Ultra-fast terahertz optical switch based on metal vanadium dioxide

Abstract 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 (VO 2 ) to address these challenges. The switch is composed of a VO 2 layer, a dielectric spacer, and a gold plasmonic film. The ultrafast insulator-to-metal phase transition of the VO 2 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 VO 2 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 VO 2 -based optical switches for advanced terahertz optical communication and signal processing applications.