A temperature-controlled switching terahertz perfect absorption device based on a VO2 phase change metamaterial

Abstract

In this paper, we design and study a temperature-controlled switchable terahertz perfect absorber based on vanadium dioxide (VO₂), which shows excellent multi-band performance, high sensitivity and intelligent thermal management. The device consists of four layers in a metal–dielectric composite structure, which are a metal reflection layer, silicon dielectric layer, VO₂ phase change layer and top metal pattern layer from bottom to top. The simulation results show that when VO₂ is in the low-temperature insulation state, the absorption rate of the device is as high as 99.3%, 98.5%, 99.5% and 92.6% at four frequencies of 1.98 THz, 5.50 THz, 7.63 THz and 9.14 THz, respectively. When the temperature rises to 345 K, the VO₂ phase transitions to the metal state. At this time, the average absorption rate of the device is less than 7%, showing obvious high terahertz reflection characteristics, thus realizing dynamic switching between absorption and reflection states. The absorber has the advantages of a simple structure, easy preparation, polarization independence and excellent temperature control adjustability. At the same time, combined with impedance matching theory and electromagnetic field distribution, it is revealed that the mechanism of perfect absorption of the absorber mainly comes from the synergistic effect of various resonance modes. Finally, the calculation shows that the device has a very high response to changes in the environmental refractive index, and the maximum refractive index sensitivity is as high as 1137 GHz per RIU, showing good sensing potential. On the whole, the device has broad application prospects in the fields of intelligent detection, thermal management, terahertz regulation and high-performance sensing.