Lattice Plasmon Induced Large Enhancement of Excitonic Emission in Monolayer Metal Dichalcogenides

Through the integration of a strongly coupled plasmonic nanoantenna array with a monolayer MoSe₂, spatial maps of the photoluminescence (PL) are acquired on- and off-resonance to exhibit the role of the lattice plasmon modes on the enhancement of the PL from the MoSe₂ monolayer. The on-resonance excitation of the hybrid nanostructure at 785 nm reveals a significant PL enhancement of more than 25 (compared to the PL enhancement factor that a Fabry-Perot resonance provides), while the off-resonance excitation at 488 nm only results in an enhancement factor of five. Polarization-resolved optical reflection spectroscopy is also experimented to verify the role of the coupled nanoantenna array on the PL enhancement. Full-wave numerical simulations of the complete structure are also performed to support the observed experimental results. These findings enrich our knowledge regarding the light interaction with 2D materials mediated by plasmonic nanostructures and pave the way for the design of a new class of hybrid 2D material plasmonic devices that utilize enhanced light-matter interaction.