We report on first-order quasi-phase-matched frequency doubling of picosecond pulses to the green, using a sample of periodically poled lithium niobate. In cw mode-locked operation, 330 mW of average green power was generated with an average conversion efficiency of ~52%. With a quasi-cw mode-locked pulse train an average conversion efficiency of ~65% was achieved, and 1.3 W of green power (average power within the 10-µs pulse envelope) was produced. At these powers there was no significant photorefractive damage, as confirmed by measured M2 beam-quality factors of ~1.1 for both output fundamental and second-harmonic beams.
© 1996 Optical Society of America
V. Pruneri, S. D. Butterworth, and D. C. Hanna, "Highly efficient green-light generation by quasi-phase-matched frequency doubling of picosecond pulses from an amplified mode-locked Nd:YLF laser," Opt. Lett. 21, 390-392 (1996)