ITU-T G 665-2005 Generic characteristics of Raman amplifiers and Raman amplified subsystems SERIES G TRANSMISSION SYSTEMS AND MEDIA DIGITAL SYSTEMS AND NETWORKS Transmission media co.pdf

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1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.665TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2005) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media characteristics Characteristics of optical components and subsystems Generic characteristics of Raman

2、amplifiers and Raman amplified subsystems ITU-T Recommendation G.665 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 SYSTEMS G.2

3、00G.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 LINE T

4、ELEPHONY G.450G.499 TRANSMISSION MEDIA 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.649 Optical fibre cables G.650G.659 Characteristics of optical components and subsystems G.660G.699 DIGITAL TERMINAL EQUIP

5、MENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For

6、 further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.665 (01/2005) i ITU-T Recommendation G.665 Generic characteristics of Raman amplifiers and Raman amplified subsystems Summary This Recommendation identifies the definitions and test methods of performance parameters of

7、 the following fibre Raman amplifiers and Raman amplified subsystems: reverse pumped distributed Raman amplifier; forward pumped distributed Raman amplifier; bidirectionally pumped distributed Raman amplifier; reverse pumped distributed, composite Raman amplifier; bidirectionally pumped distributed,

8、 composite Raman amplifier; discrete Raman amplifier. This Recommendation describes the classification, the type code, and the reference models of various Raman amplifiers. It also outlines the general characteristics of the Raman amplifiers, and defines the performance and testing parameters for th

9、e Raman amplifiers. Source ITU-T Recommendation G.665 was approved on 13 January 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.665 (01/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in t

10、he field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ 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.

11、The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics 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 Resolutio

12、n 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared 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

13、a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation 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.

14、The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to 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 possibili

15、ty that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual 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 Recom

16、mendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information

17、 and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.665 (01/2005) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Abbreviati

18、ons 1 4 Terms and Definitions 2 4.1 Distributed and discrete Raman amplifier 2 4.2 Optical signal power parameters 3 4.3 Gain parameters 3 4.4 Gain spectrum parameters 4 4.5 Noise parameters 4 4.6 Pump power parameters . 5 4.7 Pump leakage parameters. 6 4.8 Polarization dependent parameters. 6 4.9 C

19、hannel addition/removal response . 7 4.10 Reflectance parameters. 7 4.11 Insertion loss parameters 7 4.12 Other parameters 8 5 Classification 8 5.1 Rules of classification. 8 5.2 Type code . 8 5.3 Reference model. 9 6 Generic Characteristics of Raman amplification devices. 11 7 Performance parameter

20、s and test parameters . 14 8 Optical safety 15 Appendix I Measurements of MPI for lightwave transmission system 15 I.1 Time domain extinction measurement 1 15 I.2 Electrical measurement 2. 15 Appendix II Physical and equivalent models of distributed Raman amplifiers 16 Appendix III Considerations of

21、 splice and connector loss . 17 BIBLIOGRAPHY 19 ITU-T Rec. G.665 (01/2005) 1 ITU-T Recommendation G.665 Generic characteristics of Raman amplifiers and Raman amplified subsystems 1 Scope This Recommendation identifies the definitions and test methods of performance parameters of optical fibre Raman

22、amplifiers and Raman amplified subsystems. In the case of distributed or discrete Raman amplifiers (forward pumped, reverse pumped, bidirectionally pumped) or composite distributed Raman and discrete amplifiers, the generic characteristics of those amplifiers and subsystems are also specified. 2 Ref

23、erences 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 valid. All Recommendations and other references are subject to revision; us

24、ers 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 Recommendations is regularly published. The reference to a document within this Recomme

25、ndation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation G.661 (1998), Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems. ITU-T Recommendation G.662 (1998), Generic characteristics of optical a

26、mplifier devices and subsystems. ITU-T Recommendation G.663 (2000), Application related aspects of optical amplifier devices and subsystems. ITU-T Recommendation G.664 (2003), Optical safety procedures and requirements for optical transport systems. IEC 61290 series, Optical Amplifier Test Methods.

27、IEC 61291 series, Optical fibre amplifiers (General aspects). IEC 61292 series, Technical Reports of Optical Amplifiers. IEC 60825 series, Safety of laser products. 3 Abbreviations This Recommendation uses the following abbreviations: ASE Amplified Spontaneous Emission C Optical connector associated

28、 with the Raman amplifier DOP Degree of Optical Polarization DRS Double Rayleigh Scattering EDFA Erbium-Doped Fibre Amplifier FPiSignal ingress point for the Forward Pumped Raman Amplifier FPoSignal egress point for the Forward Pumped Raman Amplifier FRA Fibre Raman Amplifier 2 ITU-T Rec. G.665 (01/

29、2005) GMP Gain Measurement Point MPI Multi-Path Interference OA Optical Amplifier OAR Optically Amplified Receiver OAT Optically Amplified Transmitter ORL Optical Return Loss PDG Polarization-Dependent Gain PMD Polarization Mode Dispersion RIN Relative Intensity Noise RPiSignal ingress point for the

30、 Reverse Pumped Raman Amplifier RPoSignal egress point for the Reverse Pumped Raman Amplifier Rx Receiver (Optical) SRS Stimulated Raman Scattering Tx Transmitter (Optical) 4 Terms and Definitions This clause outlines the definitions of various distributed Raman amplifiers and the discrete Raman amp

31、lifier. The performance parameters for these Raman amplifiers are also defined in this clause. 4.1 Distributed and discrete Raman amplifier Definitions of distributed and discrete Raman amplifiers are given in this clause. Further information can be obtained in IEC 61292-3 for these Raman amplifiers

32、. 4.1.1 distributed Raman amplifier: Distributed Raman amplifiers are amplifiers where the amplification effect is achieved via a portion of the optical fibre used for transmission. Such amplifiers are deemed to be distributed since part or all of the transmission fibre is used for amplification pur

33、poses. Distributed Raman amplifiers can be further classified into three sub-categories: Forward pumped Raman amplifier: The pump energy and signal co-propagate along the transmission fibre. Reverse pumped Raman amplifier: The pump energy and signal propagate in opposite directions in the transmissi

34、on fibre. Bidirectionally pumped Raman amplifier: The pump energy is applied in both ends of the transmission fibre. In this case, part of the pump energy co-propagates with the signal and part of the pump energy counter-propagates with the signal inside the transmission media. 4.1.2 discrete Raman

35、amplifier: A discrete Raman amplifier is an amplifier for optical signals whose amplification effect is achieved via the fibre SRS effect, where all of the physical components of the amplifier are completely contained inside the device. ITU-T Rec. G.665 (01/2005) 3 4.2 Optical signal power parameter

36、s Parameters Definitions Notes 4.2.1 Equivalent input power The power at the input reference point when the Raman pump is de-activated. For a reverse pumped Raman amplifier, the input reference point is at point RPiin Figure 1. For other Raman amplifier configurations, see 5.3. 4.2.2 Large-signal ou

37、tput stability see 4.9/G.661 4.2.3 Saturation output power (gain compression power) see 4.11/G.661 4.2.4 Nominal output signal power see 4.12/G.661 4.2.5 Maximum total output power see 4.25/G.661 4.2.6 Input power range see 4.28/G.661 4.2.7 Output power range see 4.29/G.661 4.3 Gain parameters Param

38、eters Definitions Notes 4.3.1 Raman on-off gain IEC 61291-1, 3.1.18 and 3.1.19 The increase in signal optical power at the gain measurement point (GMP) defined in 5.3 when the Raman pump is activated compared to the signal optical power at the GMP when the Raman pump is de-activated. Applicable to d

39、istributed Raman amplifiers. 4.3.2 Net Gain Net Gain is defined as the combined Raman On-Off gain and the gain from the OA, if applicable, with the loss between the input and output reference points of the amplifier subtracted from it. 4.3.3 Channel net gain Net Gain for each channel at a given wave

40、length in a multichannel configuration. 4.3.4 Small-signal net gain see 4.1/G.661 4.3.5 Reverse small-signal net gain see 4.2/G.661 4.3.6 Maximum net small-signal gain see 4.3/G.661 4.3.7 Maximum small-signal net gain wavelength see 4.4/G.661 4.3.8 Maximum small-signal net gain variation with temper

41、ature see 4.5/G.661 4 ITU-T Rec. G.665 (01/2005) Parameters Definitions Notes 4.3.9 Small-signal net gain wavelength bandwidth see 4.6/G.661 4.3.10 Small signal net gain stability see 4.8/G.661 4.4 Gain spectrum parameters Parameters Definitions Notes 4.4.1 Average slope of Multichannel net gain spe

42、ctrum envelope For the wavelength iand its correspondent net gain Gi, it is possible to approximate Givia linear equation: abGii+=Where a and b are chosen such that 20)(iniiGG =is minimized. The average slope of multichannel net gain spectrum envelope will be the b in the above linear equation. Also

43、 refer to IEC 61291-1, 3.1.7, gain-slope under single wavelength operation 4.4.2 Power wavelength band see 3.1/G.662 4.4.3 Multichannel net gain variation IEC 61291-4, IEC 61291-1, 3.1.10 4.4.4 Net Gain cross-saturation IEC 61291-4, IEC 61291-1, 3.1.11 For multichannel operation 4.4.5 Multichannel n

44、et gain-change difference IEC 61291-4, IEC 61291-1, 3.1.13 4.4.6 Multichannel net gain tilt IEC 61291-4, IEC 61291-1, 3.1.14 4.5 Noise parameters Parameters Definition 4.5.1 Multi-path interference (MPI) For Raman amplifiers with high gains, the noise from Rayleigh scattering may become dominant. In

45、 addition to ASE increased by single Rayleigh scattering, the forward propagating signal may be Rayleigh scattered twice. Such DRS may cause an increase in MPI. Measurements of MPI are referenced in Appendix I. Also refer to IEC 61291-1, 3.1.35, multi-path interference (MPI) figure of merit, and IEC

46、 61291-1, 3.1.36, double Rayleigh scattering figure of merit. 4.5.2 Differential relative intensity noise of optical signal The ratio between the input relative intensity noise (RIN) and the output RIN of the optical signal. This is mainly caused by MPI in Raman amplifiers. ITU-T Rec. G.665 (01/2005

47、) 5 Parameters Definition 4.5.3 Effective noise figure (NF) The effective noise figure is the noise figure of an equivalent discrete optical amplifier placed at the end of the optical fibre, which produces the effective gain and the same ASE output power as the distributed amplification. In the case

48、 of a composite amplifier, this includes the gain and ASE noise of the conventional OA. Also refer to IEC 61291-1, 3.1.41, equivalent total noise figure. 4.5.4 Channel effective noise figure For multiple channel operation, the effective noise figure measured at a channels centre frequency will be th

49、e channel effective noise figure. 4.5.5 Forward amplified spontaneous emission (ASE) power level see 4.14/G.661 4.5.6 Reverse ASE power level see 4.15/G.661 4.5.7 Effective noise factor (F) The effective noise figure expressed in linear form. 4.5.8 Signal-spontaneous noise figure see 4.34/G.661 4.5.9 Spontaneous-spontaneous optical bandwidth (Bsp-sp) see 4.35/G.661 4.5.10 ASE bandwidth see 4.36/G.661 4.6 Pump power parameters Parameters Definitions 4.6.1 Minimum pump power The lowest pump power(s) available at RPi(f