Coherent transmission of 60 FM-SCM video channels

A fiber-optic 60-channel FM video system using coherent subcarrier multiplexing (SCM) is described. Two receiver implementations were studied. For the 60-channel coherent experiment, a carrier-to-noise ratio of 17 dB and a corresponding signal-to-noise ratio of 56 db was achieved with a detected optical power of -32 dBm and a phase modulation index of beta -0.07. This represents a 15.2-dB improvement over a similar 60-channel direct-detection FM-SCM system and a 5.6 dB improvement compared to the performance of the system when a semiconductor optical preamplifier was used.<
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