光学减反膜是激光系统的重要组成部分, 也是在激光照射下最容易发生损伤的部分, 如何提高减反膜的激光损伤阈值是研究的热点之一。在保持目标透射光谱要求和膜系总光学厚度不变的前提下, 研究了不同梯度化减反膜与激光损伤阈值之间的关系。首先采用混合渐变膜系设计方法设计了一种渐变减反膜系, G/H1→H/L/A; 其次通过渐变折射率分层等效方法将渐变减反膜系进行不同的梯度化, 并利用PECVD技术, 在K9玻璃上沉积了满足光学性能指标要求的不同渐变减反膜系(多层梯度渐变膜系和相应的坡度渐变膜系); 最后进行了激光损伤阈值(LIDT)测量。研究结果表明: 在保持目标透射光谱要求和膜系总光学厚度不变的前提下, 渐变减反膜系相比于传统减反膜系, 抗激光损伤阈值有明显的提高; 随着梯度化层数的增加, 渐变减反膜系的激光损伤阈值呈减小的趋势; 对于相同膜层的渐变折射率薄膜, 采用坡度法制备的样片抗激光损伤阈值均优于采用梯度化制备的样片。

Optical antireflection film is an important part of laser systems, and it is also most likely to be destroyed under laser irradiation. How to improve the laser induced damage threshold of antireflection film is one of the research hotspots. The relationship between different gradient antireflection films and laser induced damage threshold were studied without changing the target transmission and the total optical thickness of the films . Firstly, a hybrid inhomogeneous film was designed by MATLAB with hybrid design method, namely G/H1→H/L/A. Secondly, the inhomogeneous film was graded into different layers by the inhomogeneous film grading equivalent method. And using the plasma enhanced chemical vapor deposition (PECVD) technology, different inhomogeneous antireflection film structures (multilayer graded-index antireflection film structures and corresponding inhomogeneous film structures) satisfying optical performance indicators were deposited on K9 glass. Finally, the laser induced damage threshold (LIDT) of the films were measured. The results show that, without changing the target transmission and the total optical thickness of the films, the inhomogeneous antireflection film has a significant improvement in the LIDT compared to the conventional antireflection film. When the number of gradient layers increases, the LIDT of the inhomogeneous film structures decreases. And for the inhomogeneous films of the same layer, the LIDT of the sample prepared by the slope method is better than that of the sample prepared by the gradient.