Ultraviolet Crystal with Strong Optical Nonlinearity by Creating Halogen-Centered Secondary Building Blocks
Xuping Shi, Abudukadi Tudi, Minqiang Gai, Zhihua Yang, Shujuan Han, Shilie Pan
Abstract
Designing new ultraviolet nonlinear optical (NLO) crystals with strong second-harmonic generation (SHG) response and a deep ultraviolet cutoff edge is an unremitting pursuit of scientific researchers, accompanied by the key issues of how to realize a noncentrosymmetric structure with the ideal arrangement of ultraviolet NLO-active genes. Herein, a strategy that creates halogen-centered secondary building blocks with rare-earth atoms was used for further design, and we synthesized rationally an unprecedented NLO crystal Cs 2 La 2 B 10 O 17 Cl 4 exhibiting the largest SHG response (2.1 × KDP) among borates with [B 5 O 11 ] as the fundamental building blocks. The unique role of Cl-centered secondary building blocks in regulating the arrangement of the B–O framework and enhancing nonlinearity was discussed in detail, which will bring the researcher a perspective in designing new NLO crystals.