  The manipulation of light-matter interactions in two-dimensional atomically
thin crystals is critical for obtaining new optoelectronic functionalities in
these strongly confined materials. Here, by integrating chemically grown
monolayers of MoS2 with a silver-bowtie nanoantenna array supporting narrow
surface-lattice plasmonic resonances, a unique two-dimensional optical system
has been achieved. The enhanced exciton-plasmon coupling enables profound
changes in the emission and excitation processes leading to spectrally tunable,
large photoluminescence enhancement as well as surface-enhanced Raman
scattering at room temperature. Furthermore, at low temperatures, due to the
decreased damping of MoS2 excitons interacting with the plasmonic resonances of
the bowtie array, stronger exciton-plasmon coupling is achieved resulting in a
Fano lineshape in the reflection spectrum. The Fano lineshape, which is due to
the interference between the pathways involving the excitation of the exciton
and plasmon, can be tuned by altering the coupling strengths between the two
systems via changing the design of the bowties lattice. The ability to
manipulate the optical properties of two-dimensional systems with tunable
plasmonic resonators offers a new platform for the design of novel optical
devices with precisely tailored responses.
