为了研究脉冲激光辐照GaAs材料的热效应, 采用软件COMSOL Multiphysics构建了高斯脉冲激光辐照半导体材料的温升物理模型, 分析了1 064 nm纳秒级脉冲激光辐照半导体材料GaAs的热效应.通过求解热传导方程计算了不同功率密度激光辐照GaAs材料的径向与纵向温度场分布,讨论了单光子吸收、双光子吸收及自由载流子吸收对辐照材料的温升贡献.计算结果表明: 当激光功率密度升至1010 W/cm2, 自由载流子对材料的温升贡献已超过单光子吸收对材料温升的贡献而占主导位置; 当激光功率密度降至108 W/cm2以下时, 两种非线性吸收对材料温升的贡献可以忽略.该结果与相关实验基本相符, 表明了构建的物理模型具有科学性.

In order to research nonlinear absorption effect of pulse laser irradiation for GaAs,a physical model of Gaussian distribution pulse laser irradiation for semiconductor material was established by software COMSOL Multiphysics. The thermal effects of semiconductor material GaAs was analyzed under irradiation of nanosecond pulse laser with wavelength of 1064nm. The temperature distribution along radial direction and longitudinal direction of semiconductor material GaAs was calculated under irradiation of nanosecond pulse laser with different power density by means of solving the thermal conduction equations. The contribution of one-photon absorption, two-photon absorption and free carrier absorption to temperature of the irradiated material was discussed. The calculation results show that when the pulse laser power density is above 1010W/cm2, Free Carrier Absorption played a leading role and is more than that of One-Photon Absorption of material. When the pulse laser power destiny is below 108 W/cm2, the temperature contribution of two kinds of nonlinear absorption of materials could be ignored. The result is basically consistent with relevant experiments, which shows that physical model constructed is scientific.