| 摘要 |
PURPOSE:To make it possible to use light sources having the same wavelength and the same photodetectors by making frequencies of light emitting element driving subcarriers different from one another in an optical transmission system. CONSTITUTION:In case of the transmission from a terminal 1 to a terminal 1', the subcarrier from a subcarrier generator 8 is modulated to drive a light emitting element 3, and an optical signal is made incident to an optical fiber 5 through an optical coupler 6. The optical signal from the optical fiber 5 is branched in an optical coupler 7, and the electric signal from a photodetector 4' is allowed to pass through a band-pass filter, and a modulated subcarrier is outputted to the terminal 1'. In case of the transmission from a terminal 2 to a terminal 2', a light emitting element 3' is driven directly by the base band signal from the terminal 2, and an optical signal is made incident to the optical fiber 5. The output from a photodetector 4 is outputted from the terminal 2' through a low-pass filter 10. Since spectrums of modulation signals are different from each other, light sources having the same wavelength and the same photodetectors can be used. |
