Near-diffraction-limited wide-field achromatic metalens

In recent years, addressing chromatic aberration in metalens has drawn considerable attention. However, ensuring high imaging quality while correcting chromatic aberration remains a significant challenge. In this work, we designed a wide-field achromatic metalens with near-diffraction-limited performance, operating at wavelengths of 480nm, 532nm, and 632nm, and achieving close-to-diffraction-limited Modulation Transfer Function (MTF) at each wavelength within a 40° Field of View (FOV). Our design method innovatively combines phase compensation with a Particle Swarm Optimization (PSO) approach, First, we roughly design the phase dispersion of the metalens phase surface using the compensation phase and then fine-tune the dispersion requirements of the phase surface at different wavelengths using PSO to match our existing unit cell library. Through this method, we achieved excellent chromatic aberration correction using only traditional rectangular unit structures.