Interchannel interference in FDM coherent optical networks

The narrow channel spacing allowed by coherent systems suggests the use of a frequency division multiplexing (FDM) technique together with coherent detection to get very high speed optical networks. In the paper the effects of interchannel interference on the performance of coherent systems are investigated: indeed, the crosstalk between adjacent channels determines the channel spacing which is one of the most important parameters in FDM systems. The accurate analysis of ASK and FSK heterodyne systems is performed through a moment characterization of the contributions of phase noise and of crosstalk interference