IEC 61290-1-3:2021

IEC 61290-1-3 ®
Edition 4.0 2021-03
REDLINE VERSION
INTERNATIONAL
STANDARD
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Optical amplifiers – Test methods –
Part 1-3: Power and gain parameters – Optical power meter method

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IEC 61290-1-3 ®
Edition 4.0 2021-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Optical amplifiers – Test methods –

Part 1-3: Power and gain parameters – Optical power meter method

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.30 ISBN 978-2-8322-9527-4

– 2 – IEC 61290-1-3:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 6
4 Apparatus . 7
5 Test sample . 9
6 Procedure . 9
7 Calculation . 12
8 Test results . 14
Annex A (informative)  Optimization of optical bandpass filter spectral width . 16
Bibliography . 17

Figure 1 – Typical arrangement of optical power meter test apparatus for measurement . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL AMPLIFIERS – TEST METHODS –

Part 1-3: Power and gain parameters – Optical power meter method

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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rights. 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 61290-1-3:2015. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC 61290-1-3:2021 RLV © IEC 2021
IEC 61290-1-3 has been prepared by subcommittee 86C: Fibre optic systems and active
devices, of IEC technical committee 86: Fibre optics. It is an International Standard.
This fourth edition cancels and replaces the third edition published in 2015. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) harmonization with IEC 61290-1-1;
b) use of the term "measurement uncertainty" instead of "measurement accuracy".
The text of this International Standard is based on the following documents:
Draft Report on voting
86C/1671/CDV 86C/1698/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

OPTICAL AMPLIFIERS – TEST METHODS –

Part 1-3: Power and gain parameters – Optical power meter method

1 Scope
This part of IEC 61290 applies to all commercially available optical amplifiers (OA) and optically
amplified subsystems. It applies to OA using optically pumped fibres (OFA based on either rare-
earth doped fibres or on the Raman effect), semiconductors (SOA), and waveguides (POWA).
NOTE 1 The applicability of the test methods described in this document to distributed Raman amplifiers is for
further study.
The object of this document is to establish uniform requirements for accurate and reliable
measurements, by means of the optical power meter test method, of the following OA
parameters, as defined in IEC 61291-1:
a) nominal output signal power;
b) gain;
c) polarization-dependent gain;
d) maximum output signal power;
e) maximum total output power.
NOTE 2 All numerical values followed by (‡) are suggested values for which the measurement is assured. Other
values may can be acceptable but should be verified upon verification.
This document applies to single-channel amplifiers. For multichannel amplifiers,
IEC 61290-10 (all parts) applies.
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 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 61290-1, Optical amplifiers – Test methods – Part 1: Power and gain parameters
IEC 61291-1, Optical amplifiers – Part 1: Generic specification

– 6 – IEC 61290-1-3:2021 RLV © IEC 2021
3 Terms, definitions and abbreviated terms
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 terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Abbreviated terms
ASE amplified spontaneous emission
DBR distributed Bragg reflector (laser diode)
DFB distributed feedback (laser diode)
ECL external cavity laser (diode)
FWHM full width at half maximum
LED light emitting diode
OA optical amplifier
OFA optical fibre amplifier
OSA optical spectrum analyzer
PDL polarization dependent loss
POWA planar optical waveguide amplifier
SOA semiconductor optical amplifier

4 Apparatus
A diagram of the measurement set-up is given in Figure 1 a), Figure 1 b), Figure 1 c) and
Figure 1 d).
a) Measurement of input signal power

b) Measurement of optical bandpass filter loss and jumper loss

c) Measurement of output signal power and gain

d) Measurement of total output power
Key
J1, J2 optical connector
Figure 1 – Typical arrangement of optical power meter test apparatus for measurement

– 8 – IEC 61290-1-3:2021 RLV © IEC 2021
The test equipment listed below, with the required characteristics, is needed.
a) Optical source: The optical source shall be either at fixed wavelength or wavelength-
tuneable.
– Fixed-wavelength optical source: This optical source shall generate a light with a
wavelength and optical power specified in the relevant detail product specification.
Unless otherwise specified, the optical source shall emit a continuous wave with FWHM
of the spectrum narrower than 1 nm (‡). A distributed feedback (DFB) laser, a distributed
Bragg reflector (DBR) laser, an external cavity laser (ECL) diode, a light emitting diode
(LED) with a narrow-band filter and a single line laser are applicable, for example.
The suppression ratio for the side modes for the DFB laser, the DBR laser or the ECL
shall be higher than 30 dB (‡). The output power fluctuation shall be less than 0,05 dB
(‡), which may can be better more easily attainable with an optical isolator at the output
port of the optical source. Spectral broadening at the foot of the lasing spectrum shall
be minimal for laser sources, and the ratio of the source power to total spontaneous
emission power of the laser shall be more than 30 dB.
– Wavelength-tuneable optical source: This optical source shall be able to generate a
wavelength-tuneable light within the range specified in the relevant detail product
specification. Its optical power shall be specified in the relevant detail product
specification. Unless otherwise specified, the optical source shall emit a continuous
wave with the full width at half maximum (FWHM) of the spectrum narrower than 1 nm
(‡). An ECL or an LED with a narrow bandpass optical filter is applicable, 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 can be better more easily
attainable with an optical isolator at the output port of the optical source. Spectral
broadening at the foot of the lasing spectrum shall be minimal for laser sources, and the
ratio of the source power to total spontaneous emission power of the laser shall be more
than 30 dB.
b) Optical power meter: It shall have a measurement accuracy better uncertainty of less than
±0,2 dB, irrespective of the state of polarization, within the operational wavelength
bandwidth of the OA. A maximum optical input power shall be large enough [e.g. +20 dBm
(‡)]. Sensitivity shall be high enough [e.g. −40 dBm (‡)]. A dynamic range exceeding the
measured gain is required (e.g. 40 dB).
c) Optical isolator: Optical isolators may be used to bracket the OA. The polarization
dependent loss (PDL) of the isolator shall be better less than 0,2 dB (‡). Optical isolation
shall be better more than 40 dB (‡). The reflectance from this device shall be smaller than
–40 dB (‡) at each port.
d) Variable optical attenuator: The attenuation range and stability shall be over 40 dB (‡) and
better less than  ± 0,1 0,2 dB (‡), respectively. The reflectance from this device shall be
smaller than −40 dB (‡) at each port.
e) 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 consist of a linear polarizer followed by an all-fibre-type polarization
controller, or by 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
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 can be necessary to
achieve the desired accuracy for OA devices exhibiting significant polarization dependent
gain.
f) 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 than –40 dB (‡) at each port, and the length of
the jumper shall be shorter than 2 m.
Standard optical fibres defined in IEC 60793-2-50, B1 are recommended. However, other
fiber type may be used as input/output fiber. In this case, the type of fibre will be considered.

The optical fibre jumpers used shall be of the same fibre category defined in IEC 60793-2-
50 as the fibres used as input and output ports of the OA, so that the mode field diameters
of the optical fibre jumpers closely match those of the input and output fibres of the OA. The
reflectance from this device shall be smaller than −40 dB (‡) at each port, and the length of
the jumper shall be shorter than 2 m.
g) Optical connectors: The connection loss repeatability shall be better less than ± 0,2 dB.
The reflectance from this device shall be smaller than −40 dB (‡).
h) Optical bandpass filter: The optical bandwidth (FWHM) of this device shall be less than 3 nm
(‡). It shall be either wavelength-tuneable or an appropriate set of fixed bandpass filters.
During measurement, the difference between the centre wavelength of this bandwidth and
the optical source centre wavelength shall be no more than 1,5 nm (‡). The PDL of the
bandpass filter shall be less than 0,2 dB (‡). The reflectance from this device shall be
smaller than −40 dB (‡).
NOTE 1 Optimization of optical band pass filter spectral width is discussed in Annex A.
i) Optical coupler: The polarization dependence of the branching ratio of the coupler shall be
less than 0,1 dB (‡). Any unconnected port of the coupler shall be properly terminated, in
such a way as to decrease the reflectance below −40 dB (‡).
NOTE 2 The change of the state of polarization of the input light is typically negligible.
j) Wavelength meter: It shall have a wavelength measurement accuracy better uncertainty of less
than 0,1 nm (‡). If the optical source is so calibrated that the accuracy uncertainty of the
wavelength is better less than 0,1 nm (‡), the wavelength meter is not necessary.
5 Test sample
The OA shall operate at nominal operating conditions. If the OA is likely to cause laser
oscillations due to unwanted reflections, use of optical isolators is recommended to bracket the
OA under test. This will minimize reduce the signal instability and the measurement uncertainty.
Standard optical fibres type B-652.B or B-652.D as defined in IEC 60793-2-50 are
recommended. Even if fibre type other than B-652.B or B-652.D is used as input/output fibre,
the mode field diameter of the optical fibre jumpers closely matches those of the input and
output fibres of the OA [see Clause 4 f)].
For all parameter measurements except polarization-dependent gain, care shall be taken to
maintain the state of polarization of the input light 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, thus leading
to measurement errors uncertainty.
6 Procedure
a) Nominal output signal power: The nominal output signal power is given by the minimum
output signal optical power, for an input signal optical power specified in the relevant detail
product specification, and under nominal operating conditions, given in the relevant detail
product 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 product
specification. The measurement procedures described below shall be followed, with
reference to Figure 1.
In order to minimize the amplified spontaneous emission (ASE) power contribution to the
signal power output from the OA, several methods may be used. The optical bandpass filter
method is given below.
1) Set the optical source at the test wavelength specified in the relevant detail product
specification, measuring the input signal wavelength (e.g. with a wavelength meter).

– 10 – IEC 61290-1-3:2021 RLV © IEC 2021
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 bandpass filter and the optical fibre jumper between
bj
the OA and the optical power meter [see Figure 1 b)] by the insertion loss technique [see
method B (insertion loss) in IEC 60793-1-40].
4) Activate the OA under test and evaluate the ASE power level passed through the optical
filter, P , by measuring the optical output power from the OA, as shown in Figure 1 c),
ASE
without input signal.
NOTE 1 In large-signal conditions, the measurement of the ASE power is sometimes omitted.
The small-signal regime is when the OA under test operates in the linear regime, whereas the large-signal
regime is when it operates in the saturated regime. The distinction between small-signal and large-signal
regimes can be made by plotting G versus the input signal power with a constant pump drive. The linear
regime requires the time-averaged input signal power to be in the range in which the gain is quite
independent of the input signal power (see IEC 61290-1). An input 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, so that the measurement of the ASE power is sometimes omitted.
NOTE 2 For consideration of measurement uncertainty, refer to the last paragraph of Annex A, which
concerns the optimization of the optical band pass filter spectral width.
5) Set the optical source and the variable optical attenuator in such a way as to provide, at
the input port of the OA, the input optical signal power (P ) specified in the relevant
in
detail product specification. Record the optical power (P ) measured with an optical
o
power meter at the other (second) output port of the optical coupler, as shown in Figure 1
a).
Instantly applying signal light into the active OA can cause the generation of an optical
surge which may damage the optical components. Applying signal light with short rise
time into the OA operating without signal light can cause the generation of an optical
surge which can damage the optical components. The input signal shall have sufficiently
small power to prevent the optical surge, when it is launched to the OA initially. The
input power shall be gradually increased to the specified level.
6) Keep the optical signal power at the OA input constant (P ) during the following
in
measurements, by monitoring the second output port of the coupler and, if necessary,
setting the variable optical attenuator in such a way that the optical power (P ) exiting
o
the second output port of the optical coupler remains constant.
7) Connect the fibre jumpers to the input and output port of the OA under test, as shown in
Figure 1 c) and evaluate the optical output power (P ) with input signal.
out
If the polarization controller is used, the following procedure shall be adapted.
8) Set the polarization controller at a given state of polarization as specified in the relevant
detail product specification; activate the OA, and monitor, by means of the optical power
meter, the 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 measure maximum and minimum output optical signal powers with
the optical power meter, and repeat procedure 8).
10) Repeat procedure step 9) for the different states of polarization indicated in the relevant
detail product specification and, finally, take the absolute minimum and maximum output
optical signal powers recorded in the various conditions: P and P .
out-min out-max
Optical connectors J1 and J2 shall not be removed during the measurement to avoid
measurement errors uncertainty due to reconnection.
The measurement error uncertainty shall be reduced by eliminating the effect of the ASE
simultaneously detected with the signal. This is better attainable by placing an optical
bandpass filter having the narrower passband at the output of the OA under test, as it has
been discussed in the main text Clause 6 a). For large optical signal power levels, the optical
bandpass filter may not be is often not necessary to achieve an accurate measurement. The
use of the optical bandpass filter is important, especially important when the input signal to

the OA is small. This is because the ASE power increases as the input signal decreases.
However, if this kind of optical filter is already built in the OA, the external optical filter is
not needed. The effectiveness of the optical band pass filter is further discussed in Annex A.
b) Gain and polarization dependent gain:
1) to 7) As in procedures 1) to 7) in a), but this method permits determination of the gain
through the measurements of the OA input signal power P and the OA output power
in
P , taking into account the OA amplified spontaneous emission (ASE) power P at
out ASE
the signal wavelength.
11 8) Repeat procedures 5) to 7) in a), with increasing input signal power gradually to the
maximum input signal power given in the relevant detail product specification. Maintain
the pump power or pump current with the firstly set point.
c) Polarization-dependent gain: as in a), but this parameter is determined through the
measurements of the OA input signal power, Pin, the OA output power, Pout-min and
Pout‑max, taking into account the OA amplified spontaneous emission (ASE) power, PASE
at the signal wavelength, by repeating all procedures at different states of polarization as
specified in the relevant detail product specification.
The state of polarization of the input signal shall be changed after each measurement of
P , P and P by means of the polarization controller, so that substantially all the states
in out ASE
of polarization, in principle, are successively launched into the input port of the OA under
test.
The polarization controller shall be operated as specified in the relevant detail product
specification. A possible way, when using a linear polarizer followed by a quarter-wave
rotatable plate, is the following: the linear polarizer is adjusted so that the OA output power
is maximized; the quarter-wave plate is then rotated by a minimum of 90 ° step-by-step
continuously. At each step, the half-wave plate is rotated by a minimum of 180 ° step-by-
step continuously.
A short optical jumper at the OA input, kept as straight as possible, shall be used, in order
to minimize the change of the state of polarization induced in it by possible stress and
anisotropy.
The PDL of the optical connector shall be less than 0,2 dB (‡).
c) Maximum output signal power: As in a), but this parameter is determined by repeating all
procedures at different wavelengths specified in the detailed specification, and replace
procedures 1), 4), 5) with the following.
1) Set the wavelength-tuneable optical source at a test wavelength within the specified
wavelength range, measuring the input signal wavelength (e.g. with a wavelength
meter).
4) Activate OA and adjust the maximum pump power or maximum pump current of OA to
the nominal condition as specified in the relevant detail product specification. When the
OA under test is integrated with control circuitry, the OA shall be tested with constant
pump power mode or constant pump current mode.
5) Set the optical source and the variable optical attenuator in such a way as to provide, at
the input port of the OA, the maximum input optical signal power P specified in the
in-max
relevant detail product specification. Record the optical power P measured with an
o
optical power meter at the other (second) output port of the optical coupler, as shown in
Figure 1 a).
Instantly applying signal light into the active OA can cause the generation of an optical surge
which may can damage the optical components. The input signal shall have sufficiently small
power to prevent the optical surge, when it is launched into the OA initially. The input power
shall be gradually increased to the specified level.
d) Maximum total output power: The maximum total output power is given by the highest optical
power level at the output port of the OA operating within the absolute maximum ratings. To
find this maximum 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

– 12 – IEC 61290-1-3:2021 RLV © IEC 2021
and other instabilities, as specified in the relevant detail product specification. The
measurement procedures described below shall be followed, with reference to Figure 1.
12 1) Measure the branching ratio of the optical coupler through the signal power levels
exiting the two output ports with an optical power meter.
13 2) Set the optical source and the variable optical attenuator in such a way as to
provide, at the input port of the OA, the maximum input optical signal power P
in-max
specified in the relevant detail product specification. Record the optical power P
o
measured with an optical power meter at the other (second) output port of the optical
coupler, as shown in Figure 1 a).
Putting signal light into the active OA can cause the generation of optical surge which may
can damage the optical components. Input signal shall have sufficiently small power to
prevent the optical surge, when it is launched to the OA in the beginning. And the input
power shall be gradually increased to a certain level.
14 3) Keep the optical signal power at the OA input constant (P ) during the following
in-max
measurements by monitoring the second output port of the coupler and, if necessary,
setting the variable optical attenuator in such a way that the optical power (P ) exiting
o
the second output port of the optical coupler remains constant.
15 4) Connect the fibre jumpers to the input and output port of the OA under test, as
shown in Figure 1 d) and activate OA and adjust the maximum pump power or maximum
pump current of OA to the absolute maximum ratings, given in the relevant detail product
specification. When the OA under test is integrated with control circuitry, the OA shall
be tested with constant pump power mode or constant pump current mode, and evaluate
the optical output power (P ) with input signal.
total-out
If the polarization controller is used, procedures 5), 6), 7) shall be followed.
16 5) Set the polarization controller at a given state of polarization as specified in the
relevant detail product specification; activate the OA, and monitor, by means of the
optical power meter, the optical signal power at the output of the OA, for the specified
period of time, recording the minimum maximum value.
17 6) Change the state of polarization of the input signal by means of the polarization
controller, trying to measure maximum and minimum output optical powers with the
optical power meter, and repeat procedure 5).
18 7) Repeat procedure 5) and 6) for the different states of polarization indicated in the
relevant detail product specification, and finally take the absolute minimum and
maximum output optical powers recorded in the various conditions: P and
total-out-min
P .
total-out-max
Optical connectors J1 and J2 shall not be removed during the measurement to avoid
measurement errors uncertainty due to reconnection.
The measurement error shall be reduced by eliminating the effect of the ASE simultaneously
detected with the signal. This is better attainable by placing an optical bandpass filter having
the narrower passband at the output of the OA under test, as it has been discussed in the
main text. For large optical signal power levels, the optical bandpass filter may not be
necessary to achieve an accurate measurement. The use of the optical bandpass filter is
important, especially when the input signal to the OA is small. This is because the ASE
power increases as the input signal decreases. However, if this kind of optical filter is
already built in the OA, the external optical filter is not needed. The effectiveness of the
optical band pass filter is further discussed in Annex A.
7 Calculation
a) Nominal output signal power: The nominal output signal power P (in dBm) shall be
sig-out-nom
calculated as
P = 10 log (P – P ) + L (dBm)
(1)
sig-out-nom 10 out ASE bj
where
P is the recorded absolute value of output optical signal power (in mW);
out
P is the recorded absolute value of output ASE power through the optical bandpass

ASE
filter (in mW);
L is the insertion loss of the optical bandpass filter and fibre jumper placed between
bj
the OA and the optical power meter (in dB).
NOTE 1 If optical bandpass filter is already built in the OA, the external optical filter is not needed. In this case,
the insertion loss L is equal to that of the fibre jumper.
bj
NOTE 2 A comparison of the measured values obtained with OSA, with the calculated values with optical power
meter using various band pass filters, is referred to in Annex A.
b) Gain: the gain G at the signal wavelength shall be calculated as
G = (P – P )/P (linear units) (2)

out ASE in
or as
G = 10 log [(P – P )/P ] (dB) (3)
10 out ASE in
G = 10 log [(P – P )/P ] (dB)
(2)
10 out ASE in
If the FWHM of the filter is very narrow so that the detected P is sufficiently small, P
ASE ASE
could be omitted in the above calculation. In large-signal regime, if P is sufficiently larger
out
than P , P could be negligible with respect to P . A comparison of the measured

ASE ASE out
values obtained with OSA, with the calculated values with optical power meter using various
band pass filters, is referred to in Annex A.
NOTE 3 The small-signal regime is when the OA under test operates in the linear regime, while the large-signal
regime is in the saturated regime. The distinction between small-signal and large-signal regimes can be
confirmed by plotting G versus the input signal power. The linear regime demands the time-averaged input signal
power to be in the range in which the gain is quite independent from it (see IEC 61290-1). An input 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 43 The measurement error can be better than ± uncertainly can be less than 0,2 dB (‡), depending
mainly on the uncertainty of the optical power meter.
c) Polarization-dependent gain: Calculate the gain values at the different states of polarization
as described in b). Calculations are processed using the following procedure.
1) Calculate the gain values at the different states of polarization, as in b).
2) Identify the maximum G and the minimum G gain as the highest and the
max-pol min-pol
lowest of all these gain values, respectively.
3) The polarization-dependent gain ∆G shall be calculated as follows
pol
∆G = G – G (dB)
(43)
pol max-pol min-pol
NOTE 54 G is defined as the same as G in b). G is defined as G in which P is replaced by
min-pol max-pol out-min
P .
out-max
NOTE 65 ∆G does not necessarily indicate the possible maximum variation of the polarization
pol
dependency. This is because the attenuation through the OA under test is maximum only when each input
state of polarization simultaneously yields maximum attenuation for each component in the OA under test.

– 14 – IEC 61290-1-3:2021 RLV © IEC 2021
NOTE 76 The measurement error can be better than  ± uncertainly can be less than 0,5 dB (‡), depending
mainly on the optical power meter polarization dependency.
The input signal power at which the parameter is specified and measured should be stated.
Larger input power is recommended considering the ASE factor contained in the output
power.
d) Maximum output signal power: Calculate the maximum output signal power P
sig-out-max
(in dBm) as in a).
e) Maximum total output power: The maximum total output power P (in dBm) shall be
out-max
calculated as
P = 10 log (P ) (dBm) (5)
out-max 10 out-max
where
linear
P P is the recorded absolute maximum value of output optical power (in mW).
out-max out-max
linear
P = 10 log P (dBm) (4)
out-max 10 out-max
where
linear
P is the recorded absolute maximum value of output optical power (in mW).
out-max
8 Test results
The following parameters shall be recorded in the test reports unless otherwise stated in the
relevant product specification.
a) Nominal optical signal power
The following details shall be presented:
1) arrangement of the test set-up;
2) spectral linewidth (FWHM) 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) input signal optical power P ;
in
6) FWHM of the optical bandpass filter;
7) central wavelength of the optical bandpass filter;
8) wavelength of the measurement;
9) nominal optical signal power levels P
sig-out-nom;
10) change in the state of polarization given to the input signal light.
b) Gain: The details 1) to 8) previously listed for the nominal optical signal power levels shall
be presented and, in addition:
11 9) gain:
Parameters 5) and 9) may be replaced with the gain versus input optical signal power
curve.
Parameters 8) and 10 9) may be replaced with the gain versus input signal wavelength
curve.
c) Polarization-dependent gain: The details 1) to 8) previously listed for the gain shall be
presented and, in addition:
12 9) polarization dependency of the optical power meter uncertainty;
13 10) the maximum and minimum gain, G and G ;
max-pol min-pol
14 11) polarization-dependent gain;
15 12) change in the state of polarization given to the input signal light.
d) Maximum output signal power: The details 1) to 8) previously listed for the gain shall be
presented and, in addition:
16 9) maximum output signal power P
sig-out-max.
e) Maximum total output power: The details 1) to 8) previously listed for the gain shall be
presented and, in addition:
17 9) maximum total output power P .
out-max
– 16 – IEC 61290-1-3:2021 RLV © IEC 2021
Annex A
(informative)
Optimization of optical bandpass filter spectral width
The measurement uncertainty of this method depends on the choice of the band pass filter, e.g.
in terms of the its spectral width (FWHM). In fact, as mentioned, The purpose of this filter is to
cancel remove the ASE contribution from the measurement. As such, it is intuitive that the
smaller the filter FWHM is chosen, the greater is the ASE cancellation and, hence, the smaller
is the measurement uncertainty. However, if the filter spectral width is excessively narrow,
problems of alignment between the filter central frequency and the signal frequency can arise,
leading to stability problems which can be detrimental to measurement uncertainty. These
considerations indicate that an optimal spectral width of the filter should be chosen to minimize
the measurement uncertainty.
A possible procedure to determine such an optimal filter is to calibrate this optical power meter
(OPM) method with the OSA technique (see IEC 61290-1-1), which is intrinsically more accurate.
For a given OA typology, OPM optical power meter measurements using successively different
filters (with FWHM e.g. from 1 nm to 5 nm) can be compared with an OSA measurement. The
optimal band pass filter to be chosen will be is the one which minimizes the difference between
the results from the two measurement methods.
For example, applying this calibration procedure in a numerically simulated case, the use of a
band pass filter of Lorentzian type with FWHM of 2 nm demonstrated to sufficiently cancel the
effect of ASE and achieve a difference with respect to OSA measurements result less than only
0,05 dB. This difference increased to approximately 0,15 dB for a filter with FWHM of 5 nm. It
should be noted that, while the effect of ASE can be accurately evaluated in small-signal regime,
even in large-signal regime, notwithstanding less accurate evaluation of ASE power, the portion
of ASE power becomes less significant with respect to the signal power. As a result, an accurate
OPM optical power meter measurement can be maintained over entire input signal levels by
choosing an optimally narrow FWHM of band pass filter.

Bibliography
IEC 60793-1-1, Optical fibres – Part 1-1: Measurement methods and test procedures – General
and guidance
IEC 60793-1-40, Optical fibres – Part 1-40: Attenuation measurement methods
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
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 60874-1, Fibre optic interconnecting devices and passive components – Connectors for
optical fibres and cables – Part 1: Generic specification
IEC 61290-1, Optical amplifiers – Test
...