Graded-index fiber

An optical fiber cable design in which the index of refraction of the core is lower toward the outside of the core and progressively increases toward the center of the core, thereby reducing modal dispersion of the signal. Light rays are refracted within the core rather than reflected as they are in step-index fibers. Graded-index fibers were developed to lessen the modal dispersion effects found in multimode fibers with the intent of increasing bandwidth.