飞秒激光对高反膜的破坏及其超快动力学过程

Femtosecond Laser-Induced Damage and Ultrafast Dynamics in Highs Reflection Coating

研究了800nm飞秒激光照射下45°高反膜ZrO2-Si O2的破坏及其超快动力学过程。利用原子力显微镜和扫描电镜观察了材料的烧蚀形貌,测量了破坏阈值与脉冲宽度、烧蚀深度与脉冲能量的依赖关系。随着脉冲宽度从50fs增加到900fs,其烧蚀阈值从0.35J/cm2增加到1.78J/cm2。烧蚀深度与激光能流密度近似成对数关系。当激光强度略高于烧蚀阈值时,材料很快被烧蚀到几百纳米,烧蚀深度表现出明显的层状特性。同时,利用建立的抽运探针实验系统,测量了高强度抽运脉冲作用下材料对探针光的反射率随延迟时间的变化,揭示了薄膜烧蚀的超快动力学过程。实验结果表明高反膜表层的材料对烧蚀特性有重要影响。

The damage and ultrafast dynamics processes induced by 800 nm femtosecond laser in ZrO2/SiO2 800 nm 45° high-reflection coating are studied. The damage morphology, and threshold fluence as a function of pulse duration and the dependence of ablation depths on the pulse fluences are measured. The damage threshold increases from 0.35 J/cm^2 to 1. 78 J/cm^2 with pulse duration enlarged from 50 fs to 900 fs. The ablation depth is linearly proportional to the logarithm of pulse fluence, which suddenly reaches hundreds of nanometers once the laser fluence is above the threshold, and the layered ablation shows. By using of a pump and probe experimental system, the time- resolved reflectivity irradiated by high intensity laser pulses in the reflector ZrO2/SiO2 is measured. The results indicate that the optical properties of the surface layer of high-reflection coating play a very important role during the damage process.