Multiband switchable terahertz vanadium dioxide-GeTe hybrid metasurface

Abstract

We proposed a multi-band switchable terahertz metasurface based on vanadium dioxide (VO2) and the chalcogen phase change material (GeTe). By controlling the phase transition of VO2 and GeTe, the operation function of the metasurface can be switched among linear-to-linear polarization converter, linear-to-circular polarization converter, and bandstop filter. The results show that the metasurface works in linear-to-linear polarization conversion mode as the VO2 is in insulating state (at 25°C). The polarization conversion rate (PCR) is more than 90% within 3.50-3.55 THz and 3.81-4.29 THz. When the VO2 is in the metallic state, it becomes a linear-to-circular polarization conversion mode. The normalized ellipticity is -1 in the range of 2.65-3.60 THz. While the GeTe is transitioned to the crystalline state, the structure operates as terahertz bandstop filter with 3 dB band-stop bandwidth of 355 GHz. Furthermore, the working principle of the proposed metasurface is analyzed by electric field distribution. Based on these characteristics, the proposed metasurface is expected to be used in various terahertz systems.