Vanadium-dioxide-assisted multifunctional switchable terahertz metamaterial devices

A multifunctional, switchable terahertz (THz) metamaterial (MM) device with wideband absorption and polarization conversion capabilities has been developed, based on the insulator-metal phase transition of vanadium dioxide (VO 2 ). In its metallic state, the device operates as a wideband absorber within the range of 2.56–6.74 THz, achieving a bandwidth of 4.18 THz and an absorption rate of ≥90%. The wideband absorption is insensitive to both oblique incident angles and polarization. When VO 2 is in its insulating state, the device switches to a polarization converter, facilitating linear-to-cross polarization (LTX) conversion between 1.04 and 4 THz, and linear-to-circular polarization (LTC) conversion between 1 and 1.04 THz, with a conversion efficiency exceeding 90%. Additionally, the effects of incident angle and polarization angle on the device’s performance were analyzed. This THz device offers advantages of wide angle, wide bandwidth, and high efficiency, making it a valuable reference for research into new multifunctional THz devices. It has great potential applications in short-range wireless THz communication, ultrafast optical switches, high-temperature resistant switches, transient spectroscopy, and optical polarization control devices. In specific application scenarios, particularly in fields requiring efficient detection, transmission, and analysis—such as security and non-destructive testing, secure communication systems, imaging and sensing, multidimensional spectral analysis, pollutant detection, smart stealth coatings, dynamic optical control devices, and integrated optical systems—these devices offer multifunctional capabilities. They enhance system performance and flexibility, meeting diverse application needs.