Patent ID: 7646955

Claim:
A multimode optical fiber, comprising: a graded index core having a radius a greater than 23 μm and smaller than 33 μm, a first relative refractive index difference Δ 1 between the core center and a cladding being greater than 0.9%; a depressed extended gradient core which is an extension of said graded index core, the depressed extended gradient core having the radial dimension b which is greater than 3 μm and smaller than 5.5 μm, a second relative refractive index difference Δ 2 between the minimum of the extended gradient core and the cladding having a negative value between −0.45% and −0.1%; a depression surrounding said extended gradient core, the refractive index of said depression being lower than the refractive index of the cladding, and the radial dimension c of the depression being between 1 μm and 5 μm; and the cladding surrounding said depression.