5.32 W ultraviolet laser generation at 266 nm using sum-frequency method with CsBO crystal.

Ultraviolet (UV) beam generation at 266 nm using the sum-frequency (SFG) method with CsBO (CBO) crystals was first suggested in 1997 [Opt. Lett.22, 1840 (1997).10.1364/OL.22.001840]; however, there has been no further research in the past 25 years. Herein, by sum-frequency mixing in CBO crystals, we obtained a high conversion efficiency picosecond (ps) and a high-power nanosecond (ns) 266 nm UV beam output. First, a ps laser device with simultaneously radiated wavelengths of 1064 and 355 nm and repetition frequency of 10 Hz was used as the fundamental laser source, and the conversion efficiency from 1064 + 355 nm to 266 nm reached 20.35%. We then used a 1064 nm ns laser with a high output power and repetition frequency of 10 kHz as the pump source. We accurately modified the optimal phase matching direction of the CBO crystal, and the achieved output power at 266 nm reached 5.32 W.