Cubic optical nonlinearity of KTiOPO4

摘要

We perform angular non-critical phase-matching third-harmonic generation (THG) experiments in KTiOPO4 (KTP). From these experiments, we determine the magnitude and sign of the two phase-matched nonlinear coefficients of KTiOPO4 by a complete analysis of phase-matching properties of the cascaded quadratic and pure cubic processes, the resolution of the coupled propagation equations and by the calculation of the quadratic and cubic dielectric susceptibility tensor by an extended bond charge model; we find: χ24(3)(539 nm) = 14.6×10-22 m2 V-2 and χ16(3)(491 nm) = 8.0×10-22 m2 V-2. We also demonstrate that the two studied THG are mainly governed by the cubic interaction.