| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a configuration and a method for adjusting an operational state of an optical modulation device including a semiconductor mach-zehnder type modulator. <P>SOLUTION: An optical modulation device is provided, which includes a modulator, a modulation signal generator, a superimposer, and a bias controller. The modulator includes a light guide which is provided on a semiconductor substrate having an electro-optical effect, and a signal electrode which provides an electrical field in response to bias voltages and modulation signals to the light guide. The modulation signal generator generates the modulation signals. The superimposer superimposes a signal having predetermined frequency on the bias voltages. The bias controller controls a bias voltage having a modulating direction of the modulator, and a bias voltage having an orthogonal direction perpendicular to the modulating direction on the basis of a phase of a predetermined frequency component extracted from a modulation optical signal generated by the modulator. <P>COPYRIGHT: (C)2012,JPO&INPIT |
