Current status and future prospects of non-toxicity carbon-dot-based miniaturized lasers.

With rapid advances in on-chip photonic integration and flexible optoelectronic devices, miniaturized laser devices are increasingly desired for various fields including optical communication, biosensing and biomedicine. However, a major barrier to their industrial deployment is the development of solution-processable gain media that are affordable, non-toxic and highly stable. Conventional solution-processable gain media often exhibit high toxicity and limited optical stability, considerably restricting their scalability and practical use. Carbon dots (CDs), as emerging solution-processable gain media, offer a compelling solution for developing environmentally friendly miniaturized lasers owing to their simple synthesis, affordability, non-toxicity, high biocompatibility, superior stability and excellent optical properties. This review summarizes progress in CD-based lasers with diverse resonator configurations, elucidates their gain mechanisms in the context of CD luminescence theories, and proposes strategies to optimize laser performance. Furthermore, it discusses current application prospects alongside critical challenges that must be addressed to advance CD-based miniaturized lasers. Overall, this review highlights the promising nature of CD-based miniaturized lasers and is anticipated to drive further in-depth research in this field.