Single crystals of methylammonium lead trihalide perovskites with high optical transparency and well‐defined facets are grown via solution process. Using these high‐quality crystals, the photocarrier‐induced refractive‐index change is observed for the first time in organic–inorganic hybrid perovskites. The photorefractive properties are measured using a laser interferometric technique that enables to monitor the time‐resolved refractive phase shifts. It is found that these phase shifts are determined by the initial density of photogenerated carriers and they are surprisingly retained even after carrier recombination. Utilizing the extremely long‐lived phase shift, it is demonstrated that the perovskite single crystal works as a phase shifter of laser light to generate any desired polarization. Furthermore, a periodic polarization‐modulation technique is established using the time‐dependent refractive phase shift. This refractive property can be used for advanced optical applications of organic–inorganic hybrid perovskites.

中文翻译：

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有机-无机杂化钙钛矿中的光折变效应及其在光学移相器中的应用

甲基铵三卤化铅钙钛矿的单晶具有高的光学透明性和明确的刻面，是通过溶液法生长的。使用这些高质量的晶体，在有机-无机杂化钙钛矿中首次观察到了光子载体引起的折射率变化。使用激光干涉技术测量光折变特性，该技术能够监控时间分辨的折光相移。已经发现，这些相移由光生载流子的初始密度决定，并且即使在载流子重组之后也令人惊讶地保留了这些相移。利用超长寿命的相移，可以证明钙钛矿单晶可以作为激光的相移器以产生任何所需的偏振。此外，使用与时间有关的折射相移建立了周期性的偏振调制技术。这种折射特性可用于有机-无机杂化钙钛矿的高级光学应用。