Wang Yue, Yao Zhenyu, Cui Zijian, Sun Guangcheng, Zhang Dachi
Key Laboratory of Ultrafast Photoelectric Technology and Terahertz Science in Shaanxi, Xi'an University of Technology, Xi'an, 710048, China.
Nanophotonics. 2023 Nov 9;12(23):4339-4349. doi: 10.1515/nanoph-2023-0550. eCollection 2023 Nov.
As a high-degree-of-freedom approach to manipulate the electromagnetic wave, metasurfaces are widely used in high-capacity information technology. Extensive investigations have explored multiplexing techniques using polarization, incident angle, wavelength, and infinite-dimensional multiplexing through Orbital Angular Momentum (OAM). However, due to the limited spatial resolution and array size of the metasurface, the number of multiplexing channels that can be actually realized is limited. Therefore, research on the combination of OAM multiplexing and polarization degrees of freedom is of great significance. Here, we propose and experimentally demonstrate a metasurface holography multiplexing scheme based on multiple polarization channels combined with OAM. Taking advantage of the orthogonal independence of spin angular momentum and orbital angular momentum, multiple OAM multiplexing holograms are constructed in multiple different spin-polarization channels. Utilizing the well-established compatibility between OAM multiplexing and polarization multiplexing, we successfully integrated two multiplane holograms and 15 OAM multiplexing holograms on a single metasurface. Subsequently, we introduced an optical nested encryption framework designed for parallel communication. This work facilitates high-capacity and high-security holography by employing multiplexing metasurfaces, thereby providing innovative design concepts for optical communication, information encryption, and related domains.
作为一种操纵电磁波的高自由度方法，超表面在高容量信息技术中得到了广泛应用。大量研究探索了利用偏振、入射角、波长以及通过轨道角动量（OAM）进行无限维复用的复用技术。然而，由于超表面的空间分辨率和阵列尺寸有限，实际可实现的复用通道数量受到限制。因此，研究OAM复用与偏振自由度的结合具有重要意义。在此，我们提出并通过实验证明了一种基于多个偏振通道与OAM相结合的超表面全息复用方案。利用自旋角动量和轨道角动量的正交独立性，在多个不同的自旋偏振通道中构建多个OAM复用全息图。利用OAM复用与偏振复用之间已确立的兼容性，我们成功地在单个超表面上集成了两个多平面全息图和15个OAM复用全息图。随后，我们引入了一种为并行通信设计的光学嵌套加密框架。这项工作通过采用复用超表面促进了高容量和高安全性的全息术，从而为光通信、信息加密及相关领域提供了创新的设计理念。
