Comparison of Nonlinear Impairments in Graded-Index and Trench- Assisted Graded-Index Fibers for SDM Transmissions

The additional trench in trench-assisted graded-index fibers reduces the effective areas and influences the spatial overlap in multimode fibers. We investigate in which way the increased nonlinear coupling coefficients lead to an additional penalty. Our results indicate that a potential penalty can be neglected and that the trench can be fully utilized to optimize the linear fiber properties without adversely affecting the modal overlaps.