Tunable ultra-sensitive four-band terahertz sensors based on Dirac semimetals

This article presents a classic three-layer structure terahertz four-band absorber that is composed of Dirac semimetals (BDS) and silica. By regulating the Fermi energy of the Dirac semimetals, it becomes possible to adjust the frequency of the absorption peaks of the absorber. Specifically, when a Fermi energy of 50 meV was chosen for the Dirac semimetal, four absorption peaks were generated within the 4-8 THz range, and all of these peaks boasted absorption rates exceeding 95 %. Firstly, the structural characteristics of the absorber were introduced, and its feasibility was demonstrated by relying on the impedance matching theory. Subsequently, the variations in the electric field on the surface of the absorber were investigated through the application of the Local Surface Plasmon Resonance (LSPR) theory. Moreover, by modifying the structural parameters, it was found that the absorber possesses excellent physical tuning capabilities. After exploring how changes in the environmental refractive index influence the device's functionality, it was also discovered that the absorber shows remarkable sensitivity to the refractive index, reaching 1840 GHz/RIU. This makes it a highly promising candidate for sensing applications. In conclusion, the design of this absorber offers a novel approach for tunable terahertz metamaterial absorbers, which holds great significance in various fields like detection and sensing.