A subwavelength terahertz plasmonic waveguide based on bulk Dirac semimetal (BDS)-insulator-metal (BIM) structure is investigated, which indicates that there is an optimized frequency range with the better confinement as well as lower loss. A broadband mode confinement up to λ0/15 with a relatively low loss of 1.0 dB/λ0 can be achieved. We also show that two silicon ribbons introduced into the BIM waveguide can form a dynamically tunable filter tailoring terahertz surface plasmon polaritons in deep-subwavelength scale, which can be further exploited for the design of ultra-compact THz plasmonic devices with dynamical tunability. Our results may also provide potential applications in optical filtering.
Keywords: Dirac semimetals; Nanoparticles; Optical materials and properties.