Experimental studies on the random lasing characteristics of carbon quantum dots

We present a simple yet effective method for achieving directional and coherent random lasing (RL) emission using carbon quantum dots (CQDs) as scattering elements. Through experimental demonstration, we show that a gain dye combined with CQDs facilitates RL under optical pumping. The resulting emission forms a well-defined spatial pattern, which is modulated by the CQDs and can be externally controlled via the optical pump. This study introduces a novel approach to tunable laser operation, enabling a transition from stable single-mode to multimode behavior. Our innovative gain material design holds significant promise for optically controlled light amplification and advances the development of cavity-free lasers with engineered multi-mode beams. Furthermore, we provide detailed experimental insights into CQD-molded random lasers, underscoring their potential to drive progress in the miniaturization and integration of nano-device.