Speaker
Description
In recent years, there has been much research focusing on tunable plasmonic structures and metamaterials for dynamic nanoscale control of electromagnetic radiation. The response of plasmonic structures is highly dependent on factors set during the fabrication process, including the size, shape, and material composition. The inability to tune the optical response of such structures post fabrication is a limiting factor in the implementation of metamaterials in various optoelectronic applications. To overcome this, we present tunable plasmonic elements comprising noble metal nanostructures on a thin film of vanadium dioxide (VO2), a phase change material. VO2 is an attractive option as a phase change material due to its large, reversible transition from a monoclinic semiconducting to a metallic rutile phase at a critical temperature of 68oC, a temperature significantly closer to room temperature than competing phase change materials. In addition to the thermal actuation, the phase transition can be triggered by an electric field of the order 106 V/m, significantly lower than other material options such as GST and AIST, making our hybrid nanostructures ideal candidates for low power consumption applications. While much previous research focuses on the large change in dielectric function seen in the IR upon the phase transition, the changes in the dielectric function in the <1µm spectral range allow a significant shift in plasmonic response of coupled nanoparticles. Upon the phase change of the VO2 thin film from a semiconducting to metallic phase, plasmon resonance blue shifts of up to 250nm can be seen. Additionally, the modification of the plasmonic response allows for dynamic control of the photoluminescence (PL) of coupled emitters. The emission enhancement for the coupled emitter-nanoparticle systems for the metallic VO2 phase is seen to compensate for the thermally induced luminescence quenching above the VO2 critical temperature.
| Speaker Country | Ireland |
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