Centimeter-size achromatic metalens in long-wave infrared

Abstract

Metalens has shown its significantly ultra-light and ultra-thin features. However, large-aperture achromatic metalens is constrained by both maximum dispersion range and computational memory. Here, we propose a fully device optimizing framework that engineers phase dispersion and amplitude transmittance to create centimeter-size achromatic metalens operating in long-wave infrared regime (8–12 μm). Via wrapping group delay within a defined range and optimizing dispersion phase of desired wavelengths, chromatic aberrations can be effectively corrected. We verify our design by characterizing all-silicon 3.18-cm-diameter and 6.36-cm-diameter LWIR achromatic metalenses. Diffraction-limited tight-focusing can be achieved, and the normalized focal length shift is less than 3.3 × 10−4. Thermal imaging performance is verified on targets of holes or letters with a diameter or line width exceeding 2 mm. These findings facilitate the development of large-aperture achromatic metalenses and open up possibilities for lightweight imaging systems in long-wave infrared.