LOW VOLTAGE OPTICAL MODULATOR USING SUBSTRATE OF LOW PERMITTIVITY

摘要

PURPOSE: A low voltage optical modulator using a substrate of low permittivity is provided to minimize phase velocity matching and characteristic impedance matching between a laser beam and an RF data signal by minimizing the thickness of a LiNbO3 layer. CONSTITUTION: A substrate(30) of low permittivity is formed of a material having the permittivity lower than the permittivity of LiNbO3. A LiNbO3 layer(31') is formed on the substrate. An optical waveguide is formed on the LiNbO3 layer and is branched into two optical waveguides(11,12) at an input waveguide. The branched optical waveguides are combined with each other to be extended to an output waveguide. A buffer layer(32) is formed on the optical waveguide and the LiNbO3 layer. A positive electrode(23) is formed on the buffer layer of one of the branched optical waveguides for receiving an RF data signal. A first ground electrode(22) is separated from one side of the positive electrode and is formed on the buffer layer of the other branched optical waveguide. A second ground electrode(24) is separated from the other side of the positive electrode and is formed on the buffer layer.