WO2018150867A1 - Fibre multicœur et ruban de fibre multicœur l'utilisant - Google Patents

Fibre multicœur et ruban de fibre multicœur l'utilisant Download PDF

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Publication number
WO2018150867A1
WO2018150867A1 PCT/JP2018/003039 JP2018003039W WO2018150867A1 WO 2018150867 A1 WO2018150867 A1 WO 2018150867A1 JP 2018003039 W JP2018003039 W JP 2018003039W WO 2018150867 A1 WO2018150867 A1 WO 2018150867A1
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Prior art keywords
core
core fiber
clad
cores
fiber
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PCT/JP2018/003039
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English (en)
Japanese (ja)
Inventor
雄佑 佐々木
竹永　勝宏
晋聖 齊藤
盛岡　敏夫
エムディ ノールズザマン
Original Assignee
株式会社フジクラ
国立大学法人北海道大学
テクニカル・ユニヴァーシティ・オブ・デンマーク
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Priority to JP2018568087A priority Critical patent/JPWO2018150867A1/ja
Publication of WO2018150867A1 publication Critical patent/WO2018150867A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/04—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres

Definitions

  • the present invention relates to a multi-core fiber capable of arranging many cores while suppressing deterioration of long-term reliability.
  • An optical fiber used in a widely used optical fiber communication system has a structure in which an outer peripheral surface of one core is surrounded by a clad, and information is transmitted by propagation of an optical signal in the core.
  • a multi-core fiber in which the outer peripheral surfaces of a plurality of cores are surrounded by one clad. According to the multi-core fiber, a signal can be transmitted by each light propagating through a plurality of cores, so that the amount of information that can be transmitted by one optical fiber can be increased.
  • Patent Document 1 describes such a multi-core fiber.
  • a multi-core fiber a plurality of cores are arranged in one clad.
  • a part of light propagating through mutually adjacent cores may overlap, and crosstalk may occur between the cores.
  • As a method for suppressing the crosstalk for example, increasing the interval between adjacent cores can be considered. Since crosstalk is determined by the integration of overlap between lights propagating through adjacent cores, crosstalk can be suppressed by increasing the inter-core distance to reduce this overlap.
  • Crosstalk can also be suppressed by a trench structure in which each core is surrounded by a low refractive index layer formed by glass or holes having a lower refractive index than that of the core or cladding. Since the core is surrounded by a low refractive index layer, the spread of light propagating in the core in the radial direction can be reduced, so that the overlap between lights propagating in adjacent cores is reduced and crosstalk is suppressed. Is done.
  • Non-Patent Document 1 describes a single mode with a bending diameter of 30 mm and a proof level of 1% with a cladding diameter of 125 ⁇ m in an actual use environment of a multi-core fiber having a bending diameter of 30 to 60 mm or a proof level of 1 to 2%.
  • the upper limit of the diameter of the clad of the multi-core fiber that is equal to the fiber breaking probability is described as 250 ⁇ m.
  • Non-Patent Document 2 has a parameter called maximum bending strain, and this parameter is described in the following non-patent documents 3 and 4.
  • an object of the present invention is to provide a multicore fiber in which a large number of cores can be arranged while suppressing deterioration of long-term reliability, and a multicore fiber tape using the same.
  • a multi-core fiber of the present invention includes a plurality of cores arranged in a matrix and a single clad surrounding each of the cores, and has an outer shape in a cross section perpendicular to the longitudinal direction of the clad. Is a non-circular shape having the smallest diameter in the predetermined direction and having no recess, and two or more cores are disposed along the predetermined direction and along a direction perpendicular to the predetermined direction. A larger number of cores than the number of cores arranged along the predetermined direction are arranged and bent in the predetermined direction.
  • the upper limit of the number of cores that can be arranged in a predetermined direction is equal to the upper limit of the number of cores that can be arranged in a direction perpendicular to the predetermined direction.
  • the clad cross-sectional area can be made larger than that of a conventional multi-core fiber having a diameter equal to the diameter of the clad of the multi-core fiber of the present invention in a predetermined direction.
  • the number of cores arranged along the direction perpendicular to the predetermined direction is larger than the number of cores arranged along the predetermined direction.
  • the multi-core fiber of the present invention is bent in a predetermined direction. That is, the multi-core fiber of the present invention is used by being bent in a predetermined direction.
  • the largest stress applied to the clad is that of the multi-core fiber of the present invention and the clad of the multi-core fiber of the present invention.
  • the conventional multi-core fiber having a diameter equal to the diameter in the predetermined direction is approximately the same size.
  • the breaking probability thereof is substantially equal to the breaking probability of the conventional multi-core fiber. Therefore, according to the multi-core fiber of the present invention, deterioration of long-term reliability can be suppressed.
  • the outer shape of the clad may be a D type.
  • the multi-core fiber tape of the present invention includes a plurality of the above-mentioned multi-core fibers arranged in parallel to each other, and a single tape layer covering each multi-core fiber, and each of the multi-core fibers Are arranged such that the predetermined direction is oriented in a direction perpendicular to the parallel direction of the multi-core fibers.
  • each multi-core fiber bends in a predetermined direction. Therefore, it can suppress that the fracture probability of each multi-core fiber deteriorates. Further, a larger number of cores can be arranged by arranging a plurality of multi-core fibers in parallel.
  • a multi-core fiber of the present invention includes a plurality of cores arranged in a matrix and a single clad surrounding each of the cores, and a cross section perpendicular to the longitudinal direction of the clad.
  • the outer shape is an elliptical shape with an ellipticity of 2.5 or less, and two or more cores are arranged along the minor axis direction of the ellipse, and along the minor axis direction along the major axis direction of the ellipse.
  • a larger number of the cores than the number of the cores to be disposed are disposed and bent in a direction of 30 degrees or less with respect to the minor axis direction.
  • the present inventors compared the fracture probability of a multi-core fiber with a circular cladding outer shape and the fracture probability of a multi-core fiber with an elliptical cladding outer shape, The conditions for the same break probability were measured with the multi-core fiber.
  • the clad outer shape of each multi-core fiber is more elliptical than a circular multi-core fiber. It has been found that a certain multi-core fiber can have a larger cross-sectional area. Therefore, with such a multi-core fiber, more cores can be arranged while suppressing deterioration in long-term reliability.
  • the multi-core fiber tape of the present invention includes a multi-core fiber having an elliptical outer shape of the clad parallel to each other, and a single tape layer covering each multi-core fiber,
  • Each of the multicore fibers is arranged such that the minor axis direction is 30 degrees or less with respect to a direction perpendicular to the parallel direction of the multicore fibers.
  • each multi-core fiber bends in a direction of 30 degrees or less with respect to the minor axis direction. Therefore, it can suppress that the fracture probability of each multi-core fiber deteriorates. Further, a larger number of cores can be arranged by arranging a plurality of multi-core fibers in parallel.
  • a multi-core fiber of the present invention includes a plurality of cores arranged in a matrix and a single clad surrounding each of the cores, and a cross section perpendicular to the longitudinal direction of the clad.
  • the outer shape of the racetrack shape is a racetrack shape in which a ratio of a minor axis to a major axis formed by a pair of parallel lines connected by a semicircular curve is 2.5 or less, along the minor axis direction of the racetrack shape.
  • Two or more cores are disposed, and a larger number of cores than the number of cores disposed along the minor axis direction are disposed along the major axis direction of the racetrack shape, It is characterized by being bent in a direction of less than 45 degrees with respect to the direction.
  • the lengths of the respective straight lines are equal to each other, and the diameter becomes the smallest in the minor axis direction which is a direction perpendicular to the respective straight lines.
  • the present inventors compared the breaking probability of a multi-core fiber having a circular cladding outer shape with the breaking probability of a multi-core fiber having a cladding outer shape having the racetrack shape described above. The conditions under which the same breaking probability was obtained with the multi-core fiber having the racetrack shape as described above were measured.
  • the outer shape of the clad having the racetrack shape when bent at less than 45 degrees with respect to the minor axis direction, the outer shape of the clad has a more racetrack shape than the multicore fiber having the circular outer shape. It was found that the cross-sectional area of the multi-core fiber can be increased. Therefore, with such a multi-core fiber, more cores can be arranged while suppressing deterioration in long-term reliability.
  • the multi-core fiber tape of the present invention comprises a multi-core fiber having a track-shaped outer shape of the clad parallel to each other, and a single tape layer covering each multi-core fiber,
  • Each of the multi-core fibers is characterized in that the minor axis direction is arranged at less than 45 degrees with respect to a direction perpendicular to the parallel direction of the multi-core fibers.
  • each multi-core fiber bends in a direction of less than 45 degrees with respect to the minor axis direction. Therefore, it can suppress that the fracture probability of each multi-core fiber deteriorates. Further, a larger number of cores can be arranged by arranging a plurality of multi-core fibers in parallel.
  • the number of the plurality of cores may be larger than 37.
  • Non-Patent Document 1 in a multi-core fiber having a clad with a circular outer shape, if the limit of the diameter of the clad is 250 ⁇ m, generally, the number of cores is limited to 37. Therefore, the above multi-core fiber is more useful when the number of cores is greater than 37.
  • the present invention it is possible to provide a multicore fiber in which a large number of cores can be arranged while suppressing deterioration in long-term reliability, and a multicore fiber tape using the same.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area of a multi-core fiber and the probability of fracture when the ellipticity is 1.5, the bending proof is 1%, and the bending diameter is 60 mm in the multi-core fiber having the clad outer shape shown in FIG.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.0, the bending proof is 1%, and the bending diameter is 60 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.5, the bending proof is 1%, and the bending diameter is 60 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 1.5, the bending proof is 2%, and the bending diameter is 30 mm in the multi-core fiber having the clad outer shape shown in FIG.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.0, the bending proof is 2%, and the bending diameter is 30 mm in the multi-core fiber having the clad outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.5, the bending proof is 2%, and the bending diameter is 30 mm in the multi-core fiber having the clad outer shape shown in FIG.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the probability of fracture when the ellipticity is 1.5, the bending proof is 2%, and the bending diameter is 60 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.0, the bending proof is 2%, and the bending diameter is 60 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1.
  • FIG. 1 is a diagram showing the relationship between the cross-sectional area and the probability of fracture when the ellipticity is 1.5, the bending proof is 2%, and the bending diameter is 60 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.5, the bending proof is 2%, and the bending diameter is 60 mm in the multi-core fiber having the clad outer shape shown in FIG.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 1.5, the bending proof is 1%, and the bending diameter is 30 mm in the multi-core fiber having the clad outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing a relationship between a cross-sectional area and a fracture probability when the ellipticity is 2.0, the bending proof is 1%, and the bending diameter is 30 mm in the multi-core fiber having the clad outer shape shown in FIG. 1.
  • FIG. 2 is a diagram showing the relationship between the cross-sectional area and the fracture probability when the ellipticity is 2.5, the bending proof is 1%, and the bending diameter is 30 mm in the multi-core fiber having the cladding outer shape shown in FIG. 1. It is a figure which shows a core element. It is a figure which shows the 1st example of the multi-core fiber in 1st Embodiment.
  • the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.0, the bending proof is 1%, and the bending diameter is 60 mm.
  • FIG. In the multi-core fiber having the clad outer shape shown in FIG. 22, the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.5, the bending proof is 1%, and the bending diameter is 60 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 1.5, the bending proof is 2%, and the bending diameter is 30 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.0, the bending proof is 2%, and the bending diameter is 30 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.5, the bending proof is 2%, and the bending diameter is 30 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 1.5, the bending proof is 2%, and the bending diameter is 60 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.0, the bending proof is 2%, and the bending diameter is 60 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.5, the bending proof is 2%, and the bending diameter is 60 mm.
  • FIG. 22 the relationship between the cross-sectional area and the probability of breakage when the ratio of the distance between the straight lines to the length of the straight line is 1.5, the bending proof is 1%, and the bending diameter is 30 mm.
  • FIG. 22 the relationship between the cross-sectional area and the fracture probability when the ratio between the distance between the straight lines and the length of the straight lines is 2.0, the bending proof is 1%, and the bending diameter is 30 mm.
  • FIG. 22 In a multi-core fiber in which the shape of the clad is a racetrack, it is a diagram showing the relationship between the ratio between the distance between straight lines and the length of the straight lines and the number of cores that can be arranged. It is a figure which shows the 1st example of the multi-core fiber in 2nd Embodiment. It is a figure which shows the 2nd example of the multi-core fiber in 2nd Embodiment. It is a figure which shows the 3rd example of the multi-core fiber in 2nd Embodiment.
  • FIG. 1 is a diagram showing the appearance of the cladding in a cross section perpendicular to the longitudinal direction of the multi-core fiber in the first embodiment of the present invention.
  • the multi-core fiber of this embodiment is a communication multi-core fiber used for communication.
  • the clad 21 of the multi-core fiber of the present embodiment has an elliptical cross-sectional shape perpendicular to the longitudinal direction.
  • the clad 21 has a predetermined direction as a minor axis direction and a direction perpendicular to the minor axis direction as a major axis direction. Therefore, the outer shape of the clad 21 is a non-circular shape having the smallest diameter in the predetermined direction and having no recess.
  • the size of the minor axis is a
  • the size of the major axis is b.
  • the ellipse is defined by Equation 1 below.
  • the ellipticity e is defined by b / a
  • the area S is defined by the following equation 2.
  • Non-Patent Document 2 when the fracture probability is F, the fracture probability F is expressed by the following formula 3.
  • N p is the average break times during proofing
  • L is the length of the effective optical fiber count bending turn becomes 10 times
  • n represents the 20 be the fatigue factor
  • m is Weibull parameters ( a shape index)
  • t p is 1 second a proof time
  • t is the 20 years be age
  • sigma p is 1% or 2% be proof level
  • sigma is the maximum bending strain Is done.
  • the maximum bending strain ⁇ can be approximated by the following formula 4.
  • E is the Young's modulus of the glass
  • R b is the bending radius
  • r is the coordinates of the multicore fiber for obtaining the probability of breakage.
  • the position is the outermost side of the clad 21 when the multi-core fiber is bent.
  • the coordinate r is (0, a / 2).
  • the single mode fiber is required to have a fracture probability under the condition that the access diameter is 30 mm and the bending diameter is 30 mm.
  • multi-core fibers with high spatial multiplicity are expected to be used in the trunk line system for long-distance communications, and the probability of breakage may be reduced by setting the bending diameter to 60 mm, or the probability of breakage may be reduced by setting the proof level to 2%. it can.
  • the bending proof is 1%, the bending diameter is 60 mm, the ellipticity e is 1.5 in FIG. 2, and in FIG.
  • the calculation was performed with the ellipticity e set to 2.0 and the ellipticity e set to 2.5 in FIG. 5-7, the bending proof is 2%, the bending diameter is 30 mm, the ellipticity e is 1.5 in FIG. 5, and the ellipticity e is FIG.
  • the bending proof is 2%, the bending diameter is 60 mm, the ellipticity e is 1.5 in FIG.
  • the ellipticity e is FIG.
  • the bending proof is 1%
  • the bending diameter is 30 mm
  • the ellipticity e is 1.5 in FIG. 11
  • the ellipticity e is FIG.
  • the calculation was performed by setting the ellipticity e to 2.5 in FIG.
  • the solid line represents the relationship between the cross-sectional area and the breaking probability of the multi-core fiber with the clad having a circular outer shape under the above conditions.
  • the horizontal line shown in each figure is the probability of breakage when a standard single mode fiber having a cladding diameter of 125 ⁇ m is bent at a bending diameter of 30 mm, and its value is 3.2 ⁇ 10 ⁇ 6 .
  • the cross-sectional area of the multi-core fiber can be made larger than that of the multi-core fiber having a circular cladding shape.
  • Table 1 shows the cross-sectional area of the clad, the cross-sectional area ratio of the clad having an elliptical cross-sectional shape with respect to the clad having a circular cross-sectional shape, and the minor axis of the clad.
  • the minor axis when the cross-sectional shape of the cladding is a circle indicates the diameter of the circle.
  • Table 2 shows the same items as the items shown in Table 1 based on the calculation results shown in FIGS.
  • the multi-core fiber having an elliptical clad shape has a clad shape.
  • the cross-sectional area can be made larger than that of a circular multi-core fiber.
  • the cross-sectional area ratio is 1. when the angle ⁇ from the minor axis direction of the bending direction is 0 degree or more and 30 degrees or less. It can be 10 or more.
  • the cross-sectional area ratio tends to be smaller than 1.10. Therefore, the ellipticity e is preferably 1.5 or more and 2.5 or less, and more preferably 1.5 or more and 2.0 or less.
  • the cross-sectional area ratio is 1.46 or more and 2.43 or less if the ellipticity e is 1.5 or more and 2.5 or less.
  • the ellipticity e is preferably 2.0 or more.
  • FIG. 14 is a diagram illustrating core elements
  • FIGS. 15 to 19 are diagrams illustrating first to fifth examples of the multi-core fiber of the present embodiment.
  • the multi-core fibers 1A to 1E of these examples include at least two types of core elements 10A, 10B, and 10C arranged in a matrix and a single elliptical clad 21 surrounding each core element. And the covering layer 30.
  • the plurality of core elements are of different types from each other.
  • the core element 10A is indicated by a solid line
  • the core element 10B is indicated by a broken line
  • the core element 10C is indicated by a dotted line.
  • the core element 10A includes a core 11A, an inner cladding 12A surrounding the core 11A, and a low refractive index layer 13A surrounding the inner cladding 12A and surrounded by the cladding 21.
  • the core element 10B includes a core 11B, an inner cladding 12B surrounding the core 11B, and a low refractive index layer 13B surrounding the inner cladding 12B and surrounded by the cladding 21, and the core element 10C includes the core 11C, An inner cladding 12C surrounding the core 11C and a low refractive index layer 13C surrounding the inner cladding 12C and surrounded by the cladding 21 are included.
  • the multi-core fibers 1A to 1E have at least two types of core elements among the plurality of core elements 10A, 10B, and 10C arranged in a matrix
  • the multi-core fibers 1A to 1E are arranged in a matrix. And having at least two types of cores among the plurality of cores 11A, 11B, and 11C.
  • the cores 11A to 11C have a refractive index higher than that of the cladding 21, the low refractive index layers 13A to 13C have a refractive index lower than that of the cladding 21, and the inner cladding 12A has a gap between the core 11A and the low refractive index layer 13A.
  • the inner cladding 12B has a refractive index between the core 11B and the low refractive index layer 13B, and the inner cladding 12C has a refractive index between the core 11C and the low refractive index layer 13C.
  • the inner claddings 12A to 12C have the same refractive index as that of the cladding 21.
  • each of the core elements 10A to 10C has a trench type refractive index profile.
  • the refractive index difference with respect to the refractive index of the clad 21 of the core 11A of the core element 10A is the largest, and thus a high refractive index difference core, and the refractive index difference with respect to the refractive index of the clad 21 of the core 11C of the core element 10C.
  • the refractive index difference with respect to the refractive index of the clad 21 of the core 11B of the core element 10B is between the core 11A and the core 11B to be a medium refractive index difference core.
  • the multi-core fiber shown below has two or more cores arranged along the minor axis direction of the ellipse and cores arranged along the minor axis direction along the major axis direction of the ellipse. More cores than the number are arranged. Further, in the present embodiment, when the axis along the minor axis direction passing through the center of the major axis is the minor axis, the number of cores arranged along the minor axis at a position close to the minor axis is the minor axis. More than the number of cores arranged along the minor axis at a position far from the center.
  • the cores 11A to 11C are shown as a part of the core elements 10A to 10C, and the clad 21 is connected to the cores 11A to 11C via the inner clads 12A to 12C and the low refractive index layers 13A to 13C. It indirectly surrounds 11C.
  • the inner claddings 12A to 12C and the low refractive index layers 13A to 13C may be omitted, and the cladding 21 may directly surround the respective cores 11A to 11C.
  • a multi-core fiber 1A of the first example shown in FIG. 15 has a clad 21 having an ellipticity e of 1.5, and two types of core elements 10A and 10C are arranged in the clad 21. These core elements 10A and 10C are arranged in a square lattice so that the adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, an array of 2-6-8-8-6-2 is obtained, and the core elements 10A, 10A, The total number of 10C is 32.
  • the proof when the proof is 2%, the bending diameter is 30 mm, and the angle ⁇ in the bending direction of the multi-core fiber is 30 degrees, the proof is 1% when the standard single mode fiber is bent at a bending diameter of 30 mm.
  • the sectional area when the fracture probability is the same as the fracture probability of 3.2 ⁇ 10 ⁇ 6 is approximately 56.1 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Therefore, the minor axis is approximately 218 ⁇ m and the major axis is approximately 327 ⁇ m. In this case, the distance between the cores can be 28.8 ⁇ m.
  • the ratio of the area occupied by the core elements 10A and 10B to the area surrounded by the outer periphery of the clad 21 is the core exclusive area ratio
  • the core exclusive area ratio is 37.8%.
  • FIG. 16 is a diagram illustrating a second example of the multi-core fiber of the present embodiment.
  • the multi-core fiber 1B has a clad 21 having an ellipticity e of 1.5, and three types of core elements 10A, 10B, and 10C are arranged in the clad 21.
  • These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. In this way, the core elements 10A, 10B, and 10C are arranged in a triangular lattice shape, so that the core elements 10A, 10B, and 10C are arranged in a close-packed form.
  • the array becomes 6-9-10-9-6, and the core elements 10A, 10B, The total number of 10C is 40.
  • the multi-core fiber 1B of this example has the same ellipticity e as the multi-core fiber 1A. Therefore, when the proof is 2%, the bending diameter is 30 mm, and the angle ⁇ in the bending direction of the multi-core fiber is 30 degrees, the fracture probability is 3.2.
  • the cross-sectional area in the case of ⁇ 10 ⁇ 6 is approximately 56.0 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Therefore, the minor axis is approximately 218 ⁇ m and the major axis is approximately 327 ⁇ m. Further, the distance between the cores can be 28.8 ⁇ m. In addition, the area occupied by the core is 47.2%.
  • FIG. 17 is a diagram illustrating a third example of the multi-core fiber of the present embodiment.
  • the multi-core fiber 1C has a clad 21 having an ellipticity e of 2.0, and three types of core elements 10A, 10B, and 10C are arranged in the clad 21. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, the array becomes 7-10-11-10-7, and the core elements 10A, 10B, The total number of 10C is 41.
  • the cross-sectional area when the fracture probability is 3.2 ⁇ 10 ⁇ 6 is FIG. Therefore, it is approximately 56.1 ⁇ 10 ⁇ 8 ⁇ m 2 . Therefore, the major axis is approximately 189 ⁇ m and the major axis is approximately 378 ⁇ m. Further, the distance between the cores can be 28.8 ⁇ m. In addition, the area occupied by the core is 48.3%.
  • the multicore fibers 1A to 1C when the angle ⁇ from the minor axis direction is bent and used in a direction of 30 degrees or less, the multicore fibers 1A to 1C have substantially the same reliability as the single mode fiber. Optical communication can be performed.
  • FIG. 18 is a diagram illustrating a fourth example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 1D has a clad 21 with an ellipticity e of 1.5, and three types of core elements 10A, 10B, and 10C are arranged in the clad 21. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, the array becomes 6-7-8-7-6, and the core elements 10A, 10B, The total number of 10C is 34.
  • the cross-sectional area when the fracture probability is 3.2 ⁇ 10 ⁇ 6 is shown in FIG. Therefore, it is approximately 48.8 ⁇ 10 ⁇ 8 ⁇ m 2 .
  • the minor axis is approximately 204 ⁇ m and the major axis is approximately 305 ⁇ m.
  • the distance between the cores can be 28.8 ⁇ m.
  • the area occupied by the core is 52.7%.
  • the parameters of each core element in this example are the same as the parameters of each core element in the second example and the third example.
  • FIG. 19 is a diagram illustrating a fifth example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 1E has a clad 21 having an ellipticity e of 2.0, and three types of core elements 10A, 10B, and 10C are arranged in the clad 21. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, the array becomes 6-9-10-9-6, and the core elements 10A, 10B, The total number of 10C is 40.
  • the cross-sectional area when the fracture probability is 3.2 ⁇ 10 ⁇ 6 is shown in FIG. Therefore, it is approximately 48.8 ⁇ 10 ⁇ 8 ⁇ m 2 . Accordingly, the minor axis is approximately 176 ⁇ m and the major axis is approximately 353 ⁇ m. Further, the distance between the cores can be 28.8 ⁇ m. In addition, the area occupied by the core is 47.4%.
  • the parameters of each core element in this example are the same as the parameters of each core element in the second example and the third example.
  • the optical communication has the same reliability as a single mode fiber. It can be performed.
  • the ellipticity e of the clad 21 and the arrangement of the core elements 10A to 10C shown in the above example are merely examples, and the arrangement of the ellipticity e and the core elements 10A to 10C can be changed as appropriate.
  • the multi-core fibers 1A to 1E of this embodiment include the plurality of cores 11A to 11C arranged in a matrix and the single clad 21 surrounding each of the cores 11A to 11C.
  • the outer shape in a cross section perpendicular to the longitudinal direction of the clad 21 is an elliptical shape having an ellipticity e of 2.5 or less, two or more cores are disposed along the minor axis direction of the ellipse, and the major axis direction of the ellipse is A larger number of cores are disposed along the minor axis direction.
  • the multi-core fibers 1A to 1E are used by being bent in a direction of 30 degrees or less with respect to the minor axis direction.
  • the multi-core fibers 1A to 1E having the elliptical outer shape of the clad 21 are bent at 30 degrees or less with respect to the minor axis direction, as described above, when the fracture probability is the same,
  • the cross-sectional area of the multi-core fibers 1A to 1E having an elliptical outer shape of the clad can be larger than that of the multi-core fiber having a circular outer shape. Therefore, with such multi-core fibers 1A to 1E, more cores can be arranged while suppressing deterioration in long-term reliability.
  • FIG. 20 is a diagram of the first embodiment showing that many cores can be arranged in the multicore fiber in the first embodiment when the angle ⁇ is 0 degree.
  • the covering layer 30 is omitted.
  • the multi-core fiber 101 with a circular cross-sectional shape of the clad the multi-core fiber 1F with an elliptical cross-sectional shape of the clad and an ellipticity e of 2.0, and an elliptical shape with the elliptical cross-sectional shape of the clad.
  • a multi-core fiber 1G having an e of 2.5 is shown superimposed. That is, in FIG.
  • the multi-core fiber 101 having the circular clad shape and the multi-core fibers 1 ⁇ / b> F and 1 ⁇ / b> G having the elliptical clad 21 having a short diameter equal to the diameter of the clad of the multi-core fiber 101. It is shown.
  • the most stressed position is the position on the outermost side of the clad in the bent state. Therefore, when the multi-core fibers 1F and 1G having such a cladding are bent at an angle ⁇ from the minor axis direction of 0 degree, the magnitude of the stress at the most stressed position is bent with the same curvature. The magnitude of the stress at the most stressed position in the multi-core fiber 101 is the same. Therefore, when the multi-core fibers 1F and 1G are bent at an angle ⁇ of 0 degrees as described above, the break probability of the multi-core fibers 1F and 1G is equal to the break probability of the multi-core fiber 101 bent with the same curvature. For this reason, compared with the multi-core fiber 101, the multi-core fibers 1F and 1G can suppress deterioration in long-term reliability.
  • the short diameter of the clad of the multicore fibers 1F and 1G is the same as the diameter of the clad of the multicore fiber 101 as compared to the multicore fiber 101 having a circular cross-sectional outer shape. It is assumed. Accordingly, the cross-sectional area of the clad of the multi-core fibers 1F and 1G is made larger than the cross-sectional area of the clad of the multi-core fiber 101.
  • the multi-core fibers 1F and 1G can have more core elements than the multi-core fiber 101 having the same diameter as the minor axis of the clad of the multi-core fibers 1F and 1G.
  • the core elements that can be disposed in the clad of the multi-core fiber 101 are a core element that overlaps the broken line and a core element that is disposed inside the broken line in FIG. Therefore, the number of core elements included in the multi-core fiber 101 is 37.
  • the core elements that can be disposed in the clad of the multi-core fiber 1F are a core element that overlaps with a dotted line and a core element that is disposed inside the dotted line in FIG. Accordingly, the number of core elements included in the multi-core fiber 1F is 77.
  • the number of core elements included in the multi-core fiber 1G is 89.
  • FIG. 21 is a diagram of the second embodiment showing that many cores can be arranged in the multi-core fiber in the first embodiment when the angle ⁇ is 0 degree, as in FIG. 20.
  • the multi-core fiber 102 with a circular cross-sectional shape of the clad the multi-core fiber 1H with an elliptical cross-sectional shape and an ellipticity e of 2.0, and an elliptical shape with an elliptical cross-sectional shape.
  • a multi-core fiber 1I with an e of 2.5 is shown superimposed. That is, in FIG.
  • the multi-core fiber 102 having a circular clad shape and the multi-core fibers 1H and 1I each having an elliptical clad 21 having a short diameter equal to the diameter of the clad of the multi-core fiber 102 are shown. It is shown.
  • the break probability of the multi-core fibers 1H and 1I is the multi-core fiber 102 bent with the same curvature. Is made equal to the probability of breakage. Therefore, the multi-core fibers 1H and 1I can suppress deterioration in long-term reliability as compared with the multi-core fiber 102.
  • the cross-sectional area of the clad of the multi-core fibers 1H and 1I is made larger than the cross-sectional area of the clad of the multi-core fiber 102.
  • the multi-core fibers 1H and 1I along the major axis direction of the ellipse. More core elements than the number of core elements arranged along the minor axis direction are arranged. Therefore, the multi-core fibers 1H and 1I can have more core elements than the multi-core fiber 102 having the same diameter as the minor axis of the clad of the multi-core fibers 1H and 1I.
  • core elements that can be arranged in the clad of the multi-core fiber 102 are core elements that overlap the broken line and core elements that are arranged inside the broken line, and the number of core elements that the multi-core fiber 102 has is 37.
  • the core elements that can be arranged in the clad of the multi-core fiber 1H are the core elements that overlap with the dotted line and the core elements that are arranged inside the dotted line, and the number of core elements that the multi-core fiber 1H has is 89.
  • the number of core elements included in the multi-core fiber 1I is 105.
  • the multi-core fiber of this embodiment includes a plurality of cores 11A to 11C arranged in a matrix and a single clad 21 surrounding each of the cores 11A to 11C.
  • the outer shape in a cross section perpendicular to the longitudinal direction of the clad 21 is a non-circular shape having the smallest diameter in the predetermined direction and having no recess.
  • Two or more cores 11A to 11C are arranged along a predetermined direction, and more cores are arranged along a direction perpendicular to the predetermined direction than the number of cores arranged along the predetermined direction. Are bent in a predetermined direction.
  • the upper limit of the number of cores that can be arranged in a predetermined direction and the direction perpendicular to the predetermined direction is equal to each other.
  • the multi-core fibers 1F to 1I of the present embodiment for example, from the conventional multi-core fibers 101 and 102 having a diameter equal to the diameter of the minor axis direction which is a predetermined direction of the cladding of the multi-core fibers 1F to 1I of the present embodiment.
  • the cross-sectional area of the cladding can be increased.
  • the number of cores 11A to 11C arranged along the direction perpendicular to the predetermined direction is larger than the number of cores 11A to 11C arranged along the predetermined direction. Therefore, according to the multi-core fibers 1F to 1I of the present embodiment, more cores can be arranged than the conventional multi-core fibers 101 and 102. Further, the multi-core fibers 1F to 1I of this embodiment are used by being bent in a predetermined direction. In this case, since the position where the greatest stress is applied to the clad is the position on the outermost peripheral side of the clad 21 in the bent state, the largest stress applied to the clad is the multicore fibers 1F to 1I of the present embodiment and the conventional multicore.
  • the fibers 101 and 102 have substantially the same size. Therefore, when the multi-core fibers 1F to 1I according to the present invention are bent as described above, the break probability thereof is substantially equal to the break probability of the conventional multi-core fibers 101 and 102. Therefore, according to the multicore fibers 1F to 1I of the present invention, deterioration of long-term reliability can be suppressed.
  • FIG. 22 is a diagram showing the appearance of the cladding in a cross section perpendicular to the longitudinal direction of the multi-core fiber in the second embodiment of the present invention.
  • the outer shape of the cladding is shown, and the core and the coating layer are not described.
  • the multi-core fiber of the present embodiment is a communication multi-core fiber used for communication in the same manner as the multi-core fiber of the first embodiment.
  • the clad 22 of the multi-core fiber according to the present embodiment has a cross-sectional shape perpendicular to the longitudinal direction and a racetrack shape in which a set of straight lines 22L parallel to each other are connected by a semicircular curve 22C.
  • the respective straight lines 22L are in a relationship of being translated from each other.
  • the direction perpendicular to the straight line 22L is the minor axis direction and the direction along the straight line 22L is the major axis direction in the cross section.
  • this minor axis direction is a predetermined direction
  • the outer shape of the clad 22 is a non-circular shape having the smallest diameter in the predetermined direction and having no recess.
  • the short diameter which is the distance between the straight lines 22L is a
  • the long diameter is b.
  • the ratio (b / a) between the minor axis a and the major axis b is assumed to be e.
  • the breaking probability of the multi-core fiber is expressed by Equation 3. Therefore, in the multi-core fiber having the outer shape of the clad 22 shown in FIG. 22, the relationship between the cross-sectional area and the fracture probability when the multi-core fiber is bent in the direction of the angle ⁇ from the minor axis direction shown in FIG. It calculated
  • the relationship between the cross-sectional area and the probability of breakage is that the bending proof is 1%, the bending diameter is 60 mm, the ratio e is 1.5 in FIG. 23, and the ratio e is 2.0 in FIG.
  • the calculation was performed with the ratio e set to 2.5.
  • the bending proof is 2%, the bending diameter is 30 mm, the ratio e is 1.5 in FIG. 26, and the ratio e is 2 in FIG.
  • the calculation was performed by setting the ratio e to 2.5 in FIG. 29 to 31, the bending proof is 2%, the bending diameter is 60 mm, the ratio e is 1.5 in FIG. 29, and the ratio e is 2 in FIG.
  • the horizontal line shown in each figure is the probability of breakage when a standard single mode fiber having a cladding diameter of 125 ⁇ m is bent at a bending diameter of 30 mm, and the value Is 3.2 ⁇ 10 ⁇ 6 .
  • the ratio e of the minor axis a to the major axis b is 2.5 or less, and the same breaking probability is obtained.
  • the cross-sectional area of the multi-core fiber with the racetrack shape of the clad can be larger than that of the multi-core fiber with the circular shape of the clad.
  • the fracture probability is 3.2 ⁇ 10 ⁇ 6 when the angle ⁇ in each figure is 0 degree, 30 degrees, and 45 degrees.
  • Table 8 shows the cross-sectional area of the clad, the cross-sectional area ratio of the clad whose cross-sectional shape is a racetrack shape, and the minor axis of the clad.
  • the minor axis when the cross-sectional shape of the cladding is a circle indicates the diameter of the circle.
  • the clad shape of the racetrack-shaped multicore fiber is used.
  • the cross-sectional area can be made larger than that of a multi-core fiber having a circular cladding shape.
  • the angle ⁇ is 45 degrees
  • the cross-sectional area of the multicore fiber having the racetrack shape of the clad may be slightly smaller than the circular multicore fiber at the ratio e of 1.5.
  • the cross-sectional area of the racetrack-shaped multicore fiber is substantially the same as that of the circular multicore fiber.
  • the cross-sectional area of the multicore fiber with the racetrack shape of the clad can be larger than that of the multicore fiber with the circular shape of the clad.
  • the cross-sectional area of the multicore fiber having a racetrack shape of the clad can be more reliably increased than the multicore fiber having a circular clad shape.
  • the ratio e is 2.0 or more and 2.5 or less, the cross-sectional area of the multicore fiber with the racetrack shape of the clad is smaller than that of the circular multicore fiber when the angle ⁇ is 45 degrees or less. Since there is no, it is preferable.
  • FIG. 35 in the multi-core fiber in which the shape of the clad 22 is a racetrack shape as in the present embodiment, the relationship between the ratio e between the short diameter a and the long diameter b and the number of cores that can be arranged is shown. .
  • FIG. 35 shows the ratio e and the cross-sectional area obtained by fixing the minor axis a which is the distance between straight lines and changing the major axis b, and the core elements using the parameters of the core elements 10A to 10C described in Table 6 are shown.
  • the number obtained by dividing the cross-sectional area by the area is the number of cores.
  • FIG. 35 it can be seen that, when the ratio e is at least 2.5, regardless of the minor axis a, the larger the ratio e, the more cores that can be arranged.
  • the core elements 10A to 10C shown in FIGS. 15 to 19 can be arranged in the clad 22.
  • the inner claddings 12A to 12C and the low refractive index layers 13A to 13C may be omitted, and the cladding 22 may directly surround the respective cores 11A to 11C.
  • two or more cores are arranged along the minor axis direction of the racetrack shape, and are arranged along the minor axis direction along the major axis direction of the race track shape. More cores than the number of cores are arranged. Further, in the present embodiment, when the axis along the minor axis direction passing through the center of the major axis is the minor axis, the number of cores arranged along the minor axis at a position close to the minor axis is the minor axis. More than the number of cores arranged along the minor axis at a position far from the center.
  • a multi-core fiber 2A of the first example shown in FIG. 36 has a clad 22 having a ratio e of a minor axis a to a major axis b of 1.5, and two types of cores 10A and 10C in the clad 22 Elements are arranged in a square lattice so as to be of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, an array of 4-6-8-8-6-4 is obtained, and the core elements 10A, 10A, The total number of 10C is 36. 2.
  • the breaking probability when the standard single mode fiber is bent with a bending diameter of 30 mm is the same as 2 ⁇ 10 ⁇ 6 , the cross-sectional area is approximately 52.8 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Therefore, the minor axis is approximately 202.7 ⁇ m, and the major axis is approximately 304.1 ⁇ m. In this case, the distance between the cores can be 28.8 ⁇ m.
  • the ratio of the area occupied by the core elements 10A and 10B to the area surrounded by the outer periphery of the clad 21 is the core exclusive area ratio
  • the core exclusive area ratio is 44.4%.
  • FIG. 37 is a diagram illustrating a second example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 2B has a clad 22 having a ratio e of the minor axis a to the major axis b of 1.5, and three types of core elements 10A, 10B, and 10C are arranged in the clad 22.
  • These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. In this way, the core elements 10A, 10B, and 10C are arranged in a triangular lattice shape, so that the core elements 10A, 10B, and 10C are arranged in a close-packed form.
  • the array becomes 6-7-8-7-6, and the core elements 10A, 10B,
  • the total number of 10C is 34. 2.
  • the cross-sectional area is approximately 52.8 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG.
  • the minor axis is approximately 202.7 ⁇ m
  • the major axis is approximately 304.1 ⁇ m.
  • the distance between the cores can be 28.8 ⁇ m.
  • the core exclusive area ratio is 41.9%.
  • FIG. 38 is a diagram illustrating a third example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 2C has a clad 22 having a ratio e of 2.0, and three types of core elements 10A, 10B, and 10C are arranged in the clad 22. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, the array becomes 7-8-9-8-7, and the core elements 10A, 10B, The total number of 10C is 39. 2.
  • the probability of breakage when the standard single-mode fiber is bent with a bending diameter of 30 mm is approximately 48.6 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Accordingly, the minor axis is approximately 165.0 ⁇ m and the major axis is approximately 330.0 ⁇ m. In this case, the distance between the cores can be 28.8 ⁇ m.
  • the ratio of the area occupied by the core elements 10A, 10B, and 10C to the area surrounded by the outer periphery of the clad 21 is the core exclusive area ratio
  • the core exclusive area ratio is 52.2%.
  • FIG. 39 is a diagram illustrating a fourth example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 2D has a clad 22 with a ratio e of 1.5, and three types of core elements 10A, 10B, and 10C are arranged in the clad 22. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Further, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, an array of 5-6-7-8-7-6-5 is obtained. The total number of 10A, 10B, and 10C is 44. 2.
  • the probability of breakage when the standard single-mode fiber is bent at a bending diameter of 30 mm assuming that the proof is 2%, the bending diameter is 30 mm, and the angle ⁇ in the bending direction of the multi-core fiber is 30 degrees.
  • the cross-sectional area when the fracture probability is the same as 2 ⁇ 10 ⁇ 6 is approximately 60.6 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Therefore, the minor axis is approximately 217.1 ⁇ m, and the major axis is approximately 325.7 ⁇ m. In this case, the distance between the cores can be 28.8 ⁇ m.
  • the ratio of the area occupied by the core elements 10A, 10B, and 10C to the area surrounded by the outer periphery of the clad 21 is the core exclusive area ratio
  • the core exclusive area ratio is 47.3%.
  • FIG. 40 is a diagram illustrating a fifth example of the multi-core fiber according to the present embodiment.
  • the multi-core fiber 2E has a clad 22 with a ratio e of 2.0, and three types of core elements 10A, 10B, and 10C are arranged in the clad 22. These core elements 10A, 10B, and 10C are arranged in a triangular lattice shape so that adjacent core elements are of different types. Also, in this example, when the number of core elements arranged along the major axis direction is counted in order along the minor axis direction, an array of 8-9-10-9-8 is obtained, and the core elements 10A, 10B, The total number of 10C is 45.
  • the cross-sectional area when the fracture probability is the same as 2 ⁇ 10 ⁇ 6 is approximately 55.8 ⁇ 10 ⁇ 8 ⁇ m 2 from FIG. Therefore, the minor axis is approximately 176.8 ⁇ m, and the major axis is approximately 353.6 ⁇ m. In this case, the distance between the cores can be 28.8 ⁇ m.
  • the ratio of the area occupied by the core elements 10A, 10B, and 10C to the area surrounded by the outer periphery of the clad 21 is a core exclusive area ratio
  • the core exclusive area ratio is 52.5%.
  • the ratio e of the clad 21 and the arrangement of the core elements 10A to 10C shown in the above example are merely examples, and the ratio e and the arrangement of the core elements 10A to 10C can be changed as appropriate.
  • the multi-core fibers 2A to 2E of this embodiment include the plurality of cores 11A to 11C arranged in a matrix and the single clad 22 surrounding each of the cores 11A to 11C.
  • the outer shape of the clad 22 in a cross section perpendicular to the longitudinal direction is a race in which a pair of straight lines 22L connected to each other by a semicircular curve 22C and a ratio e between the minor axis a and the major axis b is 2.5 or less.
  • the track shape Two or more cores are arranged along the minor axis direction, and more cores are arranged along the minor axis direction along the minor axis direction.
  • the multi-core fibers 2A to 2E are used by being bent in a direction of less than 45 degrees with respect to the minor axis direction.
  • the multi-core fibers 2A to 2E having the outer shape of the clad 22 having a racetrack shape are bent and used at less than 45 degrees with respect to the minor axis direction, as described above, when the fracture probability is the same,
  • the multi-core fibers 2A to 2E having a racetrack shape with a clad outer shape can have a larger cross-sectional area than a multicore fiber with a clad outer shape being circular. Accordingly, with such multi-core fibers 2A to 2E, it is possible to arrange more cores while suppressing deterioration of long-term reliability.
  • FIG. 41 is a diagram of the first embodiment showing that many cores can be arranged in the multi-core fiber in the second embodiment when the angle ⁇ is 0 degree.
  • the coating layer 30 is omitted.
  • a multi-core fiber 101 having a circular cross-sectional shape of the clad
  • a multi-core fiber 2F having a cross-section of the clad having a racetrack shape and a ratio e of the short diameter a to the long diameter b of 2.0
  • a cross-section of the clad Is a racetrack shape
  • a multi-core fiber 2G having a ratio e of the minor axis a to the major axis b of 2.5 is superimposed. That is, FIG.
  • the most stressed position is the position on the outermost peripheral side of the clad in the bent state. Therefore, when the multicore fibers 2F and 2G having such a cladding are bent at an angle ⁇ from the minor axis direction of 0 degree, the magnitude of the stress at the most stressed position was bent with the same curvature. The magnitude of the stress at the most stressed position in the multi-core fiber 101 is the same. Therefore, when the multi-core fibers 2F and 2G are bent at an angle ⁇ of 0 degrees as described above, the break probability of the multi-core fibers 2F and 2G is made equal to the break probability of the multi-core fiber 101 bent with the same curvature. For this reason, compared with the multi-core fiber 101, the multi-core fibers 2F and 2G can suppress deterioration in long-term reliability.
  • the clad minor axis a of the multi-core fibers 2F and 2G is the same as the clad diameter of the multi-core fiber 101 as described above. It is made a size. Therefore, the cross-sectional area of the clad of the multi-core fibers 2F and 2G is made larger than the cross-sectional area of the clad of the multi-core fiber 101.
  • a larger number of core elements than the number of core elements arranged along the minor axis direction are arranged along the major axis direction. Accordingly, the multi-core fibers 2F and 2G can have more core elements than the multi-core fiber 101 having the same diameter as the minor axis a of the clad of the multi-core fibers 2F and 2G.
  • the core element that can be disposed in the clad of the multi-core fiber 101 is a core element that overlaps the broken line and a core element that is disposed inside the broken line, and is 37.
  • the core elements that can be disposed in the clad of the multi-core fiber 2F are a core element that overlaps with a dotted line and a core element that is disposed inside the dotted line in FIG. Accordingly, the number of core elements included in the multi-core fiber 2F is 93.
  • the number of core elements included in the multi-core fiber 2G is 117.
  • FIG. 42 is a diagram of the second embodiment showing that many cores can be arranged in the multi-core fiber in the second embodiment when the angle ⁇ is 0 degree.
  • the coating layer 30 is omitted.
  • the multi-core fiber 102 having a circular cross-sectional shape of the clad
  • the multi-core fiber 2H having a cross-section of the clad having a racetrack shape and a ratio e of the short diameter a to the long diameter b of 2.0
  • a cross-section of the clad Is a racetrack shape
  • a multi-core fiber 2I having a ratio e between the minor axis a and the major axis b of 2.5 is superimposed.
  • a multi-core fiber 102 having a circular clad shape and multi-core fibers 2H and 2I having a racetrack-shaped clad 22 in which the short axis a is smaller than the diameter of the clad of the multi-core fiber 102 are shown. .
  • the distance between the straight lines 22L is smaller than the diameter of the clad of the multi-core fiber 102. Is smaller than the breaking probability of the multi-core fiber 102 bent with the same curvature. For this reason, the multi-core fibers 2H and 2I can suppress deterioration of long-term reliability as compared with the multi-core fiber 102.
  • the multi-core fibers 2H and 2I have more core elements than the multi-core fiber 102, although the distance between the straight lines 22L is smaller than the diameter of the clad of the multi-core fiber 102. Can do.
  • the core element that can be arranged in the clad of the multi-core fiber 102 is 37 as in the first embodiment.
  • the core element that can be disposed in the clad of the multi-core fiber 2H is a core element that overlaps the dotted line and a core element that is disposed inside the dotted line, which is 93.
  • the number of core elements included in the multi-core fiber 2I is 117.
  • the multi-core fibers 2F to 2I according to the present embodiment are also compared with the conventional multi-core fibers 101 and 102 in which the outer shape of the cross section of the clad is circular as described with reference to FIGS.
  • the deterioration of the fracture probability can be suppressed, and many cores can be arranged.
  • FIG. 43 is a diagram showing the multi-core fiber tape of the present embodiment.
  • a multi-core fiber tape 51 shown in FIG. 43 has a plurality of multi-core fibers 1A of the first embodiment arranged in parallel in a single tape layer 50.
  • the tape layer 50 has a flat plate shape in which the parallel direction of the multi-core fibers 1A is thinned. Therefore, the multi-core fiber tape 51 is easily bent in the thickness direction.
  • the multi-core fiber 1 ⁇ / b> A disposed in the tape layer 50 is disposed so that the minor axis direction is 30 degrees or less from the thickness direction of the tape layer 50.
  • the tape layer 50 may be formed as a single tape layer 50 by molding a resin, or may be formed as a single tape layer 50 by bonding two tapes.
  • the multi-core fiber tape 51 of the present embodiment includes the multi-core fiber 1A in which the outer shapes of the clads 21 arranged in parallel with each other are elliptical, and the single tape layer 50 that covers each multi-core fiber 1A. .
  • each multi-core fiber 1A is arrange
  • a multi-core fiber tape 51 when the tape is bent, each multi-core fiber 1A bends in a direction of 30 degrees or less with respect to the minor axis direction. Therefore, it is possible to suppress the deterioration probability of each multi-core fiber 1A from deteriorating. Further, more cores can be arranged by arranging a plurality of multi-core fibers 1A in parallel.
  • the multi-core fiber tape 51 on which the multi-core fiber 1A is disposed has been described as an example.
  • the multi-core fiber disposed on the multi-core fiber tape 51 of the present embodiment is the multi-core fiber described in the first embodiment. If there is no particular limitation.
  • FIG. 44 is a diagram showing the multi-core fiber tape of the present embodiment.
  • a multi-core fiber tape 52 shown in FIG. 44 has a plurality of multi-core fibers 2A of the second embodiment arranged in parallel in a single tape layer 50.
  • the tape layer 50 has a flat plate shape in which the parallel direction of the multi-core fibers 2A is thinned. Therefore, the multi-core fiber tape 52 is easily bent in the thickness direction.
  • the multi-core fibers 2 ⁇ / b> A disposed in the tape layer 50 are disposed such that the minor axis direction is less than 45 degrees from the thickness direction of the tape layer 50.
  • the multi-core fiber 2 ⁇ / b> A is preferably arranged so that the minor axis direction is 44 degrees or less from the thickness direction of the tape layer 50.
  • the multi-core fiber 2A is arranged such that the ratio e in the second embodiment is 2.0 or more and 2.5 or less, and the minor axis direction is 45 degrees or less from the thickness direction of the tape layer 50. It is preferable.
  • the multi-core fiber tape 52 of the present embodiment includes the multi-core fiber 2A in which the outer shape of the clad 22 arranged in parallel with each other is a racetrack shape, and the single tape layer 50 covering each multi-core fiber 2A.
  • each multi-core fiber 2A is arrange
  • a multi-core fiber tape 52 when the tape is bent, each multi-core fiber 2A bends in a direction of less than 45 degrees with respect to the minor axis direction. Therefore, it is possible to suppress the deterioration probability of each multi-core fiber 2A from deteriorating. Further, more cores can be arranged by arranging a plurality of multi-core fibers 2A in parallel.
  • the multicore fiber tape 52 on which the multicore fiber 2A is disposed has been described as an example.
  • the multicore fiber disposed on the multicore fiber tape 52 of the present embodiment is the multicore fiber described in the second embodiment. If there is no particular limitation.
  • the multicore fiber and multicore fiber tape of the present invention have been described above, but the present invention is not limited to the above embodiment.
  • FIG. 45 is a diagram showing another shape of the clad.
  • the clad 23 of this example is D-type.
  • the fracture probability when bending in the predetermined direction is equivalent to the fracture probability of a multi-core fiber having a circular cross section having the same diameter as the minor axis shown in FIG. . Therefore, according to the multi-core fiber having such a clad, it is possible to arrange many cores while suppressing deterioration of long-term reliability.
  • the outer shape in the cross section perpendicular to the longitudinal direction of the clad has a non-circular shape with the smallest diameter in the predetermined direction and no recess, and two or more cores are formed along the predetermined direction.
  • a multi-core fiber that is arranged and bent along a direction perpendicular to the predetermined direction, and more than the number of cores arranged along the predetermined direction, is bent in the predetermined direction to be used. . According to this multi-core fiber, it is possible to arrange many cores while suppressing deterioration of long-term reliability as described above.
  • a multi-core fiber tape using such a multi-core fiber includes a plurality of the multi-core fibers arranged in parallel with each other and a single tape layer covering each multi-core fiber, and each multi-core fiber is a multi-core fiber. It is arranged so that a predetermined direction is oriented in a direction perpendicular to the fiber parallel direction. When this multi-core fiber tape is bent, each multi-core fiber bends in a predetermined direction. Therefore, it can suppress that the fracture probability of each multi-core fiber deteriorates. Further, a larger number of cores can be arranged by arranging a plurality of multi-core fibers in parallel.
  • the multi-core fiber and multi-core fiber tape according to the present invention can arrange many cores while suppressing deterioration of long-term reliability, and can be used in the optical communication industry.
  • Multi-core fiber 10A to 10C ... core element 11A to 11C ... core 12A to 12C ... inner cladding 13A to 13C ... low refractive index layers 21, 22 ... ⁇ Clad 30 ... Coating layer 50 ... Tape layer 51,52 ... Multi-core fiber tape

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  • Optical Couplings Of Light Guides (AREA)

Abstract

Selon la présente invention, une fibre multicœur (1A) comprend une pluralité de noyaux (11A, 11B) disposés dans une matrice, et une gaine unique (21) entourant les noyaux (11A, 11B). Une forme externe d'une section transversale perpendiculaire à la direction longitudinale de la gaine (21) est construite en une forme non circulaire ayant le plus petit diamètre dans une direction prescrite et n'ayant pas d'évidement. Au moins deux cœurs (11A, 11B) sont agencés dans une direction prescrite tandis qu'un certain nombre de cœurs (11A, 11B) hors du nombre des cœurs agencés dans la direction prescrite sont agencés dans une direction perpendiculaire à la direction prescrite. La fibre multicœur (1A) est pliée dans une direction prescrite à des fins d'utilisation.
PCT/JP2018/003039 2017-02-16 2018-01-30 Fibre multicœur et ruban de fibre multicœur l'utilisant WO2018150867A1 (fr)

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US11480727B2 (en) * 2019-07-03 2022-10-25 Sumitomo Electric Industries, Ltd. Multi-core optical fiber

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US11480727B2 (en) * 2019-07-03 2022-10-25 Sumitomo Electric Industries, Ltd. Multi-core optical fiber

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