Wildly Tunable, High-Efficiency MgO:PPLN Mid-IR Optical Parametric Oscillator Pumped by a Yb-Fiber Laser

We demonstrate a wildly tunable, high-efficiency mid-infrared (mid-IR) output-coupled single resonant optical parametric oscillator (OC-SRO) pumped by a Yb-fiber laser. The compact mid-infrared source employs a 50-mm-long, multi-grating MgO-doped periodically poled lithium niobate (MgO-PPLN) crystal, providing as much as 1.73 W idler power at 3.012 μm, and 1.27 W signal power at 1645 nm, corresponding to an overall conversion efficiency of 41.7% and a slope efficiency of 77.9%. In particular, the mid-infrared output power of 1.03 W and 0.67 W are obtained at 3.7 μm and 3.9 μm, respectively, with an optical-to-optical conversion efficiency of 14.3% and 9.3%. Furthermore, the idler light is tunable from 3 μm to 3.9 μm by changing the periods from 31 to 28.5 μm, with the output power >1 W over 78% of the tuning range. Our experimental results are pump power limited and further mid-IR power and conversion efficiency could be obtained with a suitable high-power pump source. The total OC-SRO output power rms at 2.6 W is about 0.6% during 2 h measurement.