Large-Area Plasmonic Switches Based on Crystalline Au Nanoparticles Between VO2 Layers for Enhanced Switching in Visible-Near-Infrared Regime

Vanadium dioxide (VO2) undergoes a reversible phase change, from semiconducting to metallic, with a change in temperature. Herein, plasmonic switchesbased on gold nanoparticles (Au NPs) embedded between layers of VO2 filmsthat exhibit enhanced switching of the optical transmission as the temperature is increased above the VO2 phase transition threshold are presented. The operating wavelength of the switching device can be tuned between 650 and 1000 nm using the localized surface plasmon resonance properties of the Au NPs. This is for the first time that plasmonic switches have been demonstrated in the visible spectral regime (i.e., for wavelengths shorter than 700 nm) when VO2 is employed as the phase change material. A higher switchability, i.e., a higher extinction ratio upon phase transition of VO2, than what has been shown earlier in the spectral regions less than 1000 nm is demonstrated experimentally and theoretically. All the device layers are grown at the same substrate temperature and laser intensity via a single-vacuum pulsed laser deposition process, leading to a simplified largearea fabrication process. It is also shown for the first time that the Au NPs embedded in the proposed Au-VO2 nanocomposites are crystalline.