Patent ID: 8565559

Claim:
An optical device comprising: a substrate; a dielectric film that is formed on the substrate and includes a first optical waveguide and a second optical waveguide; a transmission line that is formed on the dielectric film and includes a signal line arranged between the first optical waveguide and the second optical waveguide, a first bias electrode arranged on a side of the first optical waveguide that is opposite the second optical waveguide and a second bias electrode arranged on a side of the second optical waveguide that is opposite the first optical waveguide; and a drive circuit section that applies a first bias voltage to the first bias electrode, a second bias voltage that is different from the first bias voltage to the second bias electrode, and applies a control voltage that is between the first bias voltage and the second bias voltage to the signal line, the drive circuit section including: a first capacitor connected between a predetermined reference voltage and the first bias electrode, a second capacitor connected between the predetermined reference voltage and the second bias electrode, and a frequency signal source that supplies the signal line with a frequency signal having a predetermined frequency, wherein the first and second bias electrodes connect the frequency signal source to the predetermined reference voltage, with a low resistance, while blocking the first and second bias voltages, respectively.