An amplitude and frequency tunable terahertz absorber

• The absorber can be controlled by Fermi energy level ( E F ) and temperature ( T ). • Coupled-mode theory (CMT), perturbation theory, and the electric field distribution at the resonance point are utilized to verify the authenticity of numerical results. A perfect terahertz (THz) metamaterial absorber (MMA) based on bulk Dirac semimetal (BDS) and strontium titanate (STO) is proposed and numerically analyzed. By integrating two new materials with adjustable dielectric constant in one structure, the performance of this design can be flexibly controlled. The simulation results show that as the Fermi energy ( E F ) of BDS varies from 10 meV to 70 meV, the absorption rate can be tuned from 89% to 100%, with the resonant frequency exhibits a tiny blue shift. Meanwhile, the center frequency can be tuned by varying the temperature of STO from 150 K to 300 K. In addition, the absorption reaches 1 at 0.69 THz when the temperature of STO and E F of BDS are set as 200 K and 30 meV, respectively. The coupled-mode theory (CMT) and perturbation theory are used to explore the reason of perfect absorption and frequency tunable mechanism, respectively. Further research and analysis prove that this designed absorber shows outstanding feature of angular insensitivity. Our work provides a potential guide for designing multifunctional THz devices, such as photodetectors, modulators, sensors, and so on.