Multi-mode plasmonic resonance broadband LWIR metamaterial absorber based on lossy metal ring

Broadband perfect infrared wave absorption of unpolarized light over a wide range of angles in an ultrathin film is critical for applications such as thermal emitters and imaging. Although many efforts have been made in infrared broadband absorption, it is still challenging to cover the perfect absorption of broadband in the long-wave infrared band. We propose a long-wave infrared broadband, polarization, and incident angle insensitivity metamaterial absorber based on the supercell with four rings of two sizes. Broadband absorption covering the long-wave infrared band is realized by combining four PSPRs and LSPRs absorption peaks excited by the supercell structure. The absorptivity of our absorber exceeds 90% in the wavelength range of 7.76 similar to 14 mu m, and the average absorptivity reaches 93.8%. The absorber maintains more than 80% absorptivity as the incident angle of unpolarized light reaches 60 degrees, which may have promising applications for thermal emitters, infrared imaging, thermal detection. (c) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

In this study, we propose an ultrathin film that can achieve broadband perfect infrared wave absorption of unpolarized light over a wide range of angles. By combining four absorption peaks excited by the supercell structure, broadband absorption in the long-wave infrared band is realized. The absorber has an absorptivity exceeding 90% in a specific wavelength range and maintains more than 80% absorptivity as the incident angle of unpolarized light reaches 60 degrees.