Achromatic and wide field of view metalens based on the harmonic diffraction and a quadratic phase

Although metalens has made breakthroughs in various imaging applications due to its ultrathin, lightweight, and multi-functionality, simultaneously achieving wide field of view (WFOV) and achromatic imaging remains a challenge. Here, we demonstrate a harmonic metalens with a quadratic phase profile that enables WFOV imaging and achromatic imaging at certain discrete wavelengths. First, we quantitatively explain why the quadratic phase enables WFOV imaging using its Fourier Transform (FT). Second, we derive the complex-amplitude transmittance formula of a harmonic metalens. The derived formula integrating with the Angular Spectrum theory can calculate the transmitted field distributions of a harmonic metalens. Third, we propose an achromatic WFOV metalens based on the harmonic diffraction and quadratic phase at a large numerical aperture (NA=0.76), which enables achromatic imaging at wavelengths lambda= 600 nm, 1200 nm with a wide field of view (FOV) of 100 degrees. The proposed scheme will undoubtedly expand the applications of metalens in the imaging area.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This study demonstrates a harmonic metalens that achieves wide field of view imaging and achromatic imaging using a quadratic phase profile. The research quantitatively explains the mechanism behind the wide field of view imaging enabled by the quadratic phase and derives the complex-amplitude transmittance formula of a harmonic metalens. By combining harmonic diffraction and quadratic phase, an achromatic wide field of view metalens is proposed, enabling achromatic imaging at specific wavelengths.