Dynamic radiative tailoring based on mid-refractive dielectric nanoantennas

Abstract

Nanoantennas built by dielectric high-refractive index materials have drawn more and more attention. All-dielectric nanostructures with low loss and strong magnetic resonances are being explored based on various designs and materials. Silicon nanocavities as the most typical dielectric Mie resonators show a wide range of applications in nanophotonics and metamaterials. However, how to effectively engineer the resonant modes and how to dynamically tailor the spectrum still need to be studied. Here, we proposed mid-refractive dielectric nanostripes as a new kind of Mie resonator which can realize effective coupling between electric and magnetic resonant modes. Vanadium dioxide (VO₂) was chosen to build a typical mid-refractive nanoantenna, and comparable scattering intensity and stronger scattering directivity can be obtained compared with silicon nanoantennas. When changing the temperature, the Mie resonance in an individual VO₂ nanostripe changes because of the transformation of both the refractive index and extinction coefficient. Additionally, the active control of the photoluminescence (PL) intensities is realized owing to the interaction between VO₂ nanostripes and tungsten disulfide (WS₂) flakes. These findings suggest that mid-refractive dielectric nanoantennas with active tuning features will become an important building block of active photonic devices in the future.