Laser pulse duration influence on the fused silica treatment by laser-induced microplasma

Рымкевич В.С., Болошко А.А., Сергеев М.М. Влияние длительности импульса лазерного излучения на обработку кварцевого стекла лазерно-индуцированной микроплазмой // Оптический журнал. 2023. Т. 90. № 4. С. 68–77. http://doi.org/ 10.17586/1023-5086-2023-90-04-68-77

Rymkevich V.S., Boloshko A.A., Sergeev M.M. Laser pulse duration influence on the fused silica treatment by laser-induced microplasma // Opticheskii Zhurnal. 2023. V. 90. № 4. P. 68–77. http://doi.org/ 10.17586/1023-5086-2023-90-04-68-77

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Research subject. The lifetime and delay in the formation of a laser­induced microplasma plume obtained using femto­ and nanosecond laser sources, as well as the geometry of tracks on a fused silica plate recorded by this plume, were studied. Research Objective. Determination of the influence of a laser pulse duration in the range from femto­ to nanoseconds on the lifetime of a plasma plume and the geometric characteristics of structures formed by a microplasma plume on the fused silica surface. Method. The time characteristics of the plasma plume were measured by simultaneous recording the plume glow intensity in time with a photomultiplier and the laser pulse intensity with a photodetector connected to an oscilloscope. The start of recording coincided with the signal from the photodetector. The geometric dimensions of the tracks on the fused silica surface were obtained using optical profilometry. Main results. The lifetime of a plasma plume depends on the duration and energy of the laser pulse, and the plasma formation delay has a linear dependence on the pulse duration. The minimum average plasma plume lifetime of 7 ns is achieved with a pulse duration less than 150 ps. In the nanosecond range, with a laser pulse duration more than 30 ns, an exponential increase in the lifetime of the plasma plume occurs due to the replenishment of the plume with the remaining part of the pulse. Practical significance. The studies presented in the work allow us to form recommendations for choosing the pulse duration to achieve certain geometric characteristics of the forming tracks. According to these studies, to reduce the lateral size of the tracks, it is recommended to use a shorter pulse duration, but to achieve deeper and wider structures, for example, for microfluidics devices, pulse durations greater than 50 ns should be used.