Dual-function switchable terahertz metamaterial device assisted by a deep neural network

A dual-functional switchable terahertz metamaterial (THz MM) device with broadband absorption and polarization conversion capabilities is proposed, leveraging the insulator-to-metal phase transition of vanadium dioxide (<i>V</i><i>O</i>₂). In its metallic state, the device functions as an absorber, achieving a bandwidth of 3.93 THz within the frequency range of 2.53-6.46 THz and maintaining an absorption rate of ≥90<i>%</i>. In its insulating state, the device operates as a polarization converter, providing two conversion modes: linear-to-cross-polarization (LTX) over the range of 1.17-3.63 THz, and linear-to-circular polarization (LTC) within the ranges of 1.04-1.14 THz and 3.71-3.87 THz. This study presents a significant advancement over conventional THz devices by overcoming the limitations of single-functionality through innovative design strategies and offering what we believe is a novel approach to multifunctional integration. Leveraging the switchable properties of <i>V</i><i>O</i>₂, the device achieves outstanding performance in both broadband absorption and polarization conversion. Furthermore, deep neural networks (DNNs) significantly reduce the computational time required by traditional optimization methods by efficiently navigating multi-dimensional parameter spaces. DNNs can also capture complex nonlinear relationships between parameters that are often difficult to model with conventional techniques. This highlights the potential of artificial intelligence in the design of functional materials. With these capabilities, the device shows promising applications in fields such as THz stealth technology, energy harvesting, THz communication, polarization imaging, and optical information processing.