Patent ID: 7106934

Claim:
An optical fiber comprising: a core having a centerline and a refractive index profile; and a cladding surrounding the core; wherein the core comprises: a central region extending radially outward from the centerline; a first annular region surrounding the central region; a second annular region surrounding the first annular region; wherein the central region has a relative refractive index profile, Δ 1 (r), having a maximum relative refractive index Δ 1MAX not more than 0.55%, wherein Δ 1 (r) is positive; wherein the first annular region has a relative refractive index profile, Δ 2 (r); wherein the second annular region has a relative refractive index profile, Δ 3 (r), having a maximum relative refractive index Δ 3MAX less than 0.15%, wherein Δ 3 (r) is positive; wherein the refractive index profile of the core and the cladding are selected to provide a spectral attenuation at 1550 nm of less than 0.195 dB/km.