We present simulation and experimental results of the ablation and dicing process of a silicon wafer using a passive Q-switch nanosecond (ns) Tm: YAP lab laser operating at a wavelength of 1.940μm. This study aims to show that in the 2μm range lasers, high precision in the silicon ablation process can be achieved and can compete with existing industrial lasers in the ultraviolet or near-infrared range. At low fluences, silicon appears to be transparent when irradiated by 2μm lasers. Above a fluence threshold of 3.8J/cm2, third-order nonlinear effects, such as the lens converging Kerr n2 and the two-photon absorption βTPA effects, turn the silicon into an absorbing medium, improving the ablation process. At room temperature of 300°K, n2 = 12×10−5±2.0×10−5cm2/GW and βTPA = 0.56±0.02cm/GW, the resulting nonlinear factor of merit NFOM = 2.1 ± 2.0 is very large; conferring a self-focusing lensing action on the silicon. Based on a Comsol simulation, we observe that the silicon/Q-switch laser interaction shows that the Kerr effect reduces the diameter of the ongoing gaussian laser beam. The simulation corroborated with theoretical models confirms that the nonlinear factor of merit (NFOM) presents a maximum at 1.940μm. By varying the fluence intensity, we demonstrate the laser’s ability to engrave silicon surfaces with a series of pulses. Moreover, we also highlight the impact of TPA effects competing with the focusing Kerr effect in the ablation process, deviating from the linear power law. Our findings provide valuable insights into optimizing laser parameters specifically for drilling and dicing applications.
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