TEMPORAL-MODULATION OF A POWERFUL ULTRASHORT LASER-PULSE IN A MEDIUM WITH A RELATIVISTIC AND CHARGE-DISPLACEMENT NONLINEARITY

We present the results of three-dimensional (T-2D) numerical simulatio ns within the framework of the model of a nonlinear wave equation that governs the self-channeling of a relativistically intense ultrashort pulse of an excimer laser in a medium under conditions of experiments [1]. It is demonstrated that a laser pulse compressed in the transvers e direction, first, displays pulsations as a whole and, second, decays into a train of shorter spikes. Temporal modulation of the pulse shou ld give rise to a fine structure of a filament. A critical analysis of the available experimental data is performed. Experimental conditions necessary for the detection of this effect are discussed.