EN 61300-3-29:2006

SLOVENSKI SIST EN 61300-3-29:2006

STANDARD
julij 2006
Naprave za medsebojno povezovanje optičnih vlaken in pasivne komponente
– Osnovni preskusni in merilni postopki – 3-29. del: Preiskave in meritve –
Merilne tehnike za ugotavljanje lastnosti amplitude spektralne prenosne
funkcije komponent DWDM (IEC 61300-3-29:2005)
Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-29: Examinations and measurements –
Measurement techniques for characterizing the amplitude of the spectral transfer
function of DWDM components (IEC 61300-3-29:2005)
ICS 33.180.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD
EN 61300-3-29
NORME EUROPÉENNE
March 2006
EUROPÄISCHE NORM
ICS 33.180.20
English version
Fibre optic interconnecting devices and passive components -
Basic test and measurement procedures
Part 3-29: Examinations and measurements -
Measurement techniques for characterizing the amplitude
of the spectral transfer function of DWDM components
(IEC 61300-3-29:2005)
Dispositifs d'interconnexion  Lichtwellenleiter -
et composants passifs à fibres optiques - Verbindungselemente
Méthodes fondamentales und passive Bauteile -
d'essais et de mesures Grundlegende Prüf- und Messverfahren
Partie 3-29: Examens et mesures - Teil 3-29: Untersuchungen
Techniques de mesure pour caractériser und Messungen -
l'amplitude de la fonction de transfert Messverfahren zur Charakterisierung
spectrale des composants DWDM der spektralen Übertragungsfunktion
(CEI 61300-3-29:2005) von DWDM-Bauteilen
(IEC 61300-3-29:2005)
This European Standard was approved by CENELEC on 2006-03-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61300-3-29:2006 E
Foreword
The text of document 86B/2216/FDIS, future edition 1 of IEC 61300-3-29, prepared by SC 86B, Fibre
optic interconnecting devices and passive components, of IEC TC 86, Fibre optics, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 61300-3-29 on 2006-03-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-03-01
This European Standard makes reference to International Standards. Where the International Standard
referred to has been endorsed as a European Standard or a home-grown European Standard exists, this
European Standard shall be applied instead. Pertinent information can be found on the CENELEC web
site.
__________
Endorsement notice
The text of the International Standard IEC 61300-3-29:2005 was approved by CENELEC as a European
Standard without any modification.
__________
NORME CEI
INTERNATIONALE
IEC
61300-3-29
INTERNATIONAL
Première édition
STANDARD
First edition
2005-12
Dispositifs d'interconnexion et
composants passifs à fibres optiques –
Méthodes fondamentales d'essais
et de mesures –
Partie 3-29:
Examens et mesures –
Techniques de mesure pour caractériser
l'amplitude de la fonction de transfert
spectrale des composants DWDM
Fibre optic interconnecting devices
and passive components –
Basic test and measurement procedures –
Part 3-29:
Examinations and measurements –
Measurement techniques for characterizing
the amplitude of the spectral transfer function
of DWDM components
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61300-3-29  IEC:2005 – 3 –
CONTENTS
FOREWORD.7

1 Scope.11
2 Normative references .11
3 General description .11
3.1 Overview .11
3.2 Terms and abbreviations .13
4 Apparatus.15
4.1 Source .17
4.2 Polarisation controller.21
4.3 Device under test (DUT).21
4.4 Receiver system.23
4.5 Temporary joints (TJ) .25
5 Procedure .25
5.1 Preparation of specimens .25
5.2 System initialisation .27
5.3 System reference measurement .27
5.4 Measurement of device spectra.29
6 Characterisation of the device under test.29
6.1 Determination of transfer functions .29
6.2 Calculation of attenuation (A) .31
6.3 Transmission [T(λ)] spectra measurements .31
6.4 Polarisation dependent losses (PDL(λ)).41
7 Details to be specified .43
7.1 Tuning sub-system .43
7.2 Power detector .43
7.3 DUT .43

Annex A (informative)  Reflection spectrum measurements.45
Annex B (informative)  Determination of the wavelength increment parameter .53
Annex C (informative)  Determination of a mean value using the shorth function.57
Annex D (informative)  Precautions using IEC 61300-3-7.61

Figure 1 – Basic measurement apparatus .15
Figure 2 – Measurement apparatus for tuneable laser system.15
Figure 3 – Measurement apparatus for tuneable receiver system.17
Figure 4 – System reference for transmission measurement .27
Figure 5 – Normalised transfer functions for a band pass filter (a) and a notch filter (b) .33
Figure 6 – BW and full spectral width for a fibre Bragg grating .37
Figure 7 – Channel isolation .39
Figure 8 – Polarisation dependence of the transfer function.41

61300-3-29  IEC:2005 – 5 –
Figure A.1 – Measurement apparatus for a single port device .45
Figure A2 – Source reference set-up .47
Figure A3 – Set-up for measurement of system constant .49
Figure C1 – Example response and –x dB wavelengths .57
Figure C2 – Example showing the – 0,5 dB wavelengths based on the shorth (dotted
vertical lines) and the mean (solid vertical lines) .59
Figure D1 – Comparison of transfer function using various sources .63

61300-3-29  IEC:2005 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-29: Examinations and measurements –
Measurement techniques for characterising the amplitude
of the spectral transfer function of DWDM 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 co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) 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 61300-3-29 has been prepared by sub-committee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This standard cancels and replaces IEC/PAS 61300-3-29 published in 2002.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/2216/DIS 86B/2253/RVD
61300-3-29  IEC:2005 – 9 –
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 61300 consists of the following parts, under the general title Fibre optic interconnecting
devices and passive components – Basic test and measurement procedures:
Part 1: General and guidance
Part 2: Tests
Part 3: Examinations and measurements.

The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61300-3-29  IEC:2005 – 11 –
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-29: Examinations and measurements –
Measurement techniques for characterising the amplitude
of the spectral transfer function of DWDM components

1 Scope
This part of IEC 61300 identifies two basic measurement methods for characterising the
spectral transfer functions of DWDM filter components.
The transfer functions can be used to produce measurements of attenuation (A), polarisation
dependent loss (PDL), isolation, centre wavelength and bandwidth (BW).
2 Normative references
The following referenced documents are indispensable for the application 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 60050-731: International Electrotechnical Vocabulary – Chapter 731: Optical fibre
communication
IEC 61300-3-2: Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-2: Examinations and measurements – Polarisation
dependence of attenuation in a single mode fibre optic device
IEC 61300-3-7: Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-7:– Examinations and measurements – Wavelength
dependence of attenuation and return loss
IEC 61300-3-12: Fibre optic interconnecting devices and passive components – Basic test
and measurement procedures – Part 3-12: Examinations and measurements – Polarisation
dependence of attenuation of a single-mode fibre optic component: Matrix calculation method
3 General description
3.1 Overview
This document is complementary to the wavelength dependence of attenuation and return
loss (IEC 61300-3-7), polarisation dependence of attenuation (IEC 61300-3-2), and the
polarisation dependence of attenuation using matrix methods (IEC 61300-3-12) test
procedures. In general, these DWDM devices have channel bandwidths less than 1 nm, filter
response slopes greater than 100 dB/nm, and out-of-band rejection extending over tens
of nm.
61300-3-29  IEC:2005 – 13 –
The methods described in this standard will show how to obtain the transfer function from a
single input to a single output port (single conducting path). For an m x n device, it will be
required to repeat this procedure using all possible combinations of input and output ports.
The methods described in this standard are intended to be applicable to any wavelength band
(C, L, S, O, etc.) although examples may be shown in the C-band for illustrative purposes.
The two methods contained in this standard differ mainly in the way in which the wavelength
resolution is obtained. Method A uses a tuneable laser source and a broad band detector,
while Method B uses a broad band source and a tuneable receiver. Method A shall be
considered the reference test method for DWDM devices.
This standard also includes Annexes that illustrate the following:
Annex A: Reflection spectrum measurements;
Annex B: Determination of wavelength increment parameter;
Annex C: Determination of a mean value using the shorth function;
Annex D Precautions in using IEC 61300-3-7 for DWDM devices.
3.2 Terms and abbreviations
Many of the terms and abbreviations in this document are described in the generic standard
IEC 60050-731. Some terms and abbreviations specific to this measurement technique are
included below.
ASE: Amplified spontaneous emission.
BW: Bandwidth: The spectral width of a signal or filter. In the case of a laser signal
such as a tuneable laser source, the term linewidth is commonly preferred. Often
defined by the width at a set power distance from the peak power level of the
device (i.e. 3 dB BW or 1 dB BW). Must be defined as the distance between the
closest crossings on either side of the centre wavelength in the cases where the
spectral shape has more than 2 such points. The distance between the outermost
crossings can be considered the full spectral width.
δ: Wavelength sampling increment during the measurement.
λ : Centre channel or nominal operating wavelength for a component
h
OWR: Operating wavelength range. The specified range of wavelengths from λ to
hmin
λ centred about the nominal operating wavelength, within which a WDM
hmax
device operates.
SOP: State of polarisation. The distribution of light energy among the two linearly
independent solutions of the wave equations for the electric field.
SSE: Source spontaneous emission: Broad band emissions from a laser cavity that bear
no phase relation to the cavity field. These emissions can be seen as the baseline
noise on an optical spectrum analyzer.
TLS: Tuneable laser source.
61300-3-29  IEC:2005 – 15 –
4 Apparatus
The basic measurement set-up for the characterisation of DWDM components is shown in
Figure 1 below.
Polarisation
Source
DUT Receiver
controller
IEC  2538/05
Figure 1 – Basic measurement apparatus
As mentioned in the general discussion, this procedure contains two distinct methods that
differ fundamentally in the way in which the wavelength resolution is achieved. There are
three key influences on the wavelength resolution: the linewidth of the source or bandwidth of
the tuneable receiver, the analogue bandwidth of the detection system, and the rate of
change of wavelength.
Having determined the wavelength resolution of the measurement, the wavelength sampling
increment (δ) should be less than half the bandwidth of the system in order to accurately
measure the average value of the attenuation.
The bandwidth of the system is determined by the convolution of the effective source
bandwidth with the rate of change of wavelength over the time constant of the receiver.
Practical constraints may result in smaller or larger bandwidths than recommended. Two
cautions with smaller bandwidths: first, coherent interference effects can lead to additional
measurement errors, and second, undersampling of the device could lead to
misrepresentations of the reconstructed transfer function. If larger bandwidths are used, the
reconstructed transfer function could smear out fine structures and distort response slopes.
As the response slopes may exceed 100 nm/ dB, small uncertainties in wavelength may result
in large amplitude response errors. In general, the resolution bandwidth of the system needs
to be chosen based on the device characteristics and noted in the details to be specified.
A detailed explanation of the various components of this system and their functions is
contained below. Apparatuses for both the Tuneable Laser and the Tuneable Receiver
procedures are shown in Figures 2 and 3.

Detector
TJ2
DUT
(D1)
TJ1
RBD
PPololariarissaattiion on
(optional)
ccontontrolrolller er
Tracking
Detector
TLS filter RBD (D2)
TJ4
(optional)
(optional)
Wavelength
monitor
IEC  2539/05
Figure 2 – Measurement apparatus for tuneable laser system

61300-3-29  IEC:2005 – 17 –
Broadband
Polarisation Tuneable
source DUT
controller receiver
(unpolarised)
IEC  2540/05
Figure 3 – Measurement apparatus for tuneable receiver system
4.1 Source
4.1.1 Tuneable laser, Method A
This method uses a polarised tuneable laser source (TLS) that can select a specific output
wavelength and can be tuned across a specified wavelength range. The “source” could also
include a tracking filter, reference branching device (RBD), and wavelength monitor as shown
in Figure 2. These additions are optional as they relate to the measurement requirements and
the TLS specifications.
The power stability at any of the operating wavelengths shall be better than ± 0,01 dB over
the measuring period. This stability can be obtained using the optional detector D2 in Figure 2
as a reference detector. If D2 is synchronised with D1, then the variations in power can be
cancelled. It should be noted that the dynamic response of the two power meters should have
the same electrical bandwidth. The output power of the TLS shall be sufficient to provide the
apparatus with an order of magnitude more dynamic range than the device exhibits (i.e. the
measurement apparatus should be able to measure a 50 dB notch if the device is a 40 dB
notch filter).
The wavelength accuracy of the TLS shall be approximately an order of magnitude better than
the step size for each point in the measuring range. This accuracy may be obtained by having
the wavelength monitor feedback to the TLS. The tuning range of the TLS shall cover the
entire spectral region of the DWDM device and the source shall also be free of mode hopping
over that tuning range.
The side mode suppression ratio and the SSE of the tuneable laser source should be
sufficient to provide a signal to noise ratio one order of magnitude greater than is required for
the measurement, or the use of a tracking filter shall be required for notch filter
measurements. The SSE can be measured on an optical spectrum analyser using a 0,1 nm
resolution bandwidth. The measured points should be taken at half the distance between
possible DWDM channels (i.e. at 50 GHz from centre frequency for a 100 GHz DWDM
device). As an example, if the system needs to measure 50 dB of attenuation, the SSE should
be –60 dBc.
61300-3-29  IEC:2005 – 19 –
4.1.1.1 Tracking filter
The tracking filter is required if the dynamic range of the TLS and the detector does not allow
for measuring a depth of at least 10 dB greater than required due to the shape of the DUT
and the broadband SSE of the TLS. The filter must track the TLS so as to provide the
maximum SSE suppression and the maximum transmitted power as the TLS is scanned
across the measurement region. It should be noted that the spectral shape of the filter will
affect the effective linewidth of the system.
4.1.1.2 Reference branching device (RBD)
The configuration of the RBD is 1x2 or 2x2. If its configuration is 2x2, one port of the RBD
shall be terminated to have a back reflection <–50 dB. The splitting ratio of the RBD shall be
stable with wavelength. It shall also be insensitive to polarisation. The polarisation sensitivity
of transmission attenuation shall be less than one tenth of the wavelength dependency of
attenuation to be measured. The polarisation mode dispersion of the RBD shall be less than
one half of the coherence time of the source so as not to depolarise the input signal. The split
ratio shall be sufficient to provide the dynamic range for the measurement of the transfer
function and the power necessary for the wavelength meter to operate correctly.
4.1.1.3 Wavelength monitor
In this test procedure, the wavelength accuracy of the source needs to be extremely accurate
and closely monitored. If the tuning accuracy of the TLS is not sufficient for the measurement,
the wavelength monitor shall be required. For this measurement method it is necessary to
measure the spectral peak of any input signal within the device bandwidth to an accuracy
approximately one order of magnitude greater than the step size. Therefore, acceptable
wavelength monitors include an optical wavelength meter or a gas absorption cell (such as an
acetylene cell). If a gas absorption cell is used, the wavelength accuracy of the TLS must be
sufficient to resolve the absorption lines.
Regarding the wavelength repeatability of the TLS + monitor, it should be understood that if
the test apparatus has 0,1 dB of ripple with a 30 pm period, then a random 3 pm wavelength
variation from reference scan to device scan can result in as much as 0,03 dB of attenuation
error.
4.1.2 Broad band source (BBS), Method B
This method uses an unpolarised broadband light source such as an LED or an amplified
spontaneous emission (ASE) source. The source spectrum must provide sufficient optical
power over the full wavelength range of the DUT. This factor is especially important in the
measurement of notch filters where the dynamic resolution of the system needs to be high
(typically >50 dB) for accurate measurements.
The optical power of the light source must either be stable over the duration of the test or
normalized in a wavelength-specific fashion by means of a reference path (possibly consisting
of a RBD and a synchronised tuneable receiver).

61300-3-29  IEC:2005 – 21 –
The degree of polarization (DOP) of the source should be less than 10 % to avoid biasing
those measurements that require unpolarised light. Care should be taken to ensure that the
narrow width of the tuneable filter does not increase the effective DOP beyond this limit.
In some instances, the tuneable filter used for this method could be placed after the BBS
creating an unpolarised TLS. In this instance, the filter characteristics should be as described
in the tuneable receiver section (4.4.2).
4.2 Polarisation controller
The polarisation controller is used to control the input state of polarisation (SOP). In the event
of a polarisation dependent measurement, the controller will be used to generate four known
polarisation states for testing purposes. The states must be distinct and well known in order to
achieve accurate PDL measurements. The return loss on the input to the controller shall be
>50 dB, so as not to return any polarised light back to the TLS cavity for Method A. This may
also be achieved using an isolator to protect the TLS.
For the BBS method (B), the controller is optional if polarisation dependent measurements are
not required. If it is used in this set-up, it must provide an extinction ratio of at least 20 dB.
4.3 Device under test (DUT)
The device under test shall be a DWDM component. For the purposes of this document, the
test ports shall be a single “input-output” path. The method described herein can be
extrapolated upon to obtain a single measurement system capable of handling even an m x n
DWDM device. It is noted that these measurements are very sensitive to reflections, and that
precautions must be taken to ensure that reflection cavities are not introduced in the test set-
up.
In many cases, the characteristics of DWDM components are temperature dependent. This
measurement procedure assumes that any such device is held at a constant temperature
throughout the procedure. The absolute accuracy of the measurement may be limited by the
accuracy of any heating or cooling device used to maintain a constant temperature. For
o
example, if a device is known to have a temperature dependence of 0,01 nm/ C, and the
o
temperature during the procedure is held to a set temperature ±1 C; then any spectral results
obtained are known to have an uncertainty of 0,02 nm due to temperature.
4.3.1 Device input optics
Use an optical lens system or fibre pigtail to excite the test device. If a lens system is used,
couple the power into the test device so it is insensitive to the position of the input end face.
This can be done with a launch beam that spatially and angularly overfills the test port. In the
case of fibre pigtailed devices, use a device that extracts cladding modes. The fibre coating
will typically perform this function.
If fibre connectors or fibre butt coupling are employed, use physical contact connectors or
index matching fluid to avoid interference effects.

61300-3-29  IEC:2005 – 23 –
4.3.2 Device output optics
Use an optical lens system or fibre pigtail to couple light from the test device to the receiver.
If fibre connectors or fibre butt coupling are employed, use physical contact connectors or
index matching fluid to avoid interference effects.
4.4 Receiver system
4.4.1 Broad band detectors (D1,D2), Method A
The detectors used for this method consist of a broad band optical detector, the associated
electronics, and a means of connecting to an optical fibre. The optical connection may be a
receptacle for an optical connector, a fibre pigtail, or a bare fibre adapter. The back reflection
from detectors D1 and D2 should be minimised with any precautions available. The preferred
options would be to use either an APC connector, or a PC connector in conjunction with an
optical isolator. It should be noted that the use of an APC connector will contribute
approximately 0,03 dB of PDL to the measurement.
The dynamic range and sensitivity of the detectors should be sufficient to measure the noise
floor required by the test system and the DUT. In general, it is required to have a dynamic
range approximately 10 dB wider than the measurable isolation of the device, with a
sensitivity at least 5 dB below the expected stop band attenuation at the test system power
level. For instance if the maximum device isolation is 40 dB, the maximum device loss is 5 dB,
and the test system optical power is –5 dBm, then the detectors would need to have a
sensitivity of at least –55 dBm, and a dynamic range of at least 50 dB (i.e. should not saturate
at –5 dBm).
The detectors should have a resolution of 0,001 dB and linearity better than 0,02 dB over the
pass band wavelength range. The stability of the power detectors should exceed 0,01 dB over
the measurement period in the pass band as well. For polarisation dependent measurements,
the polarisation dependence of the detector should be <0,01 dB.
Where during the sequence of measurements a detector shall be disconnected and
reconnected the coupling efficiency for the two measurements shall be maintained. Use of a
large area detector to capture all of the light emanating from the fibre is recommended, but
care should be taken to ensure that the stability of the detector parameters are not affected
by variations in detection uniformity over the active area of the detector. It is also
recommended that the face of the detector be placed at an angle other than orthogonal to the
incoming light source to reduce back reflections while ensuring that polarisation effects are
minimised.
Another important parameter for the detectors is the electrical bandwidth. As it is desired to
make this measurement as quickly as possible, the response time of the detectors becomes a
limiting factor in the amount of time spent on each step (or in the accuracy of the reading for a
swept system).
4.4.2 Tuneable receiver, Method B
This method measures the optical output of the DUT with a narrow-band tuneable receiver
such as an optical spectrum analyser. The analyser can be a monochromator or a tuneable
bandpass filter followed by a photodiode detector. The absolute wavelength of the optical
spectral analyser, monochrometer, or tunable filter shall be calibrated precisely before taking
measurements.
61300-3-29  IEC:2005 – 25 –
As was stated in 4.1.2, it is also conceivable to use a tuneable bandpass filter immediately
after the broad band source (rather than in front of the detector) for this system with the
caveats for effective source linewidth understood.
The receiver shall have the same stability, dynamic range, sensitivity, resolution, and linearity
requirements as described in 4.4.1 for the tuneable laser method. One difference for this
method is that the power density of the BBS over the optical bandwidth of the receiver tends
to have much lower powers than an equivalent laser based system, so the sensitivity needs to
be much better to make the same measurement.
4.5 Temporary joints (TJ)
Temporary joints are specified to connect all system components including the test sample.
Examples of temporary joints are a connector, splice, vacuum chuck, or micromanipulator.
The loss of the TJ shall be stable and should have a return loss at least 10 dB greater than
the maximum return loss to be measured. In the event that connectors are used, it is
preferred to use angled ones.
5 Procedure
The following sections will outline the measurement procedure whereby data can be collected
and analysed on a DWDM device. Since these devices tend to be sensitive to polarisation, all
of the measurements shall be made using either the “all states method” of IEC 61300-3-2 or
the “Mueller matrix method” as described in IEC 61300-3-12. These methods will be reiterated
in this document. Due to the number of data points typically required to characterise these
devices, it is more practical to use the Mueller matrix method for this procedure. However, in
the event of a controversy, the all states method (with sufficient coverage) shall be the
reference. This procedure applies to both measurement systems as differences are high-
lighted in the text.
If polarisation information is not required for the measurement (possibly for an incoming
inspection test), it is acceptable to use Method B without the polarisation controller. In this
case the measured unpolarised transfer function or reference is equivalent to the “average”
transfer function or reference mentioned in the text.
In the interest of completeness, it is important to note that there are fibre components such as
the fibre Bragg grating (FBG) that are used in DWDM devices. The main difference of these
devices is that they can operate as a single port as opposed to the multi-port devices
described in the standard. To show how this measurement technique can be expanded upon
to handle single port components, the reader is advised to see Annex A of this document.
5.1 Preparation of specimens
All the input and output optics shall be cleaned and inspected in accordance with standard
industry practices or the recommendation of the device manufacturer.

61300-3-29  IEC:2005 – 27 –
5.2 System initialisation
The test system will be set-up to sweep across the wavelength region of interest (λ – λ )
min max
or span in increments of δ, as determined by the specifications of the measurement. For
reference purposes, Annex B shows how an appropriate step size can be determined using
the desired wavelength accuracy, the slope of the response curve at the crossing for the
centre wavelength, and the maximum possible power error in the pass band measurement.
5.3 System reference measurement
In the determination of the transfer function, it will be necessary to reference out the effects of
the test system itself. In the event of testing a multi-port device, it will not be necessary to
repeat the reference step before each measurement.
5.3.1 Measurement of the reference spectra for method A
For this step, the DUT is removed from Figure 2 and the output of the polarisation controller is
connected directly to the detector D1 as shown in Figure 4. The TLS shall then be scanned
across the wavelength span taking wavelength measurements from the wavelength monitor,
transmission measurements from D1, and source monitor measurements from D2. It should
be noted that the document assumes all powers are measured on a linear scale. The manner
in which the polarisation states are controlled during the sweep will vary based on the method
used.
TJ2/
Detector
TJ3
(D1)
TJ1
RBD
PPololariarissaattiion on
(optional)
ccontontrolrolller er
Tracking
Detector
TLS filter RBD
(D2)
TJ4
(optional)
(optional)
Wavelength
monitor
IEC  2541/05
Figure 4 – System reference for transmission measurement
In the event that the all states method is used, for each step in the wavelength sweep the
polarisation shall be varied over all states. For each wavelength it will be necessary to
capture the maximum, minimum, and average values of the transmission power as well as the
average value of the monitor power. This will result in matrixes for t (λ),t (λ), t (λ), and
max min ave
m (λ). Care should be taken to ensure that enough time is spent at each polarisation to get
ave
an accurate power reading.
In the event that the Mueller matrix method is used, it is more practical to complete a sweep
at each of the four known SOPs. It is typical to use: A) linear horizontal, B) linear vertical, C)
linear diagonal, and D) right-hand circular. This will result in matrixes for t (λ), t (λ), t (λ),
A B C
t (λ), m (λ), m (λ), m (λ), and m (λ). This can also be accomplished in a single sweep by
D A B C D
varying the SOP at each wavelength increment, but it is less efficient in terms of time to
complete the measurement.
61300-3-29  IEC:2005 – 29 –
5.3.2 Measurement of reference spectra for method B
As in the above case, the DUT is removed from the test set-up (Figure 3). Here the output of
the polarisation controller is connected to the tuneable receiver and the receiver is swept
across the entire measurement wavelength range. The readings from the receiver shall supply
the equivalent matrixes as in 5.3.1. If the measurement is done using unpolarised light, only
the t (λ) array is obtained.
ave
5.4 Measurement of device spectra
With the device re-inserted in the test set-up, the measurement procedure outlined in 5.3.1 (or
5.3.2) shall be repeated. In this manner the various transmission and source monitor spectra
[T(λ) and M(λ)] can be captured and stored.
6 Characterisation of the device under test
Once the measurement data has been collected, the amplitude characteristics of the devices
can be fully documented.
6.1 Determination of transfer functions
After the measurement procedures outlined in Section 5 are completed, the respective
minimum, maximum, and average transfer functions can be determined from the gathered
data.
6.1.1 Accounting for the source variations
If the source monitor port is not used in the set-up, this section may be skipped. If it is used,
the various transmission spectra should be recalculated for the Mueller matrix method as:
T’(λ) = T(λ)/M(λ) or t’(λ) = t(λ)/m(λ)
For the All States method, this recalculation need only be done for the average power array
since there is no way to correlate the maximum and minimum polarisation states between the
reference and the monitor paths without storing the results from each individual state.
It should be noted that for the remainder of the document T’ may be substituted for T or t’ for t
in the equations. The prime factor is left off for convenience.
6.1.2 Calculations for the Mueller matrix method
If the Mueller matrix method is used, it is now necessary to translate the measurements from
the known states into their approximate maximum, minimum, and average values. That is
done by establishing the Mueller matrix:
m (λ) = | ½ * [ T (λ)/t (λ) + T (λ)/t (λ) ] |
11 A A B B
m (λ) = | ½ * [ T (λ)/t (λ) – T (λ)/t (λ) ] |
12 A A B B
m (λ) = | T (λ)/t (λ) – m |
13 C C 11
m (λ) = | T (λ)/t (λ) – m |
14 D D 11
61300-3-29  IEC:2005 – 31 –
where measurements with subscript of A were done with linear horizontal, B with linear
vertical, C with linear diagonal, and D with right-hand circular polarisation in the typical case.
Maximum, minimum, and average transmissions can then be given as:
2 2 2 1/2
T (λ) = m (λ) + [m (λ) + m (λ) + m (λ) ]
max 11 12 13 14
2 2 2 1/2
T (λ) = m (λ) – [m (λ) + m (λ) + m (λ) ]
min 11 12 13 14
T (λ) = [ T (λ) + T (λ) ]/2
ave max min
6.2 Calculation of attenuation (A)
There are generally three types of attenuation or insertion loss (IL) documented for DWDM
components. The first is the attenuation of the nominal channel of the device [A(λ )]. The
h
second is the attenuation of the nearest neighbours or isolated channels [A(λ ) & A(λ )]. The
i g
final attenuation is that of the other isolated channels [A(λ ), where x ≠ h, i, or g] termed the
x
non-adjacent channel attenuation.
In any of these cases, the attenuation should be specified as a threshold throughout λ = λ ±
h
OWR/2 where λ is the nominal wavelength for which the device is intended and OWR is the
h
entire operating wavelength range specified for the device or r
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