Cavity-Induced Periodicity in Liquid-Phase Femtosecond Laser Ablation

The cavity-induced pits play a major role in fs-PLAL, and the cavity-induced periodicity is a unique phenomenon. Fine periodic features (
$\Lambda < \lambda $
/2) are visible both inside and outside the craters, according to experimental data obtained at various liquid highs. Pits are forced to self-organize due to the crowding and jostling of approximately 108 cavitation bubbles, which is the cause of the development of these patterns. Based on ablation at 100 KHz for 6 minutes and the assumption that each pulse has 5 cavities, an estimated 108 cavities can be found. The thermal effect as the mechanism of pit formation is strongly supported by the emergence of metallic droplets and heat-affected zones outside the crater. Within the crater, another periodic structure with a bigger periodicity is seen, which is explained by the laser’s incubation effect as a result of the confinement and cooling effects of water. It is surprising that basic, easily accessible technology can be used to identify the phenomenon.