Fabrication of periodic domain-inversion in X-cut LiTaO3 by heat treatment technique in an electric field

In this paper, we report a new fabrication technique, which makes it possible to obtain a deep and uniform periodic domain-inverted structure in X-cut LiTaO3. The structure is fabricated on an X-cut LiTaO3 crystal, in which a periodical proton-exchange region has been previously formed, by heat treatment under an added external electrostatic field. It is found that a uniform period of 10.8 mu m can be obtained by this method. The generation mechanism of domain-inversion is also examined. It is observed that an electric field is essentially effective not only in the proton-exchange region where the temperature is above the Curie temperature (T-c) but also in the neighboring region where the coercive field is lowered by proton-diffusion. Our result also shows that the stronger the strength of an applied electric field, the deeper the depth of domain-inversion grows.