Comparison of soliton sources for communication applications

Soliton communication technology has attracted widespread interest in recent years. Both theoretical and experimental research has demonstrated that soliton systems have the capability of transmitting signals at multi-Gbit/s capacities over transoceanic distances. A key component in such a system is the picosecond pulse source, whose quality has a decisive effect on the achievable transmission distances without soliton control. The authors examine the trade-off between source complexity and system performance. Gain switched DFB LDs (GSDFB) with spectral windowing, mode-locked semiconductor lasers (MLSL), mode-locked erbium fibre lasers (MLEFL), and DFB-electroabsorption modulators (DFB/EAM) have been used in soliton communications experiments. They present experimental results of soliton transmission using three different pulse sources: DFB/EAM, MLSL, and MLEFL, and discuss the merits of each source in terms of performance and complexity. They show that degradation of transmission performance may be related to nonideal pulse source.