FprEN IEC 61290-3-2:2026

• Status: Not Published
• Publication Date: 19-Nov-2026
• ICS: 33.180.30 - Optic amplifiers
• Technical Committee: CLC/SR 86C - Fibre optic systems and active devices
• Current Stage: 5060 - Voting results sent to TC, SR - Formal Approval
• Start Date: 31-Jul-2026
• Completion Date: 31-Jul-2026
• Ref Project: kSIST FprEN IEC 61290-3-2:2026 - Optical amplifiers - Test methods - Part 3-2: Noise figure parameters - Electrical spectrum analyzer method

• Revises: EN 61290-3-2:2008 - Optical amplifiers - Test methods - Part 3-2: Noise figure parameters - Electrical spectrum analyzer method
• Effective Date: 13-May-2025

FprEN IEC 61290-3-2:2026 is the IEC test-method standard for measuring noise figure parameters of optical amplifiers by the electrical spectrum analyzer (ESA) method. It applies to commercially available optical amplifiers, including optical fibre amplifiers (OFA), semiconductor optical amplifiers (SOA) and planar waveguide optical amplifiers (PWOA). It sets out the test setup, calibration steps, calculation methods and reporting items needed for repeatable noise-figure measurements.

What does FprEN IEC 61290-3-2:2026 specify?

FprEN IEC 61290-3-2:2026 specifies a measurement method for noise figure parameters of optical amplifiers using an ESA. The document focuses on accurate and reliable electrical noise measurements, so the result is the total noise figure rather than an optical-spectrum-based parameter.

The standard is organized into nine clauses:

• Scope
• Normative references
• Terms, definitions, abbreviated terms and symbols
• General
• Apparatus
• Test specimen
• Procedure
• Calculation
• Test results

It also includes one measurement setup figure and a bibliography. The scope is intentionally broad for amplifier types, and the introduction notes that the method should be read together with IEC 61290-3 and IEC 61291-1.

What are the key requirements of FprEN IEC 61290-3-2:2026?

FprEN IEC 61290-3-2:2026 requires a controlled optical and electrical setup so the ESA can separate shot noise, laser relative intensity noise (RIN) and amplifier noise. In practice, that means the source, attenuators, detector, amplifier and ESA all have to be suitable for low-noise work and stable enough for calibration and measurement.

Measurement principle and applicability

Clause 4 states that the method is based on direct electrical noise measurement and can be used for all types of optical amplifiers, including devices with significant noise contributions other than amplified spontaneous emission. This matters because SOA and Raman amplifiers can show noise behavior that an optical-only method may not capture.

Required apparatus

Clause 5 specifies a modulated single-line laser source, an input variable optical attenuator (VOA), a polarization controller, a modulation source, an optical power meter, a receiver module with an output VOA, detector and ESA, plus suitable jumper cables and connectors. Optional optical filtering can be used to reduce spontaneous-spontaneous mixing. In practice, the equipment has to preserve spectrum, polarization and low reflectance so the measured noise is not distorted by the test rig.

Test specimen conditions

Clause 6 requires the optical amplifier (OA) to operate at nominal conditions. It also asks the user to control polarization carefully and, when needed, to adjust the input polarization state to maximize the noise figure. This matters because polarization changes can alter input power and multiple path interference (MPI) effects.

Two measurement techniques

Clause 7 gives two alternatives: a frequency-scanning technique and a selected-frequency technique. The frequency-scanning technique is recommended when the noise versus frequency behavior is unknown or non-monotonic; the selected-frequency technique is used when the noise is essentially flat or steadily decaying. This lets the tester choose the simplest method that still matches the amplifier behavior.

Calibration and accuracy checks

Clause 7.2 requires separate calibration of shot noise and source RIN by changing optical power levels, while keeping laser conditions fixed. Clause 7.5 sets practical accuracy checks: receiver thermal noise should be sufficiently below shot noise, and source RIN should be below shot noise at the highest input power. In practice, these checks tell the lab whether the setup is quiet enough for a trustworthy result.

Calculation of results

Clause 8 explains how to calculate calibration results, noise factor, noise figure, source RIN and, when needed, MPI figure of merit and signal-spontaneous noise figure. The calculations use measured ESA noise powers, optical power, gain, linewidth and attenuation factors. This is what turns the raw measurements into reportable amplifier performance data.

What terms does FprEN IEC 61290-3-2:2026 define?

• ESA (electrical spectrum analyzer) - The instrument used to measure the electrical noise spectrum during calibration and test.
• OFA (optical fibre amplifier) - An optical amplifier based on fibre, including rare-earth-doped and Raman types.
• SOA (semiconductor optical amplifier) - An optical amplifier built on a semiconductor gain medium.
• PWOA (planar waveguide optical amplifier) - An optical amplifier implemented in a planar waveguide structure.
• RIN (relative intensity noise) - The laser source intensity fluctuation, expressed per hertz, that can add to the measured noise.
• MPI (multiple path interference) - Noise caused by internal reflections and interference inside the amplifier.
• VOA (variable optical attenuator) - A controllable attenuator used to set optical power without changing the source behavior.

Who uses FprEN IEC 61290-3-2:2026?

FprEN IEC 61290-3-2:2026 is used by optical amplifier manufacturers, test laboratories, quality engineers and product evaluators. It is relevant to anyone who needs to measure or compare amplifier noise figure, set up a repeatable ESA-based test, or document test conditions for development, production or acceptance testing. It also supports certification and conformity assessment work where amplifier noise performance has to be reported in a consistent way.

What changed in FprEN IEC 61290-3-2:2026 from the previous edition?

FprEN IEC 61290-3-2:2026 replaces the second edition published in 2008 and is described as a technical revision. The stated technical changes are:

• the scope in Clause 1 was shortened and clarified
• the normative references in Clause 2 were updated
• duplicate instructions in 7.2 about measuring time-average input power were deleted
• unused symbols in 3.3 were removed and a new symbol was added

Which standards are used with FprEN IEC 61290-3-2:2026?

FprEN IEC 61290-3-2:2026 names IEC 61291-1 as the normative reference, so its definitions apply throughout the document. It also says the standard should be read with IEC 61290-3, which gives the general noise-figure test-method framework, and it cites IEC TR 61292-2 for the theoretical background to ESA-based noise figure evaluation. IEC 60728-6 is cited for a detailed self-heterodyning linewidth measurement method used in the procedure.

What does the FprEN IEC 61290-3-2:2026 document contain?

FprEN IEC 61290-3-2:2026 contains a full measurement workflow: setup, calibration, measurement and calculation. It gives one schematic measurement arrangement in Figure 1 and formulas for modulation index, shot noise, RIN, noise factor, noise figure and MPI-related quantities. It also lists the reporting items that should be included in test results, such as wavelength, source linewidth, source RIN, modulation conditions, input power, ESA bandwidth and the resulting noise figure.

SLOVENSKI STANDARD
oSIST prEN IEC 61290-3-2:2025
01-december-2025
Optični ojačevalniki - Preskusne metode - 3-2. del: Parametri hrupa - Metoda
analizatorja električnega spektra
Optical amplifiers - Test methods - Part 3-2: Noise figure parameters - Electrical
spectrum analyzer method
Lichtwellenleiter-Verstärker - Prüfverfahren - Teil 3-2: Rauschzahlparameter - Verfahren
mit elektrischem Spektralanalysator
Amplificateurs optiques - Méthodes d'essais - Partie 3-2: Paramètres du facteur de bruit -
Méthode de l'analyseur spectral électrique
Ta slovenski standard je istoveten z: prEN IEC 61290-3-2:2025
ICS:
33.180.30 Optični ojačevalniki Optic amplifiers
oSIST prEN IEC 61290-3-2:2025 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 61290-3-2:2025
oSIST prEN IEC 61290-3-2:2025
86C/1990/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61290-3-2 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-10-24 2026-01-16
SUPERSEDES DOCUMENTS:
86C/1976/CD, 86C/1986/CC
IEC SC 86C : FIBRE OPTIC SYSTEMS, SENSING AND ACTIVE DEVICES
SECRETARIAT: SECRETARY:
United States of America Mr Fred Heismann
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Optical amplifiers - Test methods - Part 3-2: Noise figure parameters - Electrical spectrum
analyzer method
PROPOSED STABILITY DATE: 2029
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oSIST prEN IEC 61290-3-2:2025
Link to Committee Draft for Vote (CDV) online document:
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oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
CONTENTS
How to access . 2
Resource materials . 2
Contact . 2
Should you require any assistance, please contact the IEC IT Helpdesk . 2
CONTENTS . 1
FOREWORD . 2
INTRODUCTION . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, abbreviated terms, and symbols . 5
3.1 Terms and definitions . 5
3.2 Abbreviated terms . 5
3.3 Symbols . 5
4 General . 7
5 Apparatus . 7
6 Test specimen . 9
7 Procedure . 9
7.1 General remark . 9
7.2 Frequency-scanning technique: calibration . 9
7.3 Frequency-scanning technique: measurement . 11
7.4 Selected-frequency technique: calibration and measurement . 12
7.5 Measurement accuracy limitations . 12
8 Calculation . 13
8.1 General . 13
8.2 Calculation of calibration results . 13
8.3 Calculation of test results for the frequency-scanning technique . 14
8.4 Calculation of test results for the selected-frequency technique . 14
9 Test results . 15
Bibliography . 16

Figure 1 – Scheme of a measurement set-up . 8

oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Optical amplifiers - Test methods -
Part 3-2: Noise figure 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
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the technical content of IEC Publications is accurate, IEC cannot be held responsible for the
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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
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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
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
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 61290-3-2 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 third edition cancels and replaces the second edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Shortened and clarified the scope in Clause 1;
b) Updated the normative references in Clause 2;
c) Deleted duplicate instructions in 7.2 to measure the time-average input power;
d) Removed unused symbols in 3.3 and added a new symbol.
The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
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 http://www.iec.ch/members_experts/refdocs. The main document types developed by IEC
are described in greater detail at http://www.iec.ch/publications.
A list of all parts of 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, or
– revised.
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
INTRODUCTION
This part of IEC 61290 is devoted to noise figure measurements of optical amplifiers using the
electrical spectrum analyzer method. The technology of optical amplifiers is still rapidly
evolving, hence amendments and new additions to this standard can be expected.
This document should be read in conjunction with IEC 61290-3 [1] and IEC 61291-1.
Each symbol and abbreviation introduced in this document is generally explained in the text the
first time it appears. However, for an easier understanding of the whole text, a list of all symbols
and abbreviations used in this document is given in Clause 3.
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
1 Scope
This part of IEC 61290 applies to all commercially available optical amplifiers (OAs), including
OAs using optically pumped fibres (i.e. optical fibre amplifiers (OFAs) based on either rare-
earth doped fibres or on the Raman effect), semiconductor optical amplifiers (SOAs), and planar
waveguide optical amplifiers (PWOAs).
This document establishes requirements for accurate and reliable measurements of the noise
figure parameters of OAs by means of the electrical spectrum analyzer (ESA) method. The
noise figure parameters of OAs are defined in IEC 61291-1.
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 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
CW continuous wave
DFB distributed feedback
ESA electrical spectrum analyzer
FWHM full width at half maximum
MPI multiple path interference
OA optical amplifier
OFA optical fibre amplifier
PWOA planar waveguide optical amplifier
−1
RIN
relative intensity noise (of the source, expressed in Hz )
RMS root mean square
SOA semiconductor optical amplifier
VOA variable optical attenuator
3.3 Symbols
B calibrated, noise equivalent ESA electrical bandwidth (not necessarily the
e
resolution bandwidth)
c speed of light in vacuum
e electron charge
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
f baseband frequency
F (total) noise factor
F frequency-independent contribution to total noise factor
non-mpi
G OA optical signal gain
h Planck's constant
k optical power reduction factor (default k = 0,5); it can be obtained by taking
the square root of the electrical power reduction factor
v optical frequency = c/λ
∆v source FWHM linewidth with modulation on
−1 2
H ,H (f)
transfer function of receiver in watts (= S /∆P )
0 0
esa in
I multiple path interference figure of merit, the noise factor contribution caused
mpi
by multiple path interference integrated over all baseband frequencies (0 to
infinity)
I photodetector current
pd
λ wavelength in vacuum
m relative modulation amplitude (the ratio of RMS optical power modulation
amplitude to average optical power)
NF(f) (total) noise figure
NF signal-spontaneous noise figure
sig-sp
N (f) (frequency-dependent) ESA noise contribution caused by the laser relative
rin,0
intensity noise, at calibration conditions
N (frequency-independent) shot noise caused by the optical input power, at
shot,0
calibration conditions, measured with ESA
N thermal noise level as measured with ESA (optical input port of receiver
thermal
module closed)
N (f) (frequency-dependent) noise power measured with ESA with input and output
VOA set to 0 dB, thermal noise level subtracted, without OA test device
N '(f) (frequency-dependent) noise power measured with ESA with input VOA set to
3 dB (default) and output VOA set to 0 dB, thermal noise level subtracted,
without OA test device
N (f) frequency-dependent noise power, with OA inserted, thermal noise level
subtracted, measured with ESA
P time-averaged optical input power = T P (with modulation on); optical
in in in,0
power radiated from the end of the input jumper cable
P time-averaged optical input power at 0 dB setting of input VOA (with
in,0
modulation on)
∆P RMS optical power amplitude
in,rms
P total optical power radiated from the output port of the OA, including the ASE
out
r ,r (f) effective photodetector responsivity through output VOA at 0 dB setting
0 0
R (f) source relative intensity noise; generally, the square of the RMS optical power
RIN,source
fluctuation divided by the (baseband) bandwidth and the square of the CW
power
S electrical power of the modulation signal at T = 1, measured with ESA,
0 in
without OA inserted
S electrical power of the modulation signal, with OA inserted, measured with
ESA
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
T transmission factor of input VOA relative to transmission at 0 dB setting,
in
expressed in linear units
T transmission factor of output attenuator relative to transmission at 0 dB
out
setting, expressed in linear units
4 General
The present test method is based on direct electrical noise measurement, and it is directly
related to its definition including all relevant noise contributions. Therefore, this method can be
used for all types of optical amplifiers, including SOA and Raman amplifiers which can have
significant contributions besides amplified spontaneous emission, because it measures the total
noise figure. For further details of applicability, see the IEC 61290-3 series. An alternative test
method based on optical spectrum analysis can be used, particularly for different noise
parameters (such as the signal-spontaneous noise factor) but it is not included in the scope of
this standard.
All numerical values followed by (‡) are suggested values for which the measurement is
assured. Other values can be acceptable but should be verified.
A measurement accuracy for the average noise factor of ±20% (‡), respectively ±1 dB, should
be attainable with this method (see Clause 7).
NOTE General aspects of noise figure test methods are described in IEC 61290-3.
5 Apparatus
A schematic diagram of a possible implementation of the measurement set-up is shown in
Figure 1.
The test equipment listed below, with the required characteristics, is needed.
a) A source module with the following components.
1) A laser source with a single-line spectrum, for example, a distributed feedback (DFB)
laser diode. The laser source shall be amplitude modulated with a sinusoidal signal of a
single frequency that is higher than the linewidth of the laser source. A modulation
frequency at least 3 times higher than the linewidth is recommended. The relative
modulation amplitude, m (that is, the ratio of root mean square (RMS) of the optical
power modulation amplitude to the average optical power) shall be small enough to
ensure operation in the linear region. A value of m between 2 % and 10 %(‡) is
considered adequate. Direct or external modulation of the laser source may be used.
The average output power, P , of the laser source should be at least 0 dBm, to generate
in,0
the desired OA saturation state.
The linewidth FWHM (full width at half maximum) under modulation shall be between 20
MHz(‡) and 100 MHz(‡). This is considered the best range for accurate determination of the
noise contribution from multiple path interference, because it closely reflects the typical
linewidths of DFB lasers, which is the typical laser source used in conjunction with OAs. A
linewidth of 20 MHz is adequate for a minimum spacing of 7,5 m between the OA internal
reflection points. Using narrower linewidths can lead to the undesired situation that the
internal reflections in the OA interfere coherently and that substantially different noise figure
results are obtained. A linewidth of more than 100 MHz will cause OA noise contributions at
frequencies that are higher than the high end of the ESA bandwidth.
The relative intensity noise (RIN) of the laser source shall be less than −150 dB/Hz(‡) within
the frequency range of interest (for example, 10 MHz to 2 GHz).
The spontaneous emission power, relative to the signal power, shall be less than −40
dB/nm(‡) to avoid large noise contributions from spontaneous-spontaneous mixing of the
source spontaneous emission.
oSIST prEN IEC 61290-3-2:2025
IEC CDV 61290-3-2 © IEC 2025
2) A built-in or external isolator, so that external reflections have no influence on the laser
spectrum and on the laser relative i
...