Theoretical models of laser-induced ionization of transparent materials: current issues and recent improvements

摘要

The aim of this paper is to give a critical review of the influence of constant effective-mass approximation on the results provided by current theoretical models of laser-induced ionization of the solids transparent at input laser wavelength. Making transparent qualitative analysis of the models, we come to conclusion that assuming electrons and holes to have constant effective mass, one eliminates specific photo-ionization effects taking place at high intensity. The assumption of constant effective mass of conduction-band electrons is also shown to provide wrong description of the avalanche ionization almost at any laser wavelength and intensity. The presented analysis allows to give simple quantitative criteria determining the range of laser and material parameters for which the effective mass can be assumed constant.