Shock waves and acoustic signals from the optical breakdown and interaction with targets of ultrashort laser pulses

Abstract
The study and comparison of sound waves produced by nanosecond and femtosecond laser pulses in the focal region as a result of the optical breakdown in air, water and near surfaces of targets were performed. Ultrashort laser pulses focused in the medium produced highly ionized plasma with light and sound emission. For time-resolved detection of sound waves a probe-beam-deflection setup was used. The amplitude of the shock wave was evaluated by measuring the propagation velocity. The sound wave produced by a femtosecond laser pulse in the air had a delayed compressional contribution in the profile that was attributed to the recombination of charges in the plasma region.