Dynamic instability of interacting counterpropagating solitons in photorefractive crystals

This paper presents experimental results of two counterpropagating (2+1)D solitary beams propagating inside a photorefractive strontium-barium-niobate (SBN) crystal. Non-transient dynamical behaviour is observed and experimental evidence for a numerically predicted stability threshold is found. In addition, the dynamics with regard to their direction is investigated. Because the photorefractive effect in SBN is anisotropic, a preferred direction of the dynamics is expected and found. Experimental results are compared with numerical simulations and are found to be in very good agreement. Beneath single soliton interaction, high order solitons as dipole-soliton and dipole-dipole interaction are analyzed.