Estimation of the Ratio of Nonlinear Optical Tensor Components by Measuring Second Harmonic Generation and Parametric Down Conversion Outputs in a Single Periodically Poled LiNbO_3 Crystal

Measurement of the nonlinear optical coefficients is not an easy task since it requires complicated experimental setup and analysis. We suggest an easy way to estimate the relative nonlinear optical tensor components by direct measurement of the output powers of the second harmonic generation and spontaneous parametric down conversion experiments. The experiments were done in quasi-phase-matched type-0 as well as type-1 interactions at similar pump wavelengths in a 5% MgO-doped periodically poled LiNbO_3 crystal to obtain the ratio of the nonlinear optical tensor components d_33/d_31 in each experiment. The obtained ratios were then compared with the previously ascertained values [J. Opt. Soc. Am. B, 14, 2268-2294 (1997)].