Long-lived coherent traveling acoustic pulses induced by femtosecond laser pulses

In this paper, we systematically study the generation and propagation of coherent acoustic pulses in a metal–dielectric system using a two-color femtosecond pump–probe technique at different probe angles. A long-lived acoustic oscillation is observed in a borosilicate glass coated with gold and shows different attenuations and amplitude at different probe wavelengths. Our study demonstrates that the two-color optical pump–probe technique can be used as a noninvasive tool to study acoustic properties of dielectric materials.