Enhanced Single-Molecule Spontaneous Emission in an Optimized Nanoantenna with Plasmonic Gratings

摘要

In this study, we theoretically investigated the single-molecule fluorescence enhancement in a slit-groove structure. The excitation field enhancement, modified quantum efficiency, collection efficiency, and position dependence of a single-molecule spontaneous emission coupled to a plasmonic antenna are explored together. Simulation results revealed that the metal gratings play a crucial role in strengthening the local electromagnetic field enhancement in the excitation process and beaming the radiation light into a tiny angular volume in the emission process, whereas the total radiative decay rate and quantum efficiency are mainly determined by the slit cavity. Our findings provide an intuitive guideline to further optimize the plasmonic antenna for single-molecule detection and the results make a promising route to the development of photonic devices for the manipulation of single-molecule spontaneous emission.