飞秒、皮秒激光烧蚀金属表面的有限差分热分析

为描述飞秒激光烧蚀金属表面过程，对双温方程进行了约化。用有限差分法对飞秒、皮秒脉冲激光在金属表面烧蚀过程的温度场进行了一维数值模拟。分析了在飞秒领域对双温方程约化的合理性。计算模型对电子与光子耦合系数的大小对金属表层电子温度的影响进行了分析。同时考虑不同脉宽、不同能流及功率密度大小的因素。发现电子与晶格耦合系数影响材料表面电子的温升及电子与晶格温度耦合时间；与皮秒激光比较。脉冲功率密度是影响电子最终温度的主要因素；飞秒激光烧蚀金属材料的厚度可达到表层厚度(吸收系数的倒数)量级。

Finite Difference Method for Thermal Analysis of Femtosecond-Picosecond Pulse Laser Ablation on Metal Surface

To describe femtosecond laser ablation on metal surface, the double-temperature equation (DTE) was formatted simply. In this paper, numerical simulation for temperature field of femtosecond-picosecond pulse laser ablation on metal surface is performed by finite-difference method (FDM). It is reasonable to make the DTE simple in femtosecond scale. It is also analysed that the effect of electron-lattice couple coefficient g on surface temperature, and found that g determines the surface temperature rising rate and the electron-lattice couple time. Compared with picosecond pulse laser, the intense of pulse is the main factor of the finally temperature of electron. The ablated depth of femtosecond laser can be controlled as thick as the surface depth of metal.