Patent ID: 7555187

Claim:
An optical fiber comprising: a glass core extending from a centerline to a radius R 1 wherein R 1 is greater than about 5 μm; a glass cladding surrounding and in contact with the core, wherein the core and the cladding provide a fiber with cable cutoff less than 1500 nm, and an effective area at 1550 nm greater than 110 μm 2 and bend loss of ≦0.7 dB/turn on a 20 mm diameter mandrel and, wherein (i) the cladding comprises: a first annular region extending from the radius R 1 to a radius R 2 , the first annular region comprising a radial width, W 2 =R 2 −R 1 , a second annular region extending from the radius R 2 to a radius R 3 , and comprising a radial width, W 3 =R 3 −R 2 , and a third annular region surrounding the second annular region and extending from the radius R 3 to an outermost glass radius R 4 ; and (ii) the core comprises a maximum relative refractive index, Δ 1MAX , relative to the third annular region; wherein the first annular region has a refractive index delta Δ 2 (r); wherein the second annular region comprises: a minimum relative refractive index, Δ 3MIN , relative to the third annular region; wherein Δ 1MAX >Δ 2MAX >Δ 3MIN , Δ 2MIN >Δ 3MIN , and Δ 3 MIN<0 wherein Δ 1MAX is greater than about 0.1% and less than about 0.3%; and Δ 2 (r), is less than about 0.025%, and wherein Δ 3MIN , relative to the third annular region, is less than about −0.1%.