Design and optimization of submarine optical links using space-division multiplexing

Abstract

Submarine fiber systems carry nearly 95% of the data traffic between different countries and continents. These systems use space-division multiplexing (SDM), which is currently implemented by several single-mode fibers in parallel. To increase the spatial information density and enable compact scaling of components, multi-core and multi-mode fibers are interesting alternatives for the future. In long-haul systems, typically the bit rate is limited by amplified spontaneous emission (ASE) noise at low power levels, and by fiber nonlinear interference (NLI) at high power levels. Bit rate limitations due to these two effects have been extensively studied, and optimal operating regimes have been identified. On the other hand, further limitations arisein modern submarine systems, as a large number of spatial channels are required to maximizethe bit rate subject to power feed equipment (PFE) constraints. The most critical element ofsubmarine links are optical amplifiers, which compensate for optical signal losses during fiber propagation. In submarine systems subject to PFE limitations, the energy conversion efficiency between the electrical power supply of the amplifier and its resulting optical power is a key parameter for the calculation of the link capacity. A low conversion efficiency may drive optical amplifiers with insufficient electrical power to achieve the maximum system capacity. Thus, this project aims to investigate power-efficient optical amplification architectures for submarinelinks with SDM, and quantify their impact on the link capacity. Amplifier architectures based on multicore and/or multimode fibers will be analyzed by simulation, and their impact on the system performance will be evaluated using information-theoretical parameters. Finally, this project strengthens the cooperation between the groups of Prof. Joseph M. Kahn at Stanford University and Prof. Darli Mello at Unicamp, and adds advanced knowledge to two ongoing FAPESP thematic projects in which the proponent participates. (AU)