Impact of Microstructural Units Configuration and Arrangement on Phase-Matching in Nonlinear Optical KGaSe Crystals.

Achieving phase-matching (PM) behavior, which is typically derived from sufficient birefringence (Δ), is crucial for maximizing the nonlinear optics (NLO) laser power output. Δ is largely attributed to the configuration and arrangement of microstructural units, and phase transitions will significantly alter the stacking method of structural units. In this study, we successfully synthesized two diamond-like isomers of α-KGaSe (2, ) and β-KGaSe (1, ), which consist of open-honeycomb-like anionic frameworks interspersed with embedded K cations.