The spot size technique has been used to study the effect of a central dip on the performance of a dispersion compensated fibre (DCF). A Gaussian dip around the axis of the fibre core has been considered. Such a type of dip in the refractive index profile is obtained during the fibre fabrication by modified chemical vapour deposition (MCVD) technique. The percentage change in figure of merit (dFOM/FOM (%)) of a DCF with a central dip with respect to a DCF having no dip has been estimated for different dip depths and dip widths, respectively. It is seen that for larger values of bend radii with large negative dispersion values the magnitude of dFOM/FOM (%) changes rapidly with change in other fibre losses, dαr, than in case of smaller bend radii with small dispersion values.
Tewari, R., Basu, M., & Acharya, H. N. (2000). Studying the effect of a central dip on the performance of a dispersion compensated fibre. Optics Communications, 174(5–6), 405–411. https://doi.org/10.1016/S0030-4018(99)00658-6