Spin Decoupling Metasurfaces for Four‐Channel Terahertz Wavefront Shaping

Abstract Advances in wireless communication systems require multifunction‐integrated optical devices to increase information capacities. However, the wavefront‐shaping metasurfaces thus far face challenges in manipulating orthogonal polarization independently and achieving versatile wavefront shaping simultaneously. Here, the scheme of chip‐integrated multi‐section metalens geometries is proposed to operate simultaneously with efficient focusing, orthogonal polarization manipulation, and vortex beam generation. Two spin decoupling metasurfaces are prepared to implement four‐channel terahertz wavefront shaping. It can independently engineer the co‐polarized and cross‐polarized components conversion under circularly polarized incidence. One metasurface realizes the polarization conversion in four independent channels under either left‐ or right‐handed circular incidence. The other achieves different spin‐to‐orbit conversions to generate vortex beams with independent polarization manipulation in four channels. The results suggest promising applications for high‐capacity and high‐security terahertz communication.