Imaging rule of diffractive ultrathin flat lens

Abstract

With the development of nanophotonics, a number of diffractive optical lenses are designed and demonstrated experimentally, such as metasurfaces and metalens. This study demonstrates derivation the imaging rule of diffractive optical lens based on geometric optics, which treat light as rays without considering the diffraction. The derived imaging rule is theoretically verified by the Rayleigh-Sommerfeld (RS) diffraction theory to simulate the imaging performance a graphene oxide (GO) ultrathin (~200 nm) flat lens working at the wavelength of 600 nm. The results from diffraction theory based on RS model confirms the imaging rule derived from the geometric optics in the paraxial region. The imaging rule can be generally applied to any diffractive lenses, especially ultrathin flat lenses.