Thermally and Electrically Regulated Plasmonic Devices Based on VO2-Covered Gold Nanoplate Arrays with SiO2 Interface Layer for Large Plasmon Shifts

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.