Vanadium dioxide-based ultra-broadband metamaterial absorber for terahertz waves

An ultra-broadband, polarization-insensitive terahertz metamaterial absorber based on vanadium dioxide reso-nance structure is proposed in this paper. The device boasts advantages such as a straightforward design, broad absorption bandwidth, and substantial fractional bandwidth. Numerical simulations show that vanadium dioxide enables the absorber to achieve near-perfect absorption (with a rate greater than 95%) in its metallic state. It demonstrates an average absorption rate exceeding 96.5% across an ultra-broadband range (4.02 THz to 11.95 THz). The absorption bandwidth reaches 7.93 THz, with a relative bandwidth of 99.3%, representing a notable improvement over comparable absorbers. Furthermore, due to its highly symmetric pattern design, the device exhibits excellent polarization insensitivity and maintains stability even within a wide incident angle range. The operational mechanism of the absorber is elucidated through the application of impedance matching theory and near-field distribution analysis. The designed absorber structure makes vanadium dioxide materials more widely applicable in terahertz and ultra-broadband absorber devices, holding promising application prospects in fields such as security imaging, energy harvesting, and so on.