Intensity delivery to the focal area with tight focusing of a femtosecond laser beam in a gas environment

Abstract

We propose a comprehensive approach to describe the propagation regime of a tightly focused intense ultrashort laser pulse in a gaseous medium under conditions of its ionization, based on the use of a discrete aberration-free quasi-optical approximation. The proposed approach provides a good match of calculation results with available experimental data for air and helium. We have demonstrated that the use of the second harmonic ensures a noticeable advantage for all the discussed radiation parameters in the focal zone compared to the fundamental radiation. The developed integrated approach can be used to predict the intensity of an ultrashort laser pulse in the focal volume of a gas medium.