Since quasi-phase-matching of nonlinear optics was proposed in 1962, nonlinear photonic crystals were rapidly developed by ferroelectric domain inversion induced by electric or light poling. The three-dimensional (3D) periodical rotation of ferroelectric domains may add feasible modulation to the nonlinear coefficients and break the rigid requirements for the incident light and polarization direction in traditional quasi-phase-matching media. However, 3D rotating ferroelectric domains are difficult to fabricate by the direct external poling technique. Here, we show a natural potassium–tantalate–niobate (KTN) perovskite nonlinear photonic crystal with spontaneous Rubik’s cube-like domain structures near the Curie temperature of 40 °C. The KTN crystal contains 3D ferroelectric polarization distributions corresponding to the reconfigured second-order susceptibilities, which can provide rich reciprocal vectors to compensate for the phase mismatch along an arbitrary direction and polarization of incident light. Bragg diffraction and broadband second-harmonic generation are also presented. This natural nonlinear photonic crystal directly meets the 3D quasi-phase-matching condition without external poling and establishes a promising platform for all-optical nonlinear beam shaping and enables new optoelectronic applications for perovskite ferroelectrics.

自1962年提出非线性光学的准相位匹配以来，非线性光子晶体通过电或光极化引起的铁电畴反转迅速发展。铁电畴的三维（3D）周期性旋转可为非线性系数增加可行的调制，并打破传统准相位匹配介质中对入射光和偏振方向的严格要求。然而，通过直接外部极化技术难以制造3D旋转铁电畴。在这里，我们显示了居里温度40°C附近的天然钽酸铌铌（KTN）钙钛矿非线性光子晶体，具有自发的Rubik立方状畴结构。KTN晶体包含对应于重新配置的二阶磁化率的3D铁电极化分布，这可以提供丰富的互逆矢量，以补偿沿任意方向的相位不匹配和入射光的偏振。还介绍了布拉格衍射和宽带二次谐波产生。这种天然的非线性光子晶体无需外部极化即可直接满足3D准相位匹配条件，并为全光非线性光束整形建立了一个有希望的平台，并为钙钛矿铁电体提供了新的光电应用。还介绍了布拉格衍射和宽带二次谐波产生。这种天然的非线性光子晶体无需外部极化即可直接满足3D准相位匹配条件，并为全光非线性光束整形建立了一个有希望的平台，并为钙钛矿铁电体提供了新的光电应用。还介绍了布拉格衍射和宽带二次谐波产生。这种天然的非线性光子晶体无需外部极化即可直接满足3D准相位匹配条件，并为全光非线性光束整形建立了一个有希望的平台，并为钙钛矿铁电体提供了新的光电应用。