Sum-frequency generation of more than 50 W of deep-ultraviolet light at 266 nm in LBO crystals based on a spherical-aberration-compensated high-energy picosecond Nd:YVO ₄ laser

All-solid-state deep-ultraviolet (DUV) lasers hold broad application prospects across numerous fields. This work reports the sum-frequency generation of over 50 W DUV light at 266 nm. A three-stage, 888 nm laser-diode end-pumped Nd:YVO₄ laser amplifier was constructed, delivering an average power of 290 W at 1064 nm with a pulse duration of ∼12 ps and a tunable repetition rate ranging from 300 kHz to 2 MHz. The maximum pulse energy exceeded 0.9 mJ. By using a phase plate to compensate for thermally induced spherical aberrations, the beam quality factor M² was improved to below 1.3. Through sum-frequency generation in commercial LBO crystals, average powers of 121 W at 355 nm and 51 W at 266 nm were achieved. It is, to our best knowledge, the highest average power at 266 nm obtained with LBO crystals. These results demonstrate the strong suitability of LBO crystals for high-power DUV generation. Furthermore, the high pulse energy and near-diffraction-limited beam quality of the 1064 nm laser confirm that conventional rod-shaped Nd:YVO₄ crystals remain highly competitive for high-energy picosecond laser systems.