Abstract
In this work, the formation of optical waveguides in periodically poled lithium niobate (PPLN) substrates by Zn-diffusion from vapour phase is studied. It has been found that the diffusion of the Zn ions is homogeneous in the PPLN substrates and the optical waveguides can be fabricated with the same parameters used in single-domain lithium niobate. The periodic ferroelectric domain pattern initially present in the substrate is preserved in the waveguides.