All-inorganic perovskite has attracted significant attention due to its excellent nonlinear optical characteristics. Stable and low-toxic perovskite materials have great application prospects in optoelectronic devices. Here, we study the nonlinear optical properties of ${\mathrm{CsPbCl}}_x{\mathrm{Br}}_{3-x}$ ($x=1$, 1.5, 2) nanocrystals (NCs) glass by open-aperture Z-scan. It is found that the two- (2PA) and three-photon absorption (3PA) intensity can be adjusted by the treatment temperature and the ratio of halide anions. The perovskite NCs glass treated at a high temperature has better crystallinity, resulting in stronger nonlinear absorption performance. In addition, the value of the 2PA parameter of ${\mathrm{CsPbCl}}_{1.5}{\mathrm{Br}}_{1.5}$ NCs glasses decreases when the incident pump intensity increases, which is ascribed to the saturation of 2PA and population inversion. Finally, the research results show that the 2PA coefficient ($0.127\mathrm{cm}{\mathrm{GW}}^{-1}$) and 3PA coefficient ($1.21\times {10}^{-5}{\mathrm{cm}}^3{\mathrm{GW}}^{-2}$) of ${\mathrm{CsPbCl}}_1{\mathrm{Br}}_2$ NCs glass with high Br anion content are larger than those of ${\mathrm{CsPbCl}}_2{\mathrm{Br}}_1$ and ${\mathrm{CsPbCl}}_{1.5}{\mathrm{Br}}_{1.5}$ NCs glasses. This is mainly due to the greater influence of Br anions on the symmetry of the perovskite structure, which leads to the redistribution of delocalized electrons. The revealed adjustable nonlinear optical properties of perovskite NCs glass are essential for developing stable and high-performance nonlinear optical devices.

中文翻译：

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CsPbClxBr3-x 纳米晶嵌入玻璃的非线性光学特性

全无机钙钛矿因其优异的非线性光学特性而备受关注。稳定、低毒的钙钛矿材料在光电器件中具有广阔的应用前景。在这里，我们研究了非线性光学特性${\mathrm{氯化铅}}_X{溴}_{3-X}$ ($X=1$, 1.5, 2) 通过开放孔径 Z 扫描获得的纳米晶体 (NCs) 玻璃。研究发现，二(2PA)和三光子吸收(3PA)强度可以通过处理温度和卤化物阴离子的比例进行调节。经过高温处理的钙钛矿NCs玻璃具有更好的结晶度，从而产生更强的非线性吸收性能。此外，2PA 参数的值${\mathrm{氯化铅}}_{1.5}{溴}_{1.5}$当入射泵浦强度增加时，NCs 玻璃会减少，这归因于 2PA 的饱和和粒子数反转。最后，研究结果表明，2PA系数（$0.127\mathrm{厘米}{\mathrm{GW}}^{-1}$) 和 3PA 系数 ($1.21\times {10}^{-5}{\mathrm{厘米}}^3{\mathrm{GW}}^{-2}$） 的 ${\mathrm{氯化铅}}_1{溴}_2$ 具有高 Br 阴离子含量的 NCs 玻璃比那些大 ${\mathrm{氯化铅}}_2{溴}_1$ 和 ${\mathrm{氯化铅}}_{1.5}{溴}_{1.5}$NC 眼镜。这主要是由于 Br 阴离子对钙钛矿结构的对称性影响较大，导致离域电子的重新分布。钙钛矿 NCs 玻璃所揭示的可调节非线性光学特性对于开发稳定和高性能的非线性光学器件至关重要。