Patent ID: 7710638

Claim:
A wavelength conversion device comprising: a supporting substrate having a surface; a wavelength conversion element provided on said supporting substrate and comprising a ferroelectric material, said wavelength conversion element comprising a ridge optical waveguide, first grooves provided on both sides of said ridge optical waveguide, respectively, and extended portions provided on the outside of said first grooves, respectively; separate portions provided on both sides of said wavelength conversion element, respectively, and comprising a ferroelectric material, said separate portions are separated from said wavelength conversion element by second grooves respectively; and an adhesive layer bonding the surface of said supporting substrate and said wavelength conversion element and bonding said supporting substrate and said separate portions; wherein the surface is flat under the wavelength conversion element, the separate portions and the second grooves, wherein said wavelength conversion element and said separate portions have upper faces, respectively, said device further comprising an upper side buffer layer formed on said upper faces of said wavelength conversion element and said separate portions, and wherein the upper side buffer layer contacts a back side buffer layer along a plane perpendicular to the substrate surface on each second groove wall surface.