Thermally and Electrically Regulated Plasmonic Devices Based on VO₂-Covered Gold Nanoplate Arrays with SiO₂ Interface...

Integrating metal nanoparticles with vanadium dioxide (VO₂) is an effective means to realize active plasmonic regulation which has great application potential in optical devices that respond in real-time to external stimuli. However, the high temperature necessary for VO₂ growth severely reshapes the metal nanoparticles, causing reduced refractive index (RI) sensitivity and degraded modulation performance. Herein, we construct a large-area dynamically tunable plasmonic system composed of a VO₂-covered array of hexagonal gold nanoplates (AuNPLs). By introducing a SiO₂ interface layer, the thermal tolerance of the AuNPLs is effectively improved, making the high RI sensitivity (∼368.3 nm/RIU at 855 nm) survive the subsequent VO₂ deposition. Through tuning the localized surface plasmon resonance (LSPR) of the AuNPL array and the thickness of the VO₂ film, the LSPR-related transmission dip can be tailored to the near-infrared region where VO₂ shows a large two-phase RI contrast, a dip shift up to 272 nm is therefore realized upon VO₂ phase transition. Furthermore, electro-optic modulation is demonstrated through electrically triggered VO₂ partial phase transition which is accompanied by a gradually changed effective dielectric permittivity, and a continuous shift of the transmission dip from 1070 to 860 nm is achieved by varying the applied electrical current flowing through the film. This work provides a feasible route for controllably constructing stimuli-response optical devices with large wavelength modulation amplitude.