Full-Space Double-Layer Patterned 2-Bit Coding Metasurface Hologram

Metasurfaces play an important role in holographic imaging to flexibly manipulate and control electromagnetic wave fronts. However, metasurface-based holograms present weaknesses in space utilization and efficiency. In this work, a 2-bit coding metasurface based on double-face copper-cladded patterns on a single-layer substrate is proposed, where the electromagnetic waves can be independently manipulated in full space. When illuminated by an x-polarized wave, the co-polarized reflection and cross-polarized transmission components of the coding metasurface can be simultaneously manipulated at two distinct frequencies. The co-polarized reflection efficiency is greater than 0.7 at 15 GHz, and the cross-polarized transmission efficiency attains to 0.4 at 14 GHz. The proposed coding metasurface hologram can simultaneously reconstruct two different holographic images without changing the polarization state of the incident wave, while avoiding crosstalk between different channels. A coding metasurface sample is fabricated and measured, and the experimental results agree well with the numerically simulated ones. The proposed hologram imaging concept highlights great potential applications in the fields of holographic display and information encryption.