A deep-UV picosecond laser for photocathode electron gun

We report a 10 Hz Yb:YAG laser regenerative amplifier with frequency conversion to 257.3 nm. A diode-pumped solid-state Yb:YAG laser oscillator is built as the seed of the system with output power up to 1.75 W. A chirp-volume-Bragg grating (CVBG) is used both as pulse stretcher and pulse compressor. A 10-Hz Yb:YAG regenerative amplifier is built which amplifies the seed pulses to 1.58 mJ. After pulse compression, 1.36 mJ laser pulses with 2.4 ps pulse duration are obtained. Good beam quality is maintained after the compressor. LBO and BBO crystals are cascaded in frequency convertor. At the final output, 120 μJ laser pulses at 257.3 nm are obtained. This system is designed as the driving source for photocathode electron guns in electron accelerator.