Chapter 8 - STIMULATED RAMAN SCATTERING

Abstract

Stimulated Raman scattering (SRS) is an important non-linear process that can turn optical fibers into broadband Raman amplifiers and tunable Raman lasers. It can also limit the performance of multichannel lightwave systems by transferring energy from one channel to the neighboring channels. This chapter is devoted to a thorough study of SRS phenomenon in optical fibers and presents the basic theory behind stimulated raman scattering (SRS) with an emphasis on the pump power required to reach the Raman threshold. It discusses the SRS under continuous-wave (CW) and quasi-CW conditions, and the performance of the fiber-based Raman lasers and amplifiers.. The chapter discusses Raman threshold, coupled amplitude equations, and the effect of FVM through specific graphs and elaboration on each topic. Quasi-continuous SRS discusses all three aspects of SRS in optical fibers while SRS with short pump pulses mentioned in the chapter discusses the experimental and theoretical aspects of SRS in the normal-GVD regime of optical fibers. The chapter further elaborates that when the Raman pulse propagates as a soliton, it is common to refer to it as a “Raman soliton.” These solitons must be distinguished from the pair of bright and dark solitons formed during transient SRS in molecular gases. The chapter concludes that the residual birefringence of fibers, responsible for PMD, affects the performance of Raman amplifiers considerably because of its statistical nature.