Mechanisms of spatio-temporal localization of high-intensive femtosecond pulses in Kerr media: Light bullet scenarios

Summary form only given. Mechanisms of spatiotemporal localization of femtosecond powerful pulses, the problems and conditions of light bullets (LB) stability, being key issues for many applications, nowadays remain challenging and largely unresolved tasks. Therefore these questions attract much attention of scientists. As is known, in Kerr media the filamentation makes possible the generation of spatially and temporally compressed pulses. The filament is a self-organized structure formed through the competition of underlying processes such as, for example, diffraction, Kerr nonlinearity, photoinduced plasma, etc. Under anomalous group velocity dispersion (GVD) one of filamentation regimes may be realized, i.e. LB generation. As shown in experiment [1], the stability of the LB is due to their polychromatic Bessel-like structure consisting of a sharply localized high-intensity core and a weak, delocalized low-intensity periphery, which balances energy losses in the central core.In this work we investigate in detail the origin of the high-intensive light bullet, including LB for pulsed beams bearing an orbital angular momentum, as well as possible scenarios of their propagation dynamics. The system of modified nonlinear Schrödinger equation for the complex envelope of the electric field and kinetic equation for the electron plasma density (electron density in the conduction band) is exploited. Our analyze is based on combining two informative methods: firstly, semi-analytical two-scale variational analysis; secondly, direct numerical simulations based on finite-difference methods.