US Patent 7931831 Optical waveguide substrate manufacturing method

A voltage is applied on an interdigitated electrode provided on one main face of a single-domain ferroelectric single crystal substrate to form a periodic domain inversion structure. The interdigitated electrode is then removed. The optical waveguide is then formed in the substrate. An optical intensity center P1 of the optical waveguide is kept away from a location P0 of the end of the interdigitated electrode.