Patent ID: 7043126

Claim:
A graded-index multimode fiber comprising: a core containing fluorine; and a cladding which is provided at an outer periphery of the core, wherein the graded-index multimode fiber has a refractive index profile which satisfies the following Formula (1): n ⁡ ( r ) = { n 1 ⁡ [ 1 - 2 ⁢ ⁢ Δ ⁢ ⁢ ( r a ) α ] 1 / 2 ( O ≤ r ≤ a ) n 1 ⁡ ( 1 - 2 ⁢ ⁢ Δ ) 1 / 2 ( r > a ) ( 1 ) where n(r) is a refractive index of the optical fiber at a distance “r” from the center of the core, n 1 is a refractive index at the center of the core, Δ is a relative refractive index difference of the center of the core with respect to the cladding, “a” is a core radius, and α is a refractive index distribution order; wherein Δ is not less than about 0.005 and not more than about 0.025, and a is not less than about 10 μm and not more than about 35 μm.