Active tuning of Mie resonances to realize sensitive photothermal measurement of single nanoparticles†
High-index all-dielectric nanostructures with Mie-type resonances have promising applications in building optical nanodevices and metasurfaces. Very recently, great efforts have been made to explore the effective active tuning of Mie-type magnetic resonances via applied voltages, heating, etc. for more sensitive optoelectronic and photothermal applications. Here, we constructed a new platform containing vanadium dioxide (VO2) films and tungsten disulfide (WS2) flakes to realize distinctive active tuning of the collective Mie resonances from silicon nanoparticle (Si NP) clusters and measure the resonance-enhanced local heating precisely. Through increasing the thickness of WS2, we found new type active spectral evolution with high sensitivity during the phase change of VO2. The temperature increase caused by local heating of different Si NP clusters can be determined through both scattering and photoluminescence (PL) measurements with the best thermal resolution less than 1 °C. The proposed platform provides a new way to enhance the active tuning of Mie resonance and detect the local heating sensitively. More importantly, we propose a new mechanism for measuring the photothermal effects of single dielectric nanoparticles for future energy and biomedical applications.