Optical transmission system, optical phase modulator, and optical modulation method

An optical phase modulator comprising:

• a first optical modulator that performs an optical modulation process for input light;
• a second optical modulator that performs an optical modulation process for the input light;
• a third optical modulator that performs an optical modulation process for the input light;
• signal output unit that outputs a drive signal according to an input signal to the first optical modulator;
• first waveform shaping signal output unit that outputs a first waveform shaping signal to the second optical modulator;
• and
• second waveform shaping signal output unit that outputs a second waveform shaping signal to the third optical modulator, wherein
• the first waveform shaping signal output unit outputs the first waveform shaping signal at a timing relatively later than a timing of an output of a signal by the first optical modulator, and
• the second waveform shaping signal output unit outputs the second waveform shaping signal at a timing relatively earlier than the timing of the output of the signal by the first optical modulator.

An optical modulation method for modulating input light based on a drive signal, a first waveform shaping signal, and a second waveform shaping signal, the drive signal being adapted to change according to an input signal, the optical modulation method comprising:

• performing an optical modulation for the input light by using the drive signal;
• performing waveform shaping for the input light by using the second waveform shaping signal at a timing relatively earlier than a timing of the drive signal;
• and
• performing waveform shaping for the input light by using the first waveform shaping signal at a timing relatively later than the timing of the drive signal.