High-power mid-infrared 3.8 μm laser

A high-average-power high-efficiency high-repetition-rate mid-infrared laser at 3.84 μm was demonstrated.The laser was based on quasi-phase-matched periodically poled LiNbO3(PPMgLN) optical parametric oscillator(OPO),pumped by elliptical 1.06 μm laser beam.The PPMgLN crystal was 5% MgO-doped.The OPO was extra-cavity and single-resonated OPO.The pump beam polarization matched e→e+e interaction in PPMgLN, thus maximal nonlinear coefficient was effective. When pump power was 73 W at acoustic-optic Q-switch repetition rate 7.5 kHz, 8.3 W average output power at 3.84 μm was obtained with slope efficiency 14.1%.The optical beam quality factors were 1.94,4.57 in horizontal and perpendicular direction,respectively.