Patent ID: 7289686
Filing Date: 2007-10-30
Classification: G02F

Abstract:
1. An optical modulator of Mach-Zehnder type comprising: an optical waveguide of a Mach-Zehnder interferometer structure disposed on a substrate having an electro-optic effect; and a signal electrode and an earth electrode disposed along a pair of branching waveguides positioned between a branching section of said optical waveguide and a multiplexing section thereof, for applying an electric signal on said signal electrode to modulate a light being propagated through said optical waveguide, wherein said substrate includes, in an interacting portion thereof where the lights being propagated through said pair of branching waveguides and the electric signal being propagated through said signal electrode interact to each other, a first region positioned on an input side of the light in a propagation direction and a second region positioned on an output side thereof; said first and second regions each includes a polarization inversion region which is a part thereof and whose polarization direction is inverted to a polarization direction of the remaining part thereof, and the previously set wavelength chirping can be obtained independently in each of said first and second regions; and said signal electrode is arranged above either one of said pair of branching waveguides according to positions of the respective polarization inversion regions in said first and second regions, and also, an arrangement pattern of said signal electrode is determined so that a modulation direction in said second region is opposite to a modulation direction in said first region.