Morozovska A. Photoinduced processes of light scattering and microdomain formation in ferroelectrics

The theoretical investigation of the dynamical nonlinear optical phenomena in the photorefractive materials without inversion centre under their stationary irradiation by laser beam has been performed. The theoretical description of the periodic and non-stationary isotropic photoinduced light scattering in photorefractive crystals has been proposed. Such distinctive features of these effects as conic spatial structure and impulse-like temporal behaviour have been explained within the framework of coupled wave theory after the modification of material equations. Not only the longitudinal but the transverse photovoltaic current as well as transverse instability of the interacting beams and the isotropic distribution of dielectric permittivity volume fluctuations have been taken into account. The process of microdomain formation in ferroelectrics under laser irradiation has been examined. Photoinduced microdomain formation takes place at the boundary of the illuminated region polarized due to the photovoltaic effect. If the cluster surface charge density achieves its critical value, the longitudinal size of the microdomain becomes much larger than the transversal one determined by the cluster size. So microdomain acquires the needle-like form. The thesis results could be used in dynamic holography, nonlinear optics and for optical memory systems elaboration.