Tunable ultra-broadband plasmonic terahertz absorber based on ultrathin phase-change metamaterials†

The paper proposes an ultrathin and tunable ultrawideband plasmonic terahertz absorber based on vanadium dioxide (VO₂) phase transition metamaterials, with a thickness of only 5.98 micrometers, to address the current issues of insufficient frequency tunability and limited bandwidth coverage in terahertz absorbers. The absorber features a multilayer composite structure consisting of a bottom Au metal layer, a SiO₂ dielectric layer, a VO₂ layer, an upper SiO₂ layer, and a patterned VO₂ layer on the surface. Simulation results show that the absorber achieves over 90% absorption ranging from 6 to 24 THz (a bandwidth of 18 THz), and nearly perfect absorption at 20.00 THz, covering a wide terahertz frequency range. By adjusting the phase state of VO₂, the absorption characteristics are tunable, and the device is insensitive to both TE and TM polarizations. The designed absorber combines the advantages of ultrawideband, high performance, tunability, and miniaturization, making it suitable for enhancing terahertz communication technology, optimizing high-resolution imaging, and applications in high-precision sensing, providing strong support for the development of related technologies.