The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable. Herein, a lithography-free, wide-angle, and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated, based on a reversible nanochemistry approach. The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide (CuO) thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas. Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90% at the wavelength of 1.79 μm with the initial thickness of CuO taken as 150 nm. Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure, which show good agreement with experimental results. We believe that the proposed versatile approaches can be implemented for dynamic control management, allowing applications in tunable photonics, active displays, optical encryption, and gas sensing.

中文翻译：

---

用于硫化氢气体传感的动态可重构亚波长光学器件

可调谐亚波长光学器件在现代电磁和光子系统中的重要性是毋庸置疑的。在此，基于可逆纳米化学方法，提出并实验证明了一种在近红外区域具有高可调性的免光刻、广角和可重构亚波长光学器件。可重构亚波长光学器件主要包括在光学厚金基板上的超薄氧化铜 (CuO) 薄膜，通过利用暴露于硫化氢气体时 CuO 向硫化物的可逆化学转化。概念验证实验结果表明，当 CuO 的初始厚度为 150 nm 时，反射率的最大调制深度在 1.79 μm 波长处可高达 90%。采用部分反射波计算结合传递矩阵法对结构的光学特性进行了分析研究，结果与实验结果吻合良好。我们相信，所提出的通用方法可以用于动态控制管理，允许在可调光子学、有源显示器、光学加密和气体传感中应用。