Optical transmitter

An optical transmitter, comprising:

• a reference clock generation oscillator configured to oscillate a reference clock signal;
• a multi-frequency phase-synchronized light source configured to generate a plurality of continuous light beams having a frequency interval based on a clock signal that is an integral multiple of the reference clock signal and having synchronized optical phases;
• a frequency interval setting unit configured to perform setting so that an interval of the multi-frequency phase-synchronized light source is varied for each frequency;
• a frequency selection demultiplexer configured to selectively transmit the plurality of continuous light beams generated by the multi-frequency phase-synchronized light source according to the setting so as to demultiplex the transmitted continuous light beams;
• and
• a plurality of optical modulators configured to modulate light for each optical frequency from the frequency selection demultiplexer so that frequencies of the frequency interval of the multi-frequency phase-synchronized light source and frequencies of modulation of the optical modulators are synchronized with each other by using a clock signal that is an integral multiple of the reference clock signal.