Enhancement of pulsed laser-induced silicon plasma-assisted quartz ablation by continuous wave laser irradiation

Abstract

This research article reports the enhancement of quartz ablation by continuous wave (cw) laser irradiation of silicon plasma generated by a pulsed fiber laser. The fiber laser operating at 1064 nm wavelength and 5 ns pulse width is utilized to produce silicon plasma, whereas a cw laser (λ = 808 nm) is used for quartz ablation enhancement. The gap distance between the target and the substrate is 20 μm. The microfeatures and silicon craters are characterized with the help of an optical microscope and a surface profiler. It is observed that the diameter, depth, and volume of the microfeatures increase linearly with the fluence of the cw laser in the range of 3.5–10.2 μJ/cm2. Below the fluence of 3.5 μJ/cm2, there is no significant enhancement in quartz ablation. The maximum increase in diameter, depth, and volume of microfeatures due to cw laser irradiation is 35 ± 6.4%, 198 ± 11.9%, and 443 ± 48.8%, respectively. The analysis of corresponding silicon craters reveals that the silicon ablation rate also increases with the fluence of the cw laser. The variation in size (diameter and depth) and volume of the quartz microfeatures as a function of cw laser fluence is quite identical to the change in the size of silicon craters. The enhancement of quartz ablation is explained by the physical mechanism resulting from the interaction of cw laser with the silicon target.