On Possible Mechanism of Enhancement of Absorption of Powerful Laser Radiation by Metals

Abstract
In this work, it is shown that the dependence of the mass of conductive band electrons in a metal on their energy can be a reason of enhancement of the absorption of powerful laser radiation by the metal. To do this, a problem of response (current) of the electron placed in one-dimension periodic potential (lattice) to an electric field periodic in time (electromagnetic wave) is solved. The solution shows that for sufficiently large amplitude of the wave the dependence of the electron current on the wave amplitude becomes non-linear. Within a certain rangе of parameters, this dependence can be described by a simple formula that corresponds to the dependence of the electron mass on its energy. The formula was used for solving the problem of penetration of electromagnetic wave into a metal with the approach of modified Drude model. The non-linearity results in the enhancement of the wave absorption and generation of wave with frequencies close to those of plasma penetrating deep into the metal. The discussed effects manifest themselves in electric fields about. 1 V/Angstrom. The obtained results can be used in the interpretation of experiments data and in the creation of mathematical modeling of the interaction of powerful laser radiation with metal.

Keywords
laser-metal interaction, high-power laser pulse, nonlinear optic effects, Drude model
УДК 544.032.65

On Possible Mechanism of Enhancement of Absorption of Powerful Laser Radiation by Metals