Cavity-Induced Periodicity in Liquid-Phase Femtosecond Laser Ablation

• Published in: IEEE photonics technology letters 2024-01, Vol.36 (2), p.127-130
• Main Authors: Atwa, D., Ali, N., Grenni, P., Badr, Y., Soliman, W.
• Format: Article
• Language: English
• Subjects: Ablation; Cavitation; Cavity-induced periodicity; Cooling effects; Craters; femtosecond laser ablation in liquids; Heat affected zone; Heating systems; Holes; Laser ablation; Laser theory; limited high of water column; Liquid phases; Liquids; Periodic structures; Pits; Power lasers; Temperature effects; thermal effect; Vertical cavity surface emitting lasers
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2023.3340637

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.