Visualization of Plasmon-Exciton Interactions by Scanning Near-Field Optical Microscopy

The electronic properties of a substance are perturbed by interactions of elementary excitations. The optical properties of the interacting states have been extensively studied and revealed to be correlated with the eigenfunctions of the isolated systems. On the other hand, the spatial characteristics of the states have been little studied because of the diffraction limit of light. In this study, we examine plasmon and exciton interactions in silver nanoplate and organic J-aggregate hybrid structures using scanning near-field optical microscopy. We reveal that the light transmission is enhanced when the plasmon and exciton resonantly interact with each other. We visualize the spatial distribution of the interacting states and find that the interaction of the high-order plasmons with the exciton enables manipulation of the electronic states in a spatially resolved manner. This study demonstrates that the optical field can be spatially controlled via coupling of the elementary excitations.