Fresnel reflection at the boundary between two media of differing refractive indices is a major contributing factor to the overall loss in mid-infrared optical systems based on high-index materials such as chalcogenide glasses. In this paper, we present a study of broadband antireflective moth-eye structures directly nanoimprinted on the surfaces of arsenic triselenide (${\mathrm{As}}_2{\mathrm{Se}}_3$)-based optical windows. Using rigorous coupled-wave analysis, we identify a relief design optimized for high transmittance ($<1\%$ reflectance) at 6 μm, which when nanoimprinted features a transmittance improvement ($\mathrm{\Delta }T>12\%$) in the 5.9–7.3 μm spectral range as well as improved omnidirectional properties. Finally, we demonstrate the adaptability of nanoimprinted surface reliefs by tailoring the nanostructure pitch and height, achieving both extremely broadband antireflective and highly efficient antireflective surface reliefs. The results and methods presented herein provide an efficient and scalable solution for improving the transmission of bulk optics, waveguides, and photonic devices in the mid-infrared.

中文翻译：

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硫族化物玻璃中蛾眼结构的直接纳米压印用于中红外的宽带减反射

两种折射率不同的介质之间的边界处的菲涅耳反射是导致基于诸如硫族化物玻璃之类的高折射率材料的中红外光学系统整体损失的主要因素。在本文中，我们研究了直接纳米压印在三硒化砷表面上的宽带抗反射蛾眼结构（${\mathrm{作为}}_{\mathrm{2个}}{硒}_3$）为基础的光学窗口。通过严格的耦合波分析，我们确定了针对高透射率优化的浮雕设计（$<\mathrm{1个}％$ 反射率）为6μm，当纳米压印时具有改善的透射率（$\mathrm{\Delta }Ť>12％$）在5.9–7.3μm的光谱范围内，并改善了全向特性。最后，我们通过定制纳米结构的节距和高度来展示纳米压印表面浮雕的适应性，同时实现了极宽的抗反射和高效抗反射表面浮雕。本文介绍的结果和方法提供了一种有效且可扩展的解决方案，用于改善中红外中体光学器件，波导和光子设备的传输。