Interaction of two-dimensional spatial incoherent solitons in photorefractive medium

We present a review of our recent theoretical and experimental results on t he interaction of incoherent two-dimensional solitary beams in PR SBN cryst als. We show that the inherent anisotropy of PR nonlinearity strongly affec ts the interaction between solitons. Theoretical and experimental results r eveal that solitons interacting in a plane perpendicular to the direction o f external biasing field always attract, whereas those colliding in a plane of the field exhibit anomalous behaviour. They may experience both attract ive and repulsive forces, depending on their mutual separation. We also sho w that this anisotropy results in the complicated topology of soliton traje ctories, featuring periodic collisions, prolonged mutual spiraling and coll apse, depending on the initial conditions.