ИСТИНА

Using shadow photography we observed the evolution of shock waves and cavitation bubbles, excited by femtosecond laser-plasma filament in water, up to microsecond time scale under supercritical power regime. In tight focusing geometry single filament is formed. The filament becomes the source of numerous shock waves and cavitation bubbles formation. Overlapping shock waves create one contrast cylindrical shock wave. The laser-induced shock wave parameters, such as shape, amplitude and speed, can be effectively controlled by varying the energy and focusing geometry of femtosecond pulse.When aberrations were added to optical scheme “hot spots” in aberration maxima are formed. At high energies filaments in “hot spots” are fired. Therefore complex pattern of shock waves and cavitation bubbles is formed. The bubbles can be isolated from each other or form exotic “drop-shaped” cavitation region. The dynamics of the cavitation pattern was investigated from pulse energy and focusing. We have obtained significant change of the cavitation bubble evolution, which is not yet in accordance with Rayleigh model. Tight focusing of pump pulse with energy more than 80±6µJ leads to bubble formation, which evolution at the end of its “life”, before final collapse, contains the jet emission.