Optical fiber cable
AssigneeSumitomo Electric Industries, Ltd.
InventorsTetsuya Hayashi, Eisuke Sasaoka
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Abstract
The present invention relates to an optical fiber cable incorporating a multi-core fiber provided with a plurality of cores and a cladding region. The optical fiber cable has a jacket covering the multi-core fiber. The multi-core fiber is arranged so that a hold wrap holds the cores in a state in which they are provided with a bend of not more than a fixed radius of curvature, in order to reduce crosstalk between the cores.
Claims20
An optical fiber cable incorporating a multi-core fiber comprising a plurality of cores each extending along a predetermined axis, and a cladding region integrally surrounding the plurality of cores, said optical fiber cable comprising a structure to provide the multi-core fiber with a bend of the smallest value of radii of curvature Rth given by the following expression:
- R
- th
- =
- 1
- 2
-
- β
- κ
- 2
-
- D
- nm
-
- XT
- S
- L
- F
- where Dnm is an intercentral distance between core n and core m in the multi-core fiber, LF a fiber length of the multi-core fiber corresponding to a length between repeater/regenerators in laying the optical fiber cable, β a propagation constant of each core at a first wavelength, κ a coupling coefficient between adjacent cores at the first wavelength, and XTS a maximum value permitted as an average of a distribution of crosstalk after propagation of light of the first wavelength through the fiber length LF.
An optical fiber cable incorporating a multi-core fiber comprising a plurality of cores each extending along a predetermined axis, and a cladding region integrally surrounding the plurality of cores, said optical fiber cable comprising a bend providing structure to provide the multi-core fiber with a bend of a radius of curvature R given by the following expression:
- R
- ≤
- 1
- 12
-
- β
- κ
- 2
-
- Λ
-
- XT
- S
- L
- F
- where Λ is an intercentral distance between adjacent cores in the multi-core fiber, LF a fiber length of the multi-core fiber corresponding to a length between repeater/regenerators in laying the optical fiber cable, β a propagation constant of each core at a first wavelength, κ a coupling coefficient between adjacent cores at the first wavelength, and XTS a maximum value permitted as an average of a distribution of crosstalk after propagation of light of the first wavelength through the fiber length LF,
- wherein the bend providing structure incorporates the multi-core fiber in a helix shape in the optical fiber cable, thereby providing the multi-core fiber with the bend of not more than a fixed radius of curvature, and
- wherein the multi-core fiber satisfies the following expression:
- L
- p
- ≤
- 2
-
-
- π
-
-
- 1
- 12
-
- β
- κ
- 2
-
- Λ
-
- XT
- S
- L
- F
-
- r
- h
-
-
- min
- -
- r
- h
-
-
- min
- 2
-
- where rh is a radius of the helix, LP a pitch of the helix, and rhmin the smallest rh in the multi-core fiber.
An optical fiber cable incorporating a multi-core fiber comprising a plurality of cores each extending along a predetermined axis, and a cladding region integrally surrounding the plurality of cores, said optical fiber cable comprising a structure to provide the multi-core fiber with a bend of the smallest value of radii of curvature Rth given by the following expression:
- R
- th
- =
- 1
- {
- erf
- -
- 1
-
- (
- 0.9999
- )
- }
- 2
-
- (
- 2
-
-
- π
- κ
- nm
- )
- 2
-
- π
-
-
- D
- nm
-
- β
- m
-
- 0.001
- 19.09373
-
-
- L
- F
- where Dnm is an intercentral distance between core n and core m in the multi-core fiber, βm a propagation constant of core m, κnm a coupling coefficient from core n to core m, and LF a fiber length of the multi-core fiber corresponding to a length in laying the optical fiber cable, said expression defining the radii of curvature with a probability of 99.99% that crosstalk after propagation through the fiber length LF is not more than −30 dB, for all combinations of two cores selected from the plurality of cores in the multi-core fiber.
Dependencies are inferred from the claim text.