Centimeter‐size achromatic metalens in long‐wave infrared

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.