| 摘要 |
PURPOSE:To suppress the phase noises in a simple circuit constitution without using any wide band detection circuit. CONSTITUTION:The optical modulation is carried out at the transmitter side with use of a synthetic signal 104 obtained by multiplexing a transmitted signal 101 and a no-modulated signal 102 set out of a frequency band. The modulated light 106 undergoes the optical heterodyne detection, etc., through a photodetector means 107. A demodulator means 111 demodulates the signal 101 based on the electric signal 108' which is delayed by a delay means 110 by an extent equal to the time delay of a no-modulated component extractor means 109 and the no-modulated signal 112 which is extracted by the means 109. The receiver side is not required to receive the component of a wide frequency band covering the frequency component of the signal 101 through the main carrier component. The signal 101 can apply the data signal on the base band of a coherent optical communication system or the data signal which undergone the frequency multiplexing at a microwave level of a coherent SCM optical communication system. |
