Multifunctional tunable terahertz metasurface with 20 independent channels and ultra-low crosstalk via bidirectional full-polarization decoupling and frequency multiplexing

Abstract

Boosting channel density represents a core demand for terahertz (THz) metasurfaces deployed in next-generation information processing systems. However, the dense integration of multiple functions often leads to severe inter-channel crosstalk, which remains a critical bottleneck in this field. Here, we design a compact 11-layer tunable metasurface integrated with vanadium dioxide and gallium arsenide. Based on a mirror-symmetric configuration, bidirectional full-polarization decoupling of dual-linear (x/y) and dual-circular (LCP/RCP) polarizations is realized, which results in 20 independent channels with an average inter-channel crosstalk as low as −40.5 dB. While combined with frequency multiplexing across five independently controllable operating frequencies, the design enables 30 distinct wavefront manipulations, including orbital angular momentum generation, beam splitting, focusing, and holographic imaging. Results confirm the high-fidelity performance: vortex beams achieve a mode purity of 95%, beam splitting exhibits a deflection error of approximately 0.2°, focusing efficiency reaches 63.52% with a focal length error below 6%, and holographic imaging attains a peak efficiency of 53.60%. Relative to previously published schemes, this design achieves a comprehensive balance among channel capacity, functional integration, and reconfigurability, providing a valuable design reference for high-capacity THz metasurface devices.