为了研究毫秒量级脉宽激光与半导体材料的相互作用机理,建立了一维有限元模型,对长脉冲激光与硅相互作用的气化现象进行了数值模拟.在计算中,利用热焓法处理了固一液相变过程,并根据热流方程考虑了气化产生的能量损失.在人射激光功率密度相同的条件下,定量地描绘了不同脉宽激光辐照材料的温度分布,前表面的温度历史,以及气化速度和气化深度,并估算出气化深度为0.5 μm时,物质蒸汽使激光产生光学自聚焦现象的激光功率阈值仅为0.2 W,此阈值远小于长脉冲激光的功率.因此,在长脉冲激光与硅材料相互作用过程中,气化的物质蒸汽会使后续激光产生光学自聚焦现象.得到的结果可为长脉冲激光的应用提供理论依据.%To explore the mechanism of the long-pulse laser interaction with semiconductor materials, a one-dimensional finite element calculational model was established to investigate the vaporization effect of the long-pulse laser interaction with the silicon. In the calculation, Enthalpy method was used to resolve the process of solid-liquid phase change, and the heat flux equation was used to analyze the energy loss of vaporization. With the certain incident laser power density and different pulse widths, the long pulse laser interaction with the silicon in the process of melting and vaporization phenomena was simulated. The vaporization velocity, temperature evolvement, and the effect of vaporization on ablation depth during and after the laser irradiation were emphatically analyzed. Furthermore, the atomic vapor induced self-focusing threshold by laser transmission was estimated to be about 0. 2 W when vaporization depth was about 0.5 μtm, which was far less than the long-pulse laser power. Therefore, the follow-up laser will cause optical self-focusing phenomenon by vaporization in the long pulse laser interaction with the silicon, obtained results can provide the theoretical basis for the research on the mechanism of the laser interaction with the silicon.
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