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Fibre optic communication systems P9

Soliton Systems The word soliton was coined in 1965 to describe the particle-like properties of pulses propagating in a nonlinear medium [1]. The pulse envelope for solitons not only propagates undistorted but also survives collisions just as particles do. The existence of solitons in optical fibers and their use for optical communications were suggested in 1973 [2], and by 1980 solitons had been observed experimentally [3]. The potential of solitons for long-haul communication was first demonstrated in 1988 in an experiment in which fiber losses were compensated using the technique of Raman amplification [4]. Since then, a rapid progress during the. | Fiber-Optic Communications Systems Third Edition. Govind P. Agrawal Copyright 2002 John Wiley Sons Inc. ISBNs 0-471-21571-6 Hardback 0-471-22114-7 Electronic Chapter 9 Soliton Systems The word soliton was coined in 1965 to describe the particle-like properties of pulses propagating in a nonlinear medium 1 . The pulse envelope for solitons not only propagates undistorted but also survives collisions just as particles do. The existence of solitons in optical fibers and their use for optical communications were suggested in 1973 2 and by 1980 solitons had been observed experimentally 3 . The potential of solitons for long-haul communication was first demonstrated in 1988 in an experiment in which fiber losses were compensated using the technique of Raman amplification 4 . Since then a rapid progress during the 1990s has converted optical solitons into a practical candidate for modern lightwave systems 5 - 9 . In this chapter we focus on soliton communication systems with emphasis on the physics and design of such systems. The basic concepts behind fiber solitons are introduced in Section 9.1 where we also discuss the properties of such solitons. Section 9.2 shows how fiber solitons can be used for optical communications and how the design of such lightwave systems differs from that of conventional systems. The loss-managed and dispersion-managed solitons are considered in Sections 9.3 and 9.4 respectively. The effects of amplifier noise on such solitons are discussed in Section 9.5 with emphasis on the timing-jitter issue. Section 9.6 focuses on the design of high-capacity single-channel systems. The use of solitons for WDM lightwave systems is discussed in Section 9.7. 9.1 Fiber Solitons The existence of solitons in optical fibers is the result of a balance between the group-velocity dispersion GVD and self-phase modulation SPM both of which as discussed in Sections 2.4 and 5.3 limit the performance of fiber-optic communication systems when acting independently on .