High Electrical-to-Optical Efficiency, Mid Infrared Intracavity OPO Using Periodically Poled Lithium Niobate

We report the generation of a mid infrared laser output using periodically poled lithium niobate used in an intracavity OPO setup pumped by a Q-switched Nd:YAG fundamental laser. The pump laser was quasi CW pumped and repetitively Q-switched from 30 KHz to 100 KHz. The output of the intracavity OPO consisted of a signal wave near 1.45 µm, and an idler wave near 4 µm in the mid infrared region. We obtained an electrical-to-optical conversion efficiency of 3.3% from diode's electrical power to combined OPO output power, and an conversion of 10% from diode's pump power to the combined OPO output power. We experimented with discrete intracavity PPLN and monolithic PPLN. Both setups show promise for scaling up the mid infrared output power to a multi-watt level in a simple and compact system.