Broadband and high-efficiency edge detection device based on quasi-continuous metasurface

In this paper, we design an optical differential device based on quasi-continuous metasurface and realize one-dimensional edge detection of an optical image. By changing the spatial orientation of quasi-continuous nanostrips, the device achieves geometric phase in the range of 0~2π, and maintains high energy efficiency over a wide wavelength range. The simulation results show that when the illumination wavelength increases from 400 nm to 1000 nm, the quasi-continuous meta-device can achieve clear images for the target edge. The maximum energy efficiency is 90.27% (the incident wavelength is 600 nm) and the average energy efficiency is 64.57% (the incident wavelength changes from 400 nm to 1000 nm). It can be expected that the proposed method can promote the application of quasi-continuous metasurface in image information processing and ultrafast optical computation.