Crosstalk Behaviors in Multicore Fibers Under Deployed Conditions: Role of Structural Fluctuations

Recently, experimental characterizations of deployed multicore fibers (MCFs) with a standard cladding diameter (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$125~\mu $ </tex-math></inline-formula>m) have been intensively reported; however, there have been a limited number of theoretical works to elucidate inter-core crosstalk (XT) properties during the cabling and installation processes. In this letter, the effect of a correlation length on the XT behaviors in MCFs under deployed conditions is investigated on the basis of a coupled-power theory. Comparing the calculated results to the measured results, it is confirmed that the XT behaviors in deployed MCFs are mainly dominated by structural fluctuations (random fluctuations of the refractive index distribution or of the fiber geometry along the MCF) and that the correlation length is estimated to be on the order of millimeters.