Ultra-broadband metamaterial absorber in the far infrared

To satisfy the requirements of infrared wide spectrum absorption, a metal–insulator-metal (MIM) metamaterial absorber is proposed and designed. Different from the ordinary MIM structure, the far-infrared (FIR) absorptivity is significantly improved through Cr/Si/Cr and periodic Cr ring design. The results of this research show that the structure has a high average absorptivity, which is up to 97.83 % in the FIR band range from 8 µm to 14 µm. And the absorptivity in the 7.93–11.47 µm band is greater than 99 %. The peak absorptivity can exceed 99.91 %. The absorber has excellent incidence angle insensitivity in TE and TM modes. The research results provide a reference for broadband FIR absorption designs.