optiquement pompées (AFO basées soit sur des fibres dopées de terres rares, soit
sur l'effet Raman), des semi-conducteurs (SOA) et des guides d'ondes optiques planaires
(POWA). Le présent document ne s'applique pas aux amplificateurs optiques à maintien de
polarisation.
Le présent document définit des exigences uniformes pour des mesures précises et fiables, au
moyen de la méthode d'essai de l'analyseur de spectre électrique, des paramètres OA suivants,
tels que définis dans l'IEC 61291-1, Article 3:
a) puissance nominale du signal de sortie;
b) gain;
c) le gain inverse;
d) gain maximal;
e) gain dépendant de la polarisation.
En outre, cette méthode d'essai fournit un moyen pour mesurer les paramètres suivants:
– longueur d'onde de gain maximal;
– bande de longueur d'onde de gain.
Le présent document couvre spécifiquement les amplificateurs monovoies. Pour les
amplificateurs multicanaux, la série IEC 61290-10 s'applique.
NOTE 1 L'applicabilité des méthodes d'essai décrites dans le présent document aux amplificateurs Raman
distribués doit faire l'objet d'études complémentaires.
NOTE 2 Une méthode d'essai pour les amplificateurs optiques à maintien de polarisation fait l'objet d'études
complémentaires.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu'ils constituent, pour tout ou partie
de leur contenu, des exigences du présent document. Pour les références datées, seule
l'édition citée s'applique. Pour les références non datées, la dernière édition du document de
référence s'applique (y compris les éventuels amendements).
IEC 60793-1-40, Fibres optiques - Partie 1-40: Méthodes de mesure et procédures d'essai -
Affaiblissement
IEC 61291-1, Amplificateurs optiques - Partie 1: spécification générique
3 Termes, définitions, abréviations et symboles
3.1 Termes et définitions
Pour les besoins du présent document, les termes et les définitions de l'IEC 61291-1, ainsi que
les suivants, s'appliquent.
L'ISO et l'IEC tiennent à jour des bases de données terminologiques destinées à être utilisées
en normalisation, consultables aux adresses suivantes :
– IEC Electropedia: disponible à l'adresse https://www.electropedia.org/
– ISO Online browsing platform : disponible à l'adresse https://www.iso.org/obp
3.2 Abréviations
ASE amplified spontaneous emission (émission spontanée amplifiée)
DBR réflecteur de Bragg distribué (diode laser)
La DFB rétroaction distribuée (diode laser)
ECL laser à cavité externe (diode)
LED diode électroluminescente
AO amplificateur optique
OFA amplificateur à fibres optiques
POWA amplificateur plan à guide d'onde optique
SOA amplificateur optique à semiconducteur
3.3 Symboles
(‡) indique une valeur suggérée pour laquelle une mesure est assurée.
4 Matériel
Un schéma du montage de mesure est donné à la Figure 1.

a) Puissance moyenne du signal d'entrée optique

b) Puissance du signal d'entrée électrique
c) Puissance du signal de sortie électrique

Légende
J1, J2 Connecteurs optiques
Figure 1 – Disposition typique de l'appareil d'essai de l'analyseur de spectre électrique
pour la mesure de la puissance moyenne du signal d'entrée optique, de la puissance du
signal d'entrée électrique et de la puissance du signal de sortie électrique
Les équipements d'essai avec leurs caractéristiques exigées énumérées des a) à k) du présent
article doivent être utilisés.
a) Source optique: la source optique doit être soit à une longueur d'onde fixe, soit accordable
en longueur d'onde.
1) Source optique à longueur d'onde fixe: la source optique doit générer de la lumière avec
une longueur d'onde et une puissance optique indiquées dans la spécification
particulière applicable. La source optique doit émettre de la lumière modulée sur toute
la largeur à la moitié du spectre inférieur à 1 nm (‡), sauf indication contraire dans la
spécification particulière applicable. Un laser à rétroaction distribuée (DFB), un laser à
réflecteur de Bragg distribué (DBR), une diode laser à cavité externe (ECL) ou une diode
électroluminescente (DEL) avec filtre à bande étroite peuvent être utilisés comme source
optique, par exemple. Le rapport de suppression des modes latéraux pour le laser DFB,
le laser DBR et l'ECL doit être supérieur à 30 dB (‡). La fluctuation de la puissance de
sortie doit être inférieure à 0,05 dB (‡), ce qui peut exiger l'insertion d'un isolateur
optique au niveau du port de sortie de la source optique. Il convient que l'élargissement
spectral au pied du spectre laser soit minimal pour les sources laser.
2) Source optique accordable en longueur d'onde: cette source optique doit être en mesure
de générer un rayonnement lumineux accordable en longueur d'onde dans la plage de
longueurs d'onde stipulée dans la spécification particulière applicable. Sa puissance
optique doit être stipulée dans la spécification particulière applicable. La source optique
doit émettre de la lumière modulée sur toute la largeur à la moitié du spectre inférieur à
1 nm (‡), sauf indication contraire dans la spécification particulière applicable. Une ECL
ou une DEL avec un filtre optique passe-bande étroit peut être utilisée comme source
optique, par exemple. Le rapport de suppression des modes latéraux pour l'ECL doit
être supérieur à 30 dB (‡). La fluctuation de la puissance de sortie doit être inférieure à
0,05 dB, ce qui peut exiger l'insertion d'un isolateur optique au niveau du port de sortie
de la source optique. Il convient que l'élargissement spectral au pied du spectre laser
soit minimal pour l'ECL.
Il convient que l'utilisation d'une DEL soit limitée aux mesures de gain en petits signaux.
NOTE 1 Le régime de gain de petits signaux est la plage de puissance du signal d'entrée suffisamment
petite pour que l'OA soumis à essai fonctionne dans la région linéaire. Ce régime peut être obtenu en traçant
le gain du signal G par rapport à la puissance moyenne du signal optique d'entrée [voir Formule (3)]. La
région linéaire est la plage des puissances du signal optique d'entrée où le gain est quasiment indépendant
de la puissance du signal optique d'entrée (voir Figure 2). Une puissance moyenne du signal optique
d'entrée comprise entre −30 dBm et −40 dBm se situe généralement bien dans cette plage. Dans la région
saturée, la puissance du signal est suffisamment grande pour bien supprimer l'ASE.
Figure 2 – Variation typique du gain en fonction de la puissance du signal d'entrée
b) Appareil de mesure de puissance optique: il doit avoir une incertitude de mesure inférieure
à 0,2 dB, quel que soit l'état de polarisation, dans la largeur de bande de longueur d'onde
de fonctionnement de l'OA. Le mesureur de puissance optique doit avoir une plage
dynamique supérieure au gain mesuré (par exemple 40 dB).
c) Analyseur de spectre électrique: l'erreur de mesure de puissance spectrale doit rester à
±0,5 dB (optique). La linéarité doit être à ±0,2 dB (optique).
d) Isolateur optique: des isolateurs optiques peuvent être utilisés aux ports d'entrée et de
sortie de l'OA. La variation de perte de l'isolateur dépendante de la polarisation doit être
inférieure à 0,2 dB (‡). L'isolement optique doit être supérieur à 40 dB (‡). Le facteur de
réflexion de ce dispositif doit être inférieur à −40 dB (‡) à chaque accès.
e) Affaiblisseur optique variable: la plage d'affaiblissement et la stabilité doivent être
respectivement supérieures à 40 dB (‡) et à ±0,1 dB (‡). Le facteur de réflexion de ce
dispositif doit être inférieur à –40 dB (‡) à chaque accès.
f) Contrôleur de polarisation: ce dispositif doit être en mesure de fournir comme signal
lumineux d'entrée tous les états de polarisation possibles (par exemple linéaire, elliptique
et circulaire). Par exemple, le contrôleur de polarisation peut être constitué d'un polariseur
linéaire suivi d'un contrôleur de polarisation de type tout fibre, ou d'un polariseur linéaire
suivi d'une lame quart d'onde pouvant tourner d'au moins 90° et d'une lame demi-onde
pouvant tourner d'au moins 180°. La variation de perte du contrôleur de polarisation doit
être inférieure à 0,2 dB (‡). Le facteur de réflexion de ce dispositif doit être inférieur à
−40 dB (‡) à chaque accès. L'utilisation d'un contrôleur de polarisation est considérée
comme facultative, sauf pour la mesure du gain dépendant de la polarisation, mais elle peut
être nécessaire pour obtenir la précision souhaitée pour d'autres paramètres de puissance
et de gain pour des dispositifs OA présentant un gain dépendant de la polarisation
significatif.
g) Cavaliers à fibres optiques: il convient que le diamètre du champ de mode des cavaliers à
fibres optiques utilisés soit aussi proche que possible de celui des fibres utilisées comme
ports d'entrée et de sortie de l'OA. La réflectance de ce dispositif doit être inférieure à
−40 dB (‡) à chaque accès, et la longueur de la jarretière doit être inférieure à 2 m.
h) Connecteurs optiques (J1 et J2 dans la Figure 1): la répétabilité de la perte de connexion
doit rester à ±0,2 dB.
i) Détecteur optique: ce dispositif doit être hautement insensible à la polarisation et présenter
une linéarité à ±0,2 dB près. Pour réduire le plus possible les effets de saturation dus aux
niveaux élevés de courant continu, la sortie du détecteur optique doit être couplée en
courant alternatif
...

IEC 61290-1-2 ®
Edition 3.0 2026-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical amplifiers - Test methods -
Part 1-2: Power and gain parameters - Electrical spectrum analyzer method

Amplificateurs optiques - Méthodes d'essai -
Partie 1-2: Paramètres de puissance et de gain - Méthode de l'analyseur de
spectre électrique
ICS 33.180.30  ISBN 978-2-8327-0943-6

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CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms, definitions, abbreviated terms, and symbols . 4
3.1 Terms and definitions. 4
3.2 Abbreviated terms . 5
3.3 Symbols . 5
4 Apparatus . 5
5 Test sample . 8
6 Procedures . 8
7 Calculation . 11
8 Test results . 13
Bibliography . 15

Figure 1 – Typical arrangement of the electrical spectrum analyzer test apparatus for
measurement of average optical input signal power, electrical input signal power, and
electrical output signal power . 6
Figure 2 – Typical variation of gain as a function of input signal power . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Optical amplifiers - Test methods -
Part 1-2: power and gain parameters -
Electrical spectrum analyzer method

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61290-1-2 has been prepared by subcommittee 86C: Fibre optic systems, sensing and
active devices, of IEC technical committee 86: Fibre optics. It is an International Standard.
This third edition cancels and replaces the second edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) addition of information on the applicability of this document to the scope;
b) harmonization of the scope with the IEC 61290-1 series;
c) addition of safety recommendations to Clause 4 and Clause 5;
d) correction of an error in Clause 7, item e);
e) replacement of the term "wavelength measurement accuracy" with "wavelength accuracy".
The text of this International Standard is based on the following documents:
Draft Report on voting
86C/1973/CDV 86C/1991/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/publications.
A list of all parts in the IEC 61290 series, published under the general title Optical amplifiers -
Test methods, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
1 Scope
This part of IEC 61290 applies to all commercially available optical amplifiers (OAs) and
optically amplified sub-systems. It applies to OAs using optically pumped fibres (OFAs based
on either rare-earth doped fibres or on the Raman effect), semiconductors (SOAs), and planar
optical waveguides (POWAs). This document does not apply to polarization-maintaining optical
amplifiers.
This document defines uniform requirements for accurate and reliable measurements, by means
of the electrical spectrum analyzer test method, of the following OA parameters, as defined in
IEC 61291-1, Clause 3:
a) nominal output signal power;
b) gain;
c) reverse gain;
d) maximum gain;
e) polarization-dependent gain.
In addition, this test method provides a means for measuring the following parameters:
– maximum gain wavelength;
– gain wavelength band.
This document specifically covers single-channel amplifiers. For multichannel amplifiers, the
IEC 61290-10 series applies.
NOTE 1 The applicability of the test methods described in this document to distributed Raman amplifiers is for
further study.
NOTE 2 A test method for polarization-maintaining optical amplifiers is for further study.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60793-1-40, Optical fibres - Part 1-40: Measurement methods and test procedures -
Attenuation
IEC 61291-1, Optical amplifiers - Part 1: Generic specification
3 Terms, definitions, abbreviated terms, and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61291-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.2 Abbreviated terms
ASE amplified spontaneous emission
DBR distributed Bragg reflector (laser diode)
DFB distributed feedback (laser diode)
ECL external cavity laser (diode)
LED light emitting diode
OA optical amplifier
OFA optical fibre amplifier
POWA planar optical waveguide amplifier
SOA semiconductor optical amplifier
3.3 Symbols
(‡) indicates a suggested value for which a measurement is assured.
4 Apparatus
A diagram of the measurement set-up is given in Figure 1.

a) Average optical input signal power

b) Electrical input signal power
c) Electrical output signal power

Key
J1, J2 Optical connectors
Figure 1 – Typical arrangement of the electrical spectrum analyzer test apparatus for
measurement of average optical input signal power, electrical input signal power, and
electrical output signal power
The test equipment items with their required characteristics listed in a) to k) in this clause shall
be used.
a) Optical source: the optical source shall be either at a fixed wavelength or wavelength
tuneable.
1) Fixed-wavelength optical source: the optical source shall generate light with a
wavelength and optical power specified in the relevant detail specification. The optical
source shall emit modulated light with the full width at half maximum of the spectrum
narrower than 1 nm (‡), unless otherwise specified in the relevant detail specification. A
distributed feedback (DFB) laser, a distributed Bragg reflector (DBR) laser, an external
cavity laser (ECL) diode, or a light-emitting diode (LED) with a narrow-band filter can be
used as the optical source, for example. The suppression ratio of the side modes for the
DFB laser, the DBR laser, and the ECL shall be higher than 30 dB (‡). The output power
fluctuation shall be less than 0,05 dB (‡), which can require the insertion of an optical
isolator at the output port of the optical source. Spectral broadening at the foot of the
lasing spectrum should be minimal for laser sources.
2) Wavelength-tuneable optical source: this optical source shall be able to generate
wavelength-tuneable light within the wavelength range specified in the relevant detail
specification. Its optical power shall be specified in the relevant detail specification. The
optical source shall emit modulated light with the full width at half maximum of the
spectrum narrower than 1 nm (‡), unless otherwise specified in the relevant detail
specification. An ECL or a LED with a narrow bandpass optical filter can be used as the
optical source, for example. The suppression ratio of side modes for the ECL shall be
higher than 30 dB (‡). The output power fluctuation shall be less than 0,05 dB, which
can require the insertion of an optical isolator at the output port of the optical source.
Spectral broadening at the foot of the lasing spectrum should be minimal for the ECL.
The use of a LED should be limited to small-signal gain measurements.
NOTE 1 The regime of small-signal gain is the range of input signal power sufficiently small so that the OA
under test operates in the linear region. This regime can be found by plotting the signal gain G versus the
averaged input optical signal power [see Formula (3)]. The linear region is the range of input optical signal
powers where the gain is nearly independent of input optical signal power (see Figure 2). An averaged input
optical signal power between −30 dBm and −40 dBm is generally well within this range. In the saturated
region, the signal power is large enough to well suppress the ASE.
Figure 2 – Typical variation of gain as a function of input signal power
b) Optical power meter: it shall have a measurement uncertainty less than 0,2 dB, irrespective
of the state of polarization, within the operational wavelength bandwidth of the OA. The
optical power meter shall have a dynamic range that exceeds the measured gain (e.g.
40 dB).
c) Electrical spectrum analyzer: the spectral-power-measurement error shall be within ±0,5 dB
(optical). The linearity shall be within ±0,2 dB (optical).
d) Optical isolator: optical isolators may be used at the input and output ports of the OA. The
polarization-dependent loss variation of the isolator shall be less than 0,2 dB (‡). Optical
isolation shall be higher than 40 dB (‡). The reflectance from this device shall be less than
−40 dB (‡) at each port.
e) Variable optical attenuator: the attenuation range and stability shall be over 40 dB (‡) and
within ±0,1 dB (‡), respectively. The reflectance from this device shall be less than –
40 dB (‡) at each port.
f) Polarization controller: this device shall be able to provide as input signal light all possible
states of polarization (e.g. linear, elliptical and circular). For example, the polarization
controller can consist of a linear polarizer followed by an all-fibre-type polarization
controller, or of a linear polarizer followed by a quarter-wave plate rotatable by minimum of
90° and a half-wave plate rotatable by minimum of 180°. The loss variation of the
polarization controller shall be less than 0,2 dB (‡). The reflectance from this device shall
be less than −40 dB (‡) at each port. The use of a polarization controller is considered
optional, except for the measurement of polarization-dependent gain, but can be necessary
to achieve the desired accuracy of other power and gain parameters for OA devices
exhibiting significant polarization-dependent gain.
g) Optical fibre jumpers: the mode field diameter of the optical fibre jumpers used should be
as close as possible to that of fibres used as input and output ports of the OA. The
reflectance from this device shall be less than −40 dB (‡) at each port, and the length of the
jumper shall be shorter than 2 m.
h) Optical connectors (J1 and J2 in Figure 1): the connection loss repeatability shall be within
±0,2 dB.
i) Optical detector: this device shall be highly polarization insensitive and have a linearity
within ±0,2 dB. To minimize the saturation effects due to high DC levels, the optical detector
output shall be AC coupled. The maximum safe input power of the optical detector should
be sufficiently large to ensure safe testing of the OA.
NOTE 2 The maximum safe input power to the optical detector can be effectively increased by adding an optical
attenuator with very low polarization sensitivity in front of the optical detector and using it as an integral part of
the optical detector.
j) Signal generator: the signal generator shall generate a sinusoidal wave at a frequency
higher than several hundreds of kilohertz with a linearity within ±1,5 dB.
NOTE 3 For small-signal gain measurements an optical chopping system can be used alternatively.
k) Optical coupler: the polarization dependence of the branching ratio of the coupler should be
minimal. Change of the state of polarization of the input light should be negligible. Any free
port of the coupler shall be properly terminated in such a way as to decrease the reflectance
to less than −40 dB (‡).
5 Test sample
The sample type and test parameters shall be confirmed prior to the test.
The OA shall operate at nominal operating conditions. If the OA is likely to cause laser
oscillations due to unwanted reflections, optical isolators should be used at the input and output
ports of the OA under test. This will minimize the signal instability and the measurement
uncertainty.
For measurements of parameters a) to d) of Clause 1, the state of polarization of the input light
shall be maintained during the measurement. Changes in the polarization state of the input light
can result in input optical power changes because of slight polarization dependence of the
optical components used in the amplifier. This polarization dependence can lead to
measurement errors.
For safety reasons, the optical signal power should be reduced by adjusting the optical source
or variable optical attenuator each time a connector is inserted or removed during the
measurement. Other protective measures are described in IEC 60825-1 and IEC 60825-2.
6 Procedures
The related measurement procedure is as a) to h).
a) Nominal output signal power: the nominal output signal power is the minimum output signal
optical power that is obtained at the input signal optical power specified in the relevant detail
specification under the nominal operating conditions specified in the relevant detail
specification.
To find this minimum value, input and output signal power levels shall be continuously
monitored for a given duration of time, and in presence of changes in the state of polarization
and other instabilities, as specified in the relevant detail specification. The measurement
procedures described below in steps 1) to 10) shall be followed, with reference to Figure 1.
1) Set the optical source at the test wavelength specified in the relevant detail specification.
2) Measure the branching ratio of the optical coupler through the signal power levels exiting
the two output ports, with an optical power meter.
3) Measure the loss, L , of the optical fibre jumper between the OA and the optical detector
j
[see Figure 1c)] by the insertion loss technique described in IEC 60793-1-40, Method B.
4) Set the signal generator in a way that the light emitted by the optical source is intensity
modulated at the frequency specified in the detail specification. The modulation
frequency shall be higher than several hundreds of kilohertz (e.g. 1 MHz) to avoid
waveform distortion due to slow gain response, unless otherwise specified. The
modulation depth shall be unchanged during the measurement.
5) For measuring optical powers with the electrical spectrum analyzer, the electrical
spectrum analyzer shall be calibrated as follows using an optical power meter:
i) set the time-averaged optical power P using an optical power meter [see
cal
Figure 1a)], as specified in the relevant detail specification;
ii) measure the AC component of the input signal electrical power P with the optical
e,cal
detector and the electrical spectrum analyzer.
Keep the modulation depth unchanged during the measurement. The time-averaged
optical signal power P shall be derived from the AC component of the corresponding
signal electrical power P (measured with the electrical spectrum analyzer) using
e
Formula (1).
P= P PP
(1)
cal e e,cal
6) Set the optical source and the variable optical attenuator in such a way as to provide,
at the input port of the OA, the time-averaged input optical signal power specified P
in
in the relevant detail specification. Record the time-averaged optical power P
o
measured with an optical power meter at the other (second) output port of the optical
coupler, as shown in Figure 1a).
7) Keep the time-averaged optical signal power P at the OA input constant during the
in
following measurements, by monitoring the second output port of the coupler and, if
necessary, setting the variable optical attenuator in such a way that the time-averaged
optical power P exiting the second output port of the optical coupler remains constant.
o
8) Set the polarization controller at a given state of polarization as specified in the
relevant detail specification, and monitor, by means of the electrical spectrum
analyzer, the (time-averaged) optical signal power at the output of the OA for the
specified period of time, recording the minimum value.
9) Change the state of polarization of the input signal by means of the polarization
controller, trying to minimize the output optical signal power measure with the electrical
spectrum analyzer, and repeat step 8).
10) Repeat step 9) for the different states of polarization indicated in the relevant detail
specification, and finally take the absolute minimum output optical signal power
recorded in the various conditions: P .
out-min
Optical connectors J1 and J2 should not be removed during the measurement to avoid
additional measurement uncertainty due to reconnection.
The polarization controller should be operated as specified in the relevant detail
specifications. When using a linear polarizer followed by a rotatable quarter-wave plate
and a rotatable half-wave plate, the polarization controller can be operated as follows:
i) the linear polarizer is adjusted so that the OA output power is maximized;
ii) the quarter-wave plate is then rotated by at least 90° in small steps;
iii) at each step of the quarter-wave plate, the half-wave plate is rotated by at least
180° in small steps.
b) Gain: as in a), but this method permits determination of the gain, by measuring the
modulated electrical power, S and S , corresponding to the OA input and output signal
in out
powers, respectively, at the signal wavelength. The method, using a modulated input signal
and an electrical spectrum analyzer, permits discrimination of the output signal from the
amplified spontaneous emission (ASE) because the ASE is free of modulation at the
specified frequency. Thus, after filtering out the DC power component, the electrical output
power at the modulation frequency is considered free of the ASE. The measurement
procedures described below in steps 1) to 5) shall be followed.
1) Set the signal generator in such a way that the light emitted by the optical source is
intensity modulated at the frequency specified in the detail specification. The modulation
frequency shall be higher than several hundreds of kilohertz (e.g. 1 MHz) to avoid
waveform distortion due to slow gain response, unless otherwise specified.
2) Set the optical source to the test wavelength specified in the relevant detail specification.
3) Measure the time-averaged input optical signal power with the optical power meter, as
shown in Figure 1a), for reference. Set the optical source and the variable optical
attenuator in a way to provide, at the input port of the OA, the time-averaged input optical
signal power specified in the relevant detail specification.
4) Measure the electrical power, S , corresponding to the specified time-averaged input
in
optical signal power at the modulation frequency by means of the optical detector and
the electrical spectrum analyzer, as shown in Figure 1b).
5) Measure the electrical power, S , corresponding to the OA output optical signal at the
out
modulation frequency by means of the optical detector and the electrical spectrum
analyzer, as shown in Figure 1c).
c) Reverse gain: as in b), but with the OA operating with the input port used as output port and
vice-versa.
d) Maximum gain: as in b), but using a wavelength-tuneable optical source. Repeat steps 1) to
5) at different wavelengths to cover the wavelength range specified in the relevant detail
specification, and replace step 2) with the following step 2):
2) Set the wavelength-tuneable optical source at a test wavelength within the specified
wavelength range.
The wavelength should be changed by steps smaller than 1 nm (‡) around the wavelength
where the ASE spectral profile, observed (e.g. with an optical spectrum analyzer or a
monochromator) without the input signal, takes its maximum value, unless otherwise
specified.
NOTE A wavelength accuracy of ±0,01 nm, around 1 550 nm, can be attained with commercially available
wavelength meters based on interference-fringes counting techniques. Some tuneable external-cavity laser-
diode instruments provide a wavelength accuracy of ±0,2 nm or better.
e) Maximum gain wavelength: as in d).
f) Gain wavelength band: as in d).
g) Gain variation: as in d).
h) Polarization-dependent gain: as in b), but using a polarization controller between the
variable optical attenuator and the connector J1 (see Figure 1); repeat steps 1) to 5) at
different states of polarization as specified in the relevant detail specification, and replace
step 2) with the following step 2):
2) Set the optical source to the test wavelength specified in the relevant detail specification.
Set the polarization controller at a given state of polarization as specified in the relevant
detail specification.
The state of polarization of the input signal should be changed after each measurement
of S and S by means of the polarization controller, so that substantially all the states
in out
of polarization, in principle, are successively launched into the input port of the OA under
test.
The polarization controller should be operated as specified in the relevant detail
specifications. When using a linear polarizer followed by a rotatable quarter-wave plate
and a rotatable half-wave plate, the polarization controller can be operated as follows:
i) the linear polarizer is adjusted so that the OA output power is maximized;
ii) the quarter-wave plate is then rotated by at least 90° in small steps;
iii) at each step of the quarter-wave plate, the half-wave plate is rotated by at least 180°
in small steps.
Alternatively, the polarization controller can be operated to select four known and specified
states of polarization to allow matrix calculation of the resulting polarization-dependent gain.
A short optical jumper at the OA input, kept as straight and stable as possible, should be
used, in order to minimize the change of the state of polarization induced in the jumper by
possible stress and anisotropy.
The polarization-dependent loss of the optical connector should be less than 0,2 dB (‡).
7 Calculation
Calculation is carried out as described below in steps a) to h).
a) Nominal output signal power: the nominal output signal power P (in dBm) shall be calculated
using Formula (2).
P 10 log PL+
( )
(2)
10 out-min j
where
P is the recorded absolute minimum value of output optical signal power (in mW);
out-min
L is the insertion of the optical fibre jumper placed between the OA and the optical
j
detector (in dB).
NOTE 1 The measurement uncertainty can be better than ±0,5 dB (‡), depending mainly on the accuracy of the
electrical spectrum analyzer.
b) Gain: the gain G at the signal wavelength shall be calculated either in linear units using
Formula (3) or in units of dB using Formula (4).
SS−
out-m out-0
G=
(3)
S −S
in-m in-0
SS−
out-m out-0
G= 5 log (4)

S −S
in-m in-0
=
where
S is the modulated electrical power measured by the electrical spectrum analyzer at
out-m
the OA output, expressed in mW;
S is the modulated electrical power measured by the electrical spectrum analyzer at
in-m
the OA input, expressed in mW;
is the electrical power measured by the electrical spectrum analyzer at the OA
S
out-0
output without intensity modulation of the optical source, expressed in mW;
S is the electrical power measured by the electrical spectrum analyzer at the OA input
in-0
without intensity modulation of the optical source, expressed in mW.
NOTE 2 The measurement uncertainty can be better than ±0,4 dB (‡), depending mainly on the linearity of the
optical detector and the linearity of the electrical spectrum analyzer.
c) Reverse gain: as in b).
d) Maximum gain: calculate the gain values at the different wavelengths, as in b). The
maximum gain shall be given by the highest of all these gain values.
e) Maximum gain wavelength: calculate the maximum gain as in d). The maximum gain
wavelength shall be that wavelength at which the maximum gain occurs.
f) Gain wavelength band: calculate the maximum gain as in d). Identify those wavelengths at
which the gain is N dB below the maximum gain. The gain wavelength band shall be given
by the wavelength interval(s), comprised between those wavelengths, within which the gain
is between the maximum gain value and a value N dB below the maximum gain.
NOTE 3 A value of N = 3 is typically applied.
g) Gain variation: calculate the maximum gain as in d). Calculate the minimum gain as the
lowest of all gain values within the specified measurement wavelength range. The gain
variation shall be the difference between the maximum and the minimum gain values.
h) Polarization-dependent gain: calculate the gain values at the different states of polarization,
as in b). Identify the maximum gain, G , and the minimum gain, G , as the highest and
max min
the lowest of all these gain values, respectively. The polarization-dependent gain ∆G ,
p
expressed in dB, is calculated using Formula (5).
ΔGG−G
(5)
p max min
where
G is the maximum gain, expressed in dB;
max
G is the minimum gain, expressed in dB.
min
NOTE 4 G is defined as the same as G in b). G is defined as G in which P is replaced by P .
min max out-min out-max
NOTE 5 ∆G does not necessarily indicate the possible maximum variation of the polarization dependency.
p
This is because the attenuation through the OA under test is maximum only when each input state of polarization
simultaneously yields maximum attenuation in each component in the OA under test.
NOTE 6 The measurement error can be within ±0,4 dB (‡), depending mainly on the polarization dependency
of the optical detector.
=
8 Test results
The following test results shall be recorded.
a) Nominal output signal power:
the following details shall be recorded:
1) arrangement of the test set-up;
2) spectral linewidth (full width at half maximum) of the optical source;
3) indication of the optical pump power and possibly driving current of pump lasers for
OFAs and injection current for SOAs (if applicable);
4) operating temperature (if required);
5) time-averaged input signal optical power P ;
in
6) resolution bandwidth of the electrical spectrum analyzer;
7) wavelength of the measurement;
8) nominal output signal power levels;
9) change in the state of polarization given to the input signal light.
b) Gain: the details 1) - 7) from a) shall be recorded in addition to:
8) gain.
NOTE 1 Details 5) and 8) can be replaced with the gain versus the averaged input signal optical power curve.
c) Reverse gain: the details 1) to 7), previously listed for the gain, shall be recorded and, in
addition:
9) reverse gain.
NOTE 2 Details 5) and 8) can be replaced with the reverse small-signal gain versus the averaged input signal
optical power curve.
d) Maximum gain: the details 1) to 7), previously listed for the gain, shall be recorded and, in
addition to:
8) wavelength range of the measurement;
9) wavelength accuracy;
10) maximum gain.
NOTE 3 Details 5) and 10) can be replaced with the maximum gain versus the averaged input signal optical
power curve.
e) Maximum gain wavelength: the details 1) to 7), previously listed for the gain, shall be
recorded and, in addition to:
8) wavelength range of the measurement;
9) wavelength accuracy;
10) maximum gain wavelength.
NOTE 4 Details 8) and 10) can be replaced with the gain versus input signal wavelength curve.
f) Gain wavelength band: The details 1) to 7), previously listed for the gain, shall be recorded
and, in addition to:
8) wavelength range of the measurement;
9) wavelength accuracy;
10) gain wavelength band;
11) the value of N chosen for the determination of the wavelength bandwidth.
NOTE 5 Details 8) and 10) and 11) can be replaced with the gain versus input signal wavelength curve.
g) Gain variation: The details 1) to 7), previously listed for the gain, shall be recorded and, in
addition:
8) wavelength range of the measurement;
9) wavelength accuracy;
10) gain variation.
NOTE 6 Details 8) and 10) can be replaced with the gain versus input signal wavelength curve.
h) Polarization-dependent gain: The details 1) to 8), previously listed for the gain, shall be
recorded and, in addition:
9) polarization dependency of the optical detector;
10) the maximum and minimum gain, G and G ;
max min
11) polarization-dependent gain;
12) change in the state of polarization given to the input signal light.

Bibliography
IEC 60825-1, Safety of laser products - Part 1: Equipment classification and requirements
IEC 60825-2, Safety of laser products - Part 2: Safety of optical fibre communication systems
(OFCS)
IEC 61290 (all parts), Optical amplifiers - Test methods
IEC 61290-10 (all parts), Optical amplifiers - Test methods - Part 10: Multichannel parameters
___________
SOMMAIRE
AVANT-PROPOS . 2
1 Domaine d'application . 4
2 Références normatives . 4
3 Termes, définitions, abréviations et symboles . 5
3.1 Termes et définitions . 5
3.2 Abréviations . 5
3.3 Symboles . 5
4 Matériel . 5
5 Échantillon d'essai . 8
6 Procédure . 8
7 Calcul . 11
8 Résultats des tests . 13
Bibliographie . 15

Figure 1 – Disposition typique de l'appareil d'essai de l'analyseur de spectre électrique
pour la mesure de la puissance moyenne du signal d'entrée optique, de la puissance
du signal d'entrée électrique et de la puissance du signal de sortie électrique . 6
Figure 2 – Variation typique du gain en fonction de la puissance du signal d'entrée . 7

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
Amplificateurs optiques - Méthodes d'essai -
Partie 1-2 : paramètres de puissance et de gain -
Méthode de l'analyseur de spectre électrique

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