Two-millijoule, 1-kHz, 355-nm picosecond laser pulse generation in LiB3O5 crystal

A third-harmonic-generation picosecond pulse with several millijoules per pulse at 355 nm has been achieved by nonlinear optical materials LiB 3 O 5 (LBO). The single pulse energy of third harmonic was up to 2 mJ at the repetition rate of 1 kHz. The conversion efficiency was up to 33.3% from 1064 to 355 nm with the M 2 factor of 2.4. The system is based on a Nd:YAG regenerative amplifier with a simple double-pass post-amplifier.