Patent ID: 7561810

Claim:
An optical communication apparatus for modulating an electrical signal to an optical signal and transmitting the optical signal, the optical communication apparatus comprising: a light source; a bias voltage generation means for generating a bias voltage in accordance with a control signal; a pilot signal generation means for generating a pilot signal; an adding means for adding the pilot signal and the bias voltage; an optical modulation means for modulating light output from the light source in accordance with the electrical signal, performing modulation also in accordance with a signal from the adding means, and outputting the optical signal; a monitor means for monitoring the level of the optical signal and outputting a monitor signal; a reference signal output means for outputting a reference signal which is in phase with the pilot signal contained in the monitor signal; a synchronous pilot-signal detection means for performing synchronous detection of the monitor signal by using the reference signal; a synchronous noise detection means for extracting noise from the monitor signal and performing synchronous detection by using the reference signal; and a control signal output means for subtracting a synchronous detection value obtained by the synchronous noise detection means from a synchronous detection value obtained by the synchronous pilot-signal detection means, and outputting the control signal.