3D Dirac semimetals supported tunable hybrid plasmonic terahertz waveguides with a dielectric wedge

A novel design of tunable hybrid plasmonic waveguide in the terahertz (THz) regime is present based on three-dimensional Dirac semimetals (3D DSM) with wedge-shaped structure. The propagation characteristics at a broad band from 0.5 THz to 3.3 THz are systematically investigated considering the structural parameters and Fermi energy of DSM, in terms of the normalized mode area, propagation length, figure of merit, and mode field distributions. By tuning the Fermi energy of DSM from 0.03 eV to 0.15 eV, the propagation length of the hybrid plasmonic waveguides could be effectively modulated with a modulation depth more than 95%. The crosstalk between adjacent waveguides is evaluated by analyzing the symmetric/anti-symmetric modes coupling process, which demonstrates the effective crosstalk suppression requires a minimum center-to-center separation of 60 μm. These results not only provide valuable insights for understanding the propagation mechanism of 3D DSM hybrid plasmonic waveguides, but also open new avenues for the applications of tunable and broadband THz waveguides devices.