Single-layer reflective metasurface design for multi-vortex beams in the terahertz band

This paper proposes a single-layer reflective meta-surface based on Pancharatnam-Berry phase theory for generating multimodal vortex beams in the terahertz band. Precise modulation of the wavefront is achieved through phase superposition, enabling the generation of vortex beams with different topological charges. Full-wave simulations using CST Microwave Studio validate the effectiveness of the designed metasurface, demonstrating its utility in orbital angular momentum multiplexing technology and offering new ideas for the development of terahertz wireless communications. Experimental results show that the metasurface can simultaneously and efficiently generate four vortex beams with ±1 or ±2 modes, maintaining high mode purity over an ultra-wideband range of 0.77 to 1.77 terahertz.