We report our theoretical studies on optical bistability in a periodically poled LiNbO3 crystal. The optical resonance and the nonlinearity essential for bistability are induced by the electro-optic effect and the cascaded χ(2):χ(2) effect, respectively.
An analysis is made of nonlinear optical phenomena associated with a change in the orientation of the director of a liquid crystal induced by an optical field and resulting in optical bistability. The usual configurations with a nonlinear Fabry-Perot resonator and several other configurations are considered. Bistable cells with cholesterics are proposed: in these cells the nonlinearity is associated with the absorption of the incident and reflected light and is related—via the temperature of the cell—to the cholesteric helix period. Devices are considered in which switching from one state to another takes place as a result of a change in radiation parameters (such as the frequency or polarization) other than the power.
Analitical and numerical investigation of the wave-front conjugation in electrooptic crystals (LiNbO3, BaTiO3, SBN) show that noncavity optical bistability and hysteresis /1,2/ depends on the dominant mechanism of nonlinear responce (diffusion or drift) as on the orientation of the crystal C axis, and is strongly influensed by absorption or gain. Calculation show that critical effects may be observed for crystal length 0.1 cm (SBN, BaTiO3) and 1.5 cm (LiNbO3) for the optimal experimental geometry.
The results of classical and quantum studies of the laser-radiation self-frequency conversion processes in periodically poled active nonlinear crystals are overviewed. The theoretical and experimental results of studying quasi-phase-matched self-frequency doubling and summation of the laser and pump frequencies in an active nonlinear periodically poled Nd:Mg:LiNbO 3 crystal are presented. The possibility of producing frequency-and polarization-entangled states and the sub-Poisson field statistics through a consecutive nonlinear optical frequency conversion in periodically poled nonlinear crystals is considered.