1、 International Telecommunication Union ITU-T G.656TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2010) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media and optical systems characteristics Optical fibre cables Characteristics of a fibre and cable with non
2、-zero dispersion for wideband optical transport Recommendation ITU-T G.656 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTE
3、MS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND
4、LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 General G.600G.609 Symmetric cable pairs G.610G.619 Land coaxial cable pairs G.620G.629 Submarine cables G.630G.639 Free space optical systems G.640G.649 Optical fibre cables G.650G.659Characteristics of opti
5、cal components and subsystems G.660G.679 Characteristics of optical systems G.680G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TR
6、ANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.656 (07/2010) i Recommendation ITU-T G.656 Chara
7、cteristics of a fibre and cable with non-zero dispersion for wideband optical transport Summary Recommendation ITU-T G.656 describes the geometrical, mechanical, and transmission attributes of a single-mode optical fibre which has the positive value of the chromatic dispersion coefficient greater th
8、an some non-zero value throughout the wavelength range of anticipated use 1460-1625 nm. This dispersion reduces the growth of non-linear effects which are particularly deleterious in dense wavelength division multiplexing systems. This fibre can be used for both CWDM (coarse wavelength division mult
9、iplexing) and DWDM (dense wavelength division multiplexing) systems throughout the wavelength region between 1460 and 1625 nm. Edition 2 limits the chromatic dispersion coefficient by a pair of bounding curves vs wavelength for the range of 1460 nm to 1625 nm, which provides information to support C
10、WDM and DWDM applications. Edition 3 removes jumper cut-off wavelength definition and adds a note allowing higher maximum cabled attenuation for short jumper cables. History Edition Recommendation Approval Study Group 1.0 ITU-T G.656 2004-06-13 15 2.0 ITU-T G.656 2006-12-14 15 3.0 ITU-T G.656 2010-0
11、7-29 15 ii Rec. ITU-T G.656 (07/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ
12、 of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the to
13、pics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are pr
14、epared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation
15、may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to
16、 express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual
17、 Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received noti
18、ce of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2
19、011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.656 (07/2010) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 2 5 Fibre attributes 2 5.1 Mode field diameter . 2 5.2
20、Cladding diameter 2 5.3 Core concentricity error 2 5.4 Non-circularity . 3 5.5 Cut-off wavelength . 3 5.6 Macrobending loss 3 5.7 Material properties of the fibre . 4 5.8 Refractive index profile 4 5.9 Longitudinal uniformity of chromatic dispersion . 4 5.10 Chromatic dispersion coefficient 4 6 Cabl
21、e attributes . 5 6.1 Attenuation coefficient . 5 6.2 Polarization mode dispersion (PMD) coefficient . 5 7 Table of recommended values 6 Appendix I Information for link attributes and system design . 8 I.1 Attenuation . 8 I.2 Chromatic dispersion 8 I.3 Differential group delay (DGD) . 9 I.4 Non-linea
22、r coefficient . 9 I.5 Tables of common typical values . 10 I.6 Chromatic dispersion coefficient limits 10 Bibliography. 12 Rec. ITU-T G.656 (07/2010) 1 Recommendation ITU-T G.656 Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport 1 Scope This Recommendation
23、describes a single-mode fibre with chromatic dispersion that is greater than some non-zero value throughout the wavelength range of 1460-1625 nm. This dispersion reduces the growth of non-linear effects that can be particularly deleterious in dense wavelength division multiplexing (DWDM) systems. Th
24、is fibre uses non-zero dispersion to reduce four-wave mixing and cross-phase modulation over a wider wavelength range than the fibre described in b-ITU-T G.655. Extensions are possible, in the future, to wavelengths beyond the 1460-1625 nm region (to be determined). The geometrical, optical, transmi
25、ssion, and mechanical parameters are described below in three categories of attributes: fibre attributes are those attributes that are retained throughout cabling and installation; cable attributes that are recommended for cables as they are delivered; link attributes that are characteristics of con
26、catenated cables, describing estimation methods of system interface parameters based on measurements, modelling, or other considerations. Information for link attributes and system design are given in Appendix I. This fibre can be utilized for CWDM and DWDM systems throughout the extended wavelength
27、 transmission region between 1460 and 1625 nm. This Recommendation, and the category found in the table of clause 7, is intended to support the following related system Recommendations: b-ITU-T G.691; b-ITU-T G.692; b-ITU-T G.693; b-ITU-T G.695; b-ITU-T G.959.1; b-ITU-T G.698.1; b-ITU-T G.696.1. The
28、 meaning of the terms used in this Recommendation and the guidelines to be followed in the measurement to verify the various characteristics are given in ITU-T G.650.1 and ITU-T G.650.2. The characteristics of this fibre, including the definitions of the relevant parameters, their test methods and r
29、elevant values, will be refined as studies and experience progress. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were va
30、lid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendation
31、s is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 2 Rec. ITU-T G.656 (07/2010) ITU-T G.650.1 Recommendation ITU-T G.650.1 (2010), Definitions and test methods for linear, deterministic attribu
32、tes of single-mode fibre and cable. ITU-T G.650.2 Recommendation ITU-T G.650.2 (2007), Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable. ITU-T G.694.1 Recommendation ITU-T G.694.1 (2002), Spectral grids for WDM applications: DWDM frequency
33、 grid. 3 Definitions For the purposes of this Recommendation, the definitions given in ITU-T G.650.1 and ITU-T G.650.2 apply. Values shall be rounded to the number of digits given in the table of Recommended values before conformance is evaluated. 4 Abbreviations This Recommendation uses the followi
34、ng abbreviations: AeffEffective Area CWDM Coarse Wavelength Division Multiplexing DGD Differential Group Delay DWDM Dense Wavelength Division Multiplexing PMD Polarization Mode Dispersion PMDQStatistical parameter for PMD link SDH Synchronous Digital Hierarchy TBD To Be Determined 5 Fibre attributes
35、 Only those characteristics of the fibre providing a minimum essential design framework for fibre manufacturers are recommended in this clause. Ranges or limits on values are presented in the table of clause 7. Of these, cable manufacture or installation may significantly affect the cabled fibre cut
36、-off wavelength and PMD. Otherwise, the recommended characteristics will apply equally to individual fibres, fibres incorporated into a cable wound on a drum, and fibres in an installed cable. 5.1 Mode field diameter Both a nominal value and tolerance about that nominal value shall be specified at 1
37、550 nm. The nominal value that is specified shall be within the range found in clause 7. The specified tolerance shall not exceed the value in clause 7. The deviation from nominal shall not exceed the specified tolerance. 5.2 Cladding diameter The recommended nominal value of the cladding diameter i
38、s 125 m. A tolerance is also specified and shall not exceed the value in clause 7. The cladding deviation from nominal shall not exceed the specified tolerance. 5.3 Core concentricity error The core concentricity error shall not exceed the value specified in clause 7. Rec. ITU-T G.656 (07/2010) 3 5.
39、4 Non-circularity 5.4.1 Mode field non-circularity In practice, the mode field non-circularity of fibres having nominally circular mode fields is found to be sufficiently low that propagation and jointing are not affected. It is, therefore, not considered necessary to recommend a particular value fo
40、r the mode field non-circularity. It is not normally necessary to measure the mode field non-circularity for acceptance purposes. 5.4.2 Cladding non-circularity The cladding non-circularity shall not exceed the value found in clause 7. 5.5 Cut-off wavelength Two useful types of cut-off wavelength ca
41、n be distinguished: a) Cable cut-off wavelength, cc. b) Fibre cut-off wavelength, c. NOTE For some specific submarine cable applications, other cable cut-off wavelength values may be required. The correlation of the measured values of cand ccdepends on the specific fibre and cable design and the tes
42、t conditions. While in general, cc4000 12.0 10 Gbit/s 400 5.0 40 Gbit/sNOTE This value applies also for 10 Gigabit Ethernet systems. NOTE Cable section length is 10 km except for the 0.10 ps/km/ 4000 km link, where if set to 25 km, the probability level is 6.5 108. I.6 Chromatic dispersion coefficie
43、nt limits The equations bounding the chromatic dispersion coefficient vs wavelength are based on a survey for the ITU-T G.656 fibres. There were nine products from seven vendors. Each provided average and standard deviation as a function of wavelength for wavelengths from 1460 nm to 1625 nm in 5 nm
44、increments. For wavelength and vendor, the average plus and minus three standard deviation was calculated. Then the minimum and maximum across vendors was calculated. These results were fitted with a line spline using a breakpoint at 1550 nm to minimize the sum of absolute values of the difference w
45、hile maintaining the principle of including all the data within the envelope. The result is shown in Figure I.1. The dashed lines are the limits from clause 7. The rest of the data represents the survey results. Rec. ITU-T G.656 (07/2010) 11 16.014.012.010.08.06.04.02.00.01440 1460 1480 1500 1520 15
46、40 1560 1580 1600 1620 1640Wavelength nmChromatic dispersion coefficientps/nmkmType 1 3 sigmaType 1 +3 sigmaType 2 3 sigmaType 2 +3 sigmaType 3 3 sigmaType 3 +3 sigmaType 4 3 sigmaType 4 +3 sigmaType 6 3 sigmaType 6 +3 sigmaType 7 3 sigmaType 7 +3 sigmaType 9 3 sigmaType 9 +3 sigmaprior ITU-T G.656(
47、ver.1, 2004)upper limit curvelower limit curveG.656(10)_FI.1Figure I.1 Table 1 fibre dispersion 12 Rec. ITU-T G.656 (07/2010) Bibliography b-ITU-T G.655 Recommendation ITU-T G.655 (2009), Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable. b-ITU-T G.663 Recommendati
48、on ITU-T G.663 (2000), Application related aspects of optical amplifier devices and subsystems. b-ITU-T G.691 Recommendation ITU-T G.691 (2006), Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers. b-ITU-T G.692 Recommendation ITU-T G.692 (1998), Optical interf
49、aces for multichannel systems with optical amplifiers. b-ITU-T G.693 Recommendation ITU-T G.693 (2009), Optical interfaces for intra-office systems. b-ITU-T G.694.2 Recommendation ITU-T G.694.2 (2003), Spectral grids for WDM applications: CWDM wavelength grid. b-ITU-T G.695 Recommendation ITU-T G.695 (2009), Optical interfaces for coarse wavelength division multiplexing applications. b-ITU-T G.696.1 Recommendation ITU-T G.696.1 (2005), Longitudinally com
