Independent bidirectional wavefront multiplexing based on dual-band multi-polarization full-space metasurfaces.

Metasurfaces have revolutionized electromagnetic and optical wavefront engineering by offering subwavelength control over incident wave properties. However, conventional designs are typically restricted to half-space operations, functioning exclusively in either the reflective or transmissive domain. To transcend this limitation, reflection-transmission-integrated metasurfaces have emerged to enable bidirectional manipulation across the full space. While such architectures have been widely explored, integrating simultaneous multiplexing across the frequency, polarization, and spatial domains within a single compact platform remains a formidable challenge. Here, we demonstrate a passive dual-band, multi-polarization (DBMP) full-space metasurface to address this bottleneck. By leveraging a symmetry-broken tri-layer architecture, the device achieves independent full-space wavefront control: it manipulates dual-linearly polarized waves in a lower frequency band and dual-circularly polarized waves in a higher frequency band, with both bands supporting simultaneous transmission and reflection modes. Crucially, the proposed design exhibits high operational efficiency, robust angular stability under oblique incidence, and negligible interband crosstalk. Experimental characterizations of a fabricated prototype exhibit excellent agreement with full-wave numerical simulations, confirming the high-fidelity generation of four independent, highly directive beams. This work establishes a versatile platform for multi-dimensional electromagnetic integration, which can be readily scaled to terahertz and optical frequencies for compact metaphotonic devices.