Rubass A. Conversion of the optical vortices at the singular beams, transmitted under a angle to an optical axis in the anisotropic media

The conversion of the optical vortices in paraxial singular beams with the initial circular polarization transmitting through a birefringent uniaxial crystal is experimentally and theoretically revealed when tilting the beam axis relative to the crystal optical axis. The vortex conversion is of the transformation of the vortex topological charge by two units in the orthogonally circularly polarized beam component. We have also shown that the tilting of the initially linearly polarized Laguerre-Gaussian beam results in exchanging the optical vortices between two circularly polarized beam components inside the crystal. We have theoretically predicted and experimentally investigated the indistinguishability limit of two birefringent singular beams. This limit enables us to divide two groups of singular beams - the beams that cannot on principle be splintered into two individual beams and the beams that can be splintered. We have revealed that there are two independent branches of C-lines in each splintered beams that do not coincide with each other for any crystal length so that the field of the splintered beams remains a nonuniformly polarized in vicinity of the polarization singularities. The observable effects are interpreted in the frameworks of the conservation law of the projection of the total angular momentum flux onto the crystal optical axis.