Vector mode analysis of dispersion-shifted single-mode triangular-index fibers with a trench

A vector mode analysis of dispersion-shifted-mode triangular-index fibers with a trench is presented. The aspects considered are the total dispersion, splice losses and bending loss of such fibers as a function of the trench width and location, wavelength fluctuations, index difference, as well as core radius change. The presence of a trench has pronounced effects on the performance of these fibers, yielding combined advantages of dispersion-shifted and dispersion-flattened fibers, and also improves the splice loss and bending loss characteristics. Some fiber characteristics due to the presence of a trench found in this study are interesting and have not been noted previously. As for the fabrication aspect, the effects of the parameter variations on the fiber performance are examined in detail.Unlike other authors' results obtained using the scalar modal fields, our formulas here derived from the vector modal fields facilitate the study of the polarization dependence of the splice and bending losses. For weakly guiding fibers with a small index gradient, the polarization dependence becomes negligible