An ultra-broadband, polarization and angle-insensitive metamaterial light absorber

Abstract

We propose a new ultra-broadband metamaterial absorber based on a titanium–silica–titanium sandwich structure, which is composed of a periodic array of titanium–silica elliptical nanodisks and a titanium bottom film. The absorption bandwidth reaches 1376 nm in the wavelength range from the visible to near-infrared region with the spectral absorptivity >90%. Moreover, the spectrally averaged absorption is up to 94.6%, indicating the achievement of ultra-broadband near-perfect absorption. In addition, the near-perfect absorption is polarization-independent and incident-angle insensitive. The ultra-broadband absorption mainly results from the strong plasmonic near-field coupling by the adjacent metal parts and the intrinsic material absorption in the wide wavelength range by the refractory metal. The proposed ultra-broadband metamaterial absorber could have broad application prospects in solar photovoltaic generation, infrared detection, and hot-electron devices.