Theoretical and Experimental Investigations on High Average Power Laser at 281 nm by Second-Harmonic Generation of a Frequency-Doubled Nd:YAG Laser in Cr

In this paper, we report on the theoretical simulation and experimental investigation on a novel ultraviolet (UV) laser at 281 nm by second-harmonic generation (SHG) of a frequency-doubled nanosecond Nd:YAG laser in CsB₃O₅ (CBO) crystal. We firstly presented a numerical model that describes the nanosecond type-I SHG of CBO, accounting for pump depletion, beam divergence, beam spatial walk-off, linear absorption, and phase-mismatch in the Gaussian approximation of both spatial and temporal profiles. In experiment, we demonstrated the high average power UV at 281 nm up to 1.3 W by the cascaded SHG of an 1123-nm Nd:YAG laser to 561.5 nm in LBO at first SHG stage and then frequency-doubled again to 281 nm in CBO at second SHG stage. Moreover, we investigated the SHG efficiency and the UV 281-nm laser beam quality theoretically under the experimental conditions, and the calculations agreed well with the experimental results.