Controlled emission and coupling of small-size YAG:Ce³⁺ nanocrystals to gold nanowire

We report a controlled emission of Ce³⁺ ions inside single Yttrium Aluminum Garnet $Y3Al5O12$ (YAG:Ce³⁺) nanocrystals with a diameter of 22 ± 10 nm as a result of a coupling of a surface plasmon mode propagating along single gold nanowire (NW). From the photoluminescence images, the intensity for single YAG:Ce³⁺ nanocrystals in the proximity of the single gold NW increases by a factor of two in comparison with that without the NW. Also, we observe a maximum of 3.8-fold emission rate enhancements for the single nanocrystal close to the single gold NW. The emission rate enhancements of YAG:Ce³⁺ nanocrystals are two folds the enhancements of 100-nm fluorescent nanospheres. This value is in agreement with the calculation of a combination from the analytical scattering model and boundary element method. We also confirm that the small size light sources are more efficient for the emission rate enhancements. Thus, the controlled emission of small YAG:Ce³⁺ nanocrystals with the perfect photostabilities will pave the way for the ultimate efficient nanoscale light sources.