Differential group delay behavior in homogeneous weakly coupled multicore fiber under bending and twisting condition

Abstract

Abstract The impacts of core count/layout on the mode effective refractive index, bend and twist induced differential group delay (DGD) of different cores, worst-case DGD, and intercore DGD, in weakly coupled homogeneous multicore fibers (WC-HMCFs) have been analyzed to select the proper core layout with low DGD value for a particular core count. Further, in order to calculate the intercore DGD values, the generalized expressions of core pitch for the different core layouts have been derived. Moreover, the impacts of core radius, relative refractive index difference, and core pitch on the mode effective refractive index and DGD levels for the 3-core WC-HMCFs, with linear and triangular core layouts, have been analyzed numerically by using the finite element method based FemSIM simulation platform, and MATLAB. It is observed that for a certain core count value, the core layout and core pitch have significant impacts on the DGD levels; while, the variations in the values of core radius and relative refractive index difference have no significant impact on the DGD levels. Further, increase in core count normally increases the DGD levels in all core layouts. On the other hand, for the fixed values of core count, cladding diameter, and outer cladding thickness, the core layout which has the lowest core pitch leads to the lowest value of intercore DGD, as compared to the other core layouts. The investigations carried out in this work may provide the guidelines in different MCF applications, such as MCF based multi-parameter sensing, signal processing in microwave photonics, etc.