TYPE-II PHASE-MATCHED KNBO3 OPTICAL PARAMETRIC OSCILLATOR

A Type-II phase-matched KNbO3 optical parametric oscillator (OPO) pump ed at 1.064 mum is described. Calculations shown that the full tuning range of 1.4 to 4.2 mum is attainable, that the peak nonlinear drive i s achieved near the phi = 45-degrees plane, and that the walk-off angl es for this interaction are a maximum of approximately 3-degrees. The tuning curve in the phi = 45-degrees plane was experimentally verified , and the OPO was operated at signal and idler wavelengths of 1.87 and 2.47 mum, respectively. The relative OPO thresholds measured here ind icate that the effective nonlinear coefficient for the Type-II interac tion is smaller than that of the corresponding Type-I interaction.