Interaction of spatial photorefractive solitons

We present a review of our recent theoretical and experimental results on t he interaction of two-dimensional solitary beams in photorefractive SBN cry stals. We show that the collision of coherent solitons may result in energy exchange, fusion of the interacting solitons, the birth of a new solitary beam or the complete annihilation of some of them, depending on the relativ e phase of the interacting beams. In the case of mutually incoherent solito ns, we show that the photorefractive nonlinearity leads to an anomalous int eraction between solitons. Theoretical and experimental results reveal that a soliton pair may experience both attractive and repulsive forces; depend ing on their mutual separation. We also show that strong attraction leads t o periodic collision or helical motion of solitons depending on initial con ditions.