11 - Soliton-Raman effects

Summary

Introduction

The earliest experimental schemes for generating optical solitons, see for example the chapter by Mollenauer in this book or the original paper by Mollenauer et al. (1980), relied on launching pulses with power and transform limited spectral characteristics which matched the soliton requirements for the particular optical fibre used. However, it was shown by Hasegawa and Kodama (1981), that a pulse with any reasonable shape could evolve into a soliton. In such a case, the energy not required to establish the soliton appears as a dispersive wave in the system.

An alternative mechanism for soliton generation was proposed by Vysloukh and Serkin (1983), based on stimulated Raman scattering in fibres, which was later verified by Dianov et al. (1985), through compression in multisoliton Raman generation from a pulsed laser source. Since then, there has been a considerable number of experimental reports of soliton generation through stimulated Raman scattering in various configurations and using several different pump sources, Islam et al. (1986), Zysset et al. (1986), Kafka and Baer, (1987), Gouveia-Neto et al. (1987), Vodopyanov et al. (1987), Nakazawa et al. (1988) and Islam et al. (1989). More generally, it has been shown theoretically by Blow et al. (1988a), that soliton formation is possible in the case where there is coupling between waves leading to energy transfer, specifically via a gain term in the non-linear Schrödinger (NLS) equation description of the system.