Ultra-broadband and high absorbance metamaterial absorber in long wavelength Infrared based on hybridization of embedded cavity modes

Abstract

We present a novel ultra-broadband, polarization-independent, and wide-angle metamaterial absorber whose metal–insulator–metal cavities are embedded into bulk insulator nanodisks. The hybridization of multiple embedded cavity modes generated by the combination of dielectric-loaded surface plasmon polaritons waveguide and cavity modes contributes to large bandwidth and high absorption in the long wavelength infrared (LWIR) region. The proposed structure exhibits more than 94% absorbance in the interval from 8μm to 16μm; and more than 95% absorbance over the whole LWIR band (8–14μm), which is superior than the initial MIM structure (absorption greater than 90% from 8.10–14.33μm) and similar kinds of metamaterial absorber based on noble metal. In addition, a nearly perfect absorbance (more than 99%) is obtained in the 11.22–12.46μm and 13.26–14.59μm wavebands. Moreover, results show that the resonant wavelength and operating bandwidth can be adjusted flexibly by varying related geometry parameters. Thus, the wavelength-selective metamaterial absorber is promising for thermal emitters, energy harvester and microbolometers.