Colloidal Quantum Dot Liquid Lasers

Thermal management of lasers fundamentally limits the upper limit of their output power as well as their operational stability. In this context, liquid-state lasers exhibit an unparalleled advantage in power scalability and stability, owing to their highly efficient heat dissipation facilitated by continuous fluid circulation. Additionally, the intrinsic compatibility of liquid lasers with microfluidic platforms also holds great promise for integration into energy-efficient, miniaturized photonic systems. Colloidal quantum dots (QDs), which are solution-processed semiconductor nanocrystals, have emerged as highly versatile optical gain materials. While research over the past decade has been predominantly centered on solid-state QD lasers made from densely packed QD films or composite matrices, there has been a recent surge of interest in exploring QDs in their native dispersion form as active gain media for liquid-state lasers. This review provides a systematic overview of recent advances in QD-based liquid lasers, detailing their operational principles, critical performance metrics, and highlighting their unique advantages. Moreover, we point out current technical bottlenecks and explore prospective strategies for overcoming these limitations to pave the way for practical QD-based liquid lasing technologies.