Controlling bubble generation by femtosecond laser-induced filamentation

• Published in: Scientific reports Vol. 12; no. 1; pp. 15742 - 16
• Main Authors: Rao, D. Chaitanya Kumar, Mooss, Veena S., Mishra, Yogeshwar Nath, Hanstorp, Dag
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-09-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/985; 639/166/988; 639/624/1075; 639/766/189; ablation; Bubbles; Coalescence; contrast agents; dependence; Emulsification; Energy; Ethanol; Filamentation; Fysik; Glycerol; Humanities and Social Sciences; induced breakdown; Lasers; microbubbles; multidisciplinary; nanosecond; Physical Sciences; Population density; Science; Science & Technology - Other Topics; Science (multidisciplinary); Size distribution; technology; thresholds; water
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-022-20066-1

Femtosecond laser-induced optical breakdown in liquids results in filamentation, which involves the formation and collapse of bubbles. In the present work, we elucidate spatio-temporal evolution, interaction, and dynamics of the filamentation-induced bubbles in a liquid pool as a function of a broad spectrum of laser pulse energies (∼1 to 800 µJ), liquid media (water, ethanol, and glycerol), and the number of laser pulses. Filament attributes such as length and diameter have been demarcated and accurately measured by employing multiple laser pulses and were observed to have a logarithmic dependence on laser energy, irrespective of the medium. The size distribution of persisting microbubbles is controlled by varying the pulse energy and the number of pulses. Our experimental results reveal that introducing consecutive pulses leads to strong interaction and coalescence of the pulsating bubbles via Bjerknes force due to laser-induced acoustic field generation. The successive pulses also influence the population density and size distribution of the micro-bubbles. We also explore the size, shape, and agglomeration of bubbles near the focal region by controlling the laser energy for different liquids. The insights from this work on filamentation-induced bubble dynamics can be of importance in diverse applications such as surface cleaning, fluid mixing and emulsification, and biomedical engineering.