Ultra-fast terahertz optical switch based on metal vanadium dioxide

The performance of optical switches in optical systems is often constrained by the material's limited response speed and tunable range. In this study, we propose a novel terahertz optical switch based on vanadium dioxide (VO2) to address these challenges. The switch is composed of a VO2 layer, a dielectric spacer, and a gold plasmonic film. The ultrafast insulator-to-metal phase transition of the VO2 layer facilitates precise modulation of the coupling between surface plasmon modes and incident electromagnetic waves. Through comprehensive time-domain and frequency-domain analyses, the ultrafast response time of VO2 was experimentally validated. The results demonstrate near-perfect absorption (99.99%) and an exceptionally high modulation depth of absorption efficiency (99.92%) during the phase transition. Furthermore, the reflectivity of the switch dramatically changes from -0.38 dB to -23.3 dB, achieving a switching ratio of 22.92 dB. These findings highlight the potential of VO2-based optical switches for advanced terahertz optical communication and signal processing applications.