3D Dirac semimetal rectangular quad-hole array supported tunable THz extraordinary transmission

Based on 3D Dirac semimetal (3D DSM) subwavelength rectangular quad-hole arrays, the tunable propagation properties have been investigated in the THz region, including the effects of asymmetric parameters, 3D DSM Fermi levels, and different dielectric filling materials. If the right double apertures are displaced along the x direction, an obvious transmission dip (reflection peak) is observed, and the amplitude modulation (MD) of the transmission dip (reflection peak) reaches 90.8% (87.5%) if the shift distance changes in the range of 3–20 µm. With the help of the 3D DSM layer, the resonance curves can be modulated efficiently; the MD amplitude of the transmission dip (reflection peak) reaches 66.7% (32.7%) when the Fermi level changes in the range of 0.01–0.15 eV. By filling the right sections of the hole arrays with different refractive index media, the intensity of the resonant curves is significantly affected. As the value of the refractive index of the dielectric filling material increases, the dip amplitude of the transmission curve is varied in the range of 0.793–0.132 with a maximum MD of 83.4%. These results demonstrate significant potential for the development of THz functional devices, such as filters, switchers, and modulators.