Straight-line 4×2.5 gbit/s WDM transmission over 2600 km on a manufactured optically-amplified submarine cable system with 95 km repeater spacing

Single wavelength optically amplified submarine system technology has rapidly moved towards maturity to meet requirements for high capacity long-haul undersea systems. The developments of wavelength division multiplexing (WDM) technologies for submarine applications will enable increased system capacity and enhanced network topologies for the provision of traffic between multiple landing points. A number of technical issues have to be addressed in the development of long-haul WDM transmission including the effect of a restricted concatenated amplifier gain bandwidth and also the accumulation of multi-channel non-linear interactions such as four-wave mixing and cross-phase modulation. We report the results of error-free 4×2.5 Gbit/s straight line transmission over 2600 km on a manufactured optically amplified submarine cable system with an average repeater spacing of 95 km. In these experiments channel power pre-emphasis was used to limit the signal-noise-ratio (SNR) imbalance resulting from the restricted concatenated amplifier bandwidth. Additionally unequal channel wavelength spacing gave a reduction in the effects of four-wave mixing products. System simulations confirm the experimental results indicating their applicability in predicting the performance of future high capacity WDM submarine links. These results show the potential for provision of economic system solutions for future submarine cable networks