This article is cited in 19 papers

Interaction of laser radiation with matter. Laser plasma

Influence of transient self-defocusing on the propagation of high-power femtosecond laser pulses in gases under ionisation conditions

V. P. Kandidov, O. G. Kosareva, S. A. Shlenov

M. V. Lomonosov Moscow State University

Abstract: A transient three-dimensional model is used in a numerical investigation of the spatiotemporal and spectral characteristics of a femtosecond pulse of 10¹⁴–10¹⁶ W cm^-2 intensity propagating in rare gases. It is shown that nonlinear defocusing caused by the ionisation of a gas may result in a 20-fold reduction of the peak intensity in the beam waist. The transverse distribution of the intensity beyond the waist is a ring with a minimum on the beam axis at a pressure of 1 bar and with a local maximum on the axis at 5 bar. The frequency spectra of such a pulse are in quantitative agreement with experimental data.

PACS: 42.65.Re, 42.50.Md, 51.50.+v

Received: 21.07.1994

 English version: Quantum Electronics, 1994, 24:10, 905–911

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