Five narrow bands terahertz metamaterial absorber based on metal and Dirac semi-metal for high sensitivity refractive index sensing

A five narrow bands terahertz metamaterial absorber based on metal and Dirac semi-metal for high sensitivity refractive index sensing is designed in this paper. The absorber is a traditional sandwich structure. And the most remarkable difference is that two hybrid materials (metal and Dirac semi-metal) are used in the top layer. The numerical results show five absorption peaks can be achieved at 5.527, 5.759, 7.247, 9.257 and 10.186THz, among which the perfect absorption achieve at 5.759, 7.247 and 10.186THz, respectively. The physical mechanism of the proposed absorber is analyzed qualitatively and quantitatively by electric field distributions and Couple-mode theory. In addition, the sensing application of the proposed absorber is also studied. The sensitivity of the sensing band can reach up to 3.89THz/RIU by computation. Finally, we design a specific application scenario to ensure the accuracy of the absorber in application through calculation. We believe that the absorber we designed will shine brilliantly in the fields of thermal imaging, thermal radiation and photothermal detection.