Fully polarized detection of mid-infrared broadband achromatic metalenses

Infrared polarization technology is generally applied in object detection and analysis. However, chromatic aberration restricted the development of Infrared polarization detectors. Metalenses are two-dimensional artificial electromagnetic materials to balance chromatic aberration and an ideal platform for miniaturization and integration of infrared polarization technology. In this paper, a fully polarized detection of mid-infrared achromatic metalens is designed, with a single metalens unit diameter of 30μm, a focal length of 15μm, and a working wavelength of 3μm-5μm. Through FDTD software simulation, the results show that the metalens focuses at focal plane for any polarized state light throughout the working wavelength band, with a full width at half maximum (FWHM) of the peak of less than 6&μm, achieving achromaticity. The maximum aspect ratio of the nanopillar is 15:1, meeting the requirements of electron beam lithography processing. The designed metalens achieves full-polarization detection a wider working wavelength band comparing with existing polarization detection devices, which indicates a potential application value for mid-infrared polarization detection and imaging technology.