Bifunctional terahertz metamaterial device with switchable properties between transmission and broadband absorption

A bifunctional terahertz metamaterial device with switchable properties between transmission and broadband absorption is proposed. The simulated results show that the switchable functional characteristics of the bifunctional terahertz metamaterial device can be achieved by taking advantage of the phase transition property of VO₂. When VO₂ is in the insulating state, there are transmission spectra with a maximum transmittance of 90 % and a minimum transmittance of 25 % in the frequency range from 1 THz to 10 THz. Meanwhile, transmission spectra be adjusted by controlling the Fermi level of graphene. When VO₂ is in the fully metal state, the broadband absorptivity achieves over 90 % in the frequency range from 2.54 THz to 7.65 THz. Not only that, the absorption spectra can be continuously adjusted by controlling the conductivity of VO₂ from 20 to 200000 S/m. Alternatively, the proposed bifunctional terahertz metamaterial device can work and show the same absorption spectra when the conductivity of VO₂ is 200000 S/m under TM and TE polarized normal incidences. Our current research work has a potential to provide a valuable reference for the advancement of transmissive and broadband absorbent metamaterial devices in the terahertz range.