Numerical study of nanochannel on a silicon-silver dimer gap for significantly enhanced fluorescence

The metal-dielectric dimer is an ideal structure for enhancing single-molecule fluorescence. When a single-molecule interacts with the metal-dielectric dimer, the metal-dielectric plasmonic system creates strong resonance, which amplifies the electric field by several orders of magnitude. One-dimensional photonic crystals (1D PCs) provide a photonic bandgap (PBG) and nearly perfect reflection for specific wavelengths. These phenomena contribute significantly to fluorescence enhancement. Herein, we propose the structure of 1D PCs with a silicon-silver dimer to achieve remarkable fluorescence enhancement under numerical study. Specifically, our design involves a 20 nm gapped silicon-silver dimer with a 50 nm nanochannel positioned above it. Through the optimization of structural parameters, our results demonstrate that quantum dots with a high intrinsic quantum yield, such as 100 %, are capable of achieving a fluorescence directional emission enhancement of up to three orders of magnitude compared to the bare structure, with an average enhancement factor reaching 407-fold. These findings stand for the unique sensitivity of the device, making it a promising choice for applications in biological nanoparticle detection, environmental monitoring, and other fields in the future.