Exciton-plasmon coupling in monolayer molybdenum disulfide

Two-dimensional materials such as monolayer molybdenum disulfide (MoS$_{2})$ represent a unique platform for investigating the dynamics of exciton-plasmon coupling. We report on the generation and modulation of coherent and incoherent coupled states between excitons in monolayer MoS$_{2}$ and plasmons in an array of gold nanoparticle deposited onto the surface of MoS$_{2}$. We study the behavior of these coherent states, termed plexcitons using a combination of photoluminescence, extinction and ultrafast spectroscopies. The close proximity of the two characteristic exciton bands of MoS$_{2}$ presents multiple coherent coupling configurations, including A-or-B exciton-plasmon, and A-and-B exciton-plasmon interactions. These configurations of plexciton formation that are shown to modulate both the extinction and photoluminescence spectra of the hybrid system. This includes broadband photoluminescence and Fano-type resonances. This behavior is distinct from the spectral response of the MoS$_{2}$ and plasmonic components of the system. Incoherent exciton-plasmon coupling, achieved by detuning from the plasmon extinction peaks, enhances the interaction of MoS$_{2}$ with light by focusing the plasmon energy. Depending on which coupling configuration is chosen, our results show that the MoS$_{2}$/plasmon hybrid systems can act as high efficiency light harvesters, broadband emitters and as tunable visible and NIR photodetectors.