Deep neural network-based ultra-wideband to multi-narrowband switchable terahertz metamaterial absorber

This paper introduces a reconfigurable terahertz metamaterial (THz MM) perfect absorber supported by deep neural networks (DNNs). The device achieves both ultra-wideband (UWB) absorption and multi-narrowband perfect absorption by leveraging the phase-transition properties of vanadium dioxide (VO 2 ). Specifically, when VO 2 is in its metallic state, the device functions as a UWB absorber in the range of 3.77–9.5 THz, with an absorption rate exceeding 90% and a relative bandwidth (RBW) of 86.36%. Conversely, when VO 2 is in its insulating state, the device switches to a quadruple narrowband absorber, with absorption peaks exceeding 90% at frequencies of 3.376, 4.4075, 4.455, and 4.53 THz. The absorption mechanisms are explained through impedance matching and electromagnetic field distribution theories. Additionally, both the quadruple narrowband and wideband absorption modes exhibit strong polarization insensitivity and wide-angle incidence tolerance. Overall, this device offers excellent absorption performance, enabling mode switching and dynamic adjustment of absorption characteristics across modes to meet diverse functional requirements. This research has broad applications in 6G communications, integrated photonics, optoelectronic sensors, optical polarization control devices, and biomedical diagnostics, providing an effective strategy for the design of multi-functional THz devices.