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

• Published in: Nano letters Vol. 21; no. 7; pp. 3331 - 3339
• Main Authors: Zhao, Jiaxin, Su, Rui, Fieramosca, Antonio, Zhao, Weijie, Du, Wei, Liu, Xue, Diederichs, Carole, Sanvitto, Daniele, Liew, Timothy C. H, Xiong, Qihua
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.04.2021
• Subjects: Life Sciences; room-temperature polariton condensate; temporal coherence; exciton polariton; microcavity; transition-metal dichalcogenides; strong light−matter coupling
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.1c01162

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