The effect of internal conical refraction in biaxial crystals is applied for transforming the lowest-order Gaussian
laser beams into optical vortex beams and annular beams with radial and azimuthal polarization. The evolution
of the emerging vortex beams upon propagation is analyzed and compared with the reference Laguerre-Gauss
beam. The formation of beams with radial and azimuthal polarization with the aid of two biaxial crystals placed
into the arms of a Mach-Zehnder interferometer is demonstrated.
Generation of tunable resonance-enhanced third and fifth harmonics of the fundamental laser light in xenon and krypton have been studied under excitation by different non-Guassian (Bessel, Mathieu, annular) laser beams. Conversion efficiency, tuning curves, and spatial profiles of harmonic output have been analyzed and compared with the case of ordinary Gaussian beams in different excitation geometries. Some interesting and useful properties of novel laser beams in nonlinear optics are discussed.
Presented are the results of a study of resonance-enhanced third-harmonic generation and multiphoton ionization in dense zenon under excitation by the Bessel beams. Bessel beams with inclination angles from 10 degree(s) to 90 degree(s) are shown to produce ionization spectra with significant differences, as compared with the case of the ordinary Gaussian. Several features of ionization spectra are considered and discussed. Results of numerical simulation of third-harmonic generation in Bessel beams are presented and compared with experimental observations.
The results of comprehensive investigations of a compact UV-preionized XeCl laser are presented. It has been shown that the gas lifetime increased to more than three times if BCl<sub>3</sub> was used as a halogen donor instead of HCl. The analysis of chemical degradation products suggests the possibility of a 'self-regeneration' of BCl<sub>3</sub>-containing gas mixtures, where volatile contaminants can be converted into solid products. The temporal and spatial dependences of the densities for several plasma components: Ne<sup>*</sup>, Xe<sup>*</sup>, Xe<sup>+*</sup>, Cl<sup>-</sup>, XeCl<sup>*</sup> and boron atoms were measured by the dye laser absorption (gain) probing. The halogen donor depletion in volume and constricted phases of the discharge was traced by the temporal dependence of the ground-state boron atoms density. The evolution of filamentary instabilities in the discharge was monitored from the Stark broadening of Xe<sup>*</sup> absorption lines.