Plasmon-Exciton Coupling in Complex Systems

In recent years, optical properties of the complex systems involving both metal plasmons and molecular/semiconductor excitons have attracted great attentions due to their rich and varied optical characteristics. In this type of hybrid systems, the plasmon plays a role to drastically enhance the coupling between the system and external field, while the exciton plays a role to control the detailed spectral properties, providing tempting avenues for manipulating new optical control beyond what can be achieved using either of the components. In addition to the mutual coupling between the plasmon and exciton, their different linewidths and the abilities to couple with external field provide a variety of control handles to tune the optical properties of the hybrid systems. It thus allows to precisely manipulate light on the nanometer-scale, opening up opportunities for novel sensing, light-emitting, and photovoltaic devices. Here, the recent progress in both theoretical and experimental developments is reviewed. The theoretical part is focused on studies of the absorption/scattering spectral line shapes of the hybrid systems, especially the transition between Fano resonance and Rabi splitting peaks. The various technical approaches to tune the plasmon-exciton coupling in complex systems are reviewed in the experimental part.