Anisotropy of steady-state two-dimensional lenses in photorefractive crystals with drift nonlinearity

Abstract

Abstract As a result of the original theoretical analysis in different approximations we show that the steady-state photoinduced photorefractive lens formed under an external transverse d.c. electric field by the light beam with cylindrical symmetry is essentially astigmatic. This behaviour is demonstrated in self-focusing-defocusing experiments with cubic Bi12 TiO20 photorefractive crystals at λ=633 nm. The result implies in particular that the steady-state (2+1)-dimensional spatial solitons generated in photorefractive crystals under similar conditions are to be characterized by an elliptic cross-section.