Patent ID: 7072551

Claim:
Single mode optical fibre comprising a first central region having a radius r 1 , a maximum refractive index value n 1 and at least one second ring surrounding said first central region, which second ring has a radius r 2 and a minimum refractive index value n 2 , wherein n 2 <n 1 , characterized in that the refractive index value n 1 is substantially constant in the first central region having radius r 1 , and in the second ring having radius r 2 the refractive index value decreases in radial direction from n 1 to n 2 over a distance r 1 −r 2 , with the decrease, which is substantially linear, taking place in accordance with the following equation: slope=( D 1 −D 2)/( r 2 −r 1), where 0.11<slope<0.22, and D i = n i 2 - n Cl 2 2 · n i 2 · 100 ⁢ % ⁢ ⁢ and ⁢ ⁢ n i > n Cl , D i =refractive index contrast for position i, n i =refractive index of position i, n C1 =refractive index of an outer fibre cladding, wherein a dispersion slope ranges from 0.07 to 0.095 ps/km 2 at 1550 nm.