IEC TS 62627-09:2016

IEC TS 62627-09 ®
Edition 1.1 2025-12
TECHNICAL
SPECIFICATION
CONSOLIDATED VERSION
Fibre optic interconnecting devices and passive components -
Part 09: Vocabulary for passive optical devices
ICS 33.180.20  ISBN 978-2-8327-0935-1
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CONTENTS
FOREWORD . 2
INTRODUCTION . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 5
3.1 General . 5
3.2 Basic terms and definitions . 5
3.3 Component terms and definitions . 7
3.4 Performance parameter terms and definitions . 10
3.5 Abbreviated terms . 14
Annex A (informative) Generic specifications for passive optical devices . 15
Bibliography . 16

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Fibre optic interconnecting devices and passive components -
Part 09: Vocabulary for passive optical devices

FOREWORD
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This consolidated version of the official IEC Standard and its amendment has been prepared
for user convenience.
IEC TS 62627-09 edition 1.1 contains the first edition (2016-10) [documents 86B/3993/DTS
and 86B/4016/RVC] and its amendment 1 (2025-12) [documents 86B/5108/DTS and
86B/5163/RVDTS].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendment 1. Additions are in green text, deletions are in strikethrough red text.
A separate Final version with all changes accepted is available in this publication.

The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62627-09, which is a Technical Specification, has been prepared by subcommittee
SC 86B: Fibre optic interconnecting devices and passive components, of IEC technical
committee 86: Fibre optics.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
86B/3993/DTS 86B/4016/RVC
Full information on the voting for the approval of this technical specification 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.
A list of all parts in the IEC 62627 series, published under the general title Fibre optic
interconnecting devices and passive components, can be found on the IEC website.
The committee has decided that the contents of this document and its amendment will remain
unchanged until the stability date indicated on the IEC website under webstore.iec.ch in the
data related to the specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
SC 86B, Fibre optic interconnecting devices and passive components, specifies several
passive optical devices. Each passive optical device has generic specification and
performance specifications. Generic specifications define terms, definitions and requirements
(classifications, documentations, standardization systems and so on). Some basic terms and
definitions are defined and used in two or more generic specifications. In order to harmonize
terms and definitions in generic specifications, this technical specification defines terms and
definitions commonly used in multiple generic specifications.

1 Scope
This part of IEC 62627, which is a Technical Specification, applies to passive optical devices
(components). It provides the definitions which are commonly used in the generic
specifications, performance standards and tests and measurement standards for passive
optical devices (components) prepared by SC 86B. It has the following three types of terms
and definitions:
• basic terms and definitions;
• component terms and definitions;
• performance parameter terms and definitions.
The generic specifications for passive optical devices (components) are listed in Annex A.
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.
This document contains no normative references.
3 Terms, definitions and abbreviated terms
3.1 General
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
3.2 Basic terms and definitions
3.2.1
port
optical fibre or fibre optic connector attached to a passive component for the entry and/or exit
of optical power
[SOURCE: IEC 60876-1:2014, 3.1.1]
3.2.2
input port
port where the optical power enters the device
3.2.3
output port
port where the optical power exits the device
3.2.4
transfer matrix
n × n matrix of coefficients where n is the number of ports, and the coefficients represent the
fractional optical power transferred between designated ports
Note 1 to entry: In general, the transfer matrix T is:
t t . t
 
11 12 1n
 
t
T =
 
t (1)
ij
 
t t t
 
 n1 n2 nn 
where t is the ratio of the optical power P transferred out of port j with respect to input power P into port i, that is:
ij ij i
P
ij
t =
ij (2)
P
i
[SOURCE: IEC 60875-1:2015, 3.1.3, modified – The definition has been rephrased, the last
sentence in note 1 has been deleted, as well as notes 2 and 3.]
3.2.5
transfer coefficient
element t of the transfer matrix
ij
[SOURCE: IEC 60875-1: 2015, 3.1.4]
3.2.6
logarithmic transfer matrix
n × n matrix of logarithmic transfer coefficients of a where n is the number of ports
ij
Note 1 to entry: In general, the logarithmic transfer matrix A is:
a a . a 
11 12 1n
 
a
 
A =
 
a
(3)
ij
 
a a a
 n1 n2 nn 
where a is the optical power reduction, in decibels, out of port j with unit power into port i,
ij
that is:
a = −10log t
ij 10 ij
(4)
where t is the transfer coefficient.
ij
3.2.7
logarithmic transfer coefficient
element a of the logarithic transfer matrix
ij
3.2.8
conducting port pair
two ports i and j between which t is nominally greater than zero
ij
Note 1 to entry: For optical switches of conducting ports, conducting port pair is defined at a specified switching
state. For wavelength-selective branching devices and fibre optic filters, conducting port pair is defined at a
specific wavelength. For wavelength switches, conducting port pair is defined at a specific switching state and a
specified wavelength.
3.2.9
isolated port pair
two ports i and j between which t is nominally zero, and a is nominally infinite
ij ij
Note 1 to entry: For optical switches of isolated ports, isolated port pair is defined at a specified switching state.
For wavelength-selective branching devices and fibre optic filters, isolated port pair is defined at a specific
wavelength. For wavelength switches, isolated port pair is defined at a specific switching state and a specified
wavelength.
3.2.10
port configuration
relation of connection which satisfies the following requirements, between the M port group
possessing M ports and the N port group possessing N ports for passive device possessing n
ports (n = M + N):
a) any port of the M port group is not the relation of conducting, attenuating, splitting, and
coupling with the others of M port group;
b) any port of the N port group is not the relation of conducting, attenuating, splitting, and
coupling with the others of N port group;
c) any port of the M port group can be connected to conducting, attenuating, splitting, and
coupling with any port of N port group;
d) any port of the N port group can be connected to conducting, attenuating, splitting, and
coupling with any port of M port group
Note 1 to entry: In the case of a branching device composed of an input port group possessing M ports and the
output port group possessing N ports, M × N is often expressed even if M is more than N.
Note 2 to entry: In the case of wavelength selective branching device, the connection as conducting, attenuating,
splitting and coupling is for any passband.
Note 3 to entry: In the case of optical switch, the connection as conducting, attenuating, splitting and coupling is
for any state.
Note 4 to entry: The port configuration is expressed as M × N. Unless otherwise noted, N is equal to or larger than
M.
3.3 Component terms and definitions
3.3.1
passive optical device
optical device (component), other than an optical dynamic device or an optical active device,
which does not require external power for its operation, unless to control the stability of its
own characteristics
Note 1 to entry: Passive optical devices (components) may comprise optical detectors for monitoring purposes
only.
[SOURCE: IEC TS 62538:2008, 2.1.3, modified – The term has been changed from "optical
passive device" to "passive optical device", and the bracket "(component)" has been added to
the definition and the note.]
3.3.2
fibre optic power control device
passive optical device (component) which controls a transmittance with a designed
wavelength independent transfer coefficient
Note 1 to entry: Transfer coefficient may be controlled for all intensity of input power or for input power over a
threshold power.
3.3.3
optical attenuator
passive optical device (component), which produces a wavelength independent controlled
signal attenuation in an optical fibre transmission line
[SOURCE: IEC 60869-1:2012, 3.2.1, modified – The definition has been rephrased.]
3.3.4
fibre optic isolator
non-reciprocal passive optical device (component) intended to suppress backward
transmittance along an optical fibre transmission line while the forward direction is the
direction for which optical power transmission is intended
Note 1 to entry: Fibre optic isolators are commonly used to avoid reflections back into laser diodes and optical
amplifiers, which can make the laser and amplifiers oscillate unstably, and cause noise in the fibre optic
transmission system.
[SOURCE: IEC 61202-1:2009, 3.2.1, modified – The definition has been rephrased.]
3.3.5
fibre optic circulator
passive optical device (component) possessing three or more ports which input and output
are cyclic
Note 1 to entry: In the case of 3 ports circulator with port 1, port 2 and port 3, supposing optical power is
transmitted from port 1 to port 2, optical power from port 2 is transmitted to port 3.
[SOURCE: IEC 62077:2015, 3.2.1, modified – The term "optical device" and the brackets have
been added.]
3.3.6
optical switch
passive optical device (component) processing two or more ports which selectively transmits,
redirects or blocks optical power in an optical fibre transmission line
[SOURCE: IEC 60876-1:2014, 3.2.1, modified – The term "optical device" and the brackets
have been added.]
3.3.7
wavelength switch
optical switch which is designed to operate in two of more defined wavelength bands of
operation and which can selectively route or block light in one or more of the bands of
operation as a function of the wavelength band
[SOURCE IEC 62099:2001, 1.3.2, modified – The adjective "optical" has been added to the
term "switch" in the definition.]
3.3.8
non-wavelength-selective branching device
optical coupler
optical splitter
bidirectional passive optical device (component) possessing three or more ports which
operates non-selectively over a specified range of wavelengths, divides or combines optical
power coming into one or more input port(s) among its one or more output port(s) in a
predetermined fashion, without any amplification, switching, or other active modulation
[SOURCE: IEC 60875-1:2015, 3.2.1, modified – The term "passive component" has become
"passive optical device (component)" in the definition.]
3.3.9
etalon
passive optical device consisting of a cavity formed by a pair of parallel reflective mirrors
3.3.10
fibre Bragg grating
FBG
fibre type passive optical device (component) which has modulated refractive index profile in
the core of the optical fibre
[SOURCE: IEC 61978-1:2014, 3.2.4, modified – The words "passive", "(component)" and "of
the optical fibre" have been added.]
3.3.11
fibre optic filter
passive optical device (component) used in fibre optic transmission to modify the spectral
intensity distribution of a signal in order to transmit or attenuate some wavelengths and block
some others
Note 1 to entry: There are two types of fibre optic filters: fibre optic fixed filters and fibre optic tuneable filters.
Note 12 to entry: The wavelength band where the signal is transmitted is called the passband. There may can be
more than one passband.
[SOURCE: IEC 61977:2015, 3.2.4, modified – The term "optical device" and the brackets have
been added. In the term definition, "passive component" has been replaced with "passive
optical device (component)", Note 1 to entry has been modified, Note 2 to entry has been
added"]
3.3.12
wavelength-selective branching device
wavelength multiplexer
wavelength demultiplexer
passive optical device (component) with three or more ports that shares optical power among
its ports in a predetermined fashion, without any amplification or other active modulation but
only depending on the wavelength, in the sense that at least two different wavelength ranges
are nominally transferred between two different pairs of ports
[SOURCE: IEC 62074-1: 2014, 3.2.1, modified – The preferred terms "wavelength multiplexer"
and "wavelength demultiplexer" have been added, as well as the words "optical device" and
the brackets.]
3.3.13
coarse wavelength division multiplexing device
CWDM device
WDM device which is intended to operate for channel spacing less than 50 nm and greater
than 1 000 GHz
[SOURCE: IEC 62074-1:2014, 3.2.4]
3.3.14
dense wavelength division multiplexing device
DWDM device
WDM device which is intended to operate for a channel spacing equal or less than 1 000 GHz
(approximately 8 nm at 1 550 nm and 5,7 nm at 1 310 nm)
[SOURCE: IEC 62074-1:2014, 3.2.3]
3.3.15
wide wavelength division multiplexing device
WWDM device
WDM device which is intended to operate for channel spacing equal to or greater than 50 nm
[SOURCE: IEC 62074-1:2014, 3.2.5, modified – The abbreviated term "WDM" in the first
preferred term has been spelled-out.]
3.3.16
cyclic arrayed waveguide grating
cyclic AWG
multi wavelength-selective branching device which can perform the function of a wavelength
multiplexer and/or demultiplexer with DWDM channel spacing
3.3.17
passive chromatic dispersion compensator
PCDC
two-port in-line passive optical device (component) used to perform chromatic dispersion
compensation
Note 1 to entry: PCDCs are commonly used to compensate the chromatic dispersion of an optical path by adding
the opposite sign chromatic dispersion.
Note 2 to entry: The typical optical paths comprise single-mode fibre, dispersion shifted fibre and/or non-zero
dispersion shifted fibre. PCDCs have either negative or positive chromatic dispersion values depending on the
chromatic dispersion sign of the optical path.
[SOURCE: IEC 61978-1:2014, 3.2.1, modified – The term "passive device" has been replaced
by "passive optical device (component)" in the definition.
3.3.18
fibre optic fixed filter
fibre optic filter in which any performances cannot be changed
3.3.19
fibre optic tuneable filter
fibre optic filter in which one or more performances can be changed
Note 1 to entry: There are mainly four types of fibre optic tuneable filters: tuneable band pass filters, tuneable
short wavelength pass filters, tuneable longwave pass filters and tuneable notch filters.
Note 2 to entry: There are mainly three types of fibre optic tuneable bandpass filters: wavelength tuneable
bandpass filters, bandwidth tuneable filters, and wavelength and bandwidth tuneable bandpass filters. These terms
are defined in IEC 63032.
3.4 Performance parameter terms and definitions
3.4.1
operating temperature
temperature at which a passive optical device (component) is designed to operate with
specified performance
Note 1 to entry: The case temperature may be used for a passive optical device which emits heat. For a passive
optical device (component) which does not emit heat, the ambient temperature is used.
3.4.2
operating temperature range
specified range of temperatures including all operating temperatures
3.4.3
operating wavelength
λ
nominal wavelength at which a passive optical device (component) is designed to operate
with the specified performance
Note 1 to entry: The term "operating wavelength" includes the wavelength to be nominally transmitted
(propagated), attenuated and isolated.
3.4.4
operating wavelength range
specified range of wavelengths including all operating wavelengths
Note 1 to entry: It includes all passbands and isolation wavelength ranges.
[SOURCE: IEC 61977:2015, 3.3.2]
3.4.5
channel
nominal wavelength or frequency of passband
Note 1 to entry: There are one or more channels for passive optical devices.
Note 2 to entry: For a passive optical components used in DWDM systems, a channel is expressed and
characterised in frequency (Hz).
3.4.6
passband
one wavelength range within which a passive optical device (component) is required to
operate with optical attenuation less than or equal to a specified optical attenuation value
Note 1 to entry: Passband is defined for conducting port pair.
Note 2 to entry: There may be two or more passbands in the operating wavelength range.
3.4.7
passband ripple
maximum peak-to-peak variation of insertion loss (attenuation) in the passband
3.4.8
insertion loss
insertion attenuation
maximum value of logarithmic transmission coefficient, a (where i ≠ j) within the passband of

ij
a passive optical devide (component) in case of a 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 is a positive value in decibels. It is calculated as:
 
P
out
IL = −10log  
 
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: The term "attenuation" is sometimes used for the same meaning. However, attenuation for optical
attenuators means optical attenuation for the port pair to be attenuated.
3.4.9
return loss
RL
element a (where i = j) of the logarithmic transfer matrix
ij
Note 1 to entry: It is the fraction of input power that is returned from a port of a passive device (component) and
is defined as follows:
 
P
refl
RL = −10log  
i 10
 
P
 i 
where
P is the optical power launched into a port;
i
P is the optical power received back from the same port.
refl
3.4.10
crosstalk
ratio of the transfer coefficient of the power to be isolated, to the transfer coefficient for the
power to be conducted for an output port
Note 1 to entry: Crosstalk is a generally negative value expressed in the unit of dB.
Note 2 to entry: For fibre optic filters and wavelength-selective branching devices, crosstalk is defined for one
port pair at different two or more wavelengths (channels).
Note 3 to entry: For fibre optic switches, crosstalk is defined for two or more port pairs at one wavelength.
Note 4 to entry: Crosstalk for a passive optical device (component) is generally the maximum value of crosstalks
for all port pairs defining crosstalks.
3.4.11
isolation
value of a (where i ≠ j) for isolated port pair
ij
Note 1 to entry: Isolation is a positive value expressed in dB.
Note 2 to entry: For passive optical devices, isolation is generally the minimum isolation of all isolations for all
isolated port pairs.
Note 3 to entry: In case of an optical isolator and an optical circulator, isolation is an attenuation value of reverse
direction for a conducting port pair.
Note 4 to entry: In case of wavelength-selective branching device, isolation is attenuation in isolated wavelength
range for a conducting port pair in passband.
Note 5 to entry: For add-drop wavelength-selective branching device, the relations between add-port group and
drop-port group are isolated for all channels. The isolation in this case is called "add-drop isolation".
3.4.12
group delay
time delay between two (2) closely spaced wavelengths or frequencies inside the passband
by which a pulse is widened by a passive optical device (component)
Note 1 to entry: The group delay is generally different for passbands.
Note 2 to entry: The group delay is mathematically defined as the first-order derivative of the wavenumber or
effective index of refraction (β = kn) as a function of frequency.
3.4.13
chromatic dispersion
CD
derivative of group delay with respect to wavelength or frequency
Note 1 to entry: A typical unit is ps/nm or ps/GHz. The chromatic dispersion generally varies with the operating
wavelength.
Note 2 to entry: The units of ps/GHz are not commonly used; however, it is suitable for the evaluation of
transmission system influence.
Note 3 to entry: The chromatic dispersion is mathematically defined as the second-order derivative of the
wavenumber or effective index of refraction (β) as a function of frequency.
[SOURCE: IEC 61978-1:2014, 3.3.3, modified – The abbreviated term "CD" has been added
as a preferred term, and note 3 has been added.]
3.4.14
directivity
value of a for two ports which is not conducting nor isolated at any state
ij
Note 1 to entry: Directivity is a positive value expressed in the unit of dB.
Note 2 to entry: Directivity is applied for passive optical devices having three or more ports.
Note 3 to entry: Directivity for a passive optical device is generally the minimum value of directivities for all port
pairs defining directivities.
Note 4 to entry: In case of optical circulator, directivity is applied for the port pair which is not conducting nor
isolated.
Note 5 to entry: Directivity is not applied for add-drop port pair in case of wavelength-selective branching device.
Note 6 to entry: Directivity is not applied for a bypass path of 2 x 2 bypass optical switch.
Note 7 to entry: Isolation is applied for designed isolated port pair. Directivity is applied for no-designed but
expected isolated port pair. No-designed isolated means expecting isolation of leackage of light and/or stray light.
3.4.15
polarization dependent loss
PDL
maximum variation of insertion loss caused by a variation in the state of polarization (SOP)
over all the SOPs
Note 1 to entry: The terms "attenuation" is sometimes used for the same meaning. However, attenuation for
optical attenuators means optical attenuation for the port pair to be attenuated.
Note 2 to entry: PDL is defined for conducting port pair.
[SOURCE: IEC 61978-1:2014, 3.3.15, modified – The notes have been added.]
3.4.16
wavelength dependent loss
WDL
maximum variation of the insertion loss over the passband
Note 1 to entry: The terms "attenuation" is sometimes used for the same meaning. However, attenuation for
optical attenuators means optical attenuation for the port pair to be attenuated
[SOURCE: IEC 61978-1:2014, 3.3.16, modified – The words "the passband" have been
replaced by "operating wavelength range", and the note has been added.]
3.4.17
polarization mode dispersion
PMD
average delay of the travelling time between the two principal states of polarization (PSP),
when an optical signal passes through an passive optical device (component)
Note 1 to entry: Distortion in the time domain of the output signal induced by variation, inside of the passband, of
the two principal states of polarization (PSP) with frequency. The PSP are the two states of polarization (SOP) that
have the minimum and maximum delays between the input and output of a passive optical device (component). The
arrival time difference between the two PSPs at the output of a passive optical device (component) is called the
differential group delay (DGD). The statistical average (linear or RMS) of the variation of the DGD as a function of
wavelength or frequency gives the value of the polarization mode delay (PMD). Most of passive optical devices
(components) do not exhibit a strong variation of the DGD, if any. If there is not enough variation of the DGD as a
function of wavelength or frequency, the PMD value can be approximately equal to the DGD.
[SOURCE: IEC 61978-1:2014, 3.3.17, modified – The term "passive optical component" has
been replaced by "passive optical device (component)" in the definition, and the note has
been added.]
3.4.18
reflectance
element of t
ii
Note 1 to entry: Reflectance is expressed in %.
Note 2 to entry: In a passive optical device (component), reflectance corresponds to the reflection of a single
optical interface while return loss corresponds to the sum of all possible optical interfaces inside the passive
optical device (component), if any. In that case, the definition of reflectance is the same as for return loss with
units of dB, except for the opposite sign.
3.4.19
transmittance
element of t
ij
Note 1 to entry: Transmittance is generally expressed in %.
Note 2 to entry: For a passive optical device (component) having one port, transmittance is the same as
reflectance.
3.4.20
differential mode delay
DMD
difference in optical pulse delay time between the fastest and slowest modes excited for all
radial offset positions between and including the outer and inner limits of the radial offset
position
Note 1 to entry: DMD can also be related to the strength of intermodal dispersion. DMD is then useful for
characterizing the modal structure of a passive optical device (component) when used with short-pulse, narrow
spectral-width laser sources.
3.4.21
maximum input power
maximum allowable input power below which a passive optical device (component) keeps
designed performances
3.5 Abbreviated terms
AWG arrayed waveguide grating
CD chromatic dispersion
CWDM coarce wavelength division multiplexer
DMD differential mode delay
DWDM dense wavelength division multiplexer
FBG fibre Bragg grating
IL insertion loss
PCDC passive chromatic dispersion compensator
PDL polarization dependent loss
PMD polarization mode dispersion
RL return loss
WDL wavelength dependent loss
WWDM wide wavelength division multiplexer

Annex A
(informative)
Generic specifications for passive optical devices
The following generic specifications have been published.
IEC 60869-1, Fibre optic interconnecting devices and passive components – Fibre optic
passive power control devices – Part 1: Generic specification
IEC 60875-1, Fibre optic interconnecting devices and passive components – Non-wavelength-
selective fibre optic branching devices – Part 1: Generic specification
IEC 60876-1, Fibre optic interconnecting devices and passive components – Fibre optic
spatial switches – Part 1: Generic specification
IEC 61202-1, Fibre optic interconnecting devices and passive components – Fibre optic
isolators – Part 1: Generic specification
IEC 61977, Fibre optic interconnecting devices and passive components – Fibre optic filters –
Generic specification
IEC 61978-1, Fibre optic interconnecting devices and passive components – Fibre optic
passive chromatic dispersion compensators – Part 1: Generic specification
IEC 62074-1, Fibre optic interconnecting devices and passive components – Fibre optic WDM
devices – Part 1: Generic specification
IEC 62077, Fibre optic interconnecting devices and passive components – Fibre optic
circulators – Generic specification
IEC 62099, Fibre optic wavelength switches – Generic specification

Bibliography
IEC 60050-731, International Electrotechnical Vocabulary – Chapter 731: Optical fibre
communication (available at www.electropedia.org)
IEC TR 61931, Fibre optic – Terminology
IEC TS 62538, Categorization of optical devices

___________
CONTENTS
FOREWORD . 2
INTRODUCTION . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 5
3.1 General . 5
3.2 Basic terms and definitions . 5
3.3 Component terms and definitions . 7
3.4 Performance parameter terms and definitions . 10
3.5 Abbreviated terms . 14
Annex A (informative) Generic specifications for passive optical devices . 15
Bibliography . 16

INTERNATIONAL ELECTROTECHNICAL COMMISSION
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Fibre optic interconnecting devices and passive components -
Part 09: Vocabulary for passive optical devices

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