Rapid Growth of Microbubbles in a Focused Laser Beam

Rapid bubble growth occurs in both nature and industry, such as the snapping of a shrimp's claw or high‐density laser exposure. Here, it is reported that microbubbles can also grow rapidly via laser‐induced photothermal interfacial evaporation. In a focused laser beam, bubbles smaller than a critical diameter ( D ≤ D cri ) have violent laser interaction at their interface, resulting in rapid growth. For larger bubbles ( D > D cri ), they have weak interfacial interaction, and laser energy is absorbed far from the interface, leading to slight growth. Modeling reveals that bubble size determines the location of maximum laser absorption, which shifts from near the interface to deeper inside the liquid as diameter increases. This position controls the efficiency of photothermal conversion and interfacial evaporation, determining the bubble's growth rate. The findings uncover a diameter‐dependent mechanism of bubble growth at the microscale and offer insights into microscale laser‐interface dynamics. These results would help further light‐bubble applications, such as laser‐assisted surgery and bubble‐based microfluidics.