Broadband mid-infrared metalens with polarization-controlled at-will chromatic dispersion

Abstract

Mid-infrared metalenses are promising for potential applications in a range of fields, including molecular detection, imaging, and optical sensing. To fulfil the different requirements of these diverse application scenarios, engineering of the ability to control the chromatic dispersion of these lenses at will is vitally important. Herein, we demonstrate broadband mid-infrared metalenses with polarization-controlled at-will chromatic dispersion capability based on all-silicon metasurfaces. Both polarization-insensitive and polarization-sensitive mid-infrared metalenses with at-will chromatic dispersion capabilities are demonstrated numerically for operation at wavelengths ranging from 3.75 μm to 4.75 μm. The average focusing efficiency of all these metalenses exceeds 40% in the wavelength range of interest, and the highest focusing efficiency ranges up to 67%. The mid-infrared metalenses with at-will chromatic dispersion proposed here may be beneficial for mid-infrared sensing, communications, and imaging applications in the future.