Numerical simulations of dark hollow laser beams self-focusing and filamentation in air
Yu.E. Geints, A.A. Zemlyanov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: self-focusing, filamentation, ultra-short laser radiation, profiled beams
Abstract
The problem of nonlinear propagation of intense femtosecond laser pulses in the near-infrared spectral range in air is theoretically considered. By numerically solving of the paraxial propagation equation for optical wave envelope the dynamics of self-focusing and filamentation of dark hollow light beams having a ring-shaped transverse intensity profile are investigated in the conditions of a wide variation of beam initial angular divergence. We found that the filamentation region of such beams in comparison with the Gaussian beam filamentation of equal power is located much father on the optical path, and posseses a significantly greater longitudinal extent, as well as the density of the free-electron laser plasma. By changing the initial angular divergence or the width of the annular region of initial intensity profile it is possible to effectively control the position and length of the filaments on the propagation path.
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