Wang, Yen-YuYen-YuWangLee, Xing-HaoXing-HaoLeeChen, Chiung-HanChiung-HanChenYuan, LinchynLinchynYuanLai, Yin-TiYin-TiLaiPeng, Tzu-YuTzu-YuPengChen, Jia-WernJia-WernChenCHU-CHEN CHUEHLu, Yu-JungYu-JungLu2025-06-172025-06-172025-05-09https://www.scopus.com/record/display.uri?eid=2-s2.0-105004862538&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/730118Room-temperature nanolasers are crucial for advancing optical communication and photonic quantum technologies due to their capability to generate coherent light at a subwavelength scale. However, their development is constrained by challenges such as insufficient gain, material instability, and high lasing thresholds. By integrating quasi–two-dimensional (quasi-2D) perovskites with high-Q plasmonic nanostructures, we demonstrate a stable, wavelength-tunable, single-mode laser operating at room temperature. This device leverages a unique exciton relocalization effect in quasi-2D Ruddlesden-Popper perovskites with additives, substantially enhancing optical gain and improving stability. When coupled with a waveguide-hybridized surface lattice resonance mode, the enhanced light-matter interaction facilitates single-mode lasing with a notably low threshold of 0.9 millijoules per square centimeter. In addition, the device achieves robust lasing performance with extended operational stability (1.8 × 106 excitation pulses). These results provide a scalable, low-cost, and energy-efficient platform for nanolasing, with potential applications in next-generation photonic technologies, including light detection and ranging, sensing, optical communication, and computation.[SDGs]SDG7journal article10.1126/sciadv.adu6824