Evaluation of Crosstalk in Nonlinear Regime for Weakly Coupled Multi-Core Fiber With Random Perturbations Using a Split-Step Numerical Model

We introduce a split-step coupling method to solve the nonlinear coupled mode equation (NCME) reference to the split-step Fourier method. Basing on this method, a split-step numerical model (SNM) is initially proposed for evaluation on inter-core crosstalk in nonlinear regime. In this model, linear coupling and fiber nonlinear effect are treated as two independent operators in the process of optical signal transmission. Experiments and numerical simulations are performed on a 10 km 7-core-fiber. The results show that about 4.26 dB benefit of crosstalk suppression can be achieved with a high launch power level of 20 dBm in nonlinear region. Further researches indicate that this benefit is proportional to launch power, transmission length and nonlinear coefficient while independent of bending and twisting perturbations. Compared with the traditional linear models such as discrete changes model (DCM) and universal semi-analytical model (USAM), SNM is more accurate in evaluation of inter-core crosstalk in nonlinear regime. Moreover, in a trade-off between accuracy and computational efficiency, the SNM with segment length distribution in exponential form is more appropriate for NIXCT estimation. Finally, the theoretical model is experimentally validated in corresponding MCF with random perturbations.