Investigation on poling of Lithium Niobate patterned by interference lithography

We realized one and two dimensional. periodic ferroelectric domain structures obtained by an electric-field poling process applied to 500 mum thick Lithium Niobate crystal samples patterned by means of interference lithography. The fringe pattern is realized using a Michelson interferometric set-up and a He-Cd laser. We report on the appearance of high density and micrometer-sized single dot domains aligned along the direction of the interference fringes, as consequence of overpoling procedures. These structures are similar to those induced by back-switching. The effect seems to be originating by inverted domains' merging under the photoresist fringe pattern after spreading. We investigate the possibility to obtain a highly regular and homogeneous dot-structure which can find application for photonic crystals technology and nonlinear optics.