A high efficiency picosecond (ps) 532 nm green laser with high pulse energy and high peak power at 5 kHz repetition rate was demonstrated by second harmonic generation (SHG) from a 1064 nm master oscillator power amplifier (MOPA). The MOPA was based on the Innoslab structure under diode directly pumping, producing 4.8 mJ, 25 ps fundamental laser at the repetition rate of 5 kHz after a 3-stage Innoslab amplification system. With a pulse energy of 2.93 mJ in the fundamental and using a type I noncritically phase matched lithium triborate (LBO) crystal, the pulse energy of SHG was up to 1.96 mJ per pulse with a pulse width of 18.9 ps, which corresponds to a peak power of 104 MW in the green and SH conversion efficiency as high as 67 %. The SHG green beam quality factor was measured to be M2=1.75.

Photonics Technology Letters, 2015