1、 TECHNICAL REPORT IEC TR 61282-8First edition 2006-11Fibre optic communication system design guides Part 8: Calculating dispersion penalty from measured time-resolved chirp data Reference number IEC/TR 61282-8:2006(E) Publication numbering As from 1 January 1997 all IEC publications are issued with
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8、st edition 2006-11Fibre optic communication system design guides Part 8: Calculating dispersion penalty from measured time-resolved chirp data 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 mech
9、anical, including photocopying and microfilm, without permission 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 R For pri
10、ce, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission 2 TR 61282-8 IEC:2006(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms and definitions .6 4 Measuring dispersion penalty using a bit-error-ratio test set .7
11、 5 Obtaining time-resolved chirp data .8 6 Calculating dispersion penalty from time-resolved chirp data9 6.1 Calculate BER for a particular condition.9 6.2 Calculate dispersion penalty10 6.3 Calculate transmitter and dispersion penalty .11 6.4 Calculate total transmitter power penalty.11 7 An exampl
12、e measurement and calculation of power penalties.11 8 A comparison of dispersion penalty measurements from BER and TRC measurements12 Annex A (informative) Data analysis of bit error ratio versus received power in digital systems 13 Bibliography20 Figure 1 Equipment setup for direct power penalty me
13、asurements.8 Figure 2 Typical TRC data suitable for dispersion penalty calculations.9 Figure 3 An example measurement of the three power penalties12 Figure 4 Comparison of dispersion penalty results for measurements with a BER test set and for calculation from TRC data.12 Figure A.1 Plot of Equation
14、 (A.1) with SNR plotted linearly 14 Figure A.3 Example plot and analysis using the exact procedure. 18 Figure A.4 Example plot and analysis using the log-log procedure .19 Table A.1 Values for BER versus SNR.15 Table A.2 Experimental data for exact linearization18 Table A.3 Experimental data for log
15、-log analysis19 TR 61282-8 IEC:2006(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ FIBRE OPTIC COMMUNICATION SYSTEM DESIGN GUIDES Part 8: Calculating dispersion penalty from measured time-resolved chirp data FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organizatio
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26、ical 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, for example “state of the art“. IEC 61282-8, whic
27、h 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/686/DTR 86C/721/RVC Full information on the v
28、oting for the approval of this technical report can be found in the report on voting indicated in the above table. 4 TR 61282-8 IEC:2006(E) This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of the IEC 61282 series, published under the general ti
29、tle 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 site under “http:/webstore.iec.ch“ in the data related to the specific
30、 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 61282-8 IEC:2006(E) 5 INTRODUCTION Dispersion penalty is a commonly used parameter of laser transmitters an
31、d is usually included as a specification for transmitters designed for 2,5 Gb/s and higher data rates. The value of the dispersion penalty is a function of the interaction of laser chirp, spectral width and fibre dispersion and will depend on the particular type of fibre. Because the type and length
32、 of the fibre specified for a particular transmitter is fixed, the dispersion penalty is determined by the temporal characteristics of the transmitter chirp, which include the spectral characteristics of the laser. As developers and manufacturers of laser transmitters are attempting to go to higher
33、rates and longer distances, they are finding that chirp is limiting their ability to achieve a required dispersion penalty. Direct measurement of dispersion penalty requires two BER measurements over a reference receiver input range that yields BER values typically from 10 4to 10 12 . This is typica
34、lly a long measurement. Measuring time-resolved chirp (TRC) and calculating dispersion penalty can be a considerably shorter measurement. This technical report describes the procedure for calculating dispersion penalty from TRC data. 6 TR 61282-8 IEC:2006(E) FIBRE OPTIC COMMUNICATION SYSTEM DESIGN G
35、UIDES Part 8: Calculating dispersion penalty from measured time-resolved chirp data 1 Scope This part of IEC 61282 provides definitions of dispersion penalty and other related penalties. It describes the direct measurement of these penalties using a BER test set and the calculation of the penalties
36、from time-resolved chirp (TRC) data. Annex A provides the theory for power penalty calculations. The calculations are valid for all types of single longitudinal mode (SLM) laser transmitters intended for use in telecommunications applications at data rates of 2,5 Gbit/s and higher with NRZ modulatio
37、n format. These include but are not limited to directly modulated DFB lasers, DFB lasers with integrated electro-absorption modulators, and DFB lasers with external Mach- Zehnder modulators. This technique is not suitable for multiple longitudinal mode (MLM) lasers or LEDs. Chromatic dispersion indu
38、ced power penalty values in this technical report are characteristics of the transmitter, which is considered to be the device-under-test (DUT). Other power penalty sources, such as nonlinear effects and amplifier noise are not covered by this document. Since dispersion penalty for a transmission li
39、nk depends on the transmitter, receiver and fibre, the dispersion penalty parameter for a transmitter is based on a specified fibre dispersion and receiver characteristic, which should be reported with the test results. 2 Normative references The following referenced documents are indispensable for
40、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 61280-2-8, Fibre optic communication subsystem test procedures Digital systems Part 2-8: Determination
41、 of low BER using Q-factor measurements IEC 61280-2-10, Fibre optic communication subsystem test procedures Digital systems Part 2-10: Time-resolved chirp and alpha-factor measurement of laser transmitters ITU-T Recommendation G.957, Optical interfaces for equipments and systems relating to the sync
42、hronous digital hierarchy 3 Terms and definitions Power penalty measurements compare BER versus received power curves for two conditions. The first condition is a reference condition. The second condition introduces impairment. Changing the received power influences BER by altering the ratio of opti
43、cal signal power to the receiver noise. Therefore it is useful, but equivalent, to express BER versus received power curves as BER versus OSNR curves, where this “optical signal to noise ratio” compares average optical signal power to all noise including the electrical noise of the receiver. General
44、ly, the OSNR, based on average signal power, differs from the SNR of a digital signal, which is based on the average difference between the signal of the 1 and 0 bits, as described in IEC 61280-2-8. TR 61282-8 IEC:2006(E) 7 3.1 dispersion penalty apparent change in receiver sensitivity due to distor
45、tion of the signal waveform during its transmission over a path with a specified chromatic dispersion and minimal PMD. It is manifested as a shift of the systems BER curves from the fibre path to a no-fibre path: reference condition: DUT without dispersive fibre; impaired condition: DUT with specifi
46、ed fibre path NOTE 1 It is normal that the impaired condition will shift the BER to a higher received power and yield a dispersion penalty that is a positive value. Under some conditions, for example, when fibre dispersion compensates for transmitter chirp, in the impaired condition, the BER curve w
47、ill be shifter to a lower received power and yield a negative dispersion penalty. NOTE 2 Minimal PMD is a necessary condition because, for example, 0,6 ps PMD causes 0,1 dB power penalty for 40 Gb/s NRZ. 3.2 transmitter and dispersion penalty TDP apparent change in receiver sensitivity due to distor
48、tion of the signal waveform during its transmission over a path with a specified chromatic dispersion for a transmitter with a defined extinction ratio. It is manifested as a shift of the systems BER-curves for these two cases: reference condition: ideal transmitter (specified with maximum rise and
49、fall times only) with the same extinction ratio as the actual DUT with no dispersive fibre in the path; impaired condition: DUT with specified fibre path NOTE This parameter is defined in IEEE 802.3ae-2002, 10Gb/s Ethernet. The IEEE standard does not specify a transmitter with the same ER as the DUT, but accomplishes the equivalent by specifying a measurement of optical modulation amplitude (OMA) as opposed to average pow
