Dual-Polarization Analog 2D Image Processing with Nonlocal Metasurfaces
Optical analog computing using metasurfaces has been the subject of numerous studies, aimed at implementing highly efficient and ultrafast image processing in a compact device. The proposed approaches to date have shown limitations in terms of spatial resolution, overall efficiency, polarization and azimuthal angular dependence. Here, we present the design of a polarization-insensitive metasurface with tailored nonlocality based on a Fano resonant response, enabling both odd- and even-order analog mathematical operations on an incoming image. The metasurface is formed by a single-layered triangular lattice of holes in a suspended silicon membrane, which induces a strong nonlocal response in the transverse spatial frequency spectrum. Our paper provides a path to realize highly efficient optical metasurfaces performing isotropic and polarization-insensitive edge detection on an arbitrary 2D optical image.