Chang Xin, Pivnenko Mike, Shrestha Pawan, Wu Weijie, Zhang Wenhan, Chu Daping
Opt Express. 2023 Feb 13;31(4):5378-5387. doi: 10.1364/OE.483452.
Active metasurfaces add a new dimension to static metasurfaces by introducing tunability, and this has received enormous attention from industry. Although various mechanisms have been proposed over the past few years in literature, solutions with good practicality are limited. Liquid crystal (LC)-based active metasurface is one of the most promising approaches due to the well-established LC industry. In this paper, an electrically tunable active metasurface was proposed and experimentally demonstrated using photoaligned nematic LC. The good quality of the LC photoalignment on the metasurface was demonstrated. Tunable transmission was obtained for telecommunication C band and the modulation depth in transmission amplitude of 94% was realized for 1530 nm. Sub-millisecond response time was achieved at operating a temperature of 60°C. The progress made here presents the potential of LC-based active metasurfaces for fast-switching photonic devices at optical communication wavelengths. More importantly, this work lays the foundations for the next-generation liquid crystal on silicon (LCoS) devices that are integrated with metasurfaces (meta-LCoS).
有源超表面通过引入可调谐性为静态超表面增添了新的维度，这已引起业界的广泛关注。尽管在过去几年的文献中提出了各种机制，但具有良好实用性的解决方案仍然有限。基于液晶（LC）的有源超表面由于成熟的液晶产业而成为最有前途的方法之一。本文提出了一种基于光对准向列型液晶的电可调有源超表面，并进行了实验验证。展示了超表面上液晶光对准的良好质量。在电信C波段实现了可调谐传输，在1530 nm波长处实现了94%的传输幅度调制深度。在60°C的工作温度下实现了亚毫秒级的响应时间。这里取得的进展展示了基于液晶的有源超表面在光通信波长下用于快速切换光子器件的潜力。更重要的是，这项工作为与超表面集成的下一代硅基液晶（LCoS）器件（超表面-LCoS）奠定了基础。
