Recent advances in nonlinear optical rare earth structures

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.