Enhanced imaging performance in broadband achromatic metalens via optimized meta-atom selection

Abstract

Broadband achromatic metalenses require meta-atoms to provide specific phase responses across a continuous spectral range. In conventional achromatic metalens design, the required phase response is typically assumed to vary linearly with frequency. However, complex meta-atom geometries often introduce nonlinear phase dispersion, which degrades achromatic imaging performance. To address this, we propose a more efficient and accurate meta-atom selection strategy, together with an improved linear fitting scheme for the phase and frequency response of meta-atoms. Using this approach, we design an achromatic metalens with a radius of 84 µm, an operating bandwidth of 850–1850 nm and an effective focal length of 375 µm. Numerical simulations indicate improved imaging performance across the entire operating bandwidth. This work provides a simple and effective approach for high-performance achromatic metalens in imaging and related optical applications.