“Removing Center”─An Effective Structure Design Strategy for Nonlinear Optical Crystals

Nonlinear optical (NLO) crystals are crucial parts of the tuned laser, which can be used in laser processing, lithography, weapons, and other fields. Until now, the major challenge for this field is how to design NLO crystals with good performance, which is also the commanding point for researchers to face. Structural design is a wonderful strategy for exploring NLO crystals. In this paper, we summarized the structure design strategy "removing center" by analyzing the structure of the classical NLO crystal KBe2BO3F2 and other classical NLO crystals. Through the guidance of the "removing center" strategy, two NLO crystals Rb6Si10O23 and Cs6Si10O23 having large second harmonic generation responses (>1 × KDP) in silicate and deep-ultraviolet cut-off edges, were synthesized and grown. The "removing center" design strategy can induct spontaneous micro symmetry breaking to improve the NLO performance of the crystal. It is expected to become a universal structural design strategy.