A metamaterial absorber for the terahertz regime: Design, fabrication   and characterization
  We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a single unit cell in the propagation direction, thus achieving an absorption coefficient $\alpha$ = 2000 cm$^{-1}$. These metamaterials are promising candidates as absorbing elements for thermally based THz imaging, due to their relatively low volume, low density, and narrow band response. 
Hu Tao, Nathan I. Landy, Christopher M. Bingham, Xin Zhang, Richard D.   Averitt, and Willie J. Padilla