Periodically poled Cs-exchanged optical waveguides: High-resolution x-ray diffraction, scattering, and topography study

Abstract

A crystal of periodically poled (Formula presented) in which optical channel waveguides have been produced by Cs ion exchange, has been studied using combined optical and x-ray diffraction imaging, reciprocal-space mapping, and diffuse scattering. The lattice strains which result from the uptake of Cs in periodically poled (Formula presented) are determined and are found to be (Formula presented) for different orientations of the sample in the (001¯) plane, (Formula presented) and (Formula presented) to within the resolution of reciprocal-space measurement. The detailed microstructural features of the periodically domain-inverted structure and the modulation of the Cs uptake in the ion-exchanged regions are shown directly in x-ray diffraction images from the (001¯) surface. Evidence of defect clusters, formed during the ion-exchange processing and of size approximately 180 nm, is presented from analysis of the x-ray diffuse scattering around the Bragg peaks from the ion-exchanged layer and substrate. Discussions of the domain-inversion and ion-exchange processing and the consequences for the microstructure of the waveguiding layer and its properties are given in terms of our observations. © 1998 The American Physical Society.