N. Korneev et al., ANISOTROPY OF STEADY-STATE 2-DIMENSIONAL LENSES IN PHOTOREFRACTIVE CRYSTALS WITH DRIFT NONLINEARITY, J. mod. opt., 43(2), 1996, pp. 311-321
As a result of the original theoretical analysis in different approxim
ations 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 behavio
ur is demonstrated in self-focusing-defocusing experiments with cubic
Bi12TiO20 photorefractive crystals at lambda = 633 nm. The result impl
ies in particular that the steady-state (2+1)-dimensional spatial soli
tons generated in photorefractive crystals under similar conditions ar
e to be characterized by an elliptic cross-section.