Exciton-Polaritons Dynamics of a Monolayer Tungsten Disulphide (WS2) Coupled to a Semiconductor Microcavity
We present a theoretical model that allows us to describe the dynamics of exciton polaritons in the strong-coupling regime in a monolayer WS2 based semiconductor microcavity. Numerical simulations using Boltzmann equations give an overall description of polariton kinetics over a temperature range of 130-230K, under nonresonant excitation. Here, only the scattering rate via optical phonons (LO) from the upper (UP) towards lower (LP) polariton branches is considered. According this model we show the importance of the radiative lifetime of the polaritonic states relative to polariton relaxation rate. Our results show as the cavity detuning changes from negative (130 K) to positive (230 K) values, the UP branch can be tuned from a more excitonlike to a more photonlike state at small wave vector k. We deduce that the UP states have a faster lifetime and the polariton relaxation time into the LP energy states becomes very efficient. Thus, the UP occupation starts to decrease, and we observe a simultaneous increase in the occupation of the LP branch. Furthermore, the polariton states are less occupied for small excitation pump rate, the calculated behavior is linear. In the high pumping regime, we observe the nonlinear behavior of cavity polaritons and occupation factors much larger than unity are reached.