Dual-controlled tunable terahertz coherent perfect absorption using Dirac semimetal and vanadium dioxide

We proposed and investigated a dual-controlled broadband tunable terahertz metamaterial coherent perfect absorber based on Dirac semimetals and vanadium dioxide (VO2). In such an absorber, the absorptivity at 2.75 THz can be varied between 0.13% and 99.4% by adjusting the phase difference between the incident waves. When VO2 is in the insulating state and Fermi energy (E-F) of the Dirac semimetals is 95 meV, the proposed device behaves as a tunable perfect single-band absorber. Further, the resonance frequency of the proposed absorber shifts from 1.46 THz to 1.86 THz by varying E-F of the Dirac semimetals from 90 to 110 meV. Therefore, with the transition of VO2 from the insulator to metal state, the designed system functions as a tunable perfect dual-band absorber. Furthermore, by using these two independent controls in series, broadband absorption with an absorption rate greater than 90% can be obtained.