Soliton WDM transmission

The large gain bandwidth of erbium doped fiber amplifiers has stimulated interest in WDM systems with many channels. For trans-oceanic and other such long-haul systems, the number of channels is limited by the accumulated gain bandwidth, which tends to decrease rapidly with distance. For NRZ systems, additional limitations arise from four wave mixing among the channels. Soliton transmission reduces these problems and allows for greatly reduced channel spacing. In particular, in recent experiment the adjacent channel spacing was just 25 GHz, or ~0.2 nm. The main sources of limitations in soliton systems are timing jitter and amplitude noise In WDM systems there is an additional contribution to the timing jitter from interactions between channels. Here, we examine the limitations of soliton WDM systems.