Tunable plasmonic filter based on parallel bulk Dirac semimetals at terahertz frequencies.

A plasmonic bandpass filter based on parallel bulk Dirac semimetals (BDSs) is proposed and numerically investigated using the finite-difference time-domain method. The proposed filter is realized by the evanescent coupling between the resonator and waveguide, and Fabry-Parot resonant theory is used to analyze its realization mechanism. The performance of the filter can be tuned by changing the coupling distance, length of the resonator, and Fermi levels of the BDSs. We further simulate a plasmonic broadband filter using coupling mode splitting by locating two identical resonators along the waveguide direction. The pass band of the proposed broadband filter can be tuned by adjusting the coupling distances between the resonators and waveguide.