1、 TIA STANDARD TR 61282-3 Fibre Optic Communication System Design Guides Part 3: Calculation of Polarization Mode Dispersion TIA/TR-1029 FEBRUARY, 2004 TELECOMMUNICATIONS INDUSTRY ASSOCIATION Representing the telecommunications industry in association with the Electronic Industries Alliance ANSI/TIA/
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6、ser of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (From Standards Proposal No. 3-0140, formulated under the cognizance of the TIA FO-4.1 Subcommittee on Fiber Optic) Published by TELECOMMUNICATIONS I
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17、IAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES (INCLUDING DAMAGES FOR LOSS OF BUSINESS, LOSS OF PROFITS, LITIGATION, OR THE LIKE), WHETHER BASED UPON BREACH OF CONTRACT, BREACH OF WARRANTY, TORT (INCLUDING NEGLIGENCE), PRODUCT LIABILITY OR OTHERWISE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. THE
18、 FOREGOING NEGATION OF DAMAGES IS A FUNDAMENTAL ELEMENT OF THE USE OF THE CONTENTS HEREOF, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS. TR 61282-3 IEC:2002 adopted as TIA/TR-1029 CONTENTS FOREWORD .iii INTRODUCTION v 1 Scope and object .1 2 Basic design models for total
19、 system PMD performance2 2.1 Notation 2 2.2 Calculation of system PMD 2 2.2.1 System maximum PMD 3 2.2.2 Calculation of system maximum DGD.4 3 Calculation of cabled fibre PMD6 3.1 Method 1: Calculating PMDQ, the PMD link design value 7 3.1.1 Determining the probability distribution of the link PMD c
20、oefficients 7 3.1.2 Determining the value of PMDQ9 3.2 Method 2: Calculating the probability of exceeding DGDmax 11 3.2.1 Combining link and Maxwell variations .12 3.2.2 Convolution: Theory of method 213 3.3 Equivalence of methods.15 3.3.1 Equivalence of the default specifications 15 3.3.2 Discussio
21、n regarding the basis of the default specifications for method 2 16 3.3.3 Calculation of the parameters of figure 4 17 4 Calculation of optical component PMD17 4.1 Calculation for random components.18 4.2 Calculation for deterministic components .18 4.2.1 Worse case calculation 18 4.2.2 Calculation
22、for embedded deterministic components 19 5 Summary of acronyms and symbols20 Annex A (informative) PMD concatenation fundamentals23 A.1 Definitions .23 A.2 Concatenation General .24 A.3 Application to random elements .24 A.4 Application to deterministic elements .25 Annex B (informative) Combining M
23、axwell extrema from two populations28 B.1 Maxwell distribution definitions.28 B.2 Convolution definition 29 B.3 Convolution of optical fibre cable and random components.29 B.4 Evaluation of the double convolution 30 Annex C (informative) Worked example .33 TR 61282-3 IEC:2002 adopted as TIA/TR-1029
24、iiAnnex D (informative) Relationship of probability to system performance35 Annex E (informative) Concatenation experiment .37 Bibliography .39 TR 61282-3 IEC:2002 adopted as TIA/TR-1029 iiiINTERNATIONAL ELECTROTECHNICAL COMMISSION _ FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 3: Calculation
25、 of polarization mode dispersion FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote international co-operation on all questi
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33、d as an International Standard, for example “state of the art”. Technical reports do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful by the maintenance team. IEC 61282-3, which is a technical report, has been prepared by subcommittee 86C
34、: Fibre optic systems and active devices, of IEC technical committee 86: Fibre optics. The text of this technical report is based on the following documents: Enquiry draft Report on voting 86C/296/DTR 86C/346/RVC Full information on the voting for the approval of this technical report can be found i
35、n the report on voting indicated in the above table. Annexes A, B, C, D and E are for information only. TR 61282-3 IEC:2002 adopted as TIA/TR-1029 ivThis publication has been drafted in accordance with the ISO/IEC Directives, Part 3. This document, which is purely informative, is not to be regarded
36、as an International Standard. The committee has decided that the contents of this publication will remain unchanged until 2006 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 dat
37、e. TR 61282-3 IEC:2002 adopted as TIA/TR-1029 vINTRODUCTION Polarization 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
38、 cabled fibres and optical components causes an optical pulse to spread in the time domain, which may impair the performance of a fibre optic telecommunication system, as defined in IEC 61281-1. TR 61282-3 IEC:2002 adopted as TIA/TR-1029 viTR 61282-3 IEC:2002 adopted as TIA/TR-1029 FIBRE OPTIC COMMU
39、NICATION SYSTEM DESIGN GUIDES Part 3: Calculation of polarization mode dispersion 1 Scope The purpose of this technical report is to provide guidelines for the calculation of polarization mode dispersion (PMD) in fibre optic systems to accommodate the statistical variation of PMD and differential gr
40、oup delay (DGD) in optical fibre cables and components. This guideline describes methods for calculating PMD due to optical fibre cables and optical components in an optical link. Example calculations are given to illustrate the methods for calculating total optical link PMD from typical cable and o
41、ptical component 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. NOTE The statistical specification of the distribution of th
42、e PMD of optical fibre cables is a current work item to amend IEC 60794-3, in SC86A/WG3 21. The agreements following the last ballot (86A/501/CD) are aligned with the methods given in this technical report. The calculations described cover first order PMD only. This study of PMD continues to evolve,
43、 therefore the material in this technical report may be modified in the future. The following subject 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)
44、if it is assumed that PDL is negligible in optical fibre cables; system impairments (power penalty) due to PMD; interaction with chromatic dispersion and other nonlinear effects. Measurement of PMD is beyond the scope of this technical report. Guidelines on the measurement of PMD of optical fibre an
45、d cable are given in IEC 61941. The measurement of optical amplifier PMD will be documented in IEC 61290-11-12. The measurement of component PMD will be documented in IEC 61300-3-323. _ 1Figures in brackets refer to the bibliography. 2To be published 3To be published TR 61282-3 IEC:2002 adopted as T
46、IA/TR-1029 22 Basic design models for total system PMD performance 2.1 Notation For cabled fibre and components with randomly varying DGD, the PMD frequency domain measurement is based on averaging the individual DGD values for a range of wavelengths. The probability density function of DGD values i
47、s known to be Maxwell for fibre, and is assumed to be Maxwell for random components. The single parameter for the Maxwell distribution scales with the PMD value. For long fibre and cable (typically longer than 500 m to 1000 m), the PMD value is divided by the square root of the length to obtain the
48、PMD coefficient. For components, the PMD value is reported without normalization. The following terms and meanings will be used to distinguish the various expressions: DGD value The differential group delay at a time and wavelength (ps) PMD value The wavelength average of DGD values (ps) PMD coeffic
49、ient The length normalized PMD (ps/sqrt(km) DGD coefficient The length normalized DGD (ps/sqrt(km) NOTE The term “DGD coefficient” 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 on the number and characteristics of the sub-components within. For these types of components, e