Main Page | See live article | Alphabetical index For an optical fiber, a step-index profile is refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the core-cladding interface. Note 1: The step-index profile corresponds to a power-law index profile with the profile parameter approaching infinity. Note 2: The step-index profile is used in most single-mode fibers and some multimode fibers. Source: from Federal Standard 1037C and from MIL-STD-188 This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.