针对不同厚度的镍膜以及金膜,利用多物理场耦合分析软件COMSOL Multiphysics研究了波长248 nm、矩形脉冲宽度14 ns激光辐照损伤阈值随膜厚变化的物理过程。本研究与他人的理论计算和实验测得的结果基本一致,研究表明:在高强度单脉冲激光均匀辐照下,金属薄膜表面的损伤主要是由于激光能量在其材料内部的沉积而导致的热效应引起的;当金属薄膜的厚度小于其光学吸收长度时(镍膜厚度＜8 nm,金膜厚度＜12 nm),其熔融损伤阈值随着薄膜厚度的增加而减小;当薄膜厚度大于光学吸收长度而小于其热扩散长度时(镍膜厚度8~730 nm,金膜厚度12~1 050 nm),其熔融损伤阈值随薄膜厚度增加而线性增加;当薄膜厚度大于其热扩散长度时(镍膜厚度＞730 nm,金膜厚度＞1 050 nm),其熔融损伤阈值随薄膜厚度的增大基本保持不变。

The damage threshold and the physical processes of Ni and Au films irradiated by single UV laser pulse(248 nm,14 ns) are investigated by using COMSOL Multiphysics as a function of layer thickness.The present simulation results arequite consistent with the previous theoretical and experimental results.It indicates that the damage on these metal films is mainly due to the thermal effect caused by the deposition of the laser energy inside the films.When the thickness of metal film is less than its optical absorption length(Ni film ＜8 nm and Au film ＜12 nm),the damage threshold of the metal film decreases with the increasing of the film thickness.When the thickness of metal film is larger than its optical absorption length but less than its thermal diffusion length(Ni film 8-730 nm and Au film 12-1 050 nm),the damage threshold of the metal film increases linearly as a function of the film thickness.When the metal film thickness is larger than its thermal diffusion length(Ni film ＞730 nm and Au film ＞1 050 nm),the damage threshold of the metal film becomes almost a constant value even if increasing the film thickness further.