Excitation of higher harmonics in transient laser gratings by an ablative mechanism

Abstract

Laser-induced transient gratings were excited at the surface of an aluminum film by picosecond laser pulses. The counterpropagating surface acoustic waves with a fundamental frequency of 70 MHz that were launched were monitored outside the source region by laser probe beam deflection. The second and third harmonics were observed for ablative interaction of the laser radiation with the aluminum surface. A simple model is presented that describes the effects on the basis of nonlinear photoacoustic signal generation at the source due to a nonsinusoidal driving force.

Investigation of phase transition thresholds by nonlinear transient laser gratings on silicon surfaces

“…10 In the present experiments, we used the characteristic features of nonlinear LITG signals, generated by two picosecond laser pulses on a silicon sample, to study the threshold fluences for the onset of melting and ablation. a͒ Electronic mail: peter.hess@urz.uni-heidelberg.de…”