Zhu Meiping, Xu Nuo, Roshanzadeh Behshad, Boyd S T P, Rudolph Wolfgang, Chai Yingjie, Shao Jianda
1Laboratory of Thin Film Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800 China.
2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China.
Light Sci Appl. 2020 Feb 11;9:20. doi: 10.1038/s41377-020-0257-4. eCollection 2020.
With ever-increasing laser power, the requirements for ultraviolet (UV) coatings increase continuously. The fundamental challenge for UV laser-resistant mirror coatings is to simultaneously exhibit a high reflectivity with a large bandwidth and high laser resistance. These characteristics are traditionally achieved by the deposition of laser-resistant layers on highly reflective layers. We propose a "reflectivity and laser resistance in one" design by using tunable nanolaminate layers that serve as an effective layer with a high refractive index and a large optical bandgap. An AlO-HfO nanolaminate-based mirror coating for UV laser applications is experimentally demonstrated using e-beam deposition. The bandwidth, over which the reflectance is >99.5%, is more than twice that of a traditional mirror with a comparable overall thickness. The laser-induced damage threshold is increased by a factor of ~1.3 for 7.6 ns pulses at a wavelength of 355 nm. This tunable, nanolaminate-based new design strategy paves the way toward a new generation of UV coatings for high-power laser applications.
随着激光功率不断提高，对紫外（UV）涂层的要求也在持续增加。耐紫外激光反射镜涂层面临的根本挑战是要同时展现出高反射率、大带宽以及高耐激光性。传统上，这些特性是通过在高反射层上沉积耐激光层来实现的。我们提出一种“反射率与耐激光性一体化”的设计，利用可调谐纳米层压板作为具有高折射率和大光学带隙的有效层。通过电子束沉积实验展示了一种用于紫外激光应用的基于AlO-HfO纳米层压板的反射镜涂层。反射率大于99.5%的带宽是具有可比总厚度的传统反射镜的两倍多。对于波长为355nm的7.6纳秒脉冲，激光诱导损伤阈值提高了约1.3倍。这种基于可调谐纳米层压板的新设计策略为高功率激光应用的新一代紫外涂层铺平了道路。
