Low-threshold single-mode lasing in high-quality all-inorganic CsPbCl3 perovskite microplates

All-inorganic lead halide perovskites (CsPbX3) have emerged as game-changing gain media for micro-lasers due to their facile synthesis, ultra-high photoluminescence quantum yield, and excellent spectral tunability. However, realizing high-quality, low-threshold, and geometrically simple single-mode blue lasing, essential for integration into next-generation photonic circuits, remains a substantial challenge. Here, we report the successful, low-cost synthesis of high-quality, single-crystalline CsPbCl3 microplates with remarkably smooth facets, functioning as natural whispering-gallery mode microcavities. The outstanding blue single-mode lasing performance under optical pumping has been demonstrated. The optimized CsPbCl3 microplates achieve a low lasing threshold of 5.68 μJ cm−2 and a high quality factor (Q) exceeding 2000. Crucially, the stable single-mode emission is realized through a synergistic mechanism: the enhanced free spectral range enabled by size-controlled microplates combined with the intrinsic self-absorption effect of CsPbCl3, which effectively suppresses mode competition and parasitic modes. Our work not only introduces a high-performance, blue-emitting laser platform based on simple CsPbCl3 microplates but also offers a general, lithography-free strategy for achieving robust single-mode output in all-inorganic perovskite micro-lasers.