Multi-beam multi-mode terahertz vortex generator for multiplexing

To address the current issue of limited frequency resources, this paper proposes a multi-beam, multi-mode orbital angular momentum (OAM) wave generation scheme based on encoded metasurfaces. Utilizing the Pancharatnam–Berry phase principle, a multi-beam, multi-mode encoded metasurface with full-phase response, high reflectivity, and wide-angle characteristics has been designed. By combining phase compensation, superposition, and convolution theorems, the order of OAM modes and phase gradient sequences are cleverly integrated into the encoding sequence. This enables the reflection of a plane wave into four beams with different modes, achieving spatial multiplexing at the same frequency. Building on this, the algorithm is further optimized to propose a design scheme for generating eight-beam and full OAM beams. The multi-modal encoded metasurfaces model demonstrates through validation that the superposition theorem and convolution principle offer great flexibility and powerful capabilities in electromagnetic wave manipulation. It effectively realizes the generation of multiple modes and OAM beams, significantly enhancing the capacity of information transmission channels. This approach has substantial potential for comprehensive implementation in future wireless communication systems.