Perovskite lasers have aroused great interest in recent years due to their ultra-low lasing threshold, high quantum yields, easily tuned emission colors and great potential for electrically pumped nanolasing, which opens up new possibilities in obtaining highly coherent light sources at the nanoscale. Compared with the widely studied organic-inorganic hybrid perovskites, the inorganic (CsPbX3) have gradually become an emerging research focus because of their relatively better stability. However, some problems still hinder their actual applications, such as the seldom explored lasing quantum yield and the difficulties of further improving stability. Herein, a simple method is proposed to synthesize CsPbX3 nanowires in ambient conditions, and these CsPbX3 nanowires exhibit perfect crystallization and outstanding stability (over 1 year). Perovskite lasing with single mode and a low threshold of 12.33 μJ cm-2 as well as a high lasing quantum yield up to ∼58% are obtained. More interestingly, a high quality single-mode laser with ultra-narrow linewidth of 0.09 nm can be obtained when the CsPbX3 NWs are excited by continuous wave in low-temperature condition. Our results not only enrich the study of inorganic perovskite materials with a new synthetic method, but also uncover new lasing properties of CsPbX3 NWs, suggesting a broad application of the inorganic perovskite materials.

We report optical positioning of single quantum dots (QDs) in planar distributed Bragg reflector (DBR) cavity with an average position uncertainty of ≈20 nm using an optimized photoluminescence imaging method. We create single-photon sources based on these QDs in determined micropillar cavities. The brightness of the QD fluorescence is greatly enhanced on resonance with the fundamental mode of the cavity, leading to an high extraction efficiency of 68% ± 6% into a lens with numerical aperture of 0.65, and simultaneously exhibiting low multi-photon probability (g(2)(0) = 0.144 ± 0.012) at this collection efficiency.

Perovskite nanocrystals open up bright future for nanolasers, for their various instinct advantages (such as large absorption cross section and optical gain, high fluorescence quantum yields, etc.) can greatly benefit the design and fabrication of nanolasers with low threshold, high emission efficiency and well integration. Although numerous investigation efforts have been devoted into exploring the perovskite nanolaser of single-photon-pumped type, the study of up-conversion lasing excited by two-photon-pumping is still established on the structures of micrometer scale with multiple mode, which is not in favor of improving the working stability and scale miniaturization of future nanolasers. In order to expand the application of perovskite nanocrystal in nanolasers, we studied the perovskite (CsPbX 3 , X = Cl, Br) nanoplates fabricated by supersaturated recrystallization approach, and observed single mode up-conversion lasing from single nanoplate with low threshold of 4.84 µJ/cm 2 . In addition,

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