All-chalcogenide glass based high fill-factor long-wave infrared micro-metalens array with superior optical flexibility

Long-wave infrared (LWIR) micro-metalens arrays have emerged as highly flexible and multifunctional optical elements, significantly enhancing the performance of infrared imaging systems. In this work, two types of chalcogenide glass based LWIR micro-metalens arrays with 10 × 10 array-size and 100% fill factor were designed and investigated. Specifically, the first one possesses a uniform focal length of 110 μm, and it can efficiently focus the incident light (9.78 μm) into a spot with a full width at half maximum (FWHM) of approximately 11.5 μm (∼ 1.18λ). Additionally, the second one features flexible and configurable focal lengths of the respective micro-metalenses in the array, and focal lengths of 102 μm, 149 μm, and 182 μm can be achieved on one substrate, while it still retains the same optical performance as the micro-metalens array with a single focal length. Overall, these all-chalcogenide glass based LWIR micro-metasurface arrays possess significant potential for integrating within advanced infrared imaging systems in the future.