1、 TECHNICAL REPORT IEC TR 61282-3Second edition 2006-10Fibre optic communication system design guides Part 3: Calculation of link polarization mode dispersion Reference number IEC/TR 61282-3:2006(E) Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the
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7、elow) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00 TECHNICAL REPORT IEC TR 61282-3Second edition 2006-10F
8、ibre optic communication system design guides Part 3: Calculation of link polarization mode dispersion PRICE CODE IEC 2006 Copyright - all rights reserved No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and micro
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10、ctrotechnique Internationale International Electrotechnical Commission 2 TR 61282-3 IEC:2006(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Basic design models for total system PMD performance6 2.1 Notation.6 2.2 Calculation of system PMD 7 3 Calculation of cabled fibre PMD 9 3.1 General .9 3.2 M
11、ethod 1: Calculating PMD Q , the PMD link design value11 3.3 Method 2: Calculating the probability of exceeding DGD max 14 3.4 Equivalence of methods.18 4 Calculation of optical component PMD 20 5 Summary of acronyms and symbols 20 Annex A (informative) PMD concatenation fundamentals 22 Annex B (inf
12、ormative) Combining Maxwell extrema from two populations26 Annex C (informative) Worked example30 Annex D (informative) Relationship of probability to system performance31 Annex E (informative) Concatenation experiment32 Bibliography34 Figure 1 Various passing distributions 15 Figure 2 Worst case ap
13、proach assumption .17 Figure 3 Convolution of two Diracs .17 Figure 4 Equivalence envelopes for method 1/2 defaults.19 Figure A.1 Sum of randomly rotated elements.25 Figure A.2 Sum of randomly rotated elements.25 Table 1 Probability based on wavelength average.9 Table 2 Acronyms and definitions .21
14、Table 3 Symbols and clause of definition 21 Table E.1 Concatenation math verification33 TR 61282-3 IEC:2006(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 3: Calculation of link polarization mode dispersion FOREWORD 1) The International Electrote
15、chnical 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 t
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25、 all such patent rights. The main task of IEC technical committees is to prepare International Standards. However, a technical committee may propose the publication of a technical report when it has collected data of a different kind from that which is normally published as an International Standard
26、 for example “state of the art“. IEC 61282-3, which is a technical report, has been prepared by subcommittee 86C: Fibre optic systems and active devices, of IEC technical committee 86: Fibre optics. This second edition cancels and replaces the first edition published in 2002. It is a technical revi
27、sion that includes the following significant changes: a) the title has been changed to better reflect its applicability to links; b) Equations (1) and (2) were simplified in order to align with agreements in the ITU-T. 4 TR 61282-3 IEC:2006(E) The text of this technical report is based on the follow
28、ing documents: Enquiry draft Report on voting 86C/701/DTR 86C/720/RVC Full information on the voting for the approval of this technical report 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. A lis
29、t of all parts of the IEC 61282 series, published under the general title Fibre optic communication system design guides, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web
30、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. A bilingual version of this publication may be issued at a later date. TR 61282-3 IEC:2006(E) 5 INTRODUCTION Po
31、larization mode dispersion (PMD) is usually described in terms of a differential group delay (DGD), which is the time difference between the principal states of polarization of an optical signal at a particular wavelength and time. PMD in cabled fibres and optical components causes an optical pulse
32、to spread in the time domain, which may impair the performance of a fibre optic telecommunication system, as defined in IEC 61281-1. 6 TR 61282-3 IEC:2006(E) FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 3: Calculation of link polarization mode dispersion 1 Scope This part of IEC 61282 provide
33、s guidelines for the calculation of polarization mode dispersion (PMD) in fibre optic systems to accommodate the statistical variation of PMD and differential group delay (DGD) in optical fibre cables and components. This technical report describes methods for calculating PMD due to optical fibre ca
34、bles and optical components in an optical link. The calculations are compatible with those documented in the outdoor optical fibre cable specification IEC 60794-3. Example calculations are given to illustrate the methods for calculating total optical link PMD from typical cable and optical component
35、 data. The calculations include the statistics of concatenating individual optical fibre cables drawn from a specified distribution. The calculations assume that all components have PMD equal to the maximum specified value. The calculations described cover first order PMD only. The following subject
36、 areas are currently beyond the scope of this technical report, but remain under study: calculation of second and higher order PMD; accommodation of components with polarization dependent loss (PDL) if it is assumed that PDL is negligible in optical fibre cables; system impairments (power penalty) d
37、ue to PMD; interaction with chromatic dispersion and other nonlinear effects. Measurement of PMD is beyond the scope of this technical report. Methods of measurement of PMD of optical fibre and cable are given in IEC 60793-1-48. The measurement of optical amplifier PMD is in IEC 61290-11-1. The meas
38、urement of component PMD is in IEC 61300-3-32. Measurement of link PMD is given in 61280-4-4. A general theory and guidance on measurements is given in 61282-9. 2 Basic design models for total system PMD performance 2.1 Notation For cabled fibre and components with randomly varying DGD, the PMD freq
39、uency domain measurement is based on averaging the individual DGD values for a range of wavelengths. The probability density function of DGD values is known to be Maxwell for fibre, and is assumed to be Maxwell, in effect, for components. The single parameter for the Maxwell distribution scales with
40、 the PMD value. For long fibre and cable (typically longer than 500 m to 1 000 m), the PMD value is divided by the square root of the length to obtain the PMD coefficient. For components, the PMD value is reported without normalization. The following terms and meanings will be used to distinguish th
41、e various expressions: DGD value The differential group delay at a time and wavelength (ps) PMD value The wavelength average of DGD values (ps) PMD coefficient The length normalised PMD (ps/sqrt(km) DGD coefficient The length normalised DGD (ps/sqrt(km) TR 61282-3 IEC:2006(E) 7 NOTE The term “DGD co
42、efficient” is used only in some of the calculations. The physical square root length dependence of the PMD value does not apply to DGD. Deterministic components are those for which the DGD may vary with wavelength, but not appreciably with time. The variation in wavelength may be complex, depending
43、on the number and characteristics of the sub-components within. For these types of components, either the maximum DGD is reported or the wavelength average is reported as the PMD value. For components with multiple paths, such as an optical demultiplexer, the maximum DGD of the different paths shoul
44、d be reported as the PMD value. 2.2 Calculation of system PMD PMD values of randomly varying elements can be added in quadrature. Annex A shows the basis of this, as well as one basis for concluding that the Maxwell distribution is appropriate to describe the distribution of DGD values. Annex A desc
45、ribes the concatenation in terms of the addition of rotated polarization dispersion vectors (pdv) which are, for randomly varying components, assumed to be random in magnitude and direction over both time and wavelength. For deterministic components, the evolution of the pdv with wavelength may be q
46、uite complex, but for each wavelength, there is a value that does not vary appreciably with time. Analysis of the relationships in Annex A shows that deterministic components that are randomly aligned in combination with random elements behave like random components. For randomly varying components
47、such as fibre, the statistics of DGD variation imply that there is little wavelength dependence of the PMD value. This leads to an equivalence between PMD measurement methods such as Jones Matrix Eigenanalysis (JME) and interferometric methods (IT) where the wavelength ranges of the two are differen
48、t. For deterministic elements, there can be distinct dependence of both the DGD and PMD on the wavelength range. Therefore for these elements, when doing calculations which combine both randomly varying and deterministic elements, the combined values are only representative of the wavelength overlap
49、 The relationships of Annex A also show an analysis for an assumption that the deterministic components are randomly aligned. For this assumption, the DGD values are time randomised across the wavelengths by the fibre. The random alignment of these components with respect to the other elements leads to the following conclusions for deterministic components. The quadrature addition of PMD values can be used to calculate the
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