Four Wave Mixing Limitation in Multichannel Coherent Optical Communication,

Four-wave mixing FWM in a fiber is a nonlinear effect likely to impose severe restrictions on transmitted powers and channel spacing in optical frequency-division multiplexed FDM systems, hence limiting their information capacity. As a result of FWM waves at different frequencies can interact causing an inter-channel cross-talk. The efficiency of FWM is strongly dependent on the difference of phase velocities phase-mismatch between the interacting waves. Therefore, it will mainly play a role in dispersion shifted DS fibres and for densely spaced channels as are possible in coherent systems.