IEC TR 61292-1:2022

Optical amplifiers - Part 1: Parameters of optical fibre amplifier components

IIEC TR 61292-1:2022 which is a Technical Report, applies to optical components of optical fibre amplifiers (OFAs). This document provides information about the most relevant parameters of these optical components, especially for erbium doped fibre amplifiers (EDFAs) and fibre Raman amplifiers (FRAs). It provides introductory information for a better understanding operation and applications of EDFAs and FRAs. NOTE IEC TR 61292-6 provides more technical information on FRAs. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision.  This edition includes the following significant technical changes with respect to the previous edition:  
Change of document title from "Parameters of amplifier components" to "Parameters of optical fibre amplifier components";
Addition of parameters for optical components used in fibre Raman amplifiers;
Addition of Table 1, listing various documents that specify terms and definitions for optical components used in optical fibre amplifiers;
Addition of Figure 2 and Figure 3, showing typical component layouts for distributed and lumped fibre Raman amplifiers;
Harmonization of the descriptions of optical component parameters with the definitions in other standards on optical components.

General Information

• Status: Published
• Publication Date: 10-May-2022
• ICS: 33.160.10 - Amplifiers
• ICS: 33.180.30 - Optic amplifiers
• Technical Committee: SC 86C - Fibre optic systems, sensing and active devices
• Drafting Committee: WG 3 - TC 86/SC 86C/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 11-May-2022
• Completion Date: 10-Jun-2022

Relations

• Revises: IEC TR 61292-1:2009 - Optical amplifiers - Part 1: Parameters of amplifier components
• Effective Date: 05-Sep-2023

Overview

IEC TR 61292-1:2022 - "Optical amplifiers - Part 1: Parameters of optical fibre amplifier components" (Edition 3.0, 2022) is a Technical Report from the IEC that documents the most relevant parameters and descriptive information for optical components used in optical fibre amplifiers (OFAs). It focuses on erbium-doped fibre amplifiers (EDFAs) and fibre Raman amplifiers (FRAs) and provides introductory guidance to help engineers, manufacturers and integrators understand component behavior, measurement context and application roles. This edition replaces the 2009 edition and introduces scope extensions and harmonized definitions.

Key Topics

• Scope and purpose of parameters for OFA components with emphasis on EDFAs and FRAs.
• Definitions, symbols and abbreviated terms consistent with IEC terminology databases and referenced standards.
• Component coverage and parameter descriptions for:
  • Active fibres (EDFA active fibre, Raman gain fibre)
  • Pump lasers and pump characteristics
  • WDM couplers and pump WDM couplers
  • Polarization beam combiners (PBCs)
  • Optical isolators
  • ASE rejection filters and pump rejection filters
  • Gain flattening filters (GFFs)
  • Tap couplers, PIN photodiodes (PIN-PD), variable optical attenuators (VOAs), optical connectors
• New and revised deliverables in this edition:
  • Addition of parameters for fibre Raman amplifier components
  • Table of documents listing terms/definitions for amplifier components (Table 1)
  • Illustrative layouts for distributed and lumped Raman amplifiers (Figures 2 & 3)
  • Harmonization with parameters and definitions from related optical-component standards
• Normative references include IEC 61291-1:2018 (Fibre amplifiers - Generic specification) and IEC TR 61931 (Fibre optic - Terminology).

Applications

• Practical reference for:
  • OFA system designers specifying component tolerances and interoperability constraints
  • Component manufacturers documenting parameter definitions and testability
  • Test laboratories preparing measurement procedures and reporting formats
  • Network planners and integrators selecting amplifier modules (EDFAs, FRAs) and subcomponents
  • Procurement and quality teams evaluating vendor data sheets against standardized terminology
• Helps improve clarity in technical specifications, vendor comparisons, and system interoperability for long‑haul, metro and access optical networks relying on EDFAs and Raman amplification.

Related Standards

• IEC 61291-1:2018 - Fibre amplifiers - Generic specification
• IEC TR 61931 - Fibre optic - Terminology
• IEC TR 61292 series (other parts) and IEC measurement documents (e.g., IEC 61290 series) for specific measurement procedures.

Keywords: IEC TR 61292-1:2022, optical amplifiers, optical fibre amplifier components, EDFA, FRA, pump laser, WDM coupler, gain flattening filter, ASE rejection filter, optical isolator.

Standards Content (Sample)

IEC TR 61292-1 ®
Edition 3.0 2022-05
TECHNICAL
REPORT
Optical amplifiers –
Part 1: Parameters of optical fibre amplifier components
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IEC TR 61292-1 ®
Edition 3.0 2022-05
TECHNICAL
REPORT
Optical amplifiers –
Part 1: Parameters of optical fibre amplifier components

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.160.10; 33.180.30 ISBN 978-2-8322-0299-9

– 2 – IEC TR 61292-1:2022 © IEC 2022
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, abbreviated terms and symbols . 6
3.1 Terms and definitions . 6
3.1.1 Parameters for active fibres . 6
3.1.2 Parameters for pump lasers . 8
3.1.3 Parameters for WDM couplers . 11
3.1.4 Parameters for pump WDM couplers. 12
3.1.5 Parameters for optical isolators . 12
3.1.6 Parameters for ASE rejection filters . 14
3.1.7 Parameters for pump rejection filters . 14
3.1.8 Parameters for gain flattening filters . 15
3.1.9 Parameters for tap couplers . 16
3.1.10 Parameters for PIN-photodiodes . 17
3.1.11 Parameters for variable optical attenuators (VOAs) . 18
3.1.12 Parameters for optical connectors . 19
3.2 Abbreviated terms . 19
3.3 Symbols . 20
4 OFA components . 21
5 Parameters of optical fibre amplifier components . 24
5.1 Active fibre. 24
5.1.1 Function and technical outline . 24
5.1.2 Parameters for active fibres . 24
5.2 Gain fibre for FRA . 25
5.2.1 Function and technical outline . 25
5.2.2 Parameters for gain fibres of FRAs . 25
5.3 Pump laser . 25
5.3.1 Function and technical outline . 25
5.3.2 Parameters for pump lasers . 25
5.4 WDM coupler (for combining signal light and pump light) . 26
5.4.1 Function and technical outline . 26
5.4.2 Parameters for WDM couplers . 26
5.5 Pump WDM coupler . 26
5.5.1 Function and technical outline . 26
5.5.2 Parameters for pump WDM couplers. 26
5.6 Polarization beam combiner (PBC) . 26
5.6.1 Function and technical outline . 26
5.6.2 Parameters for PBC . 26
5.7 Optical isolator . 27
5.7.1 Function and technical outline . 27
5.7.2 Parameters for optical isolators . 27
5.8 ASE rejection filter . 27
5.8.1 Function and technical outline . 27
5.8.2 Parameters for ASE rejection filters . 27
5.9 Pump rejection filter . 27
5.9.1 Function and technical outline . 27

5.9.2 Parameters for pump rejection filter . 27
5.10 Gain flattening filter (GFF) . 28
5.10.1 Function and technical outline . 28
5.10.2 Parameters for gain flattening filters . 28
5.11 Tap coupler . 28
5.11.1 Function and technical outline . 28
5.11.2 Parameters for tap couplers . 28
5.12 PIN-photodiode (PIN-PD) . 29
5.12.1 Function and technical outline . 29
5.12.2 Parameters for PIN-photodiodes . 29
5.13 Variable optical attenuator (VOA) . 29
5.13.1 Function and technical outline . 29
5.13.2 Parameters for variable optical attenuators . 29
5.14 Optical connectors . 29
5.14.1 Function and technical outline . 29
5.14.2 Parameters for optical connectors . 30
Bibliography . 31

Figure 1 – Example of the components inside an EDFA operating in a co-propagating
pumping scheme . 23
Figure 2 – Example of the component layout of a distributed Raman amplifier (DRA) . 23
Figure 3 – Example of the component layout of a lumped (or discrete) Raman
amplifier . 24

Table 1 – Documents defining terms and definitions of each component . 22

– 4 – IEC TR 61292-1:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL AMPLIFIERS –
Part 1: Parameters of optical fibre amplifier components

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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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.
IEC TR 61292-1 has been prepared by subcommittee 86C: Fibre optic systems and active
devices, of IEC technical committee 86: Fibre optics. It is a Technical Report.
This third edition cancels and replaces the second edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Change of document title from "Parameters of amplifier components" to "Parameters of
optical fibre amplifier components";
b) Addition of parameters for optical components used in fibre Raman amplifiers;
c) Addition of Table 1, listing various documents that specify terms and definitions for optical
components used in optical fibre amplifiers;
d) Addition of Figure 2 and Figure 3, showing typical component layouts for distributed and
lumped fibre Raman amplifiers;

e) Harmonization of the descriptions of optical component parameters with the definitions in
other standards on optical components.
The text of this Technical Report is based on the following documents:
Draft Report on voting
86C/1775/DTR 86C/1784/RVDTR
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 Technical Report is English.
A list of all parts of the IEC 61292 series, published under the general title Optical amplifiers,
can be found on the IEC website.
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.
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,
• replaced by a revised edition, or
• amended.
– 6 – IEC TR 61292-1:2022 © IEC 2022
OPTICAL AMPLIFIERS –
Part 1: Parameters of optical fibre amplifier components

1 Scope
This part of IEC 61292, which is a Technical Report, applies to optical components of optical
fibre amplifiers (OFAs). This document provides information about the most relevant parameters
of these optical components, especially for erbium doped fibre amplifiers (EDFAs) and fibre
Raman amplifiers (FRAs). It provides introductory information for a better understanding
operation and applications of EDFAs and FRAs.
NOTE IEC TR 61292-6 provides more technical information on FRAs.
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 61291-1:2018, Fibre amplifiers – Generic specification
IEC TR 61931, Fibre optic – Terminology
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,
IEC TR 61931, and the following 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
3.1.1 Parameters for active fibres
3.1.1.1
maximum input signal power
maximum power of the input signal above which the active fibre gets damaged,
causing impossibility of normal operation for a given active fibre
3.1.1.2
insertion loss at out-of-band wavelength
insertion loss for a signal at the specified out-of-band wavelength(s) for a given
active fibre
Note 1 to entry: IEC 61290-7-1 defines the measurement procedure of out-of-band insertion loss.
[SOURCE: IEC 61291-1:2018, 3.2.1.59, modified – Term changed from "out-of-band insertion
loss", the specific use "active fibres" has been added, and Note 1 to entry has been added.]

3.1.1.3
polarization-dependent gain
maximum variation of the active fibre gain due to a variation of the state of
polarization of the input signal
[SOURCE: IEC 61291-1:2018, 3.2.1.12, modified – The notes to entry have been deleted and
the specific use has been added.]
3.1.1.4
polarization mode dispersion
PMD
maximum PMD at the signal wavelength which is launched into the input port of
the active fibre and exits from signal output port of the active fibre
Note 1 to entry: PMD is expressed in ps.
Note 2 to entry: When an optical signal travels through an optical fibre, optical component or subsystem (e.g. an
OFA), the change in the shape and width of the pulse due to the differential group delay (DGD) [the propagation
delay difference between the two principal states of polarization (PSPs)] and to the waveform distortion for each PSP,
is due to PMD. PMD, together with polarization dependent loss (PDL) and polarization dependent gain (PDG), can
introduce large waveform distortions leading to an unacceptable bit error ratio increase.
Note 3 to entry: The level of PMD can depend on temperature and operating conditions.
3.1.1.5
mode field diameter
MFD
2w
for a given active fibre, a measure of the transverse width of the guided mode
of a single-mode fibre, given from the far-field intensity distribution F(q) by:
−
∞
3 2
2 q F q dq
( )
2 ∫

2w=

∞
π
qF q dq
( )
∫
0
where
q= sinθλ/
( )
Note 1 to entry: For Gaussian distributions in single-mode fibres the mode field diameter is the diameter at the 1/e
points of the optical field amplitude distribution, which is also equivalent to the 1/e points of the optical power
distribution.
Note 2 to entry: Sometimes the MFD of active fibres is smaller than that of conventional single-mode fibres in order
to concentrate the pump power with the signal optical power.
[SOURCE: IEC TR 61931:1998, 2.4.31, modified – Specific use added and Note 2 to entry has
been added.]
3.1.1.6
cut-off wavelength
for a given active fibre, the free space wavelength corresponding to the cut-off
normalized frequency of a mode
[SOURCE: IEC TR 61931:1998, 2.4.38, modified – Specific use has been added.]
3.1.1.7
cladding diameter
for a given active fibre, the diameter of the circle defining the cladding centre

– 8 – IEC TR 61292-1:2022 © IEC 2022
[SOURCE: IEC TR 61931, 2.3.39]
3.1.1.8
cladding non-circularity
for a given active fibre, the difference between the diameters of the two circles
defined by the cladding tolerance field divided by the cladding diameter
[SOURCE: IEC TR 61931:1998, 2.3.51, modified – Specific use has been added.]
3.1.1.9
mode field concentricity error
for a given active fibre, the distance between the mode field centre and the
cladding centre
[SOURCE: IEC TR 61931:1998, 2.4.34, modified – Specific use has been added.]
3.1.1.10
composition
composition of the active fibre, intended as the host glass composition as well
as the dopant element and its concentration
3.1.1.11
length
length of the active fibre
Note 1 to entry: Changing fibre length can optimize gain characteristics of EDFA.
3.1.1.12
dopant distribution
concentration of dopant rare-earth ions in the active fibre as a function of the
fibre radial coordinate
3.1.1.13
slope efficiency
for a given active fibre, the slope of the laser output versus pump power curve
under specified operating conditions
Note 1 to entry: IEC TR 63309 defines the measurement procedure of slope efficiency.
3.1.1.14
saturation pump power
for a given active fibre, the minimum pump power above which the small-signal
gain shows no further increase
3.1.1.15
threshold pump power
minimum pump power necessary to reach a small-signal gain equal to 1 in a
given active fibre when the fibre length is short enough so that the pump optical power remains
constant along the fibre
Note 1 to entry: IEC TR 63309 defines the measurement procedure of threshold pump power.
3.1.2 Parameters for pump lasers
3.1.2.1
pumping wavelength
centroidal or peak wavelength of the emission spectrum of the pump laser

Note 1 to entry: In erbium-doped fibre amplifiers (EDFAs), pumping wavelengths of 980 nm and 1 480 nm are
commonly used. In fibre Raman amplifier (FRAs), the pumping wavelength depends on the wavelength of the signal
light. In this case, the frequency of the pump laser should be about 13 THz higher than that of the signal light.
Note 2 to entry: Centroidal wavelength is defined in IEC 61280-1-3.
Note 3 to entry: For multi-longitudinal-mode laser diodes (LD), centroidal wavelength is often used. For single-
longitudinal-mode LD, peak wavelength is often used.
Note 4 to entry: For 980 nm LD, a wavelength stabilizer by FBG is sometimes used to the output pigtail of the LD.
3.1.2.2
pumping scheme
set-up of the OFA characterized by the direction of pump optical power
propagation with respect to signal direction
Note 1 to entry: Usually, three schemes are used: co-propagating, where the pump and the signal propagate
through the active fibre in the same direction; counter-propagating, where the signal and the pump propagate through
the active fibre in opposite directions; bi-directional, where two pumps propagate simultaneously through the active
fibre in both directions. Regarding pumping schemes other than pump direction, a polarization combining scheme
and a wavelength combining scheme are considered in the detailed design to increase pump power. However, a
single laser diode pump scheme is described as a classic example in this technical report.
Note 2 to entry: IEC TR 61292-3 describes the pumping method.
3.1.2.3
pumping power
at the active fibre or at the output of the pump, optical power associated with
the pump, injected into the active fibre
3.1.2.4
centroidal wavelength
mean or average wavelength of an optical spectrum of pump LD
Note 1 to entry: Regarding many pump LDs of 980 nm and 1 480 nm, centroidal wavelength λ is applied for
avg
centre wavelength λ . The definition of centroidal wavelength is described as follows:
c
N
 
λ = Pλ
 
avg ∑ ii
 
P
  i= 1
where
th
λ is the wavelength of the i peak point (nm);
i
i  corresponds to mode number for output spectra of pump LD;
th
P is the power of the i peak point (nW); and
i
P is the total power summed for all peak points (nW):
N
PP=
0 ∑ i
i= 1
N is the number of peak points.
Note 2 to entry: The pump efficiency of an EDF depends on the overlap integral of the EDF absorption spectrum
and the pump LD spectrum, so the centroidal wavelength of the pump laser is crucial for EDF pumping.
3.1.2.5
peak wavelength
wavelength which corresponds to the maximum power value of the optical
spectrum of pump LD
– 10 – IEC TR 61292-1:2022 © IEC 2022
Note 1 to entry: For some pump LDs operating at 980 nm and 1 480 nm with FBG stabilizer, the peak wavelength
λ is used as the centre wavelength λ . The definition of peak wavelength is described as follows:
peak c
λλ=
c peak
Note 2 to entry: Refer to IEC 61280-1-3 for details.
3.1.2.6
root mean square (RMS) spectral width
spectral width defined by RMS
Note 1 to entry: Regarding many pump LDs of 980 nm and 1 480 nm, the RMS spectral width Δλ is used to
rms
characterize spectral width. The definition of RMS spectral width is described as follows:
N 2

Δλ P ()λ−λ
rms ∑ ii c
P

i= 1

Note 2 to entry: The pump efficiency of an EDF depends on the overlap integral of the EDF absorption spectrum
and the pump LD spectrum, so the pumping spectral width of pump laser is a crucial factor for EDF pumping in order
to quantify the power band width of the pump LD.
3.1.2.7
full-width at half maximum (FWHM) spectral width
spectral width defined by FWHM
Note 1 to entry: Regarding some pump LDs of 980 nm and 1 480 nm with FBG stabilizer, full-width at half maximum
(FWHM) Δλ is used to characterize spectral width. The definition of the FWHM spectral width is described as
fwhm
follows:
λ ,
1) The positive difference of the closest spaced wavelengths, one above and one below the peak wavelength
peak
at which the spectral power density is 3 dB down from its peak value;
2) If the pump laser does not emit light at these half-power wavelengths, the FWHM spectral width can be determined
by interpolation as follows;
3) Connect the tip of each mode to the tips of adjacent modes; draw a horizontal line 3 dB down from the peak
power point;
4) The two or more intersection points define the half-power wavelengths. The maximum difference in half-power
wavelengths is Δλ .
fwhm
Note 2 to entry: See IEC 61280-1-3 for more details.
3.1.2.8
wavelength stability
rate of variation of pumping wavelength with respect to operating and
environmental conditions
3.1.2.9
pumping spectral width
effective width of emission spectrum of the pump laser
Note 1 to entry: Commonly, RMS spectral width is used.
3.1.2.10
threshold current
driving current at which the pump laser starts to lase
Note 1 to entry: Practically, this value is specified as the crossing condition between the spontaneous emission and
lasing regions.
=
3.1.2.11
maximum allowed current
maximum driving current which can cause irreversible damage to the pump laser
Note 1 to entry: The absolute maximum rated current is generally applied.
3.1.2.12
pump LD chip temperature
temperature of LD chip to be controlled for normal operation, where performance
of pump LD is ensured
Note 1 to entry: The output power and operating wavelength are affected by laser chip temperature. Therefore,
ordinary pump LD modules include a thermoelectric cooler (TEC) so as to maintain a constant LD chip temperature.
A temperature range of 25 ˚C to 45 ˚C is commonly specified by LD suppliers. Previous generation chips are specified
at 25 ˚C, and some more recent chips are specified to operate at 35 ˚C or 45 ˚C.
3.1.2.13
pump LD case temperature
operative temperature range of LD case within which the pump laser module
can be operated while still meeting all its specified parameter values, given in the relevant detail
specification
Note 1 to entry: The power consumption of temperature-controlled pump LD modules with TEC varies with case
temperatures, since the TEC controls the LD chip temperature relative to the case temperatures. The case
temperature also affects centre wavelength and wavelength stability of pump lasers with FBG wavelength stabilizer,
since the reflection wavelength of the FBG can vary with case temperature. Therefore, the pump LD case temperature
is specified by the LD vendor to ensure normal operation of all the related performance. Most LD modules are
specified for case temperatures ranging from 0 ˚C to 75 ˚C.
3.1.2.14
temperature dependence of threshold current
temperature dependence of threshold current of pump laser
3.1.2.15
temperature dependence of wavelength
temperature dependence of the centroidal or peak wavelength among emission
wavelengths of the pump laser
3.1.2.16
device reliability
probability of performing required functions and performances at specified duration, specified
operating and environmental conditions
Note 1 to entry: The reliability of a pump laser is expressed by either of the following two parameters: mean time
between failure (MTBF) or failure in time (FIT):
1) MTBF is the mean period of continuous operation without any failure at specified operating and environmental
conditions.
2) FIT is the number of failures in an accumulated device operating time of 10 hours at specified operating and
environmental conditions.
3.1.3 Parameters for WDM couplers
3.1.3.1
signal insertion loss
ratio of the signal power incident on the signal input port of the WDM coupler
to the output power from the signal output port
Note 1 to entry: Signal insertion loss is expressed in decibels (dB).
3.1.3.2
pump insertion loss
ratio of the pump power incident on the pump input port of the WDM coupler
to the output power from the signal output port

– 12 – IEC TR 61292-1:2022 © IEC 2022
Note 1 to entry: Pump insertion loss is expressed in decibels (dB).
3.1.3.3
polarization dependent loss
PDL
maximum insertion loss variation due to the change of the input light state of
polarization
Note 1 to entry: PDL is expressed in decibels (dB).
Note 2 to entry: This term is defined for both signal input port and pump input port.
3.1.3.4
signal reflectance
ratio of the signal power incident on the signal input port of the WDM coupler
to the output power reflected back from the signal input port
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.3.5
pump leakage at the signal input port
ratio of the pump power incident on the pump input port of the WDM coupler
to the output power from the signal input port
Note 1 to entry: Pump leakage is expressed in decibels (dB).
3.1.4 Parameters for pump WDM couplers
3.1.4.1
insertion loss
th th
ratio of the pump power at the n wavelength incident on the n
wavelength pump input port of the pump WDM coupler to the output power from the common
pump output port
Note 1 to entry: Insertion loss is expressed in decibels (dB).
Note 2 to entry: This term applies to all pump input ports.
3.1.4.2
polarization dependent loss
PDL
maximum insertion loss variation due to the change of the input light
state of polarization
Note 1 to entry: PDL is expressed in decibels (dB).
Note 2 to entry: This term is defined for all pump input ports.
3.1.4.3
pump reflectance
ratio of the pump power incident on the pump input port of the pump
WDM coupler to the output power reflected back from the pump input port
Note 1 to entry: Pump reflectance is expressed in decibels (dB).
Note 2 to entry: This term applies to all pump input ports.
3.1.5 Parameters for optical isolators
3.1.5.1
insertion loss
maximum value of logarithmic transmission coefficient, a (where i ≠ j) within
ij
the passband for conducting port pair

Note 1 to entry: It is the optical attenuation from a given port to a port which is another port of conducting port pair
of the given port of a passive device. Insertion loss, a is a positive value in decibels (dB). It is calculated as:
IL
P 
out
a = −10 log
IL 10 
P
 
in
where
P is the optical power launched into the port;
in
P is the optical power received from the other port of the conducting port pair.
out
Note 2 to entry: In the case of an optical isolator as a non-reciprocal device, a is defined as the maximum value
IL
of attenuation from the input port to the output port.
Note 3 to entry: In the case of an optical isolator as nominally a wavelength independent and wavelength non-
selective device, passband is nominally same as operating wavelength range.
Note 4 to entry: In the case of a polarization-independent isolator, a is defined as the maximum value for any state
IL
of polarization of P .
in
Note 5 to entry: In the case of a polarization-dependent isolator, a is defined as the linearly polarized light which
IL
coincides with the polarizing direction of the polarizer in the isolator of P .
in
[SOURCE: IEC 61202-1:2016, 3.3.3, modified – Specific use has been added.]
3.1.5.2
isolation
minimum value of the logarithmic transmission coefficient a (where i ≠ j) for isolated port pair
ij
Note 1 to entry: Isolation is the minimum attenuation value in the backward direction.
Note 2 to entry: Isolation is a positive value expressed in decibels (dB).
[SOURCE: IEC 61202-1:2016, 3.3.4]
3.1.5.3
polarization mode dispersion
PMD
maximum PMD at the signal wavelength which is launched into the input port
of the isolator and exits from signal output port of the isolator
Note 1 to entry: PMD is expressed in picoseconds (ps).
Note 2 to entry: Refer to IEC 61753-061-2.
3.1.5.4
operating wavelength range
wavelength range within which the optical isolator operates the required
performances in the operating temperature range
Note 1 to entry: A Faraday rotator typically exhibits wavelength dependency of the rotation angle, e.g. typically
0,08 degree (angle)/nm.
3.1.5.5
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of
polarization of the input signal
Note 1 to entry: PDL is expressed in decibels (dB).

– 14 – IEC TR 61292-1:2022 © IEC 2022
3.1.6 Parameters for ASE rejection filters
3.1.6.1
insertion loss
ratio of the signal power incident on the signal input port of the ASE
rejection filter to the output power from the output port
Note 1 to entry: Insertion loss is expressed in decibels (dB).
3.1.6.2
signal reflectance on the input port
ratio of the signal power incident on the signal input port of the ASE
rejection filter to the output power reflected back from the signal input port
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.6.3
signal reflectance on the output port
ratio of the signal power incident on the signal output port of the ASE
rejection filter to the output power reflected back from the signal output port
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.6.4
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of
polarization of the input signal
Note 1 to entry: PDL is expressed in decibels (dB).
3.1.6.5
peak wavelength
wavelength at which the insertion loss of the ASE rejection filter is
minimum
3.1.7 Parameters for pump rejection filters
3.1.7.1
insertion loss
ratio of the signal power incident on the signal input port of the pump
rejection filter to the output power reflected back from the signal input port
Note 1 to entry: Insertion loss is expressed in decibels (dB).
3.1.7.2
signal reflectance on the output port
ratio of the incident on the output port of the pump rejection filter to the
output power reflected from the output port
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.7.3
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of
polarization of the input signal
Note 1 to entry: PDL is expressed in decibels (dB).

3.1.7.4
extinction ratio
ratio of the pump power incident on the input port of the pump rejection
filter to the output pump power from the output port
Note 1 to entry: Extinction ratio is expressed in decibels (dB).
3.1.8 Parameters for gain flattening filters
3.1.8.1
operating wavelength range
operating wavelength interval within which the signal gain of the OFA
is adjusted to be flattened by the GFF
3.1.8.2
insertion loss
ratio of the signal power incident on the input port of the GFF to the
output power from the output port
Note 1 to entry: Insertion loss is expressed in decibels (dB).
Note 2 to entry: This value is generally defined as the minimum value within the GFF operating wavelength range.
3.1.8.3
error function
difference between design target loss profile and actual loss profile of
the filter within the GFF wavelength range
Note 1 to entry: Error function is expressed in decibels (dB).
Note 2 to entry: The error function is defined as:
F (λ) = L (λ) – L (λ)
error actual design
where,
F (λ) is the error function as a function of wavelength;
error
L (λ) is the actual loss as a function of wavelength;
actual
L (λ) is the design target loss as a function of wavelength.
design
Note 3 to entry: The error function is a function of wavelength.
3.1.8.4
polarization dependent loss
PDL
maximum variation of insertion loss due to a variation of the state of
polarization
Note 1 to entry: PDL is expressed in decibels (dB).
3.1.8.5
signal reflectance on the input port
ratio of the signal power incident on the input port of the GFF to the
output power reflected back from the input port
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.8.6
signal reflectance of on the output port
ratio of the signal power incident on the output port of the GFF to the
output power reflected back from the output port

– 16 – IEC TR 61292-1:2022 © IEC 2022
Note 1 to entry: Signal reflectance is expressed in decibels (dB).
3.1.9 Parameters for tap couplers
3.1.9.1
coupling ratio
CR
for a given input port i, the ratio of light at a given output port k to the total light
from all output ports
Note 1 to entry: CR is calculated as
R = t / t
c.ik ik ∑ ij
j
where t (transfer matrix element) is the ratio of the optical power P transferred out of port j with respect to input
ij ij
power P into port i, that is:
i
t =PP/
ij ij i
3.1.9.2
insertion loss
reduction of optical power, when the signal transmitted between the input and
output ports of the tap coupler
Note 1 to entry: Insertion loss is expressed in decibels (dB).
3.1.9.3
PDL in the signal path
maximum variation of the insertion loss due to a variation of the state of
polarization
Note 1 to entry: PDL is expressed in decibels (dB).
3.1.9.4
PDL in the tap path
maximum variation of the output power at the tap port due to a variation of the
state of polarization
Note 1 to entry: PDL is expressed in decibels (dB).
3.1.9.5
wavelength and temperature dependent loss variation in the signal path
maximum variation of the insertion loss due to a variation of signal wavelength
and temperature
Note 1 to entry: Loss variation is expressed in decibels (dB).
3.1.9.6
wavelength and temperature dependent loss variation in the tap path
maximum variation of the coupling ratio of the tap coupler due to a variation of
signal wavelength and temperature
Note 1 to entry: Loss variation is expressed in decibels (dB).
3.1.9.7
signal reflectance on the input port
ratio of the signal power incident on the input port of the tap coupler to the
output power reflected back from the input port

Note 1 to entry: Reflectance is expressed in decibels (dB).
3.1.9.8
signal reflectance on the output port
ratio of the signal power incident on the output port of the tap coupler to the
output power reflected from the output port
Note 1 to entry: Reflectance is expressed in decibels (dB).
3.1.9.9
signal reflectance on the tap port
ratio of the signal power incident on the tap port of the tap coupler to the output
power reflected from the tap port
Note 1 to entry: Reflectance is expressed in decibels (dB).
3.1.10 Parameters for PIN-photodiodes
3.1.10.1
operating wavelength range
wavelength interval within which the PIN-PD normally operates in its
nominal specification
3.1.10.2
reverse voltage
operative reverse bias voltage applied to the PIN-PD
3.1.10.3
responsivity
ratio of an optical detector's electrical output to its optical input
Note 1 to entry: Responsivity is generally expressed in A/W or V/W of incident radiant optical power.
Note 2 to entry: "Sensitivity" is sometimes used as an imprecise synonym for responsivity.
[SOURCE: IEC 60050-731:1991, 731-06-36, modified – Specific use added.]
3.1.10.4
back reflectance
fraction of the optical power associated with the input signal which is
reflected by the facet of PIN-PD
Note 1 to entry: Back reflectance is expressed in decibels (dB).
3.1.10.5
dark current
output current of an optical detector in the absence of incident radiation
Note 1 to entry: The dark current typically incr
...