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.

Automated summary

This work introduces bilayer information metasurfaces to achieve polarization-encoded holograms in the microwave regime. The metasurfaces consist of 3-bit spin-decoupled meta-atoms with ultrathin profiles and high cross-polarization transmittance. A novel algorithm is proposed to generate coding sequences for different functionalities of corresponding circularly polarized channels. The maximum imaging efficiency can reach up to 65.1%, demonstrating the high efficiency of this holographic technology.