Dual-functional metamaterial with ultra-broadband polarization conversion and narrowband absorption based on vanadium dioxide

Abstract

In this paper, a three-dimensional dual-functional metamaterial (MM) is proposed. The polarization conversion part is entirely composed of vanadium dioxide (VO2), and the absorption part is composed of graphite and silica materials. By regulating the phase transition characteristics of VO2, the switching between dual-functional polarization conversion and absorption is realized. Through simulation and theoretical calculation, when VO2 is in the metallic state, the anisotropic polarization converter composed of VO2 plays a major role. In the frequency range of 0.67–1.99 THz, more than 90% linear polarization conversion rate (PCR) is obtained, and its relative bandwidth (RB) reaches 99.3%. The formation mechanism of broadband polarization conversion is explained by conducting current distribution. However, when VO2 is in dielectric state, the absorptance is nearly to 100% at 1.6 THz, and the formation mechanism of absorption is also explained by the distribution of electric and magnetic fields on the surface. The design of the two functions is carried out independently, and the reconfiguration and tuning of the two functions does not affect the working frequency band of the other function, thus achieving functional isolation.