41 W, 343 nm UV femtosecond laser based on rod-type PCF and LBO crystals

We have demonstrated a high-power ultraviolet (UV) femtosecond laser based on an all-fiber photonic crystal fiber (PCF) laser. By combining a short, large-mode-area (LMA), high-gain silica PCF with a large-core rod-type PCF, the B-integral accumulation of the system is reduced. This ultimately enabled the generation of UV laser output at a wavelength of 343 nm, with a repetition rate of 1 MHz, pulse duration of 309 fs, average power of 41 W, and harmonic conversion efficiency of 26%. The beam quality of the UV laser is near-diffraction-limited with <i>M</i>² factors of <i>M</i><i>x</i>2=1.11, <i>M</i><i>y</i>2=1.12. This UV femtosecond laser source has promising applications in fields such as semiconductor wafer dicing and biomedical imaging.