Optical amplifiers - Test methods - Part 4-3: Power transient parameters - Single channel optical amplifiers in output power control

IEC 61290-4-3:2018 applies to output power controlled optically amplified, elementary sub‑systems. It applies to optical fibre amplifiers (OFAs) using active fibres containing rare‑earth dopants, presently commercially available, as indicated in IEC 61291-1, as well as alternative optical amplifiers that can be used for single channel output power controlled operation, such as semiconductor optical amplifiers (SOAs). The object of this document is to provide the general background for optical amplifiers (OAs) power transients and their measurements and to indicate those IEC standard test methods for accurate and reliable measurements of the following transient parameters:
a) transient power response;
b) transient power overcompensation response;
c) steady-state power offset;
d) transient power response time.
The stimulus and responses behaviours under consideration include the following:
1. channel power increase (step transient);
2. channel power reduction (inverse step transient);
3. channel power increase/reduction (pulse transient);
4. channel power reduction/increase (inverse pulse transient);
5. channel power increase/reduction/increase (lightning bolt transient);
6. channel power reduction/increase/reduction (inverse lightning bolt transient).
These parameters have been included to provide a complete description of the transient behaviour of an output power transient controlled OA. The test definitions defined here are applicable if the amplifier is an OFA or an alternative OA. However, the description in Annex A concentrates on the physical performance of an OFA and provides a detailed description of the behaviour of an OFA; it does not give a similar description of other OA types. Annex B provides a detailed description background of the dynamic phenomenon in output power controlled amplifiers under transient conditions and Annex C details the impact of speed of transient inputs.This second edition cancels and replaces the first edition published in 2015. This edition constitutes a technical revision. This edition includes the following significant technical change with respect to the previous edition: alignment of the measure of amplified spontaneous emission (ASE) relative to signal power with the definition in IEC 61290-3-3.
Keywords: optical amplifiers (OAs) power transients
This International Standard is to be used in conjunction with IEC 61291-1:2012

Amplificateurs optiques - Méthodes d'essai - Partie 4-3: Paramètres de puissance transitoire - Amplificateurs optiques monocanaux commandés par la puissance de sortie

L'IEC 61290-4-3:2018 s'applique aux sous-systèmes élémentaires à amplification optique et commandés par la puissance de sortie. Elle applique aux amplificateurs à fibres optiques utilisant des fibres actives dopées aux terres rares disponibles sur le marché, comme indiqué dans l'IEC 61291-1, mais aussi à des amplificateurs optiques alternatifs qui peuvent être utilisés pour un fonctionnement monocanal commandé par la puissance de sortie, tels que des amplificateurs optiques à semiconducteurs.
Le présent document a pour objet de fournir le contexte général pour les puissances transitoires des amplificateurs optiques et leurs mesures, ainsi que de décrire des méthodes d'essai normalisées de l'IEC pour effectuer des mesures précises et fiables des paramètres des transitoires suivants:
a) réponse de puissance transitoire;
b) réponse de surcompensation de puissance transitoire;
c) décalage de puissance en régime permanent;
d) temps de réponse de puissance transitoire.
Les comportements des stimuli et des réponses étudiés incluent les éléments suivants:
1. augmentation de la puissance d'un canal (transitoire en échelon);
2. diminution de la puissance d'un canal (transitoire en échelon inverse);
3. augmentation/diminution de la puissance d'un canal (transitoire en impulsion);
4. diminution/augmentation de la puissance d'un canal (transitoire en impulsion inverse);
5. augmentation/diminution/augmentation de la puissance d'un canal (transitoire en éclair);
6. diminution/augmentation/diminution de la puissance d'un canal (transitoire en éclair inverse).
Ces paramètres ont été inclus pour fournir une description complète du comportement des transitoires d'un amplificateur optique commandé par la puissance transitoire de sortie. Les essais définis ici sont applicables si l'amplificateur est un amplificateur à fibres optiques ou un amplificateur optique alternatif. Toutefois, l'Annexe A décrit les performances physiques d'un amplificateur à fibres optiques et fournit une description détaillée du comportement des amplificateurs à fibres optiques, mais ne donne pas de description similaire d'autres types d'amplificateurs optiques. L’Annexe B fournit des informations contextuelles de descriptions détaillées du phénomène dynamique se produisant dans les amplificateurs commandés par la puissance de sortie dans des conditions transitoires et l’Annexe C précise l’effet produit par la vitesse des entrées transitoires. Cette deuxième édition annule et remplace la première édition publiée en 2015. Cette édition constitue une révision technique Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: alignement de la mesure d'une émission spontanée amplifiée sur la puissance d'un signal selon la définition de l'IEC 61290-3-3.
Mots clés: puissances transitoires des amplificateurs optiques
La présente Norme internationale doit être utilisée conjointement avec l'IEC 61291-1:2012.

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Published
Publication Date
26-Apr-2018
Current Stage
PPUB - Publication issued
Completion Date
27-Apr-2018
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IEC 61290-4-3
Edition 2.0 2018-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical amplifiers – Test methods –
Part 4-3: Power transient parameters – Single channel optical amplifiers in
output power control
Amplificateurs optiques – Méthodes d'essai –
Partie 4-3: Paramètres de puissance transitoire – Amplificateurs optiques
monocanaux commandés par la puissance de sortie
IEC 61290-4-3:2018-04(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61290-4-3
Edition 2.0 2018-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical amplifiers – Test methods –
Part 4-3: Power transient parameters – Single channel optical amplifiers in
output power control
Amplificateurs optiques – Méthodes d'essai –
Partie 4-3: Paramètres de puissance transitoire – Amplificateurs optiques
monocanaux commandés par la puissance de sortie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.30 ISBN 978-2-8322-5639-8

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61290-4-3:2018 © IEC 2018
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 ................................................................................................... 7

4 Apparatus ........................................................................................................................ 8

4.1 Test set-up ............................................................................................................. 8

4.2 Characteristics of test equipment ............................................................................ 8

5 Test sample ..................................................................................................................... 9

6 Procedure ........................................................................................................................ 9

6.1 Test preparation...................................................................................................... 9

6.2 Test ...................................................................................................................... 10

7 Calculations ................................................................................................................... 10

8 Test results ................................................................................................................... 11

8.1 Test setting conditions .......................................................................................... 11

8.2 Test data .............................................................................................................. 12

Annex A (informative) Overview of power transient events in single channel EDFA .............. 13

A.1 Background........................................................................................................... 13

A.2 Characteristic input power behaviour .................................................................... 13

A.3 Parameters for characterizing transient behaviour ................................................ 16

Annex B (informative) Background on power transient phenomena in a single channel

EDFA .................................................................................................................................... 17

B.1 Amplifier chains in optical networks ...................................................................... 17

B.2 Typical optical amplifier design ............................................................................. 17

B.3 Approaches to address detection errors ................................................................ 19

Annex C (informative) Slew rate effect on transient gain response ....................................... 23

Bibliography .......................................................................................................................... 24

Figure 1 – Power transient test set-up..................................................................................... 8

Figure 2 – OA output power transient response of a) input power increase and b)

decrease ............................................................................................................................... 11

Figure A.1 – Example OA input power transient cases for a receiver application ................... 14

Figure A.2 – Input power measurement parameters .............................................................. 15

Figure A.3 – OA output power transient response ................................................................. 16

Figure B.1 – Transient response to input power drop ............................................................ 21

Figure B.2 – Transient response to input power rise ............................................................. 22

Table 1 – Template for transient control measurement test conditions .................................. 10

---------------------- Page: 4 ----------------------
IEC 61290-4-3:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL AMPLIFIERS – TEST METHODS –
Part 4-3: Power transient parameters –
Single channel optical amplifiers in output power control
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

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6) All users should ensure that they have the latest edition of this publication.

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61290-4-3 has been prepared by subcommittee 86C: Fibre optic

systems and active devices, of IEC technical committee 86: Fibre optics.

This second edition cancels and replaces the first edition published in 2015. This edition

constitutes a technical revision.

This edition includes the following significant technical change with respect to the previous

edition: alignment of the measure of amplified spontaneous emission (ASE) relative to signal

power with the definition in IEC 61290-3-3.
---------------------- Page: 5 ----------------------
– 4 – IEC 61290-4-3:2018 © IEC 2018
The text of this International Standard is based on the following documents:
FDIS Report on voting
86C/1505/FDIS 86C/1512/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

This International Standard is to be used in conjunction with IEC 61291-1:2012.

A list of all parts of 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.
---------------------- Page: 6 ----------------------
IEC 61290-4-3:2018 © IEC 2018 – 5 –
OPTICAL AMPLIFIERS – TEST METHODS –
Part 4-3: Power transient parameters –
Single channel optical amplifiers in output power control
1 Scope

This part of IEC 61290 applies to output power controlled optically amplified, elementary

sub-systems. It applies to optical fibre amplifiers (OFAs) using active fibres containing

rare-earth dopants, presently commercially available, as indicated in IEC 61291-1, as well as

alternative optical amplifiers that can be used for single channel output power controlled

operation, such as semiconductor optical amplifiers (SOAs).

The object of this document is to provide the general background for optical amplifiers (OAs)

power transients and their measurements and to indicate those IEC standard test methods for

accurate and reliable measurements of the following transient parameters:
a) transient power response;
b) transient power overcompensation response;
c) steady-state power offset;
d) transient power response time.
The stimulus and responses behaviours under consideration include the following:
1) channel power increase (step transient);
2) channel power reduction (inverse step transient);
3) channel power increase/reduction (pulse transient);
4) channel power reduction/increase (inverse pulse transient);
5) channel power increase/reduction/increase (lightning bolt transient);

6) channel power reduction/increase/reduction (inverse lightning bolt transient).

These parameters have been included to provide a complete description of the transient

behaviour of an output power transient controlled OA. The test definitions defined here are

applicable if the amplifier is an OFA or an alternative OA. However, the description in

Annex A concentrates on the physical performance of an OFA and provides a detailed

description of the behaviour of an OFA; it does not give a similar description of other OA

types. Annex B provides a detailed description background of the dynamic phenomenon in

output power controlled amplifiers under transient conditions and Annex C details the impact

of speed of transient inputs.
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
---------------------- Page: 7 ----------------------
– 6 – IEC 61290-4-3:2018 © IEC 2018
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1.1
input signal
optical signal that is input to the OA
3.1.2
input power excursion

relative input power difference before, during and after the input power stimulus event that

causes an OA transient power excursion
Note 1 to entry: Input power excursion is expressed in dB.
3.1.3
input power rise time

time it takes for the input optical signal to rise from 10 % to 90 % of the total difference

between the initial and final signal levels during an increasing power excursion event

Note 1 to entry: See Figure A.2 a).
3.1.4
input power fall time

time it takes for the input optical signal to fall from 90 % to 10 % of the total difference

between the initial and final signal levels during a decreasing power excursion event

Note 1 to entry: See Figure A.2 b).
3.1.5
slew rate

maximum rate of change of the input optical signal during a power excursion event

Note 1 to entry: See Annex C.
3.1.6
transient power response

maximum or minimum deviation (overshoot or undershoot) between the OA’s target power

and the observed power excursion induced by a change in an input channel power excursion

Note 1 to entry: Once the output power of an amplified channel deviates from its target power, the control

electronics in the OA should attempt to compensate for the power difference or transient power response, bringing

the OA output power back to its original target level.
Note 2 to entry: Transient power response is expressed in dB.
3.1.7
transient power response time

amount of time taken to restore the power of the OA to a stable power level close to the target

power level

Note 1 to entry: This parameter is measured from the time when the stimulus event created the power fluctuation

to the time at which the OA power response is stable and within specification.
---------------------- Page: 8 ----------------------
IEC 61290-4-3:2018 © IEC 2018 – 7 –
3.1.8
transient power overcompensation response

maximum deviation between the amplifier’s target output power and the power resulting from

the control electronics’ instability

Note 1 to entry: Transient power overcompensation response occurs after a power excursion, when an amplifier’s

control electronics attempts to bring the power back to the amplifier’s target level. The control process is iterative,

and control electronics may initially overcompensate for the power excursion until subsequently reaching the

desired target power level.

Note 2 to entry: The transient power overcompensation response parameter is generally of lesser magnitude than

the transient power response and has the opposite sign.
Note 3 to entry: Transient power overcompensation response is expressed in dB.
3.1.9
steady state power offset

difference between the final and initial output power of the OA, prior to the power excursion

stimulus event

Note 1 to entry: Normally, the steady state power level following a power excursion differs from the OA power

before the input power stimulus event. The transient controller attempts to overcome this offset using feedback.

Note 2 to entry: Steady state power offset is expressed in dB.
3.2 Abbreviated terms
AFF ASE flattening filter
AGC automatic gain controller
APC automatic power control
ASE amplified spontaneous emission
ASEP amplified spontaneous emission power
BER bit error ratio
DFB distributed feedback (laser)
DWDM dense wavelength division multiplexing
EDF erbium-doped fibre
EDFA erbium-doped fibre amplifier
GFF gain flattening filter
NEM network equipment manufacturers
NSP network service providers
O/E optical-to-electrical
OA optical amplifier
OD optical damage
OFA optical fibre amplifier
OSA optical spectrum analyser
OSNR optical signal-to-noise ratio
PDs photodiodes
PID proportional integral-derivative
SOA semiconductor optical amplifier
Sig_ASE signal-to-ASE ratio
SigP signal power
SOP state of polarization
VOA variable optical attenuator
WDM wavelength division multiplexing
---------------------- Page: 9 ----------------------
– 8 – IEC 61290-4-3:2018 © IEC 2018
4 Apparatus
4.1 Test set-up

Figure 1 shows a generic set-up to characterise the transient response properties of output

power controlled single channel OAs.
Channel pass-
Optical
Polarization
under
Laser source VOA
band filter
modulator
scrambler
test
VOA
Function generator
O/E converter
Oscilloscope
IEC
Figure 1 – Power transient test set-up
4.2 Characteristics of test equipment
The test equipment listed below is needed, with the required characteristics:

a) Laser source for supplying the OA input signal with the following characteristics.

– ability to support the range of signal wavelengths for which the OA under test is to be

tested. This could be provided for example by a tuneable laser, or a bank of distributed

feedback (DFB) lasers;

– an achievable average output power such that at the input to the OA under test, the

power will be above the maximum specified input power of the OA, including loss of

any subsequent test equipment between the laser source and OA under test.

b) Polarization scrambler to randomize the incoming polarization state of the laser source, or

to control it to a defined state of polarization (SOP). The polarization scrambler is

optional.

c) Variable optical attenuator (VOA) with a dynamic range sufficient to support the required

range of surviving signal levels at which the OA under test is to be tested.

NOTE If the output power of the laser source can be varied over the required dynamic range, then a VOA is

not needed.

d) Optical modulator to modify the OA input signal to the defined power excursion with the

following characteristics;

– extinction ratio at rewrite without putting a number higher than the maximum drop level

for which the OA under test is to be tested;

– switching time fast enough to support the fastest slew rate for which the OA under test

is to be tested.

e) Channel pass-band filter: an optical filter designed to distinguish the signal wavelength

with the following characteristics. Note that the use of a channel pass-band filter is

optional:

– ability to support the range of signal wavelengths for which the OA under test is to be

tested. This could be provided for example by a tuneable filter, or a series of discrete

filters;
– 1-dB passband of at least ±20 GHz centred around the signal wavelength;
---------------------- Page: 10 ----------------------
IEC 61290-4-3:2018 © IEC 2018 – 9 –

– more than 20 dB attenuation level below the minimum insertion loss across the entire

specified transmission band of the OA under test, except within a range of ±100 GHz

centred around the signal wavelength.

f) VOA before the optical-to-electrical (O/E) converter to ensure the maximum power is

within the linear response range.

g) Optical-to-electrical (O/E) convertor to detect the filtered output of the OA under test with

the following characteristics:

– a sufficiently wide optical and electrical bandwidth to support the fastest slew rate for

which the OA is to be tested;

– a linear response within a ±5 dB range of all signal levels for which the OA under test

is to be tested.

h) Oscilloscope to measure and capture the transient response of the optically filtered output

of the OA under test, with a sufficiently wide electrical bandwidth to support the fastest

slew rate for which the OA is to be tested.

i) Function generator to generate the input power transient waveforms to drive the optical

modulator, with electrical pulse width short enough and electrical slew rate high enough to

support the fastest slew rate for which the OA under test is to be tested.
5 Test sample

The OA shall operate under nominal operating conditions. If the OA is likely to cause laser

oscillations due to unwanted reflections, optical isolators should be used to isolate the OA

under test. This will minimize signal instability.
6 Procedure
6.1 Test preparation

In the set-up shown in Figure 1, the input optical signal power injected into the amplifier being

tested is generated from a suitable laser source. The optical power is passed through an

optional polarization scrambler to allow randomization or control of the signal polarization

state and is subsequently adjusted with a VOA to the desired optical input power levels. The

signal then passes through an optical modulator driven by a function generator that provides

the desired input power test waveform to stimulate the transient input power excursions. The

signal is then injected into the amplifier being tested. A channel pass-band filter (such as a

tuneable optical filter, fixed optical filter or similar component) may be used to select only the

relevant channel wavelength under test, followed by an O/E converter and an oscilloscope at

the output of the amplifier. The output channel selected by the optional channel pass-band

filter including its transient response is monitored with the O/E converter and oscilloscope.

Waveforms similar to those shown in Figure A.3 are captured via the oscilloscope for

subsequent computer processing.

Prior to measurement of the transient response, the input power waveform trace shall be

recorded. Use the set-up of Figure 1 without the OFA under test. The input optical connector

from the optical modulator is connected to the channel pass-band filter.

For this test, to stimulate a power excursion at the input of the OA under test, the source laser

power at the OA input is set at some typical power level. The function generator waveform is

chosen to increase or decrease the input power to the OA under test with power excursions

and slew rate relevant to the defined test condition. For example, for a typical number in the

case of an optical receiver, the input power to the OA could be increased by 7 dB in a

timeframe of 50 µs and then held at this power value to simulate a power increase transient

power response (step transient) condition as shown in Figure A.1 a). For al
...

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