Room Temperature Fabry–Pérot Modes Microcavity Exciton–Polariton in CdS/CdS:SnS2 Superlattice Microwires

Achieving room-temperature exciton–polariton condensation represents a frontier challenge in condensed matter physics and optoelectronics. However, its mainstream approach—distributed Bragg reflector (DBR) microcavities—faces widespread application challenges due to complex fabrication and high costs. Here, we report direct observation of the interaction between exciton and microcavity photons in Sn-doped CdS microsheet without extreme fabrication conditions. In situ PL and Raman mapping demonstrate the formation of superlattice structure. Using angle-resolved photoluminescence (ARPL) spectroscopy, we obtain Rabi splitting of polaritons up to 140 meV, and the exciton-like and photon-like components in low-polariton states at different cavity–exciton detuning were revealed at room temperature. Our work demonstrates the origin of optical microcavities and the light–matter coupling in CdS/CdS:SnS2 superlattice microwires.