Simulation study of dual-focal achromatic metalens based on regional dispersion engineering

Abstract

The utilization of metalens is highly regarded as a promising solution for the advancement of planar optical systems and is anticipated to find extensive applications in areas such as near-eye display. Ensuring the elimination of chromatic aberration in metalens is imperative for their effective implementation in color imaging and display. This paper proposes a novel design strategy for achromatic metalens based on regional dispersion engineering, employing an algorithm to intelligently select rectangular nanostructures that can simultaneously fulfill the phase requirements for correcting chromatic aberration across different spectral bands. The results demonstrate that within the wavelength range of 450–630 nm, a vertical focal error of no more than 1.5 μm and a focal length deviation of 8.56% can be achieved. The average focusing efficiency is recorded at 10.27%. Furthermore, multi-focal achromatic metalens can also be obtained. For demonstration purposes, a dual-focal achromatic metalens (DF-AMLs) with vertical focal errors not exceeding 0.5 μm and average focusing efficiencies of 6.58% and 7.96% respectively is achieved. This DF-AMLs holds significant promise for applications in microscopy and 3D displays, providing new insights and possibilities for advancing related technologies.