1、TECHNICAL REPORT IECTR 61282-7 First edition 2003-01 Fibre optic communication system design guides Part 7: Statistical calculation of chromatic dispersion Guides de conception des systmes de communications fibres optiques Partie 7: Calcul statistique de la dispersion chromatique Reference number IE
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8、e contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00TECHNICAL REPORT IEC TR 61282-7 First edition 2003-01 Fibre optic communication system design guides Part 7: Statistical calculation of chromatic dispersion Guides de conception des systmes de com
9、munications fibres optiques Partie 7: Calcul statistique de la dispersion chromatique PRICE CODE IEC 2003 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 microfilm, without per
10、mission in writing from the publisher. International Electrotechnical Commission, 3, rue de Varemb, PO Box 131, CH-1211 Geneva 20, Switzerland Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmailiec.ch Web: www.iec.ch G For price, see current catalogue Commission Electrotechnique Int
11、ernationale International Electrotechnical Commission 2 TR 61282-7 IEC:2003(E) CONTENTS FOREWORD 3 1 Scope 4 2 Normative references. 4 3 Characterisation of chromatic dispersion coefficient versus wavelength. 5 4 Characterisation of chromatic dispersion coefficient statistics versus wavelength 6 5 C
12、alculation of the concatenation statistics for a single population of optical fibres 9 6 Generalisation of concatenation statistics for multiple populations including components. . 10 Figure 1 Distribution of dispersion parameters. 6 Figure 2 Histogram of values at 1 560 nm 7 Figure 3 Histogram of v
13、alues at 1 530 nm 7 Figure 4 Average dispersion coefficient versus wavelength . 8 Figure 5 Standard deviation of dispersion coefficient versus wavelength. 8 Figure 6 Fibre average 11 Figure 7 Fibre standard deviation 11 Figure 8 Dispersion compensator average. 12 Figure 9 Dispersion compensator stan
14、dard deviation. 12 Figure 10 Combined three sigma limits 13 Table 1 Computed values at two selected wavelengths . 10TR 61282-7 IEC:2003(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 7: Statistical calculation of chromatic dispersion FOREWORD 1)
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23、state of the art“. IEC 61282-7, which is a technical report, has been prepared by subcommittee 86C: 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/429/DTR 8
24、6C/468/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. The committee has decided that the contents of this publication
25、will remain unchanged until 2009-12. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition, or amended. 4 TR 61282-7 IEC:2003(E) FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 7: Statistical calculation of chromatic dispersion 1 Scope This part of IEC 61282
26、 is a guideline providing methods of representing the process statistics of the chromatic dispersion of optical fibres and related components that may be combined in a link. Chromatic dispersion (ps/nm) is the derivative, with respect to wavelength, of the group delay (ps) induced by the spectral co
27、ntent of light propagating through an optical element or fibre. Chromatic dispersion is normally a function of wavelength and can be either positive (group delay increasing with wavelength) or negative (group delay decreasing with wavelength). The presence of chromatic dispersion can induce distorti
28、ons in signals leading to bit errors depending on source spectral width; source chirp; bit period; distance. In addition, chromatic dispersion is interactive with the effects of non-linear optical effects and second order polarisation mode dispersion (PMD). The above system impairments are beyond th
29、e scope of this technical report. When different components or fibres are combined, the chromatic dispersion of the combination is the total of the chromatic dispersion values of the individuals, on a wavelength- by-wavelength basis. A section with high chromatic dispersion will be balanced by secti
30、ons with lower values. The variation in the total dispersion of links will therefore be dependent on the distributions of the products that are used in the link. This document provides methods to calculate the distribution statistics of concatenated links based on information on the distributions of
31、 different fibre or component populations. NOTE In the clauses that follow, examples are given for particular fibre and component types. These examples are not necessarily broadly representative. 2 Normative references The following referenced documents are indispensable for the application of this
32、document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60793-1-42: Optical fibres Part 1-42: Measurement methods and test procedures Chromatic dispersion IEC 60793-2-50: Optical fib
33、res Part 2-50: Product specifications Sectional specification for class B single-mode fibres ITU-T Recommendation G.652: Characteristics of a single-mode optical fibre cable ITU-T Recommendation G.655: Characteristics of a non-zero dispersion shifted single-mode optical fibre cableTR 61282-7 IEC:200
34、3(E) 5 ITU-T Recommendation G.671: Transmission characteristics of optical components and subsystems ITU-T Recommendation G.691: Optical interfaces for single-channel STM-64, STM-256 and other SDH systems with optical amplifiers 3 Characterisation of chromatic dispersion coefficient versus wavelengt
35、h This clause outlines the characterisation of dispersion as a function of wavelength for a given wavelength range. This function is often represented as a formula that includes parameters that can vary from fibre to fibre for a given fibre design. Characterisations of these formulas should give an
36、indication of the wavelength range over which the formula applies. Extrapolation beyond these ranges can result in error. For optical fibre, chromatic dispersion coefficient, D, can vary with wavelength, , according to a variety of formula types that are found in IEC 60793-1-42. The simplest is the
37、linear representation which has just two parameters, zero-dispersion wavelength, 0 , and zero- dispersion slope, S 0 , as: () ( ) 0 0 = S D (ps/nm km) (1) Measurements are based either on fitting differential group delays (DGD) or by fitting the integral to the measured group delay. Other forms defi
38、ned in 60793-1-42 are the three-term Sellmeier (Equation (2), and the five- term Sellmeier (Equation (3). Note that for the five-term Sellmeier, parameters, C j , different from the zero-dispersion wavelength and slope must be fitted. () = 4 0 0 1 4 S D (2) () 5 4 3 3 3 2 1 4 4 2 2 + = C C C C D (3)
39、 For components, similar types of expressions can be used to characterise the chromatic dispersion value, d, as a function of wavelength. For components, however, the units are most often given as ps/nm (unadjusted for length). The use of the term “coefficient,” for fibre indicates a length normalis
40、ation. 6 TR 61282-7 IEC:2003(E) Even for the products for which the linear representation of Equation (1) is appropriate for each individual fibre, the combination of the distributions of the zero-dispersion wavelength and slope will normally not lead to a very clear understanding of the distributio
41、n of chromatic dispersion. Figure 1 shows such a combined distribution that illustrates a correlation between the dispersion parameters. 0,050 0,055 0,060 0,065 0,070 0,075 0,080 0,085 0,090 0,095 0,100 1 560 1 562 1 564 1 566 1 568 1 570 1 572 1 574 1 576 1 578 Lambda-0 nm S 0 IEC 3207/02 Figure 1
42、Distribution of dispersion parameters 4 Characterisation of the chromatic dispersion coefficient statistics versus wavelength This clause outlines the technique used to characterise the distribution of a single population of fibres. Similar approaches can be applied to components. The fibre distribu
43、tion shown in Figure 1 was intended for use in the wavelength range of 1 530 nm to 1 560 nm a B4 type fibre (ITU-T G.655), see IEC 60793-2-50. The chromatic dispersion values for the lower end of this range are affected more by the variation of slope values for high zero-dispersion wavelength than f
44、or low zero dispersion wavelength. The combined contributions are therefore difficult to evaluate without some other means. The characterisation methodology suitable for use in concatenation statistics for this distribution alone, or for combination with other distributions is to calculate the dispe
45、rsion coefficient for each of the wavelengths in the range of the application for each individual fibre. This creates a distribution of dispersion coefficient values for each wavelength. Figures 2 and 3 show these distributions at two selected wavelengths for the distribution shown in Figure 1.TR 61
46、282-7 IEC:2003(E) 7 0 20 40 60 80 100 120 140 160 180 1,25 1,15 1,05 0,95 0,85 0,75 0,65 0,55 0,45 0,35 0,25 0,15 0,05 D(1 560) ps/nm km Frequency IEC 3208/02 Figure 2 Histogram of values at 1 560 nm 0 20 40 60 80 100 120 140 160 180 3,5 3,4 3,3 3,2 3,1 3,0 2,9 2,8 2,7 2,6 2,5 2,4 2,3 2,2 2,1 2,0 D(
47、1 530) ps/nm km Frequency IEC 3209/02 Figure 3 Histogram of values at 1 530 nm The distribution for each wavelength is characterised with an average and a standard deviation value. These statistics are then plotted versus wavelength. Figures 4 and 5 show the relationships. 8 TR 61282-7 IEC:2003(E) 3
48、,0 2,5 2,0 1,5 1,0 0,5 0 1 530 1 535 1 540 1 545 1 550 1 555 1 560 Wavelength nm Dispersion ps/nm km IEC 3210/02 Figure 4 Average dispersion coefficient versus wavelength 0,196 0,198 0,200 0,202 0,204 0,206 0,208 0,210 0,212 0,214 0,216 1 530 1 535 1 540 1 545 1 550 1 555 1 560 Wavelength nm Standard deviation ps/nm km IEC 3211/02 Figure 5 Standard deviation of dispersion coefficient versus wavelength Note that a linear relationship represents the average and a quadratic relationship represents the standard deviation. This is due in part to the linear representation of di
