Thermally Tunable Terahertz Smart Window Based on VO₂ Phase Change Material with Broadband Absorption and Ultrabroadband Transmission

Abstract

Metamaterial absorber devices that can both achieve broadband control and be adapted to the mid-To achieve dynamic and intelligent regulation of terahertz waves, a terahertz smart window device with a sandwich structure based on (VO₂) phase change material was designed. The top layer of VO₂ is etched into an axisymmetric square array microstructure. The thermal-induced insulator-metal phase transition process of VO₂ was simulated, and the absorption, reflection and transmission characteristics of the device were obtained through simulation. The effects of temperature, polarization direction, structural parameters and incident angle on the electromagnetic performance of the device were systematically investigated, and the intrinsic physical mechanism of absorption and transmission of the device was revealed at the same time. The results show that the device realizes dynamic switching between terahertz wave absorption and transmission by relying on the reversible phase transition of VO₂. In the low-temperature insulating state at 328 K to 333 K, it achieves a transmission rate exceeding 80% and a bandwidth of 12.1 THz for ultra-wideband transmission. In the high-temperature metallic state at 342 K to 345 K, it achieves an absorption rate exceeding 90% and a bandwidth of 6.47 THz for wideband absorption. The polarization-independent absorption and transmission characteristics of the device are attributed to the consistent electromagnetic response brought by the axisymmetric microstructure design. The synergistic effect of LSPR and CR at high temperatures is the core mechanism for achieving high absorption in the device, while the all-dielectric structure at low temperatures ensures efficient transmission of terahertz waves. In addition, the device exhibits strong tolerance to processing deviations in key structural parameters and retains superior angular stability when the incident angle is in the range of 0° to 60°., and can achieve on-demand regulation of absorption performance by fine-tuning the structural parameters. This device possesses the advantages of thermal adjustable switching, strong environmental adaptability, and high manufacturing fault tolerance. It provides important structural ideas and theoretical references for the design and practical application of terahertz intelligent window devices.