Integrated-Resonant Units for Phase Compensation and Efficiency Enhancements in Achromatic Meta-lenses

Achromatic meta-lenses have shown great promise in ultracompact and full-color optical devices. Their performances, including size, bandwidth, and numerical aperture, are originally restricted by the phase compensation provided by functional meta-atoms. Integrated-resonant units (IRUs), associating various meta-atoms, resonant modes, and functionalities into one supercell, are efficient candidates for large phase compensation in broadband achromatic meta-lenses. In this work, we propose nonlocal plasmonic IRUs with multiple nanorods to boost the phase compensation in an achromatic meta-lens over the visible band ranging from 400 to 660 nm. By exciting local and nonlocal plasmonic resonances and manipulating their interactions, the resonance phase can be flexibly controlled, achieving an effective group delay range (Δφ_max - Δφ_min)/Δω of 42.5 fs. Spherical and spiral achromatic meta-lenses are both demonstrated. To demonstrate the functionality of IRUs, an efficiency-enhanced achromatic meta-lens composed of six types of dielectric IRUs is designed by tailoring the field distribution and phase difference between two in-plane orthogonal directions. This work offers a novel design scheme for large-scale high-efficiency achromatic meta-lenses and facilitates their practical applications in advanced imaging and display. © 2023 American Chemical Society.