| 摘要 |
PURPOSE:To reduce influence caused by the wavelength dispersion of an optical fiber and to prevent an optical receiver from being deteriorated in reception sensitivity by giving a prescribed time difference to the time during which each intermediate frequency signal is transmitted to a difference synthesizer. CONSTITUTION:Signal light 1 transmitted through the optical fiber is multiplexed with local oscillation light received from a light source having CW oscillation with an optical frequency slightly different from the light 1. This synthetic light is received by a photodetector such as a photodiode. For the light 1, the mark component is set ahead of the space component when the light 1 reaches a receiver. This relative time difference is eliminated by means of a delay line 12. In other words, the line 12 is put into one of two circuit systems separated by the BPF 6 and 7 so that said relative time difference is corrected. Then the difference synthesization is carried out for reproduction of a correct base band signal. |
