High Efficiency Polarization-Encoded Holograms with Ultrathin Bilayer Spin-Decoupled Information Metasurfaces

Information metasurfaces, including digital coding and programmable metasurfaces, have reformed the design theory of metasurfaces from effective medium to coding pattern, and bridged the physical and digital world. Metasurface hologram has shown great potential in imaging and manipulating electromagnetic waves. In this work, bilayer information metasurfaces are proposed to achieve polarization-encoded holograms in microwave regime. The designed metasurfaces consist of 3-bit spin-decoupled meta-atoms, which possess ultrathin profiles (0.14 lambda(0)) and high cross-polarization transmittance (over 0.8). The incident wave, which is right-handed circularly polarized or left-handed circularly polarized, is encoded with code "0" or "1". The spin-decoupled design is combined with diffuse scattering and holographic technology. Based on this, a novel algorithm is proposed to generate coding sequences according to the code of incident wave, to achieve different functionalities for corresponding circularly polarized channels. In this way, polarization-encoded holograms, including diffuse scattering holograms (code "00"), single channel holograms (code "01" or "10"), and spin-selective holograms (code "11"), are achieved. Simulated and measured results show that the maximum imaging efficiency can reach up to 65.1%, verifying the high efficiency of this holographic technology. This work is expected to open a way of realizing more complicated and higher efficiency information metasurface holography.