Estimation of propagation characteristics of l1 series of LP modes of few-mode W-type fibers using numerical and analytical approach

Abstract

In this work, single and two parameter variational fields for the l1 series of linearly polarised (LPl1) modes of a graded index few-mode W-type fibers have been proposed. The propagation characteristics, such as, the propagation constant, the normalised dispersion parameter and the normalised group delay have been computed for lower order LPl1 modes of such fibers using these variational fields. The exact results were derived by numerically solving the scalar wave equation for the LPl1 modes of W-type fibers. Further, the cut-off frequencies for the first few lower order modes have been computed numerically. Accuracies of the estimated propagation parameters have been investigated by comparing it with the numerical results. Compared to single-parameter variational fields, the two-parameter variational fields provide superior accuracy. Additionally, it has been found that the accuracy increases for lower order LPl1 modes. Thus, few-mode graded-index W-type fiber based photonic devices may utilise these proposed trial fields.