Programmable High-Order OAM-Carrying Beams for Direct-Modulation Wireless Communications
Ya Shuang, Hanting Zhao, Wei Ji, Tie Jun Cui, Lianlin Li
Abstract
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.