脉宽1ms和10ns的激光损伤光学薄膜元件的比较分析

Analysis and comparison of coating damage induced by laser at 1ms and 10ns pulse-widths

为了研究脉宽为毫秒量级的激光对光学薄膜的损伤,根据国际标准ISO-11254和国家标准GB/T-16601建立了光学薄膜损伤阈值测试装置。测量了脉宽1ms和10ns、波长1064nm激光作用下TiO_2/SiO_2增透膜的损伤阈值,观测了损伤形貌,测量了损伤厚度及损伤半径,分析了毫秒量级激光损伤光学薄膜的损伤机理并与纳秒激光引起的损伤进行比较。脉宽1ms的激光致使光学薄膜损伤的能量密度阈值比脉宽10ns的激光高一个数量级,功率密度阈值低4个数量级,损伤半径大180μm,损伤厚度大200μm。结果表明,脉宽为毫秒量级的激光对光学薄膜的损伤更为剧烈,不但损伤了光学薄膜的膜层,而且对光学薄膜的基底也造成了毁灭性的损伤。该结果可供脉宽为毫秒量级的激光与光学薄膜相互作用的研究参考。

In order to investigate the damage induced by ms laser, the experiment installation was established according to ISO-11254 and GB/T-16601. The 1064nm laser-induced damage thresholds of TiO2/SiO2 coatings at 1 ms and 10ns pulse-widths were studied, and the damage photos, damage depth, damage radius and damage mechanisms were also investigated. The damage of the coatings induced by ms laser was compared with that induced by ns laser. The damage threshold of energy density induced by ms laser is one order of magnitude higher than that of 10ns laser, and the damage threshold of power density induced by ms laser is one ten-thousandth of that of 10ns laser. The damage radius induced by ms laser is 180μm longer than that induced by ns laser, and the damage depth is 200μm deeper. It could be concluded that 1 ms laser induced damage of optical coatings is more severe, it not only damage the coating but also destroy the substrate of the coating. The results provide important references for the researches of damage induced laser with pulse duration at millisecond scale.