Manipulating Coherent Plasmon-Exciton Interaction in a Single Silver Nanorod on Monolayer WSe2

Strong coupling between plasmons and excitons in nanocavities can result in the formation of hybrid-plexCitonic states. Understanding the dispersion relation of plexcitons is important both for fundamental quantum science and for applications including optoelectronics and nonlinear optics devices. The conventional approach, based on statistics. over-different nanocavities, suffers from large inhornogeneities from the samples, owing to the nonuniformity of nanocavities and-the lack of control over the locations and orientations of the;excitons. Here we report the first measurement of the dispersion-relationship of plexcitons in an individual nanocavity-using a single silver nanorod as a Fabry-Perot nanocavity, we realize, strong coupling of plasmon in single nanocavity with excitons in a single atomic layer of tungsten diselenide. The plexardil dispersion is measured by in situ redshifting the plasmon energy via successive deposition of a dielectric layer. Room-temperature foam-hen of plexcitons with Rabi splittings as large as 49.5-meV-is observed. The realization of strong plasmon exciton coupling-by in situ tuning of the plasmon provides a novel route for the manipulation of excitons in semiconductors.