Modeling of 3-Coupled-Core Fiber: Comparison Between Scalar and Vector Random Coupling Models

Simple, fast and accurate channel models can assist not only in a process of manufacturing of novel multi-core fibers, but also in a communication link design, providing a convenient way to investigate different properties of fibers that could be appealing for transmission. Models for coupled-core fibers are in a great demand since this type of the fiber provides advantages for data transmission, e.g. by reducing the effects of modal dispersion and fiber nonlinearity. In this work we present a comparative study of key features in a three coupled-core fiber (3CCF) for scalar and vector random coupling models. Supermodes and their group delays in an unperturbed 3CCF with polarization mode mixing are comprehensively analyzed for the first time. It is shown that birefringence does not impact significantly the group delay values but it may affect the mode mixing. The intensity impulse response and its RMS width were then investigated in a 3CCF with perturbations and compared for two types of models. The shape of the averaged intensity impulse response is found to be very similar for two models and retained for various input polarization states, while in the absence of averaging, the shape of the impulse response strongly depends on the input state of polarization. We show that the calculated RMS widths of the intensity impulse response agree well with theoretical values, as well as between scalar and vector cases.