  We investigate the evolution of decorrelation bandwidth of inter core
crosstalk (IC-XT) in homogeneous weakly coupled multicore fibers (WC-MCFs). The
modified mode-coupled equations (MCEs) are numerically solved by combining the
fourth order Runge-Kutta method and compound Simpson integral method. It can be
theoretically and numerically observed that the decorrelation bandwidth of
IC-XT decreases with transmission distance by fractional linear function. The
evolution rule of IC-XT's decorrelation bandwidth is further confirmed by
experiments, which can be used as an evaluation criterion for channel model.
Finally, we propose a new channel model with the coupling matrix of IC-XT
generated automatically by phase transfer function (PTF), which is in good
agreement with the above evaluation criterion. We believe the proposed channel
model can provide a good simulation platform for homogeneous WC-MCF based
communication systems.
