Light-matter interactions of monolayer semiconductors integrated with photonic microcavities*

Enhanced light-matter interactions in optical microcavities can enable hybrid photon-exciton quasiparticle excitations when in a regime of strong light-matter coupling. Because of their direct bandgap, atomic-scale thickness, and strong spin-orbit coupling, monolayers of transition metal dichalcogenides (TMDs) allow for exciton-polaritons in a two-dimensional regime with rich correlations between spin, momentum, and light polarization. We demonstrate integrated TMD photonic devices with MoS$_2$ grown by vapor transport and sandwiched between dielectric Bragg mirrors. We discuss evidence for exciton-polaritons in monolayer TMDs at room temperature using angle-resolved cavity reflectivity spectroscopy. This interpretation is supported by the dependence on MoS$_2$ layer number. Calculations of light-matter coupling parameters in TMDs yield values consistent with recent observations~\footnote{X. Liu, \textit{et al}. \textit{arXiv}:1406.4826, (2014)}. We discuss our approach to integrated 2D monolayer photonics in the context of the valley-sensitive bandstructure of excitons in TMDs.