Optical transmission apparatus, and output stabilization control method for an optical modulator used in the optical transmission apparatus

An output stabilization control method, for an optical modulator used in an optical transmission apparatus, of inputting an optical signal to a Mach-Zehnder optical modulator, applying a driving signal and a bias voltage, and modulating and outputting the optical signal based on the driving signal, the output stabilization control method comprising:

• a monitoring step of monitoring an optical spectrum of an output optical signal that has been modulated and output from said optical modulator;
• and
• a bias voltage control step of controlling the bias voltage based on an optical spectrum shape monitored at the monitoring step.

An output stabilization control method, for an optical modulator used in an optical transmission apparatus, of inputting an optical signal to a Mach-Zehnder optical modulator, applying a driving signal and a bias voltage, and modulating and outputting the optical signal based on the driving signal, the output stabilization control method comprising:

• a monitoring step of monitoring an optical spectrum of an output optical signal that has been modulated and output from said optical modulator;
• and
• a driving signal level control step of controlling a signal level of the driving signal based on an optical spectrum shape monitored at the monitoring step.

An output stabilization control method, for an optical modulator to be used in an optical transmission apparatus, of inputting an optical signal into a Mach-Zehnder optical modulator having two electric signal input terminals, applying a driving signal and a bias voltage, and modulating and outputting the optical signal based on the driving signal, the output stabilization control method comprising:

• a monitoring step of monitoring an optical spectrum of an output optical signal that has been modulated and output from said optical modulator;
• and
• a phase difference control step of controlling a phase difference between two driving signals input into said electric input terminals based on an optical spectrum shape monitored at the monitoring step.