Continuous Wave Singly Resonant Intracavity Optical Parametric Oscillators Using Periodically Poled LiNbO3

Abstract

Abstract : The use of continuous wave singly resonant optical parametric oscillators (CW SROs) has been limited in the past mainly because of the high threshold powers necessary. Thresholds of SROs are orders of magnitude greater than doubly resonant oscillators. While lithium niobate has long been in use as a nonlinear material, periodically poled lithium niobate (PPLN) recently emerged as an excellent source for CW SROs. Quasi-phase matching with PPLN has allowed access to the higher nonlinear coefficients of lithium niobate permitting construction of CW SROs. By placing the OPO within the laser resonator, threshold should be significantly reduced. We have designed, built, and investigated an optical parametric oscillator within a laser cavity to access the high circulating fields within the resonator. The intracavity OPO acted as the output coupler for the laser and ideally the total down converted power from the OPO should approach the maximum output power available from th pump laser under optimal output coupling. PPLN OPOs were built within the resonators of a lamp-pumped Nd:YAG laser and a diode-pumped Nd:YVO4 laser. Combined idler output at 3.3 microns from both ends of an intracavity 30-mm PPLN OPO was 1.15 W. Output of the Nd:YVO4 laser optimized for 1.064-micron output with the same resonator was 5 W. The entire device, except for power supply and cooler, fit on a 1' x 2' breadboard.