Kedyk I. Photoinduced space charge gratings in ferroelectric - semiconductor Sn2P2S6 crystals

The thesis is dedicated to investigation of the space-charge gratings of the Sn2P2S6 crystals obtained by the different methods, and possibilities of use these crystals in image optical processing systems. A number of photorefractive (PR) and electro-physical parameters of Sn2P2S6 crystals were defined using a holographic method. A dynamics of formation, spatial distribution, orientation and polarization properties of photoinduced light scattering (PLS) were studied in the samples of modified by the terms of growth Sn2P2S6 crystals. Using dynamic features of the PLS formation in modified Sn2P2S6 crystal, optical one-beam novelty filter was testified. It was shown that such a filter is characterized by high contrast and fast response. On the base of nominally pure Sn2P2S6 crystal the scheme of self-pumped phase conjugate mirror (PC) was investigated. In the case of optimal geometry, the value of conjugation efficiency RPC ~ 0.2 at the value of conjugated beam formation time t ~ 0.02 s has been obtainedexperimentally. It was shown the possibility of substantial improvement of these parameters by reduction of the reflection losses (up to RPC ~ 0.35).