Multifunctional All‐Dielectric Metasurfaces for Terahertz Multiplexing

Abstract Hermite–Gaussian (HG) beams, corresponding to high‐order transverse modes, reveal a great potential in the space division multiplexing in optical and wireless communications. Higher data rates are made possible by the introduction of multiplexing, which is critical for next‐generation wireless communications working at terahertz frequency. Here, the multifunctional all‐dielectric metasurfaces are studied both theoretically and experimentally to implement terahertz mode and polarization division multiplexing. Terahertz incidence with fundamental Gaussian mode could be converted to high‐order HG modes by the silicon‐based metasurface. More interestingly, phase distributions of the axicons and deflectors are integrated into the mode conversion to reduce the divergence of the output beam and spatially separate each mode. The proposed multifunctional metasurfaces open a new avenue to the potential application of metasurface‐based devices in terahertz communication systems.