Patent ID: 6895153

Claim:
An optical fiber for wavelength division multiplex transmission networks, said fiber comprising, successively from its center toward its periphery, a core having a varying index profile and then a cladding having a constant index, said varying index profile of said core successively comprising, from said center toward said periphery, a central slice having a maximum index higher than the index of said cladding, a buried slice having a minimum index lower than the index of said cladding, and an annular slice having a maximum index higher than the index of said cladding and lower than the maximum index of said central slice, the ratio between the absolute value of the minimum index of said buried slice and the maximum index of said central slice being greater than 50%, the index of said central slice being at least 70% of the maximum index of said central slice at least one point less than 1 μm from the center of said optical fiber, the radii and the indices of each of the slices being determined so that said optical fiber has, at a wavelength of 1,550 nm, a chromatic dispersion from 4 ps/(nm*km) to 6 ps/(nm*km), a dispersion slope from 0.02 ps/(nm 2 *km) to 0.04 ps/(nm 2 *km) and, a chromatic dispersion to dispersion slope ratio less than 240 nm, and, a zero dispersion wavelength less than 1,460 nm and, an in-cable cut-off wavelength less than 1,450 nm.