Quantitative modeling of gate-tunable cavity exciton-polaritons in transition-metal dichalcogenides

We performed a comprehensive real-space simulation study of propagative exciton-polaritons (EPs) of tungsten disulfide (WS2) inside a Fabry–Pérot cavity. Through our simulations, we were able to construct the dispersion relation and determine the propagation length (Lp) of EPs, both of which show sensitive dependence on the applied gate voltage. We found that Lp increases at higher gate voltages when excited at the exciton energy but shows opposite gate dependence at the trion energy. These observations are direct evidence of the coupling between the cavity mode with excitons and trions of WS2. Furthermore, we demonstrate a proof-of-concept device based on the tunable cavity EPs of WS2, which is promising for application as photonic transistors, modulators, or electrical-to-optical converters. Our work unveils the real-space transport properties of gate-tunable cavity EPs and paves the way for future applications of EPs in nanophotonic devices and circuits.