Chapter 9 - Stimulated Brillouin Scattering

Abstract

Stimulated Brillouin scattering (SBS) is a non-linear process that can occur in optical fibers at input power levels much lower than those needed for stimulated Raman scat- tering (SRS). Once the Brillouin threshold is reached, it manifests through the generation of a backward-propagating Stokes wave that carries most of the input power. For this reason, SBS limits the channel power in optical communication systems. At the same time, it can be useful for making fiber-based Brillouin lasers and amplifiers. This chapter is devoted to the SBS phenomenon in optical fibers and presents the basic concepts behind SBS with emphasis on the spectrum of Brillouin gain. It focuses on the Brillouin threshold in continuous-wave (CW) pump and the techniques used to control it. Fiber-Brillouin amplifiers and their properties are also discussed in the chapter. The dynamic aspects of SBS are the focus of this chapter where SBS for a pulsed pump together with phenomena such as SBS-induced modulation instability and optical chaos has been discussed.. The process of SBS is described as a non-linear interaction between the pump and the Stokes fields through an acoustic wave. The pump field generates an acoustic wave through the process of electrostriction. The acoustic wave in turn modulates the refractive index of the medium. This pump-induced index grating scatters the pump light through the Bragg diffraction.. The chapter concludes by discussing the Brillouin lasers operating continuously or pulsed.