Relative sign and absolute magnitude of d^(2) nonlinear coefficients of KTP from second-harmonic-generation measurements

We determine the absolute magnitude of the dij(2) coefficients of KTP, using type-I and type-II phase-matching second-harmonic-generation efficiency measurements: |d15 (0.532 μm)| = 1.4 ± 0.07 pm/V, |d24 (0.532 μm)| = 2.65 ± 0.13 pm/V, and |d33 (0.532 μm)| = 10.7 ± 0.5 pm/V. We establish that these coefficients have the same sign. We compare the obtained magnitudes with the main previously published results.