Rational design of a promising oxychalcogenide infrared nonlinear optical crystal.

Oxychalcogenides with the performance-advantages of both chalcogenides and oxides are emerging materials class for infrared (IR) nonlinear optical (NLO) crystals that can expand the wavelength of solid-state lasers to IR regions and are of importance in industrial and civil applications. But rationally designing a high-performance oxychalcogenide NLO crystal remains a great challenge. Herein, we chose the melilite-type SrZnSiO as the structure template. Through part isovalent substitution of S for O anions, the first hetero-anionic thiostannate SrZnSnOS with wide IR transmission has been synthesized. More importantly, compared to the maternal oxide, SrZnSiO, the second harmonic generation (SHG) response of SrZnSnOS is enhanced by two orders of magnitude. In addition, SrZnSnOS can exhibit a large band-gap and high laser damage threshold. These advantages make SrZnSnOS a promising IR NLO crystal. Our research will provide insights into the rational design of new IR NLO crystals.