Broadband High-Efficiency Co-Polarized Wavefront Manipulation Based on Multi-Layered Metasurface for Terahertz Wave

Metasurfaces can achieve multifunctional wavefront control, but most co-polarized metasurfaces can only achieve a 360° phase coverage at specific frequency points. In this paper, we propose a metasurface with efficient co-polarized Terahertz (THz) wave transmission and full 360° phase coverage over a wide band. The proposed metasurface consists of five metal layers and four dielectric layers, which can be equivalent to two cascade polarization converters to form a Fabry-Perot resonator. The forward incident y-polarized THz wave can transform into the same polarized transmission wave after transmitting the proposed metasurface. Electromagnetic waves interfere repeatedly inside the multilayer metasurface, resulting a high transmission efficiency; furthermore, by changing the structure parameters of the middle two metal layers, a full 360° phase coverage in the broadband is achieved. Wideband THz focus metalens, orbital angular momentum generator and holographic imaging are realized by properly arranging the metasurface unit cells. Simulation results show that the designed multifunctional metasurface can achieve good wavefront control over the band 0.7-1.0 THz. This paper provides a new idea for the design of broadband co-polarized metasurfaces, and has great potential value in communication, imaging, remote sensing and other fields.