Interaction of laser-generated polarization singularities in a nonlinear isotropic gyrotropic medium

The interaction of polarization singularities (C-points) of a light field in collinearly propagating beams in an isotropic gyrotropic medium with nonlocal nonlinear cubic optical response was studied numerically. The nonlinear self-action significantly affects the transversal polarization and intensity distribution in the propagating beams, while the nonlocality can change the relative weights or the polarization states of the intense peaks in the transversal section. The sum of the topological charges of all of the singularities in the propagating field remains unchanged. The scenario of their interaction is, in general, the same, as in the linear medium, but depending on the nonlinearity character it can either be quickened or slowed down by the increase of the intensity of the incident waves. In the case of very large values of the initial intensity the interaction between the C-points (pairwise creation and annihilation) ceases due to the strong separate self-focusing of circularly polarized components of the field. (paper)