Dispersion-flattened properties of high-index-core Bragg fibers

We study the group-velocity-dispersion properties of a novel class of Bragg fibers. These new structures are radially-symmetric microstructured fibers having a high-index core (silica in our case) surrounded by a cylindrical multilayer omnidirectional mirror as cladding, which is formed by a set of alternating layers of silica and a lower refractive-index dielectric. The interplay between the unusual geometric dispersion behavior shown by the multilayered cladding of the fiber and the material dispersion corresponding to the silica core allows us to establish a procedure to design flattened dispersion profiles. In this work we focus our attention on achromatic flattened dispersion fibers in the 0.8 μm wavelength window and even on ultraflattened structures about the 1.5 μm interval. We include configurations owning positive, negative, and nearly-zero dispersion in both wavelength ranges.