High-power, high-repetition-rate mid-infrared generation with PE-SRO based on a fan-out periodically poled MgO-doped lithium niobate

►In conclusion, we have employed a Q-switched Nd:YAG laser with a repetition of 10 kHz to pump a PE-SRO based on a fan-out MgO:PPLN crystal. A maximum idler output power of 3.4 W at 3781.4 nm was obtained with a pump power of 22 W. As pump power increases, the signal and idler output wavelength shows significant shift, corresponding to a rise of crystal temperature. The thermal guiding effect caused by signal absorption with pump power above 17.9 W was observed. By comparing the heating power of the heating device when the OPO operated with that not, the crystal heating power induced by signal absorption was obtained to be 4.8 W under the maximum pump power. This is, to our best knowledge, the first time to measure the crystal heating power with this method. The crystal heating power could be measured with our method conveniently whether it was induced by absorption of pump, signal or idler. With this knowledge one can know more about the thermal effects of the crystal and OPOs with better performance could be designed.