Study of the combined influence of pre-heating of the liquid and the shape of the delivery optical fiber output end on Yb,Er:Glass laser-induced hydroacoustic processes

Раед Нассер, Смирнов С.Н., Перепеляков А.Ю., Беликов А.В. Исследование совокупного влияния предварительного лазерного нагрева жидкости и формы выходного торца оптического волокна доставки на гидроакустические процессы, индуцированные излучением лазера на иттербий-эрбиевом стекле // Оптический журнал. 2026. Т. 93. № 6. С. 28–39. DOI: 10.17586/1023-5086-2026-93-06-28-39

 Raed Nasser, Smirnov S.N., Perepelyakov A.Yu., Belikov A.V. Study of the combined influence of pre-heating of the liquid and the shape of the delivery optical fiber output end on Yb,Er:Glass laser-induced hydroacoustic processes [in Russian] // Opticheskii Zhurnal. 2026. V. 93. № 6. P. 29–39. DOI: 10.17586/1023-5086-2026-93-06-28-39

Hydroacoustic processes induced in water by microsecond laser pulses. Aim of study. To evaluate the combined influence of the output end shape of the optical fiber and preliminary laser heating of the liquid (water) on the characteristics (size, temporal dynamics) of laser-induced vapor-gas bubbles and the parameters of acoustic waves associated with their collapse. Method. Microsecond pulses from a Yb,Er:Glass laser with energy up to 100 mJ were delivered into water via quartz-quartz optical fibers with a core diameter of 470 µm and different output end shapes. Preliminary heating of the liquid surrounding the fiber output end was achieved using a pre-heating laser pulse as part of dual-pulse laser exposure. The temporal dynamics of the vapor-gas bubbles were recorded using a high-speed camera (up to 105 frames/s), and acoustic waves were recorded using a hydrophone (0.25–40 MHz). Main results. Preliminary heating and the fiber end shape significantly affect the diameter of vaporgas bubbles and the amplitude of acoustic waves, reducing the cavitation threshold. The greatest influence was found in the regime combining the use of an optical fiber with a wedge-shaped output end and a pre-heating laser pulse during two-pulse exposure. Practical significance. The results of the study can be used in the development of new laser equipment and technologies and will enhance the safety and efficiency of laser hydroacoustic material processing, which is particularly important in medicine.

 this work was supported by the “Research Works of Master’s and Postgraduate Students” Program at the Institute of Laser Technologies, ITMO University, Russia.