Patent ID: 8311371

Claim:
An optical modulation device for generating an optical signal pulse, comprising: a substrate having an electro-optic effect, said substrate having a polarization non-reversal region and a polarization reversal region; an optical waveguide formed upper said substrate including a bifurcation optical waveguide for bifurcating incident light, first and second branched optical waveguide portions for transmitting bifurcated incident lights, and a mixing waveguide for mixing incident lights respectively transmitted by said first and second branched optical waveguide portions; and a traveling waveguide including a center electrode and a ground electrode to have an electric signal applied thereto, said traveling waveguide and said first and second branched optical waveguide portions collectively forming an interaction portion to have said incident light interacted with said electric signal, said interaction portion including a first interaction sub-portion and a second interaction sub-portion, said first and second interaction sub-portions being respectively positioned in regions of said substrate having opposite polarization orientations with each other, in which said center electrode is positioned in face to face relationship with one of said first and second branched optical waveguide portions at said first interaction sub-portion and the other of said first and second branched optical waveguide portions at said second interaction sub-portion to ensure that said incident light in said first and second branched optical waveguide portions are phase modulated, said interaction portion further includes an optical waveguide shift sub-portion sandwiched between said first and second interaction sub-portions to have positions of said first and second branched optical waveguide portions shifted therein such that the optical axes of said first optical waveguide at said first and second interaction sub-portions are in spaced relationship with each other while the optical axes of said second optical waveguide at said first and second interaction sub-portions being in spaced relationship with each other, ensuring that positions of said first and second branched optical waveguide portions relative to said center and ground electrodes are interchanged between said first and second interaction sub-portions, and said center electrode of said interaction portion is formed substantially straight in such a manner that said traveling waveguide is formed straight not to have any discontinuity portion at the interaction portion.