EN 61300-3-32:2006

SLOVENSKI STANDARD
01-september-2007
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Fibre optic interconnecting devices and passive components - Basic test and
measurement procedures -- Part 3-32: Examinations and measurements - Polarization
mode dispersion measurement for passive optical components (IEC 61300-3-32:2006)
Lichtwellenleiter - Verbindungselemente und passive Bauteile - Grundlegende Prüf- und
Messverfahren - Teil 3-32: Untersuchungen und Messungen - Messung der
Polarisationsmodendispersion für passive optische Bauteile (IEC 61300-3-32:2006)
Dispositifs d'interconnexion et composants passifs a fibres optiques - Méthodes
fondamentales d'essais et de mesures -- Partie 3-32: Examens et mesures - Mesure de
la dispersion de mode de polarisation pour composants optiques passifs (IEC 61300-3-
32:2006)
Ta slovenski standard je istoveten z: EN 61300-3-32:2006
ICS:
33.180.20 3RYH]RYDOQHQDSUDYH]D Fibre optic interconnecting
RSWLþQDYODNQD devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61300-3-32
NORME EUROPÉENNE
September 2006
EUROPÄISCHE NORM
ICS 33.180.20
English version
Fibre optic interconnecting devices and passive components -
Basic test and measurement procedures
Part 3-32: Examinations and measurements -
Polarization mode dispersion measurement
for passive optical components
(IEC 61300-3-32:2006)
Dispositifs d'interconnexion et Lichtwellenleiter -
composants passifs à fibres optiques - Verbindungselemente
Méthodes fondamentales d'essais und passive Bauteile -
et de mesures Grundlegende Prüf- und Messverfahren
Partie 3-32: Examens et mesures - Teil 3-32: Untersuchungen
Mesure de la dispersion de mode und Messungen -
de polarisation pour composants Messung der
optiques passifs Polarisationsmodendispersion
(CEI 61300-3-32:2006) für passive optische Bauteile
(IEC 61300-3-32:2006)
This European Standard was approved by CENELEC on 2006-09-01. 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 61300-3-32:2006 E
Foreword
The text of document 86B/2325/FDIS, future edition 1 of IEC 61300-3-32, 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 61300-3-32 on 2006-09-01.
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) 2007-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-09-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61300-3-32:2006 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 61300-3-32:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

1) 2)
IEC 60793-1-48 - Optical fibres EN 60793-1-48 2003
Part 1-48: Measurement methods and test
procedures - Polarization mode dispersion

1)
IEC/TR 61282-3 - Fibre optic communication system design - -
guides
Part 3: Calculation of polarization mode
dispersion
1)
IEC/TR 61282-9 - Fibre optic communication system design - -
guides
Part 9: Guidance on polarization mode
dispersion measurements and theory

1) 2)
IEC 61300-3-2 - Fibre optic interconnecting devices and EN 61300-3-2 1999
passive components - Basic test and
measurement procedures
Part 3-2: Examinations and measurements -
Polarization dependence of attenuation in a
single-mode fibre optic device

1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE
IEC
61300-3-32
INTERNATIONAL
Première édition
STANDARD
First edition
2006-08
Dispositifs d’interconnexion et
composants passifs à fibres optiques –
Méthodes fondamentales d’essais et de mesures –
Partie 3-32:
Examens et mesures –
Mesure de la dispersion de mode de polarisation
pour composants optiques passifs

Fibre optic interconnecting devices
and passive components –
Basic test and measurement procedures –
Part 3-32:
Examinations and measurements –
Polarization mode dispersion measurement
for passive optical components
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61300-3-32  IEC:2006 – 3 –
CONTENTS
FOREWORD.7

1 Scope.11
2 Normative references .11
3 Abbreviations .13
4 General description .13
4.1 Mode coupling.15
4.2 Narrowband devices.15
4.3 Polarization sensitivity.17
4.4 Multiple path interference .17
4.5 Fibre pigtails .17
4.6 Reference test methods .19
4.7 Polarization mode dispersion coefficient.19
4.8 Analyses used in various test methods.21
4.9 Calculation of polarization mode dispersion.21
4.10 Calibration.21
5 Device under test .21
6 Stokes parameter evaluation method.27
6.1 Apparatus.27
6.2 Procedure .33
7 Polarization phase shift measurement method.43
7.1 Apparatus.45
7.2 Procedure .49
8 Fixed analyser measurement method .55
8.1 Apparatus.55
8.2 Procedure .63
9 Interferometric method .71
9.1 Apparatus.71
9.2 Procedure .77
10 Modulation phase shift method .87
10.1 Apparatus.89
10.2 Procedure .99
11 Details to be specified .103
11.1 Wavelength range source.103
11.2 Polarizer/analyser .105
11.3 Temporary joint .105
11.4 Device under test .105

Annex A (informative) Cosine Fourier transform analysis .107

Bibliography.113

61300-3-32  IEC:2006 – 5 –
Table 1 – Technical applicability of the various test methods to different DUT types. 25

Figure 1– Effect of PMD phenomenon on transmission of an information bit pulse in a
device.15
Figure 2 – Determination of polarization dispersion vector and principal states of
polarization.23
Figure 3 – Functional diagram of a generic measurement system based on Stokes
parameter evaluation .27
Figure 4 – Test set-ups for the Stokes parameter evaluation method .29
Figure 5 – Sample results from the Stokes parameter evaluation method.41
Figure 6 – Test set-up for the polarization phase shift method .45
Figure 7 – Differential group delay versus wavelength for a 50/100 GHz interleaver .53
Figure 8 – Block diagrams for fixed analyser method .57
Figure 9 – Example of the R-function for the fixed analyser method .61
Figure 10 – Polarization mode dispersion by Fourier analysis .69
Figure 11 – Schematic diagram for the interferometric method for passive fibre optic
devices .73
Figure 12 – Typical data obtained by interferometric method .79
Figure 13 – Fringe patterns obtained with GINTY and I/O-SOP scrambling .85
Figure 14 – Apparatus to make the DGD measurement.89
Figure 15 – Apparatus to make the DGD measurement using a polarization modulation
technique.97

61300-3-32  IEC:2006 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-32: Examinations and measurements –
Polarization mode dispersion measurement
for passive optical 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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61300-3-32 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86B/2325/FDIS 86B/2378/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

61300-3-32  IEC:2006 – 9 –
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.
61300-3-32  IEC:2006 – 11 –
FIBRE OPTIC INTERCONNECTING DEVICES
AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-32: Examinations and measurements –
Polarization mode dispersion measurement
for passive optical components

1 Scope
This part of IEC 61300 presents a number of alternative methods for measuring the
polarization mode dispersion (PMD) of a passive fibre optic device under test (DUT). These
methods typically measure PMD using either a frequency domain or time domain approach. In
the frequency domain, the polarization properties of the DUT are analysed. In the time domain
approach, the pulse delay or broadening is observed.
This procedure will cover measurements of both broadband, and narrowband dense
wavelength division multiplexing (DWDM) passive fibre optic devices. Differences between
measurement practices for these varied classes of passive fibre optic devices will be noted in
the text.
This procedure can be applied to laboratory, factory and field measurements of PMD in
passive fibre optic devices. Limitation of the application of some methods will be noted in the
text when necessary.
This procedure can be applied to a transmissive or reflective DUT. In the latter case, the DUT
connection is via a coupler or circulator, which should have a known very low PMD value.
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 60793-1-48, Optical fibres – Part 1-48: Measurement methods and test procedures –
Polarisation mode dispersion
IEC 61282-3, Fibre optic communication system design guides – Part 3: Calculation of
polarization mode dispersion
IEC 61282-9, Fibre optic communication system design guides – Part 9: Guidance on
polarization mode dispersion measurements and theory
IEC 61300-3-2, Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures – Part 3-2: Examinations and measurements – Polarization
dependence of attenuation in a single-mode fibre optic device

61300-3-32  IEC:2006 – 13 –
3 Abbreviations
ASE: amplified spontaneous emission
DGD: differential group delay
DOP: degree of polarization
DUT: device under test
DWDM: dense wavelength division multiplexing
FA: fixed analyser
FAFT: fixed analyser Fourier transform
FAEC: fixed analyser extrema counting
FWHM: full width at half the maximum
INTY: interferometry
ISI: inter-symbol interference
JME: Jones matrix eigenanalysis
MMA: Mueller matrix analysis
MPS: modulation phase shift
PDL: polarization dependent loss
PMD: polarization mode dispersion
PDV: polarization dispersion vector
PPS: polarization phase shift
PS: Poincaré sphere
PSA: Poincaré sphere analysis
PSP: principal states of polarization
RBW: resolution bandwidth
RMS: root mean square
SOP: state of polarization
SPE: Stokes parameter evaluation
WDM: wavelength division multiplexing
4 General description
PMD refers to the spreading of an optical pulse due to polarization-related anomalies. In
optical communication systems, the spreading of a pulse leads to bit errors at the receiver
due to inter-symbol interference (ISI) and consequently provides bandwidth limitation.
Each optical pulse is made up of a combination of two orthogonal SOPs called the principal
SOPs (PSPs), due to birefringence possibly present in the DUT (see Figure 1). These
different polarization components travel at different group velocities and will arrive at the
output of the DUT at different times. PMD is related to the difference between the two PSP
delays, the DGD Δτ.
61300-3-32  IEC:2006 – 15 –
Δτ
t
Fast axis
z, t
Slow axis
Δτ
IEC  1546/06
Figure 1– Effect of PMD phenomenon on transmission
of an information bit pulse in a device
4.1 Mode coupling
PMD in passive fibre optic devices is usually deterministic by nature meaning that the
phenomenon is predictable and can be reproduced and controlled. However, it is important to
understand how the polarization modes can couple together in the device, and in fact they
can couple differently. In optical passive fibre optic devices, the mode coupling is typically
referred to as negligible or no or negligible (including the cases of polarization maintaining
fibres and short lengths of ordinary fibre) as opposed to random or strong mode coupling such
as frequently seen in the case of long lengths of fibre. In no or negligible mode coupling, the
axis of birefringence in the device is fixed and constant in only one section of birefringence
and consequently the DGD is constant as a function of wavelength. In that case the PMD is
equal to the DGD.
There can however be types of passive fibre optic devices exhibiting many sections of fixed
birefringence with their axes not necessarily aligned with each other making the DGD
randomly varying as a function of wavelength. In that case, the mode coupling is random.
Even if the DGD varies, as a function of wavelength and the mode coupling is random, this
variation will be constant from one measurement to another and it can still be predicted and
the phenomenon is still deterministic. In that case, the PMD is the average value of the DGD
spectral distribution (the root mean squared – RMS – value may also be used and is
accepted).
There can also be intermediate cases where the passive fibre optic device has few
birefringence sections and the DGD can vary less randomly such as a monotonous or sine
wave variation as a function of wavelength. The PMD is still the average or RMS value of the
DGD distribution and the phenomenon is still deterministic but the mode coupling is neither
negligible nor random.
The mode coupling describes how the SOPs are maintained as energy traverses the device.
Rather, each device is shown to have a polarization transfer function whereby the SOP at the
input is mapped to a different SOP at the output as a function of wavelength. This transfer
function is commonly represented using the Jones matrix and will be explained later in the
document.
4.2 Narrowband devices
There are other cases of classification that are related to the PMD phenomenon and
need to be taken into account. This includes narrowband devices. A narrowband device can
have a small DGD distribution while experiencing a wide Fourier time spectrum

61300-3-32  IEC:2006 – 17 –
with a more complex spectrum in the time domain. Care will also have to be taken when
making analysis of DGD in the time domain versus the spectral domain.
4.3 Polarization sensitivity
Another complicating factor is related to the presence of PDL in the DUT. Figure 1 illustrates
such a case where at the output of the DUT the bits are not only broadened (in absence of
PDL) but also distorted (in presence of PDL). In the case of PDL, the two PSPs are not
o
necessarily orthogonal anymore (not anymore 180 apart on the Poincaré sphere). In this
case, this test procedure will be restricted to devices with PDL equal to or less than 1 dB to
allow the application of all suggested methods. This condition is typically met inside the
passband of typical passive fibre optic devices used in DWDM systems.
PDL or polarization sensitivity may severely impact the correct determination of DUT DGD.
PDL may be measured by using IEC 61300-3-2.
However, some possible exclusions or assumptions can be made to reduce the complexity of
the situation. For example, a device with high PDL (>10 dB) will generally be used for single-
polarization operation. It is therefore possible to argue that for such a device, PDL is the
relevant parameter, not PMD.
Therefore with the above justification the scope of this document is restricted to exclude
devices that have high (>10 dB) PDL. Such devices include polarizer, polarization sensitive
splitters or modulators etc.
For devices with low PDL (<1 dB), which are the typical cases of DWDM devices, PDL
generally presents little problem to the measurements of DGD, but will marginally increase
uncertainty. As PDL rises, this uncertainty rises.
For devices with higher PDL (e.g. >10 dB) this error is likely to be unacceptably high.
4.4 Multiple path interference
Passive fibre optic devices may contain bulk optical elements, fibre-waveguide splices, and
fibre-lens interfaces etc. that can give rise to reflections due to optical index mismatch
between elements. The effect of these may be to induce multi-path dispersions that are either
PMD-related (i.e. the path difference is polarization sensitive) or not (polarization insensitive
path differences) [1] .
Reflections and multiple delay paths that are not polarization sensitive can be separately
removed from DGD. Any kind of polarization-sensitive differential delay, however, will be
recorded as DGD.
4.5 Fibre pigtails
Finally, the fibre pigtails will add PMD of their own, which will vary as the leads are bent,
coiled or twisted.
———————
Figures in square brackets refer to the bibliography.

61300-3-32  IEC:2006 – 19 –
The pigtails into and out of the DUT (typically sealed into the DUT housing) will always
contribute some PMD. Since the fibre leads are typically only a few metres long, the PMD in
the leads is essentially deterministic, with little random coupling. Typical PMD values for a few
metres of standard fibre are of the order of 1 fs/m or less. The PMD in the leads will partially
add to, or partially subtract from, the DGD of the DUT itself according to the axial alignment of
the lead birefringence and that of the DUT. This lead contribution represents a source of
uncertainty in the DUT DGD determination. To avoid bending birefringence being introduced
the pigtails should be kept as straight as possible with a bend radius greater than 50 mm. In
addition, if required, the DGD measurements may be repeated many times with the leads re-
configured each time to randomise the PMD contribution in the leads. The true device DGD
will then be the average of the results taken. Care must be taken to ensure that the leads are
arranged such that the full range of PMD variation is covered.
Components with PM pigtails are normally highly polarization sensitive or polarised sources
and, as such, the polarization axis of the pigtail is aligned with the polarization axis of the
device, and the relevant parameter is extinction ratio. Any misalignment will introduce
significant PMD.
To summarize, the main features of passive fibre optic devices are as follows:
• discrete, deterministic birefringent element(s), possibly with mutually unaligned optical
axes (low mode coupling);
• generally deterministic DGD properties, finite or low mode coupling, with fast and slow
polarization modes that may be relatively independent of wavelength;
• PMD levels which can be low (<0,1 ps) to high (>2 ps);
• finite, often quite narrow wavelength transmission/reflection band;
• fibre pigtails which contribute a varying amount of PMD;
• possible reflections and other multi-path dispersion sources within the DUT;
• potentially large amounts of PDL (>1 dB to <10 dB).
4.6 Reference test methods
In this test procedure, the reference test method shall be a full polarimetric method based on
the Stokes parameter evaluation. There are two practical analyses complying with this
criterion that are in fact formalistically equivalent to each other [2] [4]. Those are: the Jones
Matrix Eigenanalysis (JME) and the Poincaré Sphere Analysis (PSA). All other test methods
listed in this procedure shall be considered as alternative test methods. Except as indicated
below, the JME and PSA procedures are identical to those described in IEC 60793-1-48.
4.7 Polarization mode dispersion coefficient
As the PMD phenomenon is deterministic in the case of passive fibre optic devices, the
concept of PMD coefficient does not apply as it does in the case of short lengths or long
lengths of fibre. The PMD of passive fibre optic devices will only be expressed in units of ps.

61300-3-32  IEC:2006 – 21 –
4.8 Analyses used in various test methods
The mathematical model on which the test method analyses are based can be found in
IEC 61282-9.
4.9 Calculation of polarization mode dispersion
A mathematical development for calculating PMD can be found in IEC 61282-3.
4.10 Calibration
The equipment is calibrated by using a polarization maintaining fibre of known PMD, for the
case of no or negligible mode coupling. For the case of random mode coupling, a certified
randomly oriented stack of quarter wave plates is recommended. For large PMD values (> 1ps)
representative of random mode coupling, there are no simple yet standardized calibration
artifact and method.
5 Device under test
The DUT is typically a fibre-pigtailed discrete component, which is fusion spliced or connected
via suitable patch cords, pigtails etc into the PMD test apparatus. The DUT may be in normal
laboratory environments, or alternately as required the DUT may be placed in an
environmental chamber to allow it to be subject to high or low temperature or humidity etc.
during measurements.
• Ensure the DUT has less than 10 dB PDL, and that its approximate spectral bandwidth is
known.
As the PMD measurement of an optical passive fibre optic device depends on the type of
mode coupling the DUT experiences and consequently the number of birefringent sections of
which it is composed, this document has grouped the DUTs into the following categories:
• negligible or no mode coupling;
• random mode coupling;
• intermediate mode coupling;
• narrowband DWDM.
Because of the sensitivity of the SOP to the measurement, it is also necessary to make note
of the actual device configurations:
• fibre to fibre;
• plug to plug;
• receptacle to receptacle;
• receptacle to plug.
The key point to take into account is that any device with long fibre leads (longer than 1 km)
will exhibit some degree of randomness in the measurement of DGD as a function of the
length of the fibre. This is attributed to the random mode coupling properties of most fibre and
consequently making PMD a stochastic phenomenon in that case. As the DUTs of interest use
short fibre leads of much less than 1 km, this procedure will consequently assume that the
PMD will be deterministic.
61300-3-32  IEC:2006 – 23 –
For the purposes of this procedure, the DUT has two optical ports that may be terminated with
a bare fibre, plug, or receptacle. If the device is terminated with fibre, temporary splice joints
can be used to connect the DUT to the input and output polarizers. In this case, care should
be taken to ensure that interference effects due to reflections are avoided. The use of index
matching materials is recommended.
In the event that a device has multiple ports, measurements will pertain to a single optical
path, and the procedure should be repeated for all valid optical paths. In this case, the DGD
or PMD for each optical path should be reported.
The DUT and pigtails shall be fixed in position at a nominally constant temperature throughout
the entire measurement to reduce uncertainties due to random mode coupling. Mechanical
and temperature stability of the DUT may be observed by viewing the DUT output SOP on a
Poincaré sphere display. In a time period corresponding to a measurement, the change in the
output SOP should be small relative to the change produced by a wavelength increment.
When measuring PMD, or rather the DGD of passive fibre optic devices one needs to
understand the class of devices being measured, as the techniques will vary slightly in
specifications, performance, and accuracy.
For simple deterministic devices (negligible or no mode coupling), the DGD will be fairly
constant with respect to wavelength. In these cases the output SOP will trace a near circle on
the Poincaré sphere (see Figure 2). The angular velocity will be constant and the length of the
PDV and consequently the DGD will be constant. The number and accuracy of wavelength
points do not have to be very high in this case.
IEC  1547/06
Figure 2 – Determination of polarization dispersion vector
and principal states of polarization

61300-3-32  IEC:2006 – 25 –
There are however some DUTs, which could exhibit a varying angular velocity of their output
SOP. With a DUT made of two sections of equal birefringence, the PSP is changing as a
function of optical frequency (change of the PDV – its velocity – or its first order derivative as
a function of optical frequency); but the DGD (the length of the PDV) remains constant. With
three sections, both the length of the PDV (DGD) and its velocity are changing; but the DGD
variation is monotonic and consequently the DGD experiences a kind of sine wave behaviour
as a function of wavelength.
There could also be DUTs, exhibiting a large number of fixed changes of axis of birefringence
(complex DUTs with many birefringence sections). The SOP will experience a rotation about a
fixed axis of birefringence and around the fast axis PSP. But the axis of the PSP will also
change and consequently the output SOP will also follow the displacement of the PSP axis on
the Poincaré sphere. The rotation will not be monotonic anymore but rather complex. The
DGD will experience a complex though predictable variation as a function of wavelength
(random mode coupling). This case will happen when the DUT has a large number of sections
of fixed birefringence. The PMD will still be the average value of that complex variation of the
DGD as a function of wavelength.
DWDM devices are unique in that they will have very narrow bandwidth per channel and
consequently will require a very high degree of spectral resolution in order to properly
estimate the DGD as a function of wavelength and consequently the PMD. It is to be noted
that in this case the Fourier spectrum of this narrowband device could give a very complex
time spectrum. Care will have to be provided as the time spectrum could give questionable
interpretation of time delays that might not be DGD. Provisions should also be taken in order
to respect the Nyquist theorem (for instance, the source linewidth should be more than twice
the step size of the wavelength scan).
Table 1 gives a summary of the test methods technical applicability to different DUT types.
Table 1 – Technical applicability of the various test methods to different DUT types
Test methods FA INTY MPS PPS SPE PS
(arc)
FAFT FAEC TINTY GINTY
Application to passive fibre optic devices
Negligible or no mode coupling (X) N/A (X) X X X X X**
Random mode coupling (X) (X) (X) X X X X N/A
Intermediate mode coupling N/A N/A N/A X X X X N/A
Narrowband DWDM N/A N/A N/A X X X X X**
NOTE 1 Key:
X Applicable.
(X) Applicability is limited in scope, range or performance, or applicability not yet confirmed.
** Indicates that the PS arc method is only applicable to DUTs of the single element construction,
where DGD is essentially constant over the wavelength range used (negligible mode coupling).
N/A Not applicable
NOTE 2 Key to PMD measurement methods:
FAFT fixed analyser (Fourier analysis) method
FAEC fixed analyser (extrema counting) method
INTY interferometry method
TINTY traditional analysis
GINTY general analysis
MPS modulation phase shift method
PPS polarization phase shift
SPE Stokes parameter evaluation method, including JME, PSA and MMA
PS Poincaré sphere arc method
61300-3-32  IEC:2006 – 27 –
6 Stokes parameter evaluation method
6.1 Apparatus
The basic set-up for the equivalent JME and PSA method for measuring PMD is shown in
Figure 3. The various components of this system are described in the following subclauses.
SOP generator
Wavelenght-range
DUT
light source S (ω)
in
Analyser of the measured normalised
Stokes vectors S (ω)
out
PSA
JME
–1
Arcsine formula
Eigenvalues of T(ω + Δω)T (ω)
Polarisation dispersion Polarisation dispersion
vector PDV (ω) matrix PDM (ω)
–1
dT 1 dT
PDM (ω) =    T –   Tr     T
dω 2 dω
Modulus of PDV (ω) Argument formula
DGD
Link
i
PDM (ω) =   (PDV ⋅ ŝ)
DGD = DGD
PSA JME
IEC  1548/06
Figure 3 – Functional diagram of a generic measurement system
based on Stokes parameter evaluation
Figure 4 illustrates two test set-ups for the Stokes parameter evaluation (SPE) method.

61300-3-32  IEC:2006 – 29 –
Tuneable
Polarimeter
laser
DUT
0°   45°   90°
IEC  1549/06
a) Jones matrix eigenanalysis set-up
Michelson
interferometer
SOP generator
ASE
DUT
source
HeNe
laser
Analysis
Stokes
Polarimeter
vectors
Analyser
IEC  1550/06
b) Poincaré sphere analysis set-up
Figure 4 – Test set-ups for the Stokes parameter evaluation method
6.1.1 Light source
In all cases a polarised wavelength-range light source shall be used. In particular, two kinds
of light source may be used depending on the type of analyser used. For instance, a
narrowband source can be used with a polarimetric analyser while a broadband source can be
used with a narrow band pass filtering analyser. The analyser can be an optical filter that may
be placed before or after the DUT, an optical spectrum analyser or an interferometer used as
a Fourier transform spectrum analyser and the polarimeter.
For the measurement of DWDM devices, the wavelength accuracy of the measurement
system should be in accordance with the required accuracy to have meaningful and reliable
results. The wavelength resolution should be set in accordance with the device bandwidth in
order to follow the Nyquist theorem. This can be done by using a wavelength meter in the set-
up procedure if necessary.
61300-3-32  IEC:2006 – 31 –
a) Narrowband source
A single-line laser or narrow band source shall be used which is tuneable across the intended
measurement wavelength range. The spectral distribution shall be narrow enough so that light
emerging from the DUT remains polarised under all conditions of the measurement, but not
too narrow in order to avoid unnecessary noise, over-sampling and not respecting the Nyquist
criterion. A degree of polarization (DOP) of 90 % or greater is preferred, although
measurements may be performed with values as low as 25 % with reduced precision. For a
given value of DGD, Δτ, the lowest degree of polarization that can result is given by
 
1 πcΔτΔλ
FWHM
 
−
 
4ln2
λ
 0 
DOP = 100 ∗e (1)
Assuming a Gaussian spectrum of width Δλ centred at λ . DOP is expressed in percent.
FWHM 0
b) Broadband source
The source can be an LED with at least 70 nm FWHM linewidth with a polarization extinction
ratio of >20 dB. The filtering analyser should have a spectral width Δλ such that
FWHM
Equation (1) can be met with a DOP > 90 %.
6.1.2 State of polarization generator
A SOP generator is used for generating the input Stokes vectors s (ω). The SOP generator is
in
composed of a polarization adjuster, a set of linear polarizers and suitable optics.
a) Polarization adjuster and linear polarizers
A polarization adjuster follows the light source and is set to provide roughly circularly
polarised light to the polarizers, so that the polarizers never cross polarization with their input
light.
• Adjust the polarization as follows.
• Make sure that the light source wavelength range is set to the centre of the range to be
measured.
• Insert each of the three polarizers into the beam.
• Perform three corresponding power measurements at the output of the polarizer.
• Adjust the source polarization via the polarization adjuster such that the three powers fall
within approximately a 3-dB range of one another.
In an open beam version of the set-up, a waveplate may perform the polarization adjustment.
In addition to the polarization adjuster, three linear polarizers, at relative angles of
approximately 45°, are arranged for insertion into the light beam in turn. Alternatively, a
rotating polarizer can be used. The actual relative angles do not need to be known but need
to be distinct from each other.

61300-3-32  IEC:2006 – 33 –
b) Input optics
An optical lens system or single-mode fibre pigtail may be employed to excite the DUT.
If pigtails are used, interference effects due to reflections should be avoided. This may require
index matching materials. The pigtails shall be single-mode. The pigtail
...