Propagation of spatial surface waves along the interface of photorefractive crystals

The propagation of a square beam and a Gaussian beam along the interface of two photorefractive crystals is studied theoretically. Both of the crystal s have a diffusion nonlinearity of the gradient type (with a sign opposite that of the diffusion nonlinearity), which is able to balance the self-bend ing of the beams and hence to produce a photorefractive surface wave. A com parison of this wave with the symmetrical and antisymmetrical surface waves propagating along the photorefractive crystals' interface is also given. ( C) 2001 Optical Society of America.