We demonstrate a high-power high-beam-quality ultraviolet (UV) laser at 330 nm based on fourth-harmonic generation (FHG) of a diode-side-pumped 1319 nm Nd:YAG laser. A 23.2 W Q-switched Nd:YAG laser at 1319 nm with beam quality factor M2 =1.15 and optical to optical conversion efficiency of 6.5% was employed as the fundamental wave source. First, the output at 1319 nm was frequency-doubled to 660 nm in a LiB3O5 (LBO) crystal with an average output power of 11.3 W. Then, it was frequency-doubled again in another LBO crystal to obtain the FHG output at 330 nm. The maximum average output power at 330 nm was up to 7.0 W and the beam quality factor M2 was measured to be 1.45. The conversion efficiency was 48.7% at the first second-harmonic generation (SHG) stage and the conversion efficiency of the second SHG stage was 61.9%, corresponding to a total conversion efficiency from infrared to UV of 30.2%. To the best of our knowledge, this is the first 330 nm UV source generation from a diode-side-pumped frequency-quadrupled 1319 nm Nd:YAG laser.

Photonics Technology Letters, IEEE (Volume:PP , Issue: 99 )