Self-bending of the coupled spatial soliton pairs in a photorefractive medium with drift and diffusion nonlinearity.

The propagation of two incoherently coupled laser beams (coupled soliton pairs) in the photorefractive crystal with drift and diffusion components of nonlinear response is investigated. By the effective particles method we have shown that not only the well-known Manakov's soliton pairs but also asymmetric pairs can propagate undistorted in photorefractive crystal with diffusion nonlinearity along the parabolic trajectory for the definite relations of propagation constants. We numerically found the exact profiles of the specific multihump soliton solutions that are possible only in the photorefractive medium with nonlocal diffusion response. The stability properties and specific features of pair collisions are analyzed.