Optical fiber with chromatic dispersion compensation in the S band
The invention relates to the field of optical fibers for wavelength division multiplex transmission networks. It provides an optical fiber with chromatic dispersion compensation in the S band from 1 460 nm to 1 530 nm having a negative chromatic dispersion at the wavelength of 1 495 nm and at least three core slices, preferably at least four core slices. The single core slice or the first core slice is very deeply buried and preferably has as at the wavelength of 1 495 nm a chromatic dispersion to dispersion slope ratio whose absolute value is from 68 nm to 158 nm.
1. An optical fiber with compensation of chromatic dispersion in the S band from 1 460 nm to 1 530 nm, for use in wavelength division multiplex transmission networks, having a negative chromatic dispersion at the wavelength of 1 495 nm, comprising successively from the center toward the periphery a core having a varying index profile and then a cladding of constant index, said varying index profile of said core comprising successively, from said center toward said periphery, a central slice having a maximum index higher than the index of said cladding, a first buried slice having a minimum index lower than the index of said cladding, an annular slice having a maximum index higher than the index of said cladding and lower than the maximum index of said central slice, a second buried slice having a minimum index lower than the index of said cladding, radii and the indices of each of said slices being determined so that said dispersion compensating optical fiber has at the wavelength of 1 495 nm a chromatic dispersion to dispersion slope ratio whose absolute value is from 68 nm to 158 nm.
2. The optical fiber claimed in claim 1 wherein the radii and the indices of each slice are determined so that said dispersion compensating optical fiber has at the wavelength of 1 495 nm a chromatic dispersion to chromatic dispersion slope ratio whose absolute value is from 80 nm to 118 nm.
3. The optical fiber claimed in claim 2 wherein the radii and the indices of each slice are determined so that said dispersion compensating optical fiber has at the wavelength of 1 495 nm a chromatic dispersion to chromatic dispersion slope ratio whose absolute value is from 87 nm to 105 nm.
4. The optical fiber claimed in claim 1 wherein the difference between the maximum index of said annular slice and the index of said cladding is from 12×10 −3 to 20×10 −3 and the radius of the portion of said central slice having an index higher than the index of said cladding is from 1.57 μm to 2.5 μm.
5. The optical fiber claimed in claim 4 wherein the value of the integral between a zero radius and the radius of the portion of said central slice having an index higher than the index of said cladding of the index difference relative to said cladding is from 28.4×10 −3 μm to 35.5×10 −3 μm.
6. The optical fiber claimed in claim 5 wherein the value of twice the integral between a zero radius and the radius of the portion of said central slice having an index higher than the index of said cladding of the product of the index difference relative to the cladding and the radius is from 49×10 −3 μm 2 to 81×10 −3 μm 2 .
7. The optical fiber claimed in claim 1 wherein the difference between the minimum index of said first buried slice and the index of said cladding is from −12×10 −3 to −5×10 −3 and the outside radius of said first buried slice is from 4.0 μm to 7.4 μm.
8. The optical fiber claimed in claim 7 wherein the value of the integral between the radius of the portion of said central slice having an index higher than the index of said cladding and the radius of the portion of said first buried slice having an index lower than the index of said cladding of the index difference relative to said cladding is from −56×10 −3 to −20×10 −3 μm.
9. The optical fiber claimed in claim 8 wherein the value of twice the integral between the radius of the portion of said central slice having an index higher than the index of said cladding and the radius of the portion of said first buried slice having an index lower than the index of said cladding of the product of the radius by the index difference relative to said cladding is from −470×10 −3 to −130×10 −3 μm 2 .
10. The optical fiber claimed in claim 1 wherein the difference between the maximum index of said annular slice and the index of said cladding is from 1.0×10 −3 to 8.0×10 −3 and the outside radius of said annular slice is from 6.8 μm to 12 μm.
11. The optical fiber claimed in claim 10 wherein the value of the integral between the radius of the portion of said first buried slice having an index lower than the index of said cladding and the radius of the portion of said annular slice having an index higher than the index of said cladding of the index difference relative to said cladding is from 5×10 −3 to 26×10 −3 μm.
12. The optical fiber claimed in claim 11 wherein the value of twice the integral between the radius of the portion of said first buried slice having an index lower than the index of said cladding and the radius of the portion of said annular slice having an index higher than the index of said cladding of the product of the radius by the index difference relative to said cladding is from 60×10 −3 to 440×10 −3 μm 2 .
13. The optical fiber claimed in claim 1 wherein the difference between the minimum index of said second buried slice and the index of said cladding is from −12×10 −3 to 0 and the outside radius of said second buried slice is from 9 μm to 21 μm.
14. The optical fiber claimed in claim 13 wherein the value of the integral between the radius of the portion of said annular slice having an index higher than the index of said cladding and the radius of the portion of said second buried slice having an index lower than the index of said cladding of the index difference relative to said cladding is from −153×10 −3 μm to 0.
15. The optical fiber claimed in claim 1 wherein the value of the integral between a zero radius and the radius of the portion of said second buried slice having an index lower than the index of said cladding of the index difference relative to said cladding is from −138×10 −3 to 22×10 −3 μm.
16. The optical fiber claimed in claim 15 wherein the value of twice the integral between a zero radius and the radius of the portion of said second buried slice having an index lower than the index of said cladding of the product of the radius by the index difference relative to said cladding is less than or equal to 80×10 −3 μm 2 .
17. The optical fiber claimed in claim 16 wherein the value of twice the integral between a zero radius and the radius of the portion of said second buried slice having an index lower than the index of said cladding of the product of the radius and the index difference relative to said cladding and the function exp(−r 2 /b 2 ) where b=1.54 μm is from 24.1×10 −3 to 28.3×10 −3 m 2 .
18. The optical fiber claimed in claim 1 wherein the value of twice the integral between the radius of the portion of said first buried slice having an index higher than the index of said cladding and the radius of the portion of said second buried slice having an index lower than the index of said cladding of the product of the radius and the index difference relative to the cladding and the function exp(−r 2/c2) where c=4.67 μm is from 9.8×10 −3 to 42.6×10 −3 μm 2 .
19. An optical fiber transmission system comprising the combination of a line optical fiber and an optical fiber with chromatic dispersion compensation in the S band according to claim 1 , wherein said dispersion compensating optical fiber is an in-line fiber.
20. An optical fiber transmission system comprising the combination of a line optical fiber and an optical fiber with chromatic dispersion compensation in the S band according to claim 1 , wherein said dispersion compensating optical fiber is an in-module fiber.