Dual function tunable THz metamaterial device possessing broadband absorption and polarization conversion

Abstract

Based on the phase transition properties of vanadium dioxide (VO2), a novel tunable metamaterial device with functions of broadband absorption and broadband polarization conversion is constructed. The proposed structure operates in the broadband absorption mode when the VO2 is in the metallic state. The simulation results demonstrated that the absorbance can achieve more than 90% with a relative bandwidth of 76.9% in the frequency range of 1.80-4.05THz. When VO2 is in the insulating state, the proposed structure operates in the broadband polarization conversion mode. In the frequency range of 1.68-3.79THz, it can efficiently convert the incident linearly polarized terahertz (THz) wave into its cross-polarized state. The polarization conversion ratio (PCR) is above 90% and the relative conversion bandwidth is larger than 77.1%. Furthermore, for the two operating modes, it has acceptable tolerance of incident angles and polarization angles. These advantages make the proposed VO2-based dual-functional metamaterial device have potential applications in many THz areas, such as absorption, polarization conversion, imaging, and so on.