Reflective type metasurface for generating and regulating vortex beam at two frequencies

Abstract

We proposed a reflective type metasurface to generate and control vortex beams at two operating frequencies. The proposed metasurface consists of the top metal pattern, the polyimide dielectric layer and the bottom metal plate. Under incident left circularly polarized (LCP) terahertz wave, the deflected vortex beam with topological charges (l=−1, l=2), split vortex beams with topological charges (l=1, l=−2), split vortex beam with topological charge (l=−1) and deflected vortex beam with topological charge (l=−2) are generated at two frequencies of 0.38 THz and 1.14 THz. The simulation results are good consistent with the theoretical calculation expectations. The designed metasurface can independently regulate terahertz wave vortex beams at two frequencies, which provides a new design idea for multi-functional devices in terahertz frequency region.