A terahertz band multifunctional metamaterial transmission-absorption switching device based on vanadium dioxide

In this paper, a vanadium dioxide (VO₂)-based terahertz device is proposed to realize the conversion between broadband absorption and broadband transmission functions, including the VO₂ bottom layer, dielectric layer and VO₂ pattern layer in a three-layer structure. With the change of the VO₂ conductivity, the terahertz metamaterial device can switch between broadband absorption and broadband transmission. When the device exhibits broadband transmission, it has a high transmittance of 90% for terahertz waves in the 5.6 THz to 8.7 THz frequency band. When the device exhibits broadband absorption, it has a high 90% absorption of terahertz waves in the 3.66 THz to 9.98 THz frequency band. Furthermore, with increasing VO₂ conductivity, the peak transmittance of the device decreases from 93.8% to 0% and the absorption increases from 1% to 99.5%. The impedance matching theory is invoked and the physical mechanism of the device is elucidated by analyzing the surface electric field of the device. By studying the absorption characteristics for different incidence and polarization angles, the device is insensitive to polarization and has good absorption performance over large incidence angles. Compared with other absorbers of terahertz metamaterials, the device structure proposed in this study has a unique design and diverse functions and can play an important role in various fields such as communications, electromagnetic stealth, sensors, and thermal emission devices.