Patent ID: 7929818

Claim:
An optical waveguide fiber comprising: (i) a Ge free core having an effective area of 100 μm 2 to 150 μm 2 , at 1550 nm wavelength, said core comprising: (a) a central core region extending radially outwardly from a centerline to a radius r 1 , and having a relative refractive index percent profile Δ 1 (r) in % measured relative to pure silica, wherein −0.1%≦Δ 1 (r)≦0.12%, wherein the central core region has a maximum relative refractive index percent, Δ 1MAX ; (b) a first annular core region surrounding and directly adjacent to the central core region, having an α value 1.5≦α≦10, and extending to an outer radius r 2 , wherein 6 μm≦r 2 ≦10 μm, and having a relative refractive index percent profile, Δ 2 (r) in % measured relative to pure silica, a minimum relative refractive index Δ 2MIN , a maximum relative refractive index Δ 2MAX and the relative refractive index measured at a radius r=2 μm, wherein −0.45≦Δ 2 ≦0; −0.25≧Δ 2MIN ≧−0.45 and Δ 1MAX ≧Δ 2 ( r= 2 μm); (c) a fluorine doped second annular region surrounding and directly adjacent to the first annular core region and extending to a radius 20 μm≦r 3 ≦30 μm and having a negative relative refractive index percent profile, Δ 3 (r) in %, measured relative to pure silica, with a minimum relative refractive index percent Δ 3MIN and −0.5%<Δ 3MIN <−0.25%; and Δ 3MIN ≦Δ 2MIN (ii) a cladding surrounding the core and having a relative refractive index percent Δ 4 (r) in % measured relative to pure silica and a minimum refractive index delta Δ 4MIN , and −0.4%<Δ 4 <−0.2%; wherein the relative refractive index profile of the optical fiber is selected to provide attenuation of no more than 0.17 dB/km at the 1550 nm wavelength.