Photothermal microbubble-driven control of graphene-based random lasers

Random lasers have significant applications in various fields, including biomedical imaging, optical sensing, anti-counterfeiting technology, optical communication, and high-resolution displays. This study investigates the emission characteristics of graphene-based random lasers, specifically focusing on the control achieved through the formation of microbubbles induced by photothermal effects. The results show that the peak intensity of the random laser in sample 1 increases from 17.7 a.u. to 26.5 a.u. as the pump time extends from 0 s to 10 s. At the pump time of 10 s, the peak intensity and quality factor of the random laser are about 1.5 and 2.33 times larger than those at 0 s, respectively. However, when the pump time exceeds 10 s, the emission intensity of random lasers starts to weaken. These phenomena are attributed to the production of microbubbles, whose presence is confirmed by the dual-beam Z-scan technique and the dynamic behavior of graphene microsheets. Microbubbles not only enhance light scattering but also provide a new dimension for controlling random lasing. Additionally, by adjusting the concentration of polyvinyl alcohol in the suspension, we can control the formation of microbubbles, and further regulate the emission properties of random lasers. This research presents a novel approach for manipulating random lasers, and showcases the potential of photothermally induced microbubbles for laser control and micro- or nanoparticle manipulation.