Simulation study on ultra-wideband and ultra-narrowband switchable terahertz metamaterial absorbers based on deep neural networks

Supported by deep neural networks (DNNs), a simulation study on an ultra-wideband (UWB) to ultra-narrowband (UNB) switchable terahertz metamaterial absorbers (THz MAs) was designed and optimized. By leveraging the phase transition properties of vanadium dioxide (VO 2 ), the device achieves nearly perfect absorption, switching between UWB and UNB modes. Finite element analysis was used to simulate and analyze the constructed model. Simulation results indicate that when VO 2 is in its metallic state, the device functions as a UWB absorber with an absorption bandwidth of 11.54 THz over the 3.88–15.42 THz range, achieving an absorption rate exceeding 90% and a relative bandwidth (RBW) of 119.6%. When VO 2 is in its insulating state, the device switches to a UNB absorber, reaching an absorption rate close to 100% at 13.927 THz. In this state, material detection was conducted, revealing that the device has a maximum refractive index sensitivity ( S ) of 0.33 THz/RIU and a corresponding quality factor ( Q ) of up to 515.8, enabling high sensing functionality. Its absorption performance is insensitive to TE and TM polarizations. Additionally, the effects of incident and polarization angles on the operating characteristics were studied. The proposed absorber demonstrates excellent polarization insensitivity, angle stability, and UWB and UNB advantages, offering valuable insights for new multifunctional THz device research. It holds significant application potential in short-range wireless THz communication, ultra-fast optical switching, sensing, transient spectroscopy, and electromagnetic stealth.