Detection of Laser-Induced Underwater Optoacoustic Signals Using Commercial Piezoelectric Sensors

This work focuses on experimental characterization of underwater ultrasonic waves generated by high-intensity nanosecond laser pulses using two piezoelectric sensors. A pulsed laser delivering 100\,mJ per pulse with a duration of 10 ns was focused into a water tank to drive a laser-induced shock wave. The resulting laser–water interaction produced acoustic transients, which were captured using a polyvinylidene fluoride (PVDF) polymer film sensor as well as a piezo sounder disc for comparison. The time-domain response of PVDF-film's observations revealed a sharp bipolar waveform lasting approximately 5 microseconds peak-to-peak, followed by multiple reflections consistent with the tank boundaries. This study delivers a qualitative comparative analysis that lays the groundwork for subsequent calibrated pressure characterization.