Abstract

The physical and optical properties of inorganic and organic materials with large photorefractive effect are often strongly anisotropic. Three important kind of anisotropies can be identified. First, the magnitude of the electro-optic effect and of the low frequency dielectric constant depend on the direction of the internal space-charge field and, specially in inorganic crystals, is strongly affected by mechanical coupling within the material. Second, charge transport, i.e. carrier mobilities, can differ significantly for different drift directions [1]. Finally, photoexcitation cross-sections can be anisotropic with respect to wave polarization. This affects the magnitude of the photorefractive space-charge fields and can give rise to a significant enhancement of two-wave mixing gain coefficients [2].

© 1998 IEEE