Vanadium dioxide-based active metasurfaces: a nanophotonics platform for manipulating light via control of Mie and quasi-bound states in the continuum resonances

Metasurfaces (MSs), structures which are tailored artificial arrays of metallic or dielectric nanostructures, are a promising approach for controlling light propagation and its properties, like amplitude and/or phase distribution in space. Active (or tunable) MSs allow to control light not only in space, but also in time. One strategy to achieve tunability of MSs is to use phase change materials (PCMs), like vanadium dioxide (VO₂), among their constituents. By changing a critical parameter, as temperature, the PCM dielectric function suffers drastic variations, which may strongly alter the MS's light extinction properties. Two kinds of specially designed MSs employing VO₂ are discussed in this work. One, fully composed of VO₂ nanodisks on a glass substrate, presents Mie resonances in the visible while the other, composed of pairs of tilted elliptical pillars made from Si supporting a thin layer of VO₂ capped by SiO₂, show quasi-Bound States in the Continuum resonances in the Mid-IR. We demonstrate that these resonances can be continuously modulated in their amplitude by factors of at least ~3 dB, representing a relevant approach for dynamically controlling light-matter interaction on nanoscale.