Patent ID: 7853109

Claim:
A single mode optical fiber comprising: (i) a segmented core having at least three segments, wherein the first segment has a Δ max % in the range of about 0.75 to 1.1, Δ 0 %≧0.6Δmax %, and an outer radius r 1 in the range of about 1.5 to 3.0 μm; the second segment has a Δ 2 % in the range of 0.00 to 0.15%; and the third segment has a Δ 3 % less than 0.35% and volume V 3 of 3.8% μm 2 <V 3 <6.65% μm 2 , an outer radius r 3 in the range of about 7 μm to 11 μm, a width w 3 in the range of about 1.5 to 3 μm, and volume V 3 <7% μm 2 ; and (ii) a silica based clad layer surrounding and in contact with the core, the clad layer having a refractive index n c ; wherein the refractive index profiles of the core segments are selected to provide: zero dispersion wavelength in the range of about 1565 nm to 1600 nm; total dispersion at 1550 nm in the range of about −6 to −0.5 ps/nm-km; and dispersion slope at 1550 nm is greater than 0.1 ps/nm 2 -km.