Belarusian State University, Belarus

This paper presents the results of a study of interference and diffraction methods for producing and diagnosing singular light beams (optical vortices) using photopolymer materials, photorefractive materials, and liquid crystals. New methods of phase-polarization transformation of light beams by thin-film liquid crystal elements with a periodic twist-planar structure, as well as based on axisymmetric anisotropic structures (Q-plates) are proposed. The interaction patterns of gaussian and singular beams in nonlinear media are analyzed, and implementation options for algebraic operations with topological charges (addition, subtraction, and integer multiplication) are proposed. New schemes for determining the sign and magnitude of topological charge are proposed using a liquid crystal Fresnel lens and a holographic lens based on a photorefractive crystal. The capabilities of controlling microparticles with singular beams of different topological charges in an optical tweezers scheme are demonstrated. The combination of Gaussian and singular beams has increased the sensitivity of double-pulse laser-induced breakdown spectroscopy. New possibilities are opening up with the use of singular beams to generate harmonics in 2D nonlinear structures and implement functional optical devices on a chip. Using the magnitude and sign of the light beam's topological charge as information parameters has enabled information encoding, transitioning from a binary system to systems with a larger number of digital digits. This has also made it possible to introduce an additional information component into holographic security elements and improve the security of documents against counterfeiting.