Increasing information capacity is crucial for high‐capacity and high‐speed communication, especially for sub‐terahertz communication. Over the last decade, spatial multiplexing based on the orbital angular momentum (OAM) by adopting a multi‐mode OAM metasurface has attracted a lot of attention. However, current metasurface‐based OAM multiplexing methods suffer from complex and limited multiplexing channels. In this paper, a novel method to realize multi‐dimensional multiplexing combining OAM and frequency based on an angle‐multiplexed metasurface over a broadband terahertz region is proposed and investigated. A frequency‐independent phase profile formula of the angle‐multiplexed metasurface is derived. A reflective metasurface operating from 0.25 to 0.35 terahertz (THz) is designed based on this formula. For proof of concept, nine‐channel multiplexing is illustrated based on this novel method. The simulation results verify that nine‐channel off‐axis left‐hand circularly polarized beams are converted to nine orthogonal coaxial beams. Besides, according to the conventional method for OAM multiplexing, an angle‐multiplexed reflective metasurface working at 0.3 THz is designed for comparison. The simulation results show that only three‐channel multiplexing can be obtained by this model with nine‐channel incident waves. The proposed method has a great potential to enhance the transmission capacity of the communication system.

中文翻译：

---

太赫兹角复用超表面，用于空间和频域的多维复用

信息容量的增加对于大容量和高速通信至关重要，特别是对于太赫兹通信而言。在过去的十年中，通过采用多模式OAM超表面，基于轨道角动量（OAM）的空间复用引起了广泛的关注。但是，当前基于元表面的OAM复用方法存在复杂且受限的复用通道。本文提出并研究了一种基于宽带太赫兹区域上角度复用的超表面实现OAM和频率相结合的多维复用的新方法。推导了角度复用的超表面的频率无关的相位分布公式。基于此公式设计了反射超表面，其工作频率为0.25至0.35太赫兹（THz）。为了证明概念，基于这种新颖的方法说明了九通道多路复用。仿真结果验证了将九通道离轴左旋圆偏振光束转换为九个正交同轴光束。此外，根据常规的OAM复用方法，设计了一个工作在0.3 THz的角度复用反射超表面进行比较。仿真结果表明，利用九通道入射波，该模型只能获得三通道复用。所提出的方法具有增强通信系统传输容量的巨大潜力。根据用于OAM复用的常规方法，设计了一个工作在0.3 THz的角度复用反射超表面进行比较。仿真结果表明，利用九通道入射波，该模型只能获得三通道复用。所提出的方法具有增强通信系统传输容量的巨大潜力。根据用于OAM复用的常规方法，设计了一个工作在0.3 THz的角度复用反射超表面进行比较。仿真结果表明，利用九通道入射波，该模型只能获得三通道复用。所提出的方法具有很大的潜力来增强通信系统的传输容量。