VO₂-Based metasurface for dynamically tunable terahertz surface plasmonic waves

Abstract

Surface plasmonic waves (SPWs), which propagate along metal-dielectric interfaces, play a pivotal role in various photonic applications such as highly integrated photonic devices, super-resolution imaging, high-sensitivity sensing, on-chip integrated systems, etc. The ability to control the excitation direction of the SPWs is of great importance in these applications. In this work, we propose a terahertz on-chip metasurface device whose SPWs propagation direction can be dynamically tuned at the excitation source by exploiting the vanadium dioxide (VO2). Under circularly polarized light incidence, destructive or constructive interference formed in the subwavelength square ring slit resonators (SRSRs) arrays, resulting in the unidirectional propagation of terahertz SPWs. By adjusting the conductivity of VO2, the flexible control over the propagation direction of SPWs is realized. This approach significantly enhances the level of control compared to previous traditional polarization control method which can only be modulated by the polarization state, marking a notable advancement in the development of functional devices that harness the power of SPWs.