Patent ID: 8565567

Claim:
A multi-mode optical fiber, comprising: a core extending along a predetermined axis and doped with germanium dioxide (GeO 2 ); 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 both of the core and the cladding are doped with chlorine, and the cladding is doped with chlorine such that an average chlorine concentration in the cladding becomes higher than an average chlorine concentration in the core.