Structural Characterization of Periodically Poled Lithium Niobate Crystals by High Resolution X-Ray Diffraction

High Resolution X-Ray Diffraction (HRXRD) technique is non-destructive method to investigate the structural properties of Periodically Poled Lithium Niobate crystals. They, in fact, can be viewed as crystals with a periodic modulation of the inner cell structure and a shift of the cells due to the presence of both static deformations induced by the poling process and random strains due to defects. HRXRD, therefore, can be exploited to investigate the spontaneous polarization profile and the presence of lattice distortions, allowing the quantitative determination of the domain period, domain shape and the eventual domain wall inclination. To these aims, a theoretical description of the scattering process from a PPLN is however necessary and will be briefly outlined. In order to evidence both the technique potentialities and the limits, some special cases of scientific interest will be reviewed such as: the structural characterization of sub-micrometric PPLN crystals realized by interference technique and of PPLN grown by the Czochralski off-center technique.