Gap Solitons in Photorefractive Optical Lattices

Abstract

Optical spatial solitons in photorefractive media have been very attractive for research because of their relative ease of formation at low laser powers. Photonic lattices embedded in photorefractive crystals can mimic structures and properties of photonic crystals.In this chapter, we have discussed the stability and existence of gap solitons in different types of photorefractive optical lattices, i.e. optical lattices in non-centrosymmetricphotorefractives, centrosymmetricphotorefractives and pyroelectricphotorefractives. A theoretical foundation using the Helmholtz equation has been laid which serves as a general framework for photorefractive crystals having different nonlinearities and configurations. The gap soliton profiles in the first and second finite band gap for each of the three configurations of the photorefractive crystal have been studied. The first finite band gap supports entirely positive single-humped solitons and the second finite band gap supports asymmetric and double-humped or multi-humped solitons. The stability of gap solitons is analysed in all three configurations by linear stability analysis.