High-resolution X-ray characterization of periodically domain-inverted nonlinear optical crystals

Abstract

A high-resolution triple-axis diffractometer has been used for the structural characterization of periodically domain-inverted nonlinear optical crystals of KTiOPO<sub>4</sub> and LNbO<sub>3</sub>. Striations have been revealed in high strain-sensitivity multiple-crystal topographs of the domain-inverted regions of both these samples and these are dominated by orientation contrast. The combination of high-resolution reciprocal-space mapping and topography has shown that the extended diffraction streak in the q[210] direction for domain-inverted LiNbO<sub>3</sub> originates from the "minutely misoriented structure" which is related to the original configuration of dislocations. The reason for the generation of the structural imperfections via the domain-inversion processing is interpreted in terms of the converse piezoelectric effect.