Ultralow Threshold Polariton Condensate in a Monolayer Semiconductor Microcavity at Room Temperature

Exciton-polaritons, hybrid light–matter bosonic quasiparticles, can condense into a single quantum state, i.e., forming polariton Bose–Einstein condensate (BEC), which represents crucial step for the development of nanophotonic technology. Recently, atomically thin transition-metal dichalcogenides (TMDs) emerged as promising candidates novel polaritonic devices. Although formation robust valley-polaritons has been realized up to room temperature, demonstration lasing remains elusive. Herein, we report first time realization this important milestone in TMD microcavity at temperature. Continuous wave pumped is evidenced by macroscopic occupation ground undergoes nonlinear increase emission along with emergence temporal coherence, presence an exciton fraction-controlled threshold and buildup linear polarization. Our work presents critically toward exploiting polariton–polariton interactions, well offering new platform thresholdless lasing.