40 Gbps WDM Transmission Performance Comparison Between Legacy and Ultra Low Loss G.652 Fibers

G.652 standard single-mode fiber (SSMF) is today considered as the most efficient solution to transport 40 Gbps and 100 Gbps data traffic over ultra long-haul distances on terrestrial transport networks. In the early 2000s, there was a trend to replace legacy G.652 fibers, which were strongly impaired by polarization mode dispersion (PMD), by G.655 fibers. For economic reasons, incumbent operators decided to keep their legacy G.652 fiber infrastructure, while replacing gradually the most impaired fibers by low PMD G.652 fibers over the links transporting the highest amount of traffic. In this context, we performed in 2009 an experimental evaluation of the performance of a new ultra low loss (ULL) and low PMD G.652 fiber to carry 40 Gbps WDM systems over ultra long-haul distances by using various modulation formats (NRZ-OOK and NRZ-DPSK) and amplification schemes (hybrid Raman-EDFA and EDFA only). We demonstrated record transmission distance of 4400 km at 40 Gbps line rate when NRZ-DPSK was combined with hybrid Raman-EDFA amplification. We complete here this previous study with new results, coming in particular from an extensive experimental and numerical comparison of the transmission performance of this new ULL G.652 fiber with the legacy G.652 fiber, used in the field for 20 years. We demonstrate in particular that this new SMF-28^® ULL optical fiber increases the maximum transmission reach by ~30%, whatever the amplification scheme, when NRZ-DPSK is used.