Patent ID: 8774564
Filing Date: 2014-07-08
Classification: G02F

Abstract:
1. An optical modulator comprising: an optical waveguide element comprising an optical waveguide substrate made of a material having an electro-optical effect, a Mach-Zehnder optical waveguide formed on the optical waveguide substrate, and a modulating electrode that modulates a light wave propagated through the Mach-Zehnder optical waveguide; and a filter circuit provided on a modulation signal input line that inputs a modulation signal to the modulating electrode, wherein the filter circuit comprises a capacitor that is a single-layer capacitor having a dielectric having relative permittivity that is equal to or less than 1000, the filter circuit is formed on a filter circuit board provided outside the optical waveguide substrate, the filter circuit obtains flat frequency characteristics of the optical modulator, a distance between electrodes of the capacitor is 0.05 mm or less, and the filter circuit generates a resonance frequency at higher than 20 GHz.