High peak power tunable source at 550 nm from a frequency doubled Yb-doped fiber MOPA

A high-peak-power tunable green source operating in the range of 544-552 nm is demonstrated through frequency doubling a diode-seeded, nanosecond, polarization-maintaining, Yb-doped fiber master oscillator power amplifier system. Type I second-harmonic generation was implemented in a lithium triborate crystal via noncritical phase matching by temperature tuning. Narrow-bandwidth green light of average output power of up to 9 W, with a pulse duration of 1.8 ns and a peak power of 25 kW, was obtained at a repetition rate of 200 kHz. The pump-to-green conversion efficiency reached 30%. This linearly polarized, narrow bandwidth, tunable source has great potential for applications, such as material processing, sensing, and medical research.