Vortex beam information encryption in metasurface-based wireless communication systems

Electromagnetic metasurfaces have important applications in vortex beam generation and steering, which enables great potential in secure communication, imaging systems, and quantum technologies. Conventional geometric phase-based metasurfaces lack the ability to control two spins simultaneously. In this paper, we designed a set of meta-atoms with appropriate geometric dimensions and orientation angles to achieve complete spin decoupling. Metasurfaces engineered by geometric phase and propagating phase can produce various vortex beams with distinct topological charges when illuminated by right-handed circular polarization and left-handed circular polarization. The experiments are conducted to assess the near-field and far-field efficacy of vortex beams. The experimental findings align well with the theoretical predictions. This study provides novel techniques for the arbitrary generation of high-performance vortex beams generated by metasurfaces within the microwave domain, which can be widely used in information encryption and 5G/6G wireless communication systems, facilitating advancements in high-performance wireless encrypted communication systems.