Achromatic and wide-field metalens in the visible region

Optical metalens has been attracting more and more attention in recent years. To date, it is still difficult to simultaneously achieve wide field and broadband imaging in the visible region, which is very important in many applications, such as cameras, microscopy, and other imaging devices. In this paper, we design a double-layer metalens to achieve achromatic imaging over a field of view (FOV) of 60° in the visible light range of 470 nm to 650 nm, and its performance is verified by numerical simulations. The numerical aperture (NA) of the metalens is 0.61 and the average focusing efficiency is > 50% at normal incidence. The metalens has an additional advantage of polarization insensitivity.