Filamentation Phenomena and Generation of Supercontinuum in Propagation of Laser Pulses in a Nonlinear Medium
The phenomenon of filamentation of high-power pulsed laser radiation consists in localizing the energy of the light field in a thin extended filament under the action of self-focusing in a medium and nonlinearity in a self-induced laser plasma that limits the collapse of the beam. The phenomenon of self-focusing of electromagnetic waves in general form was predicted in 1962 by G. A. Askar'yan. The filament of a laser pulse is a self-forming guiding system in which an increase in the intensity of the light field occurs, together with filtration and emission at the fundamental mode axis, just as in optical fibres. The radiation diverging from the filament axis due to defocusing in the plasma interferes with the light field near the filament, forming around it ring structures. The effect of refocusing radiation in filaments has a strong influence on the spatiotemporal evolution of radiation during its propagation.