A novel promising infrared nonlinear optical selenide KAg3Ga8Se14 designed from benchmark AgGaQ2 (Q = S, Se)

Abstract

Obtaining fresh nonlinear optical (NLO) materials is an attractive and challenging topic for the development of laser techniques. Using benchmark AgGaQ₂ (Q = S, Se) as the template, new KAg₃Ga₈Se₁₄ is obtained by a solid-state reaction. Its structure can be built by the intergrowth of 2 : 1 AgGaSe₂ and Ga₂Se₃-like slabs if the K site is occupied by Ag. Powdery KAg₃Ga₈Se₁₄ demonstrates moderate phase-matchable NLO responses, and a LDT of ca. 2 × AgGaS₂. DFT calculations reveal that both AgSe₄ and GaSe₄ tetrahedral motifs contribute a lot to the NLO performance. This work reveals a new class of promising infrared NLO materials, and the design strategy may apply to other systems.