Full-Space Janus Metasurface with Six Independent Information Channels at a Single Frequency

Janus metasurfaces have achieved rapid development in enabling asymmetric and bidirectional manipulation of electromagnetic waves. However, compact full-space platforms that experimentally integrate independently addressable transmission and reflection functionalities remain comparatively scarce. In this paper, we propose a full-space Janus metasurface that supports six independently controllable channels, two in transmission and four in reflection modes, at a single frequency. The design incorporates asymmetric multiresonant meta-atoms with decoupled phase control, achieving simulated efficiencies of 94.3% in transmission and 99.9% in reflection. A hierarchical architecture combining spatial and polarization multiplexing is introduced to facilitate simultaneous and independent wavefront shaping across all channels. Experimental validation at 16 GHz demonstrates multifunctional beam manipulation with cross-talk below -13.89 dB and an average working efficiency of 30.15% (the ideal theoretical efficiency is 50%). Both numerical simulations and experimental measurements verify the capability of generating six-channel holograms for optical secret sharing applications. This approach enhances channel capacity by at least 50% compared to conventional four-channel Janus metasurfaces while maintaining structural compactness, and it realizes genuine full-space wave regulation by fully exploiting reflection and transmission channels, thereby offering improved functionality and potential for high-capacity electromagnetic communication systems.