High-efficiency UV generation at 266 nm in a new nonlinear optical crystal NaSr₃Be₃B₃O₉F₄

266 nm laser output in NaSr₃Be₃B₃O₉F₄ crystal by the fourth harmonic generation process with a picosecond mode-locked Nd-based YAG laser has been done for the first time. When the input pumping energy was 870 μJ at 532 nm, a 280 μJ 266 nm UV laser was obtained and the corresponding conversion efficiency was 35.9%. Further investigations identified that NaSr₃Be₃B₃O₉F₄ has a large acceptance angle width of 0.47 (mrad • cm), a small walk-off angle of 35.43 mrad and a large deff as 0.62 pm/V for the fourth harmonic generation. These results indicate that NSBBF is applicable for high-power 266 nm laser generation.