Yb-fiber-pumped high-average-power picosecond optical parametric oscillator tunable across 1.3−1.5 μm

Abstract

We report the generation of high-repetition-rate picosecond pulses in the 1.3-1.5 µm spectral range by internal second harmonic generation (SHG) of an idler-resonant optical parametric oscillator (OPO) based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by ∼20 ps pulses at 80 MHz using an Yb-fiber laser at 1.064 µm. By taking advantage of the high spatial quality of the resonant idler beam in the 2503-3030 nm wavelength range and using a second MgO:PPLN crystal with fanout grating structure for intracavity SHG, we have achieved spectral coverage across 1272-1515 nm with up to 1.23 W average power. The second harmonic output exhibits a power stability of 3% rms over 1 hour in pulses of 8.3 ps with Gaussian beam profile. The described approach overcomes the spectral limitation of 1.064 µm-pumped OPOs based on MgO:PPLN and other oxide-based nonlinear crystals, where signal generation below ∼1.45 µm is precluded by multi-phonon absorption of idler radiation above ∼4 µm.