Enhancement of Transmission Efficiency on Pancharatnam-Berry Geometric Phase Encoding Metasurfaces

The modulation of the required light wavefront polarization and phase based on the geometric phase encoding metasurface (GPEM) has recently become a hot topic. However, the transmission coefficient of a geometric phase metasurface is greatly decreased when the structure is rotated. To address this problem, a solution of adding a tapered antireflection layer to the substrate and design an all-dielectric encoding metasurface composed of titanium dioxide and silicon dioxide in the visible light band with a transmission coefficient of 93.65%, is proposed. When circularly polarized light is incident on the designed encoding metasurfaces with rotating unit structures, the GPEM still maintain almost perfect transmission coefficient as with initial linearly polarized light is incident. By comparing the coded metasurface with and without conical structure, the coded metasurface with conical structure can greatly improve transmission efficiency. Importantly, the Fourier convolution theorem in digital signal processing is introduced on encoding metasurfaces. The scattering angle of transmission can be controlled arbitrarily by the all-dielectric coded metasurface with Fourier convolution addition and subtraction operations.

Automated summary

The study focuses on modulating the polarization and phase of light wavefront based on the geometric phase encoding metasurface (GPEM). By adding a tapered antireflection layer to the substrate, an all-dielectric encoding metasurface composed of titanium dioxide and silicon dioxide is designed with a high transmission coefficient. The introduction of the Fourier convolution theorem allows for controlling the scattering angle of transmission in the all-dielectric coded metasurface through addition and subtraction operations.