Patent ID: 8861914

Claim:
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 K 2 ⁢ Λ ⁢ ⁢ XT S L F where Λ is an intercentral distance between adjacent cores in the multi-core fiber, L F 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, K a coupling coefficient between adjacent cores at the first wavelength, and XT S a maximum value permitted as an average of a distribution of crosstalk after propagation of light of the first wavelength through the fiber length L F .