Patent ID: 7689085

Claim:
An optical waveguide fiber comprising: (i) a Ge free core having an effective area of 90 μm 2 to 160 μm 2 , at the 1550 nm wavelength, and α value 12 ≦α≦25, said core comprising: (a) a central core region extending radially outwardly from a centerline to a radius 0 μm ≦r 0 ≦2 μm, and having a relative refractive index percent profile Δ 0 (r) wherein −0.1% ≦Δ 0 (r) ≦0.1%, wherein the central core region has a maximum relative refractive index, Δ 0MAX ; (b) a first annular core region surrounding and directly adjacent to the central core region and extending to an outer radius r 1 , wherein 4.8 μm ≦r 1 ≦10 μm, and having a relative refractive index percent profile, Δ 1 (r) and a minimum relative refractive index, Δ 2MIN , and the relative refractive index measured at a radius r=2.5 μm being: −0.15≦Δ 1 ( r= 2.5 μm)≦0 and Δ 0MAX ≧Δ 1 ( r =2.5 μm); (c) a fluorine doped second annular region surrounding and directly adjacent to the first annular core region and extending to a radius 13 μm ≦r 2 ≦30 μm and having a negative relative refractive index percent profile, Δ 2 (r), with a minimum relative refractive index Δ 2MIN being: Δ 2MIN <Δ 1 ( r= 2.5 μm) and −0.7% ≦Δ 2MIN ≦−0.28%; (ii) a cladding surrounding the core and having a relative refractive index percent Δ c (r), and Δ c (r)=Δ 2MIN ±0.3%; wherein the relative refractive index profile of the optical fiber is selected to provide attenuation of no more than 0.175 dB/km at the 1550 nm wavelength.