| 摘要 |
At the transmitting end of an optical transmission system, a wide linewidth LED (31) is intensity modulated by a first digital information signal and a narrow linewidth DFB (Distributed Feedback) laser (32) is frequency modulated by a second digital information signal and the two modulated optical signals are combined (33) for transmission over a single mode optical fiber (34). At the receiving end, the intensity modulating digital signal is recovered from the received optical signal by a photodetector (52). The frequency modulating digital signal is recovered by a coherent receiver (53) which includes a local oscillator (55) the output of which is optically combined (54) with the received optical signal. A photodetector (56) converts this combined optical signal to an electrical IF signal, and an IF demodulator (57) reconstructs the second ditital signal therefrom. |
