K.S. Grigoriev

Formation of the lines of circular polarization in a second harmonic beam generated from the surface of an isotropic medium with nonlocal nonlinear response in the case of normal incidence

For the first time we have obtained the analytical expressions describing the spatial distribution of the polarization of a second harmonic beams light field reflected from the surface of an isotropic gyrotropic medium in the case when a normally incident fundamental beam contains a polarization singularity of an arbitrary type. The contribution of bulk and surface responses of the nonlinear medium in the formation of the lines of circular polarization in the second harmonic beam were analyzed. The relation between topological characteristics and polarization states of the singularities in the incident and reflected beams was established.

Second harmonic generation in isotropic chiral medium with nonlocality of nonlinear optical response by heterogeneously polarized pulsed beams

The second harmonic generation in the bulk of an isotropic chiral liquid with spatial or temporal nonlocality of its quadratic response is studied analytically. The fundamental pulsed beam has Gaussian time envelope and carries a polarization singularity at its axis. The influence of the topological charge and the handedness of the polarization singularity on the polarization state of the signal beam is revealed.

Structure of polarization singularities of a light beam at triple frequency generated in isotropic medium by singularly polarized beam

The components of electric field of the third harmonic beam, generated in isotropic medium with cubic nonlinearity by a monochromatic light beam carrying polarization singularity of an arbitrary type, are found analytically. The relation between C-points characteristics in the fundamental and signal beams are determined, as well as the impact of the phase mismatch on the shape of the C-lines.

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.