Temperature insensitive, high-power cascaded optical parametric oscillator based on an aperiodically poled lithium niobate crystal

We report a novel temperature insensitive, APMgLN-based, high-power cascaded optical parametric oscillator (OPO) pumped by an Ytterbium-doped fiber laser. A monolithic APMgLN crystal was designed to compensate the phase mismatches for the nonlinear conversions from the pump to the idler and the primary signal to the idler simultaneously in a wide temperature range. Efficient parametric conversion with pump-to-idler conversion efficiency over 15% and slope efficiency higher than 20% was realized from 25 degrees C to 55 degrees C. The idler wavelength was down-shifted from 3.82 mu m to 3.78 mu m accordingly during the temperature rise. The highest idler power of 4.1 W at 3.8 mu m under the pump power of 26.5 W was recorded which was improved by similar to 32% in pump-to-idler conversion efficiency when compared with the PPMgLN-based conventional OPO, in which the highest idler output power was 3.1W under the same pump and thermal condition.(C) 2014 Optical Society of America