Tunable terahertz metamaterial absorber and the sensing application

In this paper, a tunable terahertz metamaterial absorber is proposed, and the resonant frequency can be controlled by the variation of temperature and the permittivity. For the top layer of the absorber, which consist of a split ring resonator (SRR), and substrate strontium titanate dielectric layer was filled into the two slits of the SRR. The simulated results show that the absorber has a distinct absorption peak at f = 1.26 THz for T = 300 K, which is close to the calculated resonant frequency f(m) approximate to 1.268 THz, and the absorptivity can achieve 99.93%. To explain the physical mechanism of the absorption, the relative impedance, the surface current and equivalent LC-circuit are analyzed, which could further demonstrate that the magnetic resonant play a major role for the absorption. Moreover, the resonant point will produce a blue-shift with the increase of the temperature, and a red-shift will be appeared with the varying of the permittivity, so that the tunable metamaterial absorber has an application in sensing.