Maximum Capacities in Submarine Cables With Fixed Power Constraints for C-Band, C+L-Band, and Multicore Fiber Systems

Achieving greater transmission capacity in submarine optical cables is of great interest as data traffic demands continue to increase worldwide. A significant constraint unique to submarine cable systems is that of electrical power that must be delivered to the entire cable from the terminals at the landing points. Recently, much focus has been on how to maximize the overall cable transmission capacity within fixed electrical power feed constraints. Until recently, all repeatered submarine cable systems were built using the erbium-doped fiber amplifier C-band, but C+L-band systems are now being considered and deployed. In parallel, there has been intense interest in spatial division multiplexing technologies, such as multicore fibers, as potential means to enabling greater transmission capacity in terrestrial and submarine systems. In this work, we examine maximum submarine cable capacities for three types of systems based on single-core fibers with C-band only or C+L-band transmission, and general multicore fiber systems with C-band-only transmission. The analysis is performed on the basis of common fixed power constraints and received signal-to-noise requirements, and comparable fiber-core characteristics. Additional losses for devices, such as C/L-band splitters and fan-in/fan-out modules, are accounted, and their impact on maximum cable capacity is estimated. For multicore fiber systems, other potential effects, such as higher fiber attenuation and crosstalk between cores, are also analyzed and evaluated with respect to capacity impacts. We find that single-core C-band systems offer the highest cable capacity, provided cable designs can accommodate the number of fiber pairs suggested.