1、 IEC/TR 61292-6 Edition 1.0 2010-02 TECHNICAL REPORT Optical amplifiers Part 6: Distributed Raman amplification IEC/TR 61292-6:2010(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2010 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be r
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10、art 6: Distributed Raman amplification INTERNATIONAL ELECTROTECHNICAL COMMISSION T ICS 33.160.10; 33.180.30 PRICE CODE ISBN 2-8318-1081-7 Registered trademark of the International Electrotechnical Commission 2 TR 61292-6 IEC:2010(E) CONTENTS FOREWORD.4 INTRODUCTION.6 1 Scope.7 2 Normative references
11、7 3 Abbreviated terms.8 4 Background 8 4.1 General .8 4.2 Raman amplification process .8 4.3 Distributed vs. lumped amplification.10 4.4 Tailoring the Raman gain spectrum10 4.5 Forward and backward pumping configuration11 4.6 Typical performance of DRA 12 5 Applications of distributed Raman amplific
12、ation.13 5.1 General .13 5.2 All-Raman systems13 5.3 Hybrid EDFA Raman systems 14 5.3.1 Long repeaterless links 14 5.3.2 Long span masking in multi-span links .15 5.3.3 High capacity long haul and ultra-long haul systems.15 6 Performance characteristics and test methods 15 6.1 General .15 6.2 Perfor
13、mance of the Raman pump module 16 6.2.1 Pump wavelengths.16 6.2.2 Pump output power16 6.2.3 Pump degree-of-polarization (DOP)17 6.2.4 Pump relative intensity noise (RIN) 17 6.2.5 Insertion loss .17 6.2.6 Other passive characteristics .18 6.3 System level performance18 6.3.1 On-off signal gain 18 6.3
14、.2 Gain flatness .19 6.3.3 Polarization dependant gain (PDG) 20 6.3.4 Equivalent noise figure.20 6.3.5 Multi-path interference (MPI)20 7 Operational issues21 7.1 General .21 7.2 Dependence of Raman gain on transmission fibre21 7.3 Fibre line quality 22 7.4 High pump power issues22 7.4.1 Laser safety
15、.23 7.4.2 Damage to the fibre line.23 8 Conclusions24 Bibliography25 TR 61292-6 IEC:2010(E) 3 Figure 1 Stimulated Raman scattering process (left) and Raman gain spectrum for silica fibres (right) .9 Figure 2 Distributed vs. lumped amplification10 Figure 3 The use of multiple pump wavelengths to achi
16、eve flat broadband gain.11 Figure 4 Simulation results showing pump and signal propagation along an SMF span in forward (right plot) and backward (left plot) pumping configurations .11 Figure 5 On-off gain and equivalent NF for SMF using a dual pump backward DRA with pumps at 1 424 nm and 1 452 nm 1
17、3 Figure 6 Typical configuration of an amplification site in an all-Raman system 14 Figure 7 Typical configuration of a Raman pump module used for counter-propagating DRA16 Figure 8 Model for signal insertion loss (IL) of a Raman pump module used for counter-propagating DRA18 Figure 9 Typical config
18、uration used to measure on of gain (a) for co-propagating DRA and (b) for counter-propagating DRA.19 Figure 10 Variations of Raman on-off gain for different transmission fibres .22 4 TR 61292-6 IEC:2010(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ OPTICAL AMPLIFIERS Part 6: Distributed Raman ampli
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30、opose 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 61292-6, which is a technical report, has been prepared by subcommittee 86C: Fibre optic systems and acti
31、ve 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/910/DTR 86C/936/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicat
32、ed in the above table. TR 61292-6 IEC:2010(E) 5 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of the IEC 61292 series, published under the general title Optical amplifiers, can be found on the IEC website. The committee has decided that the
33、contents of this amendment and the base publication will remain unchanged until the stability date indicated on the IEC web 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,
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35、this document using a colour printer. 6 TR 61292-6 IEC:2010(E) INTRODUCTION Distributed Raman amplification (DRA) describes the process whereby Raman pump power is introduced into the transmission fibre, leading to signal amplification within the transmission fibre though stimulated Raman scattering
36、. This technology has become increasingly widespread in recent years due to the many advantage that it offers optical system designers, including improved system optical signal-to-noise ratio (OSNR), and the ability to tailor the gain spectrum to cover any or several transmission bands. A fundamenta
37、l difference between distributed Raman amplification and amplification using discrete amplifiers, such as erbium-doped fibre amplifiers (EDFAs), is that the latter can be described using a black box approach, while the former is an inherent part of the system in which it is deployed. Thus, a discret
38、e amplifier is a unique and separate element with a well defined input and output ports, allowing rigorous specifications of the amplifiers performance characteristics and the methods used to test these characteristics. On the other hand, a distributed Raman amplifier is basically a pump module, wit
39、h the actual amplification process taking place along the transmission fibre. This means that many of the performance characteristics of distributed Raman amplification are inherently coupled to the system in which it is deployed. This technical report provides an overview of DRA and its application
40、s. It also provides a detailed discussion of the various performance characteristics related to DRA, some of the methods that can be used to test these characteristics, and some of the operational issues related to the distributed nature of the amplification process, such as the sensitivity to trans
41、mission line quality and eye-safety. The material provided is intended to provide a basis for future development of specifications and test method standards related to DRA. TR 61292-6 IEC:2010(E) 7 OPTICAL AMPLIFIERS Part 6: Distributed Raman amplification 1 Scope This part of IEC 61292, which is a
42、technical report, deals with distributed Raman amplification (DRA). The main purpose of the report is to provide background material for future standards (specifications, test methods and operating procedures) relating to DRA. The report covers the following aspects: general overview of Raman amplif
43、ication; applications of DRA; performance characteristics and test methods related to DRA; operational issues relating to the deployment of DRA. As DRA is a relatively young technology, and still rapidly evolving, some of the material in this report may become obsolete or irrelevant in a relatively
44、short period. This technical report will be frequently updated in order to minimize this possibility. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the la
45、test edition of the referenced document (including any amendments) applies. IEC 60825-2, Safety of laser products Part 2: Safety of optical fibre communication systems (OFCS) IEC 61290-3, Optical amplifiers Test methods Part 3: Noise figure parameters IEC 61290-3-1, Optical amplifiers Test methods P
46、art 3-1: Noise figure parameters Optical spectrum analyzer method IEC 61290-3-2, Optical amplifiers Test methods Part 3-2: Noise figure parameters Electrical spectrum analyzer method IEC 61290-7-1, Optical amplifiers Test methods Part 7-1: Out-of-band insertion losses Filtered optical power meter me
47、thod IEC 61291-1, Optical amplifiers Part 1: Generic specification IEC/TR 61292-3, Optical amplifiers Part 3: Classification, characteristics and applications IEC/TR 61292-4, Optical amplifiers Part 4: Maximum permissible optical power for the damage-free and safe use of optical amplifiers, includin
48、g Raman amplifiers ITU-T G.664, Optical safety procedures and requirements for optical transport systems ITU-T G.665, Generic characteristics of Raman amplifiers and Raman amplified subsystems 8 TR 61292-6 IEC:2010(E) NOTE A list of informative references is given in the Bibliography. 3 Abbreviated
49、terms For the purposes of this document, the following abbreviated terms apply. APR automatic power reduction DCF dispersion compensating fibre DOP degree of polarization DRA distributed Raman amplification DRB double Rayleigh backscattering DWDM dense wavelength division multiplexing EDFA erbium-doped fibre amplifier ESA electrical spectrum analyzer FBG fibre Bragg grating FWHM full width half maximum GFF gain flattening
