Patent ID: 8218929

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 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 1 =R 2 −R 1 ; a second annular region extending from the radius R 2 to a radius R 3 , the second annular region comprising a radial width W 2 =R 3 −R 2 ; a third annular region extending from the radius R 3 to a radius R 4 , the third annular region comprising a radial width W 3 =R 4 −R 3 ; and a fourth annular region extending from the radius R 4 to an outermost glass radius R 5 ; wherein the core comprises a maximum relative refractive index, Δ 0MAX , the second annular region comprises a minimum relative refractive index, Δ 2MIN , and the third annular region comprises a minimum relative refractive index, Δ 3MIN , wherein Δ 0MAX >0>Δ 2MIN >Δ 3MIN ; and wherein the core and the cladding provide a fiber with cable cutoff less than 1500 nm and an effective area at 1550 nm of greater than 130 μm 2 .