A dynamically switchable and tunable metamaterial device based on vanadium dioxide and Dirac semimetal

In this paper, a dual-function metamaterial device based on vanadium dioxide (VO₂) and Dirac semimetal (DS) operating in terahertz (THz) frequency range is designed. The reversible phase transition properties of VO₂ are exploited to achieve the dynamic switch between the function of broadband absorption and broadband polarization conversion. It is demonstrated that when VO₂ is in the metallic state and the Fermi energy level ($E_f$) of DS is set to 30 $\text{meV,}$ the broadband absorption in the operating frequency range of 1.42–3.40 THz can be achieved, and its absorbance exceeds 90 % with a relative bandwidth of 82.16 %. When VO₂ is in the insulating state and the $E_f$ of DS is set at 180 $\text{meV}$, the high efficient broadband polarization conversion can be obtained in the operating frequency range of 2.08–4.88 THz and the polarization conversion ratio (PCR) is greater than 90 % with a relative bandwidth of up to 80.46 %. Therefore, the proposed switchable dual-functional THz device can be extensively utilized in absorption, polarization conversion and other potential fields.