Multi-channel vortex beam based on single layer transmission-type metal metasurface

•We design a transmission type flexible metasurface which operates at 0.1 THz. The metasurface consists of a polyimide substrate and a metallic copper film.•Using the geometric phase principle, four vortex beams with different channels and different topological charges are generated under the linearly polarized light incident. Through three-dimensional electromagnetic field simulation and experimental tests, it is proved that the designed metsurface can generate multi-channel vortex beams, where the topological charges of the vortex beam are ± 1 and ± 2.•Metasurfaces designed based on this method can be applied in optical communication. We design a transmission type flexible metasurface which operates at 0.1 THz. The metasurface consists of a polyimide substrate and a metallic copper film. Using the geometric phase principle, four vortex beams with different channels and different topological charges are generated under the linearly polarized beam incident. Through three-dimensional electromagnetic field simulation and experimental tests, it is proved that the designed metasurface can generate multi-channel vortex beams, where the topological charges of the vortex beam are ± 1 and ± 2. The metasurface has high transmittance in the frequency band of 0.092THz to 0.106THz, 0.202THz to 0.283THz, 0.318THz to 0.345THz, and so on, which can generate multi-channel vortex beams at multiple frequency bands. Metasurfaces designed based on this method can be applied in optical communication.