Patent ID: 7167607

Claim:
A method for fabricating a symmetric optical modulator with low driving voltage comprising the steps of: forming an optical waveguide on a substrate, said optical waveguide being composed of an input portion, a pair of first and second branch portions branched off from the input portion, and an output portion where the first and second branch portions are combined; inverting and polarizing a region of the substrate including any one region of the first and second branch portions of the optical waveguide; applying a buffer layer onto a top surface of the substrate; forming first and second mask layers on regions of the buffer layer over a first and third grooves excluding a second groove located between the first and second branch portions, and then forming a center electrode and first and second side electrodes on a top surface of the buffer layer divided by the first and second mask layers; and removing the first and second mask layers, and then removing portions of the buffer layer below the first and second mask layers.