Patent ID: 7428361

Claim:
A dispersion compensating optical fiber comprising: a central core having an index difference Δn 1 with an outer optical cladding; a first buried inner cladding having an index difference Δn 2 with the outer cladding; a ring having an index difference Δn 3 with the outer cladding a second buried inner cladding having an index difference Δn 4 with the outer cladding; wherein the index difference between the first buried inner cladding and the outer cladding Δn 2 is less than or equal to −13.5×10 −3 and the index difference between the second buried inner cladding and the outer cladding Δn 4 is less than or equal to −3×10 −3 ; the fiber having, at a wavelength of 1550 nm: a negative chromatic dispersion being less than or equal to −50 ps/nm/km; and a ratio of chromatic dispersion over the slope of the chromatic dispersion (DOS) being less than or equal to 70 mm.