Graded-index fiber 41211 167695161 2007-10-28T20:25:05Z Arghlookamonkey 1647303 In [[fiber optics]], a '''graded-index''' or '''gradient-index fiber''' is an [[optical fiber]] whose [[Fiber_optics#Principle_of_operation|core]] has a [[refractive index]] that decreases with increasing radial distance from the [[fiber axis]] (the imaginary central axis running down the length of the fiber). Because parts of the core closer to the fiber axis have a higher refractive index than the parts near the cladding, light rays follow [[sinusoidal]] paths down the fiber. The advantage of the graded-index fiber compared to [[Multi-mode optical fiber|multimode step-index fiber]] is the considerable decrease in [[modal dispersion]]. The most common refractive index profile for a graded-index fiber is very nearly parabolic. The [[parabolic profile]] results in continual refocusing of the rays in the core, and minimizes modal dispersion. This type of fiber is normalized by the International Telecommunications Union ITU-T at recommendation G.651: “Characteristics of a 50/125 μm multimode graded index optical fiber cable” ==See also== *[[Step-index profile]] *[[Power-law index profile]] *[[Gradient index optics]] ==References== *[[Federal Standard 1037C]] *[[MIL-STD-188]] {{optics-stub}} [[Category:Optical fiber]]