Effects of structural defects on laser-induced damage of 355-nm high-reflective coatings sputtered on etched substrates
Effects of structural defects on laser-induced damage of 355-nm high-reflective coatings sputtered on etched substrates
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DOI：
10.1016/j.optmat.2018.12.024
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发表时间：
2019-03
影响因子：
3.9
通讯作者：
Kesheng Guo;Yanzhi Wang;Ruiyi Chen;Meiping Zhu;Kui Yi;Hongbo He;J. Shao
中科院分区：
文献类型：
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作者：
Kesheng Guo;Yanzhi Wang;Ruiyi Chen;Meiping Zhu;Kui Yi;Hongbo He;J. Shao
紫外（UV）涂层的激光损伤是其应用的一大难题。用离子束溅射法制备的薄膜致密，无结构缺陷，具有较高的激光损伤阈值。在电子束蒸发镀膜中，衬底研磨和抛光过程中不可避免地存在易被腐蚀暴露的亚表面损伤缺陷。在我们的实验中，我们发现，355纳米高反射（HR）涂层溅射在蚀刻基板上的LIDT急剧下降，同时缺陷密度增加。在基底和涂层的表面上发现凹坑，并且引起激光损伤的凹坑非常小（亚微米尺度）。激光损伤形貌显示，损伤部位易发生在酸蚀坑周围。有限元分析结果表明，电场增强和温度升高明显，且最显著的部位是凹坑周围，容易诱发损伤。总之，小的结构缺陷是敏感的双离子束溅射（DIBS）制备的HR涂层的激光诱导损伤。这一工作有助于寻找提高溅射涂层LIDT的新途径。
Laser-induced damage of ultraviolet (UV) coatings poses a great challenge and restricts its application in space. Coatings prepared by ion beam sputtering are dense and possess high laser-induced damage threshold (LIDT), which are absence of structural nodule defects. Subsurface damage defects easily exposed by etching are inevitable under substrate grinding and polishing processes, which are usually ignored in electron-beam evaporation coatings. In our experiments, we find that LIDT of 355-nm high-reflection (HR) coatings sputtered on etched substrates declines dramatically, meanwhile defect density increases. Pits are found on the surface of the substrates and the coatings, and the pits that induce laser damage are very small (submicron-scale). Laser damage morphologies reveal that damage sites are prone to occur around the pits caused by acid etching. Finite element analysis shows consistent results, enhancement of electric field and rise of temperature are obvious, and the most significant part is around the pits, which is prone to induce damage. To conclude, small structural defects are sensitive to laser-induced damage of HR coatings prepared by dual ion beam sputtering (DIBS). This work contributes to finding new ways of improving the LIDT of sputtering coatings.