Šviesos sūkurių formavimas ir jų tiesinės bei netiesinės transformacijos

The topic of this dissertation is one of the more popular themes in optics – the optical vortices, which have several practical applications such as the STED microscopy, optical tweezers and optical vortex coronagraphs in astronomy. In this work various ways to generate the optical vortices are investigated as well as their transformations during the propagation in linear and nonlinear optical media. The performed research is presented in five chapters of the dissertation: 1) A possibility to generate half-charged vortices using a radial polarization converter is investigated theoretically and demonstrated experimentally. 2) A new method is proposed and investigated, which allows generation of a doubly-charged vortex with a single radial polarization converter. 3) A computerized way to control optical vortex positions by means of a collinear interference with a Gaussian beam is presented and demonstrated experimentally. 4) The topological charge conservation in second harmonic generation pumped by a half-charged optical vortex is confirmed poth theoretically and experimentally. The second harmonic beam carries a unit-charged vortex. 5) A new method to generate radially and azimuthally polarized beams is proposed and investigated theoretically as well es demonstrated experimentally. The method uses the optical parametric amplification of an optical vortex