A pulse-reshaping optical fiber having a core with refractive index nc surrounded by a cladding layer, the diameter of the core changing monotonically along the length of the fiber. The core includes a central region having a maximum refractive index n1 and a moat region disposed radially adjacent to the central region. The moat region has a minimum refractive index n2 which is sufficiently low that the index delta DELTA 2 of the moat region with respect to nc is not greater than 0.1 %. The moat region affects the change in dispersion with respect to fiber cladding diameter, as well as providing the pulse-reshaping fiber with low dispersion versus wavelength slope. The pulse-reshaping fiber is particularly useful in association with optical transmission systems where high transmission rates and narrow pulse widths are desired, including components such as high pulse rate wavelentgh-division-multiplexers (WDMs) and optical regenerators.