Patent ID: 7082243

Claim:
An optical fiber comprising: a core having a refractive index profile and a centerline; and a cladding layer surrounding and directly adjacent the core; wherein the core comprises: a first portion extending from the centerline to a radius of 1 μm, the first portion comprising a relative refractive index profile, Δ CORE1 (r), having a maximum relative refractive index Δ 1MAX less than 0.7% and occurring at a radius rΔMAX, wherein Δ 1MAX is the maximum relative refractive index Δ MAX for the entire core, wherein Δ CORE1 (r) is greater than 0.3% and less than 0.6% for all radii between r ΔMAX and r=1 μm; a second portion surrounding and directly adjacent to the first portion, the second portion comprising a relative refractive index profile Δ CORE2 (r) having a minimum relative refractive index Δ 2MIN <0.3%, and extending from a radius of 1 μm to a radius of 2.5 μm, wherein Δ CORE2 (r) is between 0.15% and 0.5%, wherein (Δ 1MAX −Δ 2MIN )>0.25%; a third portion surrounding and directly adjacent to the second portion, the third portion comprising a relative refractive index Δ CORE3 (r) extending from a radius of 2.5 μm to a radius of 4.5 μm, wherein Δ CORE3 (r) is between 0% and about 0.6% and has a maximum relative refractive index Δ 3MAX , wherein Δ CORE3 (r=4 μm)>0.2%, wherein Δ 2MIN <Δ 3MAX <Δ 1MAX , and wherein (Δ 3MAX −Δ 2MIN )>0.10%; and a fourth portion surrounding and directly adjacent to the third portion, the fourth portion having a relative refractive index Δ CORE4 (r) extending to a radius of between 4.5 and 12 μm; wherein the cladding surrounds and is directly adjacent to the fourth portion, and wherein the core ends and the cladding begins at r CORE >4.5 μm.