QUASI-PHASE-MATCHED OPTICAL PARAMETRIC OSCILLATORS IN BULK PERIODICALLY POLED LINBO3

We review progress in quasi-phase-matched optical parametric oscillators in bulk periodically poled LiNbO3. Using the electric-field poling process, we can reliably fabricate 0.5-mm-thick crystals with uniform domain structures over a 15-mm length. Periodically poled material retains the low-loss and bulk power handling properties of single-domain LiNbO3, and quasi phase matching permits noncritical phase matching with da(33), the highest-valued nonlinear coefficient. Optical parametric oscillators pumped by 1.064-mu m pulsed Nd:YAG lasers have been operated over the wavelength range 1.4-4 mu m with tuning by temperature or by quasi-phase-matched period. We have shown an oscillation threshold as low as 0.012 mJ with a Q-switched pump laser resonant oscillator near 1.96 mu m pumped directly with a commercial cw diode laser at 978 nm. (C) 1995 Optical Society of America