Graded-index fiber

The parabolic profile results in continual refocusing of the rays in the core, and minimizes modal dispersion.Multi-mode optical fiber can be built with either a graded-index or a step-index profile.This means that the trip time of photons traversing the fiber is more consistent, allowing shorter and more frequent pulses of light to be discerned by the receiver.Modal dispersion can be further decreased by selecting a smaller core size (less than 10 μm) and forming a single-mode step index fiber.[1] This type of fiber is normalized by the International Telecommunication Union ITU-T in recommendation G.651.1.[2] Pulse dispersion in a graded-index optical fiber is given by[citation needed]
optical fiberrefractive indexoptical axisstep-index fibersinusoidalparabolicmodal dispersionMulti-mode optical fiberstep-indexsingle-mode step index fiberspeed of lightPower-law index profileGradient index opticspublic domain materialGeneral Services AdministrationMIL-STD-188optics