Nonlinear optical (NLO) crystals can be employed to expand the laser frequency and thus are of technical importance in advanced laser science. Noncentrosymmetric rare earth compounds keep attracting broad interest as a significant branch of NLO materials because the highly distorted structural motifs centered by rare earth ions could remarkably benefit the second harmonic generation. In this review, we proceed from structure–properties relationship and reveal the role of rare earth element in the optical properties of NLO materials. We believe that this work can deepen the understanding of rare earth-based NLO materials and provide some enlightenment for exploring novel practical NLO crystals.

非线性光学 (NLO) 晶体可用于扩展激光频率，因此在先进的激光科学中具有重要的技术意义。非中心对称稀土化合物作为 NLO 材料的一个重要分支一直吸引着广泛的兴趣，因为以稀土离子为中心的高度扭曲的结构基序可以显着地有益于二次谐波的产生。在这篇综述中，我们从结构-性能关系出发，揭示了稀土元素在 NLO 材料光学性能中的作用。我们相信这项工作可以加深对稀土基非线性光学材料的理解，并为探索新型实用非线性光学晶体提供一些启示。