Optical communication system

An optical communication system comprising:

• a transmitter configured to output a wavelength division multiplexing (WDM) signal including one pilot carrier and a signal group including a pair of a signal light and a phase-conjugated light on two or more wavelength channels, the signal light of the two or more wavelength channels being generated by modulating each optical carrier of a portion of an optical comb generated from a single light source light;
• and
• a receiver including
• a light phase synchronization mechanism configured to generate a synchronized light that is phase-synchronized with the WDM signal transmitted from the transmitter, the light phase synchronization mechanism including
• a second-order nonlinear optical element configured to generate a sum frequency light of the signal light and the phase-conjugated light of the transmitted WDM signal,
• a local oscillation light source configured to perform injection locking using the pilot carrier extracted from the transmitted WDM signal,
• a second-order nonlinear optical element configured to generate one second harmonic light in an optical comb generated from an injection-locked local oscillation light from the local oscillation light source, and
• a feedback loop mechanism configured to compare frequencies and phases of the sum frequency light and the second harmonic light and synchronize the phases of the transmitted WDM signal and the optical comb, the light phase synchronization mechanism being configured to output the optical comb as the synchronized light,
• a non-degenerate optical phase-sensitive amplifier configured to use the synchronized light to amplify the transmitted WDM signal, and
• a coherent receiver configured to use the synchronized light to demodulate the amplified WDM signal.