Designing high-Q Fano resonance structures for enhancing fluorescence in all-dielectric metasurfaces

Highly sensitive fluorescence detection technology is crucial for biological sensing, imaging, and photonic technologies. The fluorescence enhancement effect with the same enhancement factor at multi-wavelengths is important for highly sensitive detection. However, achieving multi-wavelength fluorescence enhancement remains challenging. Here, we introduce an all-dielectric metasurface composed of symmetry-broken silicon nanocylinders integrated with graphene, which is designed to significantly enhance and dynamically modulate the fluorescence emission of a single quantum dot. By fine-tuning structural parameters and adjusting the graphene Fermi level, we achieve a tunable high-Q Fano resonance, leading to a nearly 4000-fold fluorescence enhancement. Structural parameter adjustments enable consistent fluorescence enhancement across different wavelengths. Furthermore, at specific wavelengths, fluorescence enhancement can be similarly adjusted. The proposed structure can greatly expand the design strategy of heterogeneous all-dielectric metasurfaces with the same enhancement factor at multi-wavelengths.