REFRACTIVE-INDEXES OF ORTHORHOMBIC KNBO3 .2. PHASE-MATCHING CONFIGURATIONS FOR NONLINEAR-OPTICAL INTERACTIONS

Based on temperature-dependent refractive-index data of orthorhombic KNbO3 [J. Opt. Soc. Am. B 9, 380 (1992)], we analyze various nonlinear-optical second-order interactions. Phase-matching curves as a function of wavelength, propagation direction, and temperature are given. Both type I and type II phase matching are found to be possible in KNbO3 for second-harmonic generation and for sum-frequency generation and optical parametric oscillation. To demonstrate the precision of the calculations based on the new refractive-index data, we compare experimentally measured values with calculated values of acceptance angles, phase-matching angles, and phase-matching temperatures for some specific cases. A temperature-tuned optical parametric oscillator employing KNbO3 is demonstrated. Good agreement is found between calculated and experimental results.