All-Chalcogenide High-NA Broadband Achromatic Metalens for Long-Wavelength Infrared Regime

The long-wave infrared band, which at room temperature covers the infrared radiation of humans and objects, has significant applications across various fields including wireless communication, national defense, military, biomedical, and advanced driver assistance systems. Metalens provides a pathway to lightweight, compact, and integrated solutions for infrared imaging and sensing systems, marking an inevitable trend in future development. This study presents a design for a high numerical aperture of 0.89 in a polarization-insensitive all-chalcogenide metalens operating at 10 µm, utilizing the commercially available chalcogenide glass material As2Se3 via a transmission phase approach. Building upon this, we have achieved, for the first time, a high numerical aperture of 0.84 for an all-chalcogenide broadband LWIR achromatic metalens operating in the 9.5–10.5 µm range, with significantly improved focusing performance through the application of particle swarm optimization algorithms. The superior performance of the all-chalcogenide LWIR metalens, combined with the advantages of chalcogenide glass over traditional LWIR materials such as Si or Ge—namely, lower cost, reduced optical loss, and a smaller thermo-optic coefficient—suggests it has significant potential for broader applications.