Tri-functional metamaterials integrated with vanadium dioxide in terahertz regions

Abstract

In this paper, we theoretically and numerically demonstrate a vanadium dioxide (VO2)-based metamaterial device with triple functionalities in the terahertz region. By altering the phase transition characteristic of VO2, broadband perfect absorption and asymmetric transmission (AT) can be switchable obtained in a wideband frequency regime. When VO2 operates in the conducting state, the designed metamaterial acts like a polarization-dependent broadband perfect absorber. The absorbance is above 95% for x-polarized lights in the frequency range from 5.2 to 7.1 THz, while the absorbance is as low as 20% when the polarization is along the y-axis. When VO2 serves in the insulating state, the designed metamaterial device exhibits an AT effect with efficiency ∼0.72 in terahertz regions. Moreover, broadband polarization conversion associated with the asymmetric transmission can be achieved in the terahertz region. The electric field distributions combined with the current vectors are introduced to explore the physical mechanism. Besides, the performance of proposed metamaterial can be adjusted by altering the structural parameters. This designed metamaterial may have potential applications in exploring optoelectronic devices, such as optical switching, optical diode and thermal emitters in THz frequencies.