Characterization of CsB3O5 crystal for high-average-power third harmonic generation

High-average-power third harmonic generation (THG) from an Nd:YAG laser has been achieved with a CsB3O5 (CBO) crystal. The highest output power reaches 46.4 W at 355 nm, and the highest conversion efficiency from 1064 nm to 355 nm is 35.4%. Stable third harmonic outputs with average powers of 22.6 W and 31.5 W are realized with the stabilities of 0.52% and 1.4% respectively. Moreover, the principal refractive indices of CBO crystal are accurately measured in the wavelength range of 253.7–2325 nm for the first time, the phase-matching (PM) conditions are calculated for THG at different wavelengths, and the acceptance angle and acceptance temperature are also measured.