Wavelength-Selective Infrared Metasurface Absorber for Multispectral Thermal Detection

A wavelength-selective metasurface absorber suitable for use in multispectral microbolometer focal plane arrays in the long-wavelength infrared (LWIR) region is theoretically and experimentally investigated. We show that a thin metal metasurface, which is characterized by effective surface impedance, as an absorbing layer can be integrated with an asymmetric Fabry-Pérot cavity to construct a wavelength-selective perfect absorber. The absorbed infrared energy is mainly dissipated in a thin metal metasurface, in contrast to a multilayer metamaterial absorber. The calculated and experimental spectral responses of the metasurface absorbers show excellent wavelength-selective narrowband absorption to allow multispectral imaging in LWIR.