Abstract
We study the spectral response of a one-dimensional dielectric-metal photonic-crystal absorber. The reflection and absorption spectra in the frequency range 0.1-10 THz are obtained by applying a transfer-matrix method. The influence of different factors such as the incidence angle, the thickness and the materials of metallic and dielectric layers on the absorption spectrum of our absorber is explored. Finally, we offer a high-efficient photonic-crystal absorber based on Si-Ni with the free spectral range 1.46 THz and the finesse 2.496. The calculations reveal that high enough absorption (99.37%) and reflection (96.77%) can be achieved for our absorber. Therefore, it can be used as both a perfect absorber and a perfect reflector over a wide range of THz frequencies.