Electrically Tunable Fano Coupling in Mie‐Exciton Resonators

Electro‐optical control of spectra at the nanoscale, even at the single‐nanoparticle (NP) level, is crucial in the miniaturization and multifunctionality of optoelectronic devices. Mie resonance‐based dielectric nanostructures provide an intriguing paradigm to boost the light‐matter interaction. This makes them strong candidates for optoelectronic applications. However, achieving narrowband electrical tuning based on a single dielectric NP remains challenging due to the slight change of refractive index caused by carrier injection. Herein, a new type of nano‐resonator is reported to optimize the Mie‐exciton Fano coupling. It consists of silicon (Si) NPs placed on a tungsten disulfide (WS 2 ) /hexagonal boron nitride (hBN) hetero‐nanogap. The image magnetic mode across the hetero‐nanogap generated by Si NPs on the mirror enables effective spatial overlapping with WS 2 excitonic resonance. It also maximizes the electrostatic doping effect on spectral tailoring at the excitonic wavelength. Owing to strong Mie‐exciton coupling, the scattering intensity can be electrically controlled with a modulation depth even larger than that of plasmonic counterparts. Furthermore, Si NPs exhibit much lower heat loss than plasmonic NPs. Importantly, Si NPs on WS 2 /hBN nanogap with broadband colorful scattering but narrowband electrical tuning will act as bi‐functional nanopixels loading dynamic optical signals. This platform has potential applications in information encryption and integrated active optical devices.