Terahertz sound generation at the effect of a femtosecond pulse of laser radiation on a metal.

Abstract

Sound generation by a femtosecond laser pulse in a metal layer on a dielectric substrate is studied. The excitation of sound caused by the effect of the ponderomotive force, temperature gradients of electrons, and lattice is considered. A comparison is made of these generation mechanisms for various excitation conditions and frequencies of generated sound. It is shown that in the case when effective collision frequencies in the metal are low, sound generation dominates in the terahertz frequency range due to the ponderomotive effect of the laser pulse.