Techniques of observation and characterization of the domain structure in periodically poled lithium niobate

The domain structure of bulk periodically poled lithium niobate crystals were analyzed by different techniques. Images of topography, electrostatic force, and piezoelectric response were studied by scanning force microscopy. All these images showed the domain structure of the samples, The electrostatic force was always attractive pointing to a dielectric origin. The diffraction of a laser beam by the periodic structures was also observed, denoting a periodic change of refractive index. From the angle of diffraction the domain spatial frequency was directly obtained. The topographic profile of etched samples was studied by both scanning force and scanning electron microscopy.