Optical and structural characterization of zinc vapour diffused waveguidesin LiNbO3 crystals

All stages of vapour Zn-diffused waveguide fabrication on different cuts of lithium niobate crystals have been structurally characterised by single- a nd double-crystal X-ray diffractometry. Immediately after diffusion the zin c niobate phase ZnNb2O6 was formed on the sample surface. After annealing t he ZnO phase appeal ed with the ZnNb2O6 on the surface of the Zn-diffused w aveguides. Both these phases completely disappeared after light polishing. The lattice deformations in vapour Zn-diffused waveguides were found to dif fer from Zn-substituted solid solutions of lithium niobate. Dark mode measu rements have been used to determine the refractive-index profiles of the pl anar waveguides. Changes in refractive index higher than 0.05 have been obt ained. (C) 1999 Elsevier Science Limited. All rights reserved.