Nonlinear impairment scaling in coupled-core multi-core fibers for space-division multiplexing

We study the nonlinear impairment scaling in coupled-core multi-core fibers (CC-MCFs) with core count by evaluating four typical CC-MCFs with different numbers of cores, which have been demonstrated promising for long-haul optical fiber transmissions, using the Gaussian-noise model. The results show that nonlinear signal degradation in CC-MCFs with more cores becomes significantly weaker, which would be of great interest to ultralong-haul transmission in CC-MCFs. We further analyze how the fiber loss, differential group delay and effective mode field area impact on the trend. Moreover, we compare CC-MCFs and few-mode fibers with the same number of spatial modes in terms of nonlinear impairment and find that CC-MCFs tend to achieve better nonlinear performance. It is also shown that few-mode fibers operated in strong coupling regime are quite promising for long-haul transmission.