Picosecond laser output at 355 nm adopting sum-frequency method based on CsB3O5 crystal

Abstract

Ultraviolet (UV) light source has very important applications due to its high single photon energy, short laser wavelength and low thermal effect during processing. A high-performance way to acquire UV light source at 355 nm is using sumfrequency method. CsB₃O₅ (CBO) crystal is a good UV nonlinear optical (NLO) crystal, it can be used to generate UV laser. We acquired high output power UV picosecond (ps) light source at 355 nm through sum-frequency method based on type II phase-matched CBO crystal. As the 1064 nm laser power was 84.8 W, a 30.3 W of 355 nm UV light source with a repetition rate of 600 kHz was achieved. The optical conversion efficiency from the infrared fundamental laser to the UV third-harmonic laser was up to 35.7%. We measured the power stability of the 355 nm UV laser at the maximum power of 30.3 W. The root mean square (RMS) value of the power instability was 0.386% for about thirty minutes. These findings reveal that CBO crystal has great potential in the application of ultrafast UV light source generation with high power.