Eur. Phys. J. D 55, 745-754 (2009)
https://doi.org/10.1140/epjd/e2009-00260-0

On the focusing limit of high-power femtosecond laser pulse propagation in air

V.E. Zuev Institute of Atmospheric Optics, Siberian Branch of Russian Academy of Sciences, Zuev Square 1, 634021 Tomsk, Russia

Corresponding author: ^a ygeints@iao.ru

Received: January 1900
Revised: 11 June 2009
Published online: 9 October 2009

Abstract

Focused propagation of high-power femtosecond laser radiation in air is considered. Based on numerical solution of the nonlinear Schrödinger equation for complex envelope of light wave electric field, evolution of the beam effective radius is studied. The dependence of the effective (rms) size of a focal spot and the maximally achievable intensity of laser radiation at focal waist on the initial pulse power is established. It is shown that focal spot of tightly focused intensive ultrashort laser radiation can change its size during the pulse passage through the beam waist. This is the consequence of pulse intensity clamping in region of beam focusing caused by gas photoionization and plasma producing. This may prevent laser intensity from its further growth in the focal region and arrest the transversal compression of the beam in the linear focus as a whole.