OPTICAL VORTICES IN BEAM PROPAGATION THROUGH A SELF-DEFOCUSSING MEDIUM

We Present numerical simulations and analysis of optical vortex propagation in a 3D self-defocussing medium. On plane wave background initial conditions composed of points and lines of phase discontinuity are shown, in some cases, to evolve towards a regular crystal of fully nonlinear vortices. In other cases the solution more resembles a vortex ps. For gaussian beams, we have derived a simple set of ordinary differential equations which are shown to accurately describe the motion of a single vortex while the background beam undergoes significant spreading.