Investigation of 3D Dirac semimetal supported terahertz dielectric-loaded plasmonic waveguides

The tunable propagation properties of 3D Dirac semimetal (DSM)-supported dielectric-loaded surface plasmons structures have been investigated in the THz regime, including the influences of the Fermi level of 3D DSM layer, the fiber shape and operation frequencies. The results indicate that the shape of dielectric fiber affects the hybrid mode significantly, on the condition that if a_x (the semi-minor axis length of the dielectric semi-ellipse) is relatively small, the fiber shows good mode confinement and low loss simultaneously, and the figure of merit reaches more than 200. The propagation property can be manipulated in a wide range by changing the Fermi level of 3D DSM, e.g. if the Fermi level varies in the range of 0.05 eV–0.15 eV, the propagation length changes in the range of 9.073×10³–2.715×10⁴ μm, and the corresponding modulation depth is 66.5%. These results are very helpful to understand the tunable mechanisms of the 3D DSM plasmonic devices, such as switchers, modulators, and sensors.