Room-Temperature\nTwo-Dimensional InSe Plasmonic Laser

Two-dimensional (2D) semiconductors, owing to their strong\nexcitonic\nemission, are emerging as efficient gain media for constructing the\nultimate nanolaser. The further integration of 2D semiconductors with\nplasmonic devices holds promise for realizing the thinnest laser.\nHowever, the implementation of 2D semiconductor plasmonic lasing is\nseverely hindered by the limited cavity feedback and low gain resulting\nfrom insufficient plasmon–exciton interactions. Here, we report\nthe realization of a room-temperature 2D semiconductor plasmonic laser\nby embedding an InSe nanoflake into a plasmonic Fabry–Perot\n(F–P) cavity. This plasmonic F–P cavity shows an exceptional\nability to recycle the leaked dark surface plasmon, resulting in >2-fold\nenhancement of feedback compared to that of conventional metal–insulator–semiconductor\nnanolasers. Moreover, via combination of field enhancement and orientation\nmatching, this cavity facilitates optimized plasmon–exciton\ncoupling to ensure sufficient gain for sustaining room-temperature\nlasing. Our work may open up the possibilities for multifunctional\nphotonic devices based on 2D materials.