Chapter 5 - Nonlinear Optical Effects in Optical Fibers

Abstract

This chapter discusses the nonlinearity of silica-based fiber which is quite small. Several nonlinear optical effects manifest themselves conspicuously owing to the fact that the density is very high because light is confined in a small cross-sectional area. The interaction length between the light wave and fiber material is quite long due to the low-loss property of fibers, and coherent interaction is possible since the modal field distribution and polarization are well prescribed and maintained over the long length. The chapter explains various nonlinear optical effects in fibers, such as optical solitons, stimulated Raman scattering, Brillouin scattering, and second-harmonic generation. The interesting and important nonlinear effects in optical fibers utilizing optical Kerr effect are optical solitons, optical pulse compression, and modulational instabilities. Modulational instability is a factor observed in a nonlinear dispersive medium in which the side-band component of the amplitude-modulated light grows exponentially when a certain condition is satisfied. When the perturbation is the amplitude modulation, then the phenomenon implies that the modulation depth grows exponentially. Therefore such a phenomenon is called the modulational instability.