Mode-coupling analysis and trench design for large-mode-area low-cross-talk multicore fiber

The complete analytical solutions of the mode-coupling dynamics for seven-core multicore fibers (MCFs) with identical cores is proposed. All the coupling coefficients C(mn) of adjacent cores and nonadjacent cores as a function of the structural parameters are investigated. It is shown that the coupling coefficients can decrease by adjusting the structural parameters. In addition, the trench-assisted structure could be used for suppressing cross talk in MCF, and the effective area A(eff) can be enlarged without degrading the crosstalk properties. Simulations suggest that low cross talk and/or large A(eff) could be achieved by adjusting the trench parameters. Large mode area could be obtained by utilizing small trench (small trench width c, small refractive index difference Δ(trench)) in the trench-assisted MCF (TA-MCF), whereas low cross talk could be achieved by utilizing larger trench (large trench width c, large Δ(trench)) in the TA-MCF.