Distributed spatial mode dispersion measurement along strongly coupled multicore fibers based on the correlation analysis of Rayleigh backscattering amplitudes.

We describe a method for measuring spatial mode dispersion (SMD) distribution along a strongly coupled multicore fiber (SC-MCF). The SMD has been defined for characterizing an SC-MCF, and it changes with respect to local fiber bending and twisting. However, conventional measurement methods characterize only the overall SMD, and cannot identify fiber portions where the environmental conditions affect the SMD. This paper demonstrates distributed SMD measurement along an SC-MCF by auto-correlating Rayleigh backscattering amplitudes obtained with coherent optical reflectometry. We confirm our method experimentally, and distinguish the difference between the SMD growth along twisted and non-twisted fiber sections in concatenated SC-MCFs.