Kadan V. Localization of light pulses and charge carriers in materials with permanent and dynamic optical inhomogeneities.

The thesis deals with the study of localization of light pulses and nonequilibrium charge carriers in transparent dielectric media. An original complex of precision complementary experimental techniques by the general "pump-probe" scheme is created to perform the experiments. The complex includes a new basic methodology of time-resolved microscopy of spatio-temporal transformation of femtosecond laser pulses with a temporal resolution of ~ 70 fs and spatial - 1.5 µm. The conditions of formation, propagation and interaction of femtosecond laser filaments, i.e. physical bodies of plasma-field nature, are studied. A set of "pump-probe" experimental techniques is developed, among which a new methodology of time-resolving microscopy of spatial-temporal transformation of femtosecond laser pulses with a ~ 70 fs temporal- and ~ 2 ?m spatial resolution, occupies a central place. Using this methodology the following phenomena were for the first time directly observed in the femtosecond filaments in fused silica: deviation of the velocity of the axial intensity maximum from the speed of light, plasma-caused light defocusing in the pulse tail, self-compression and splitting in time of the femtosecond laser pulse. A method of control of the azimuthal position of the filaments by changing the phase difference between the coaxial mutually coherent optical vortex and vortex-free plane reference wave is proposed and implemented. It is shown that the conditions of Cherenkov synchronism for all the anti-Stokes conical emission, which is excited by Bessel beam, are satisfied if the axial phase velocities of the excitation beam and Stokes wave are equal. Filamented propagation mode of femtosecond laser pulses and self recording of the permanent filament-induced waveguides are observed in g-As4Ge30S66. A practical method for micromachining of transparent materials involving laser-induced plasma is proposed and tested. It is shown that an increase in the quantum yield of the photoluminescence of Si nanocrystals, incorporated in SiO2 matrix under the femtosecond laser excitation is due to the complete saturation of trap states. A model of "two-stroke charge piston" is proposed, according to which the activation capture of free carriers of the nanocrystal silicon core by the trap states in the oxide shell occurs by means of successive acts of Auger scattering.