Unified Analytical Model Based on Lorentzian and Squared Lorentzian Power Spectrum Densities for Evaluating Crosstalk in Multicore Fibers

This paper describes a unified analytical model based on Lorentzian and squared Lorentzian power spectrum densities (PSDs) for evaluating the average crosstalk (XT) in multicore fibers (MCFs). There have been unsolved problems in the conventional closed-form power-coupling coefficient (PCC) based on the Lorentzian PSD: anomalously large correlation lengths in high-spatial-multiplicity MCFs, an anomalously large correlation-length change necessary for explaining the XT change in MCFs with different cladding diameters, and an unexplained bending-radius dependence of XT with a single correlation length. Here, another closed-form PCC based on the squared Lorentzian PSD is derived, for the first time to our knowledge, and it is found that the above problems can be resolved with the newly derived PCC.