Mode-Coupling Induced Crosstalk Optimization in a Graded-Index Six-Mode Fiber

We thoughtfully investigate the feasibility of reducing the mode-coupling caused crosstalk by optimizing the practical parameters of the few-mode fiber (FMF), based on the linear coupling theory. According to our simulation results, the low crosstalk FMF could be achieved with the small fiber core, the low refractive-index (RI) related parameters, the long operating-wavelength and the low core-eccentricity (CE). Moreover, the transmission behaviors over the fixed coupling and the random coupling scenarios are also discussed. The power distribution and the signal to interference plus noise ratio (SINR) evolutions along FMF reveal the impacts from the mode-coupling induced crosstalk in the spatial division multiplexing (SDM) transmission system. The random nature of the mode coupling suggesting the turbulent results are obtained in our simulation, confirmed the observation in the SDM test. And only a 1.23 dB SINR degradation of 16-QAM signals can be realized after 100 km transmission with the optimized CE of lower than 4 × 10−3.