Delay spread in strongly coupled multi-core fibers for SDM transmission

It is well known that the mean square delay spread in strongly coupled multi-core fibers increases linearly with the propagation distance. In this paper we quantify for the first time the coefficient of this linear growth and characterize its dependence on the main fiber parameters. Our analysis shows that the root-mean mean delay spread reduces with the fluctuations of the coupling coefficient between cores, while it increases with the correlation length of these fluctuations and with the beat length of the two polarizations of each core.