On the Plasmon-Exciton Coupling in a Metal/Dielectric CTF/TMD Trilayer Structure

In this study, the effect of a columnar thin film as a spacer layer in controlling and designing the coupling between plasmons and excitons in a prism-coupled configuration is reported. It turned out that the structural parameters of the columnar thin film have a significant effect on the Rabi splitting energy and coupling strength between plasmons and excitons. We found two anticrossing behaviors between the plexcitonic hybrid states due to the interaction of a plasmonic mode of the metal thin film and two excitonic modes of the transition metal dichalcogenide thin film. The localization and the local absorbance of hybrid modes were investigated by the time-averaged Poynting vector and the divergence of the Poynting vector. The obtained results showed that the hybrid modes are more localized at the metal/CTF interface and also the low plexciton state is long-lived than the medium and upper plexciton states. In our work, the most plexcitonic states were in the strong coupling regime, and the double Rabi splitting energy was available as high as 837 meV.