Intramodal Dispersion Properties of Step-Index Few-Mode Spun Fibers

The intramodal dispersion within groups of quasi-degenerate modes in step-index few-mode fibers is studied with a semianalytic approach. By means of theoretical analyses based on accurate modeling of mode coupling, the most general problem of arbitrary high-order modes is simplified to five different cases, which are analyzed numerically. Results show that the spin may reduce intramodal dispersion if its rate is tuned finely, similarly to single-mode fibers. At variance with this case, however, spin may also increase the intramodal dispersion of high-order modes for particular conditions. Being limited to intramodal dispersion, the analysis reported here does not consider the modal dispersion accumulated between different groups of nondegenerate modes. Nonetheless, results find application in the so-called low mode coupling regime.