Electromagnetic (EM) beams carrying orbital angular momentum (OAM) are of great importance in modern wireless communications due to their attractive properties of self-reconstruction and multiplexing multiple beams. However, they are hardly deployed in a real-world scenario since they cannot be dynamically generated in a real-time and low-cost way, especially for the case of topological charges more than 2. To resolve this issue, we explore an inexpensive 2-bit programmable coding metasurface working at around 3.2 GHz along with an efficient optimization algorithm for the generation of high-order OAM-carrying beams in a reprogrammable way. Based on the designed metasurface, we can generate OAM EM beams with the electronically controlled vortex centers and topological charges of ${l}=0$ , ±1, ±2, ±3, ±4, ±5, and ±6, which have been experimentally verified. As an illustrative example, we demonstrate an interesting application of the designed 2-bit programmable metasurface in direct-modulation line-of-sight wireless communications. We believe that the developed strategy will bring a fundamentally new perspective on the design of wireless communication architectures at various frequencies.

中文翻译：

---

用于直接调制无线通信的可编程高阶 OAM 承载波束

携带轨道角动量 (OAM) 的电磁 (EM) 波束由于具有自重建和多波束复用的吸引力，因此在现代无线通信中具有重要意义。然而，它们几乎没有部署在现实世界的场景中，因为它们不能以实时和低成本的方式动态生成，特别是对于拓扑电荷超过 2 的情况。为了解决这个问题，我们探索了一种廉价的 2位可编程编码超表面在 3.2 GHz 左右工作，并采用有效的优化算法以可重新编程的方式生成高阶 OAM 承载光束。基于设计的超表面，我们可以生成具有电子控制涡中心和拓扑电荷 ${l}=0$ 、±1、±2、±3、±4、±5 和±6 的 OAM EM 光束，已通过实验验证。作为说明性示例，我们展示了设计的 2 位可编程超表面在直接调制视距无线通信中的有趣应用。我们相信，所开发的策略将为各种频率的无线通信架构的设计带来全新的视角。