Patent ID: 6928221

Claim:
An optical communication line comprising: a transmission optical fibre length with, at a wavelength λ, a positive chromatic dispersion slope s t ; a compensating optical fibre length, associated to said transmission optical fibre length, having a negative chromatic dispersion slope s c suitable to compensate at least in part the positive chromatic dispersion slope s t of the transmission fibre, said compensating optical fibre having a core region surrounded by a cladding region, the cladding region defining a first ring of holes, which substantially defines, around the core region, an annulus with an inner radius r 1 and an outer radius r 2 , and at least one second ring of holes that surrounds the first ring of holes, said holes running along the compensating optical fibre longitudinally and being spaced apart from each other substantially according to a predefined pitch Λ, wherein a) the values of said inner radius r 1 and said outer radius r 2 are selected in such a way as to substantially satisfy the following relationship (L) r 1 ≦λ/ n≦r 2 where n is the refractive index of the material making up the core region of said compensating optical fibre length; b) the holes of said first and said at least one second ring are substantially of the same diameter d; and c) the ratio d/Λ substantially satisfies the following relationship (A) 0.8 ≦d/Λ< 1.