Stability and Dynamical Evolution

Abstract

The stability of optical spatial solitons is a crucial aspect to be studied since only the stable optical spatial solitons have potential practical applications. In this chapter, we shall study the stability of photorefractive solitons by using the modulation instability theory. Modulation instability, also known as sideband instability can be said to be a phenomenon where certain perturbations of a periodic waveform get strengthened consequently leading to the generation of spectral-sidebands and the ensuing breakup of the waveform into small filaments. A generalized theory for the modulation instability gain for broad optical beams in photorefractive photovoltaic crystals is elucidated which can, in turn be reduced to the cases of broad optical beams in biased and unbiased photovoltaic crystals, non photovoltaic photorefractive crystals and centrosymmetric photorefractive crystals. Lastly, the theoretical formulation for the modulation instability gain for light beams in pyroelectric photorefractive crystals is expounded.