Control over cavity exciton polaritons in monolayer semiconductors

Integrating two-dimensional van der Waals materials with optical cavities has revealed a fascinating platform to study exciton-polariton physics. Manipulating exciton polaritons often requires external control over the electrical and optical properties of materials. Here we demonstrate the electrical control of 2D exciton polaritons by strongly coupling a transition metal dichalcogenides (TMD) heterostructure to a photonic crystal nanocavity. Through precise control of the doping level in the TMD monolayers using electrostatic gating, we demonstrate a wide range of tunability in the exciton oscillator strength and hence the exciton photon hybridization. This tunability leads to the demonstration of a continuous transition from weak to strong coupling regime, as manifested by the disappearance and emergence of exciton polaritons, showcasing the versatility of our approach. Our work paves the way to further exploring nonlinear and quantum exciton polaritons in 2D materials and their device applications.