Coherent subcarrier multiplexed optical communication system

摘要

A light is modulated in a sending equipment according to a composed signal obtained by mixing a signal frequency-multiplexed at the microwave level in a coherent SCM optical communication system with an unmodulated signal out of the frequency band of the frequency-multiplexed signal. The resultant modulated light is optical-heterodyne-detected. A demodulating unit (811) demodulates a frequency-multiplexed signal according to an electric signal delayed by a delay unit (810) by the time equal to the time delay in an unmodulated component extracting unit (809). Only the frequency components of a frequency-multiplexed signal and an unmodulated signal must be received in a receiving equipment (807), without need of receiving the component in a broad frequency band from the frequency component to the main carrier component of the frequency-multiplexed signal.