Design and optimization of weakly-coupled few-mode fiber with low nonlinearity

By investigating the influence of the difference of refractive index between core and cladding (nco-ncl), normalized frequency (V ) and core radius (?) on both the intramodal and intermodal nonlinear coefficients (NCs) respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs (< 0.5 W-1 \cdot km-1) between two degenerate modes and optimizes the parameters of differential group delays (DGDs) and chromatic dispersion. The optimized few mode fiber (FMF) is eligible for transmission and mode de-multiplexing in the receiver.