A 355 nm ultraviolet femtosecond laser through second harmonic generation using K3B6O10Br nonlinear optical crystal

We demonstrate the 355 nm ultraviolet (UV) femtosecond (fs) laser through second harmonic generation using a type-I phase-matched nonlinear optical crystal of K3B6O10Br (KBOB). The effects of the length of nonlinear optical crystals and the focal length of lenses on the output power and conversion efficiency were investigated systematically. The maximum output power of 265 mW UV fs laser at 355 nm was obtained with a pump of 1.408 W fs laser at 710 nm with a repetition rate of 80 MHz. The corresponding optical conversion efficiency was 18.8%. The experimental results show that KBOB crystal is a promising crystal in generating high-power UV fs laser because of its excellent nonlinear optical properties.