Tunable strong plasmon-exciton coupling between single silver nanocube dimer and J-aggregates

In this paper, single silver nanocube dimer with nanometer-sized gap is designed and numerically simulated. We demonstrate that the electric fields can be highly confined in the gap of nanocube dimer, leading to ultrasmall mode volume of approximate to 2 x 10(-7) mu m(3). Furthermore, the strong plasmon-exciton coupling in single nanocube dimer coupled with J-aggregate molecules is investigated using coupled oscillator model and we show that the strong plasmon-exciton coupling can be tuned by changing the background refractive index and the concentration of J-aggregate molecules. The tuning of dual strong plasmon-exciton couplings between single rounded silver nanocube dimer and J-aggregate molecules is also investigated, and dual strong couplings can be achieved closely approaching the quantum optics limit benefiting from the ultrasmall mode volume of the proposed system. The proposed systems can be easily prepared and have high experimental feasibility, which has potential applications in integrated nanophotonics such as sensing and all-optical switches.