Photoluminescence enhancement by propagating surface plasmons confined in microresonators.

A number of studies of light-emitting devices have aimed to improve the luminescence efficiency, but the luminescence is affected by the presence of a metal layer. This is because electromagnetic waves propagating along the surface of a flat metal layer (or surface plasmon polaritons [SPPs]) generally deactivate excitons in emissive materials into the ground states. To overcome this problem, we propose a way of converting the deactivating character of SPPs into the opposite character to enhance the photoluminescence (PL). To achieve the PL enhancement, we localized SPPs to generate their standing waves in a whispering gallery mode microresonator. The standing waves were exploited to produce resonance between the oscillated electromagnetic fields of the SPPs' standing waves and the transition dipoles of excitons so that the excitons can efficiently emit PL.