Abstract

When a fundamental beam propagates perpendicular to the optical axis of a nonlinear crystal with randomly distributed ferroelectric domains showing inverted sign of 2^nd order nonlinearity (χ²), the generated second harmonic (SH) signal is spatially distributed in a plane, perpendicular to the optical axis [1]. Because the angular distribution of the SH intensity in this plane depends on the particular domain size and distribution, the characterization of the angular emission pattern could bring information about these parameters, which is difficult to be obtained by imaging methods since the domain size can be very small (few hundreds of nm). The domain statistics of such nonlinear materials was considered in the study of the SH diffraction pattern in a one-dimensional (1D) model by Le Grand et al. [2-4]. However, this model yields some discrepancies between the theoretical fits and experimental results [4]. In this work we compare experimental results of the SH angular distribution with the predictions of a more precise 2D model for extracting domain statistics.

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