Zonal model of nonstationary self-focusing of femtosecond laser radiation in air: effective beam characteristics evolution
Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Academicheskii ave. 1, 634055 Tomsk, Russia
Corresponding author: a email@example.com
Revised: 9 October 2006
Published online: 17 January 2007
The generic scenario of intense femtosecond laser pulse propagation in the air from the viewpoint of evolution of its integral effective parameters (energy transfer coefficient, effective radius, effective duration, limiting angular divergence) is considered. The analysis of variation of the effective parameters along the propagation path in the single and multiply filamentation scenarios based on numerical calculations is presented. It is shown that the process of self-action of the ultrashort radiation is characterized by the formation in a medium of the nonlinearity layer, after which optical pulse propagates quasi-linearly with the limiting angular divergence that depends mainly on initial pulse power. The effective pulse temporal duration and the effective beam radius increase after the passage through the nonlinearity layer, and their values are mostly determined by the initial beam power also. The coefficient of energy transmission of femtosecond laser radiation is lower than in the linear medium and has a tendency to decrease with the increase of the pulse power.
PACS: 42.25.Bs – Wave propagation, transmission and absorption / 42.68.Ay – Propagation, transmission, attenuation, and radiative transfer / 42.65.Jx – Beam trapping, self-focusing and defocusing; self-phase modulation
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007