Sarabia-Alonso, J.A.Ortega-Mendoza, J. GabrielRamírez-San Juan, J.Zaca-Móran, P.Ramírez-Ramírez, J.Padilla-Vivanco, A.Muñoz-Pérez, Francisco MisaelRamos-García, R.2026-02-172026-02-172020-061094-4087https://riunet.upv.es/handle/10251/232606[EN] The most common approach to optically generate and manipulate bubbles in liquids involves temperature gradients induced by CW lasers. In this work, we present a method to accomplish both the generation of microbubbles and their 3D manipulation in ethanol through optothermal forces. These forces are triggered by light absorption from a nanosecond pulsed laser (¿ = 532 nm) at silver nanoparticles photodeposited at the distal end of a multimode opticalfiber. Light absorbed from each laser pulse quickly heats up the silver-ethanol interface beyond the ethanol critical-point (~ 243 °C) before the heat diffuses through the liquid. Therefore, the liquid achieves a metastable state and owing to spontaneous nucleation converted to a vapor bubble attached to the optical fiber. The bubble grows with semi-spherical shape producing a counterjet in the final stage of the collapse. This jet reaches the hot nanoparticles vaporizing almost immediately and ejecting a microbubble. This microbubble-generation mechanism takes place with every laser pulse (10 kHz repetition rate) leading to the generation of a microbubbles stream. The microbubbles¿ velocities decrease as they move away from the optical fiber and eventually coalesce forming a larger bubble. The larger bubble is attracted to the optical fiber by the Marangoni force once it reaches a critical size while being continuously fed with each bubble of the microbubbles stream. The balance of the optothermal forces owing to the laser-pulse drives the 3D manipulation of the main bubble. A complete characterization of the trapping conditions is provided in this paper.Reserva de todos los derechosCW lasersMicrobubble-generationOpticsOptothermal generationArtículo10.1364/OE.389980Abierto