Polarization-dependent terahertz metamaterial absorber with high absorption in two orthogonal directions

We fabricated a polarization-dependent terahertz (THz) metamaterial absorber consisted of a metal film, a dielectric spacer and a metal pattern layer. The measured absorptivity for x-polarized wave is about 0.9 at 1.42 THz, and that for y-polarized wave is about 0.87 at 2.15 THz. The full width at half maximum (FWHM) of peaks at 1.42 THz and 2.15 THz are about 0.23 THz and 0.38 THz, respectively. The experimental results are in good agreement with the numerical simulation. In addition, the parameters related to the absorption are presented for deeply understanding the absorption mechanism. Most importantly, these two absorption peaks can be tuned respectively by simply changing the length in x and y directions. Our results suggest potential applications based on metamaterial absorber, such as THz polarization imaging, selective spectral detection, THz sensing and polarization multiplexing.