Room-Temperature Two-Dimensional InSe Plasmonic Laser

Two-dimensional (2D) semiconductors, owing to their strong excitonic emission, are emerging as efficient gain media for constructing the ultimate nanolaser. The further integration of 2D semiconductors with plasmonic devices holds promise for realizing the thinnest laser. However, the implementation of 2D semiconductor plasmonic lasing is severely hindered by the limited cavity feedback and low gain resulting from insufficient plasmon–exciton interactions. Here, we report the realization of a room-temperature 2D semiconductor plasmonic laser by embedding an InSe nanoflake into a plasmonic Fabry–Perot (F–P) cavity. This plasmonic F–P cavity shows an exceptional ability to recycle the leaked dark surface plasmon, resulting in >2-fold enhancement of feedback compared to that of conventional metal–insulator–semiconductor nanolasers. Moreover, via combination of field enhancement and orientation matching, this cavity facilitates optimized plasmon–exciton coupling to ensure sufficient gain for sustaining room-temperature lasing. Our work may open up the possibilities for multifunctional photonic devices based on 2D materials.