Vacuum ultraviolet (VUV, 100–200 nm) light sources are crucial for advanced spectroscopy, quantum research and semiconductor lithography1–3. Compared with conventional large-scale VUV generation technologies4–7, second-harmonic generation (SHG) through nonlinear optical (NLO) crystals8–10 is the simplest and most efficient method. However, the scarcity of suitable NLO crystals has constrained the production of VUV light through SHG: existing materials fail to meet phase-matching requirements, suffer from low conversion efficiency or have severe growth limitations11–19. In this study, we report the development of the fluorooxoborate crystal NH4B4O6F (abbreviated as ABF) as a promising material for VUV light generation. VUV devices with specific phase-matching angles were constructed, achieving a record 158.9-nm light through phase-matching SHG and a maximum nanosecond pulse energy of 4.8 mJ at 177.3 nm with a conversion efficiency of 5.9%. The enhanced NLO performance is attributed to optimized arrangements of fluorine-based units creating asymmetric sublattices. This work provides further material in the NLO field, with potential for applications in compact, high-power VUV lasers using ABF.
