Multifunctional Metamaterial for Asymmetric Transmission and Perfect Absorption in Terahertz Region

A multifunctional terahertz metamaterial is proposed for achieving asymmetric transmission (AT) and broadband absorption, leveraging the phase transition property of vanadium dioxide (VO₂). By manipulating the phase state of VO₂, the metamaterial demonstrates switchable functionalities across distinct frequency ranges. When VO₂ is in its insulating state, within the frequency range of 1.15–1.88 THz and the incident angle range of 0–12°, the AT efficiencies are all above 0.6, exhibiting wideband AT characteristics. Additionally, polarization conversion is achieved during transmission in the terahertz regime. When VO₂ transitions to its conducting state, the metamaterial operates as a broadband perfect absorber, achieving absorptance exceeding 90% for both y- and x-polarized waves within the frequency range of 2.5–3.3 THz. The electric field and surface current distributions are presented to elucidate the underlying physical mechanisms. Moreover, the influence of structural parameters and angular tolerance have been comprehensively investigated. This proposed metamaterial offers a promising platform for developing multifunctional terahertz devices.