Patent ID: 8565566

Claim:
A multi-mode optical fiber comprising: a core doped with GeO 2 and extending along a predetermined axis; and a cladding provided on an outer periphery of the core and having a refractive index lower than that of the core, wherein, in a refractive index profile in a diametric direction of the multi-mode optical fiber, an α value of a portion corresponding to the core is 1.9 to 2.2, a maximum relative refractive index difference Δ between the core and a reference region in the cladding is 0.8 to 1.2%, and a diameter 2 a of the core is 47.5 to 52.5 μm, and wherein the core is doped with chlorine, and a chlorine concentration profile in the core, in the diametric direction of the multi-mode optical fiber, has a shape such that a chlorine concentration at a second measurement position within a range at a distance of from 0.9 a to 1.0 a from a center of the core in a radial direction thereof is higher than a chlorine concentration at a first measurement position at a distance of a/2 from the center of the core in the radial direction thereof.