Broadly Tunable Liquid-State Lasers and Solid-State Single-Longitudinal-Mode Near-Infrared Lasers Utilizing Halogen-Doped Graphene Quantum Dots.

Understanding the lasing mechanism of graphene quantum dots (GQDs) is crucial for enhancing their gain characteristics and developing high-performance laser devices. In this study, we investigated ultrafast excited-state dynamics to determine whether Auger recombination is the primary factor influencing the laser emission of GQDs. By effectively inhibiting Auger recombination through halogen-doping of near-infrared (NIR) GQDs, we could extend the Auger lifetime from 183.41 to 239.41 ps, prolong the gain lifetime from 170.65 to 216.42 ps, and significantly reduce the laser threshold from 159.69 to 14.07 mJ cm^{- 2}. Notably, fluorine-doped GQDs exhibited a tunable emission spectrum from 638 to 751 nm and demonstrated exceptional stability under ambient conditions. High-gain NIR composite films were fabricated by combining fluorine-doped GQDs and polyimide. Based on this, high-quality planar distributed Bragg reflector microcavities with resonant peaks matching the amplified spontaneous emission peaks of the films were prepared. Upon integration with the film, solid-state GQDs could achieve single-longitudinal-mode (SLM) NIR laser emission at 711 nm with a linewidth of 0.068 nm. This advancement can facilitate the sustainable development of miniaturized lasers.