Effects of stresses in titanium-indiffused and proton-exchanged lithium niobate waveguides

By using x-ray diffraction from different crystallographic planes, we have found the crystal structure deformations in proton-exchanged and titanium-indiffused lithium niobate waveguides. We have calculated the appearing mechanical stresses and the contribution of the photoelastic effect to the changes in refractive indices. It is shown that the waveguides have biaxial structure.