An Optimized KBe2BO3F2-Like Structure: The Unity of Deep-Ultraviolet Transparency, Nonlinear Optical Property, and Ferroelectricity

At present, only KBe2BO3F2 (KBBF) can effectively realize a deep-ultraviolet (DUV) coherent output, while the layered growth habit seriously hinders its application. Here, a new design strategy with an optimized KBBF-like structure based on the quasi-phase matching principle is proposed. Thus, the first KBBF-like ferroelectric, Li2KRb(SO4)(2), is designed. It exhibits a short DUV absorption cutoff edge of 163 nm, a large nonlinear optical (NLO) effect of 1.7 x KH2PO4 under a 1064 nm laser, and typical ferroelectricity. More importantly, it completely eliminates the layered structure by replacing K-F bonds with strong -Li-O-S- ones as the interlayer force. Therefore, this work finds a new promising DUV NLO candidate, a unity of the DUV transparency, NLO response, and ferroelectricity, which is advantageous to explore new DUV NLO materials.

Automated summary

This study proposes a new design strategy to optimize the KBBF structure and successfully design a new ferroelectric material, Li2KRb(SO4)2. This material exhibits high optical effects and ferroelectricity, and eliminates the layered structure, showing potential applications.