Interactions between two-dimensional composite vector solitons carrying topological charges - art. no. 066608

We present a comprehensive study of interactions (collisions) between two-d imensional composite vector solitons carrying topological charges in isotro pic saturable nonlinear media. We numerically study interactions between su ch composite solitons for different regimes of collision angle and report n umerous effects which are caused solely by the "spin" (topological charge) carried by the second excited mode. The most intriguing phenomenon we find is the delayed-action interaction between interacting composite solitons ca rrying opposite spins. In this case, two colliding solitons undergo a fusio n process and form a metastable bound state that decays after long propagat ion distances into two or three new solitons. Another noticeable effect is spin-orbit coupling in which angular momentum is being transferred from "sp in" to orbital angular momentum. This phenomenon occurs at angles below the critical angle, including the case when the initial soliton trajectories a re in parallel to one another and lie in the same plane. Finally, we report on shape transformation of vortex component into a rotating dipole-mode so litons that occurs at large collision angles, i.e., at angles for which sca lar solitons of all types simply go through one another unaffected.