Optical fiber ribbon

Abstract

This optical fiber ribbon is provided with a plurality of optical fiber core wires each comprising a core and a cladding, the core being formed of pure quartz or being formed as a hollow core, and the optical fiber core wires adjacent to each other in parallel among the plurality of optical fiber core wires being connected to each other. The difference between the maximum value and the minimum value of the propagation time of the light in the plurality of optical fiber cores is 0.1% or less of the average value of the propagation time of the light in the optical fiber cores.

Description

Technical Field

[0001] The present disclosure relates to optical fiber ribbons.

[0002] This application claims the benefit of priority based on Japanese Application No. 2022-088640 filed on May 31, 2022, and all the contents described in the Japanese Application are incorporated herein by reference. Background Art

[0003] In the past, optical fibers have been developed for reducing the time delay between cores included in each of a plurality of optical fibers or between a plurality of cores included in the same optical fiber. For example, Patent Document 1 discloses a multi-core optical fiber characterized in that the time delay between signal lights propagating in the plurality of cores is less than 1 ps / m, and the difference in propagation constant between two adjacent cores in the plurality of cores is greater than zero.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-228548 Summary of the invention

[0007] The optical fiber ribbon disclosed herein is an optical fiber ribbon comprising a plurality of optical fiber cores including a core and a cladding, wherein the core is formed of pure quartz or is formed as a hollow core, the optical fiber cores arranged in parallel and adjacent to each other in the plurality of optical fiber cores are connected to each other, and the difference between the maximum value and the minimum value of the propagation time of the light in the plurality of optical fiber cores is less than 0.1% of the average value of the propagation time of the light in the optical fiber cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram showing an example of an optical fiber ribbon according to an embodiment of the present disclosure.

[0009] Figure 2 It is shown Figure 1 The structure of the optical fiber core is shown in the figure.

[0010] Figure 3 This is a diagram showing an example of a modification of the optical fiber ribbon according to the embodiment of the present disclosure.

[0011] Figure 4 It shows that the Figure 3 FIG. 1 is a diagram showing an example of an optical fiber cable of an optical fiber ribbon.

[0012] Figure 5 This is a diagram showing an example of a modification of the optical fiber core wire according to the embodiment of the present disclosure.

[0013] Figure 6This is a diagram showing an example of another modified example of the optical fiber core wire according to the embodiment of the present disclosure.

[0014] Figure 7 This is a diagram showing an example of another modified example of the optical fiber core wire according to the embodiment of the present disclosure.

[0015] Figure 8 This is a diagram showing an overview of a measurement system used for measuring a difference in propagation time of light between optical fiber cores.

[0016] Fig. 9 It shows that the Figure 8 FIG. 1 is a diagram showing a list of measurement objects and measurement results measured by the measurement system shown. DETAILED DESCRIPTION

[0017] [Technical problem to be solved by the invention]

[0018] However, in order to further improve the performance of optical fiber ribbons, a technology that can further reduce the time skew between cores and increase the propagation speed of light in the cores is desired.

[0019] An object of the present disclosure is to provide an optical fiber ribbon capable of further reducing the time skew between cores and increasing the propagation speed of light in the cores.

[0020] [Effects of the present disclosure]

[0021] According to the present disclosure, the time skew between cores can be further reduced, and the propagation speed of light in the core can be increased.

[0022] [Description of Embodiments of the Present Disclosure]

[0023] First, embodiments of the present disclosure will be listed and described.

[0024] The optical fiber ribbon according to the embodiment of the present disclosure,

[0025] (1) An optical fiber ribbon having a plurality of optical fiber cores including a core and a cladding.

[0026] The fiber core is formed of pure quartz or is formed as a hollow fiber core,

[0027] The optical fiber cores arranged in parallel and adjacent to each other among the plurality of optical fiber cores are connected to each other.

[0028] A difference between a maximum value and a minimum value of propagation time of light in the plurality of optical fibers is equal to or less than 0.1% of an average value of propagation time of light in the optical fibers.

[0029] If such a fiber ribbon is used, the difference in the length of the multiple optical fiber cores included in the fiber ribbon can be reduced because the optical fiber cores are connected to each other. In addition, by making the core pure quartz or hollow, the difference in relative refractive index between the cores can be reduced (almost zero). Therefore, the time delay between the cores can be further reduced. In addition, by making the core pure quartz or hollow, the core does not contain impurities, so the propagation speed of light can be increased. Therefore, the time delay between the cores can be further reduced, and the propagation speed of light in the core can be increased.

[0030] (2) In the optical fiber ribbon of (1) above,

[0031] The difference may be equal to or less than 0.05% of the average value.

[0032] According to such a configuration, the time skew between cores can be further reduced.

[0033] (3) In the optical fiber ribbon of (1) or (2) above,

[0034] The plurality of mutually adjacent optical fiber core wires may be intermittently coupled.

[0035] According to such a structure, the flexibility of the optical fiber ribbon can be improved, and the optical fiber ribbon can be rolled into a circle or bundled to realize an optical fiber ribbon that is easy to wire.

[0036] (4) In the optical fiber ribbon of any one of (1) to (3) above,

[0037] Alternatively, each of the optical fiber cores may include a plurality of the fiber cores.

[0038] By adopting such a multi-core optical fiber structure, the cores have the same length, so the difference in the core lengths can be reduced (almost to zero), and the transmission rate can be increased.

[0039] (5) In the optical fiber ribbon of any one of (1) to (4) above,

[0040] Alternatively, the outer diameter of the optical fiber core wire may be less than 200 μm.

[0041] The outer diameter of the cladding in each of the optical fiber cores is 100 μm or less.

[0042] According to such a configuration, it is possible to provide an optical fiber ribbon that achieves high density, facilitates wiring, and is less likely to bend and break.

[0043] [Details of the embodiments of the present disclosure]

[0044] Hereinafter, specific examples of the optical fiber ribbon of the present disclosure will be described with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, but is represented by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0045] (Overall structure)

[0046] Figure 1 1 is a diagram showing an example of an optical fiber ribbon according to an embodiment of the present disclosure. Figure 1 The optical fiber ribbon 1 according to the embodiment of the present disclosure includes a plurality of optical fiber cores 10 and a connecting member 20 for connecting the plurality of optical fiber cores 10. Figure 1 In the example shown, the optical fiber ribbon 1 includes 12 optical fibers 10. The connecting member 20 covers the entirety of the 12 optical fibers 10 so as to connect the adjacent optical fibers 10 arranged in parallel.

[0047] Each optical fiber core wire 10 is, for example, a single core fiber (SCF (Single Core Fiber)), and includes a core 11, a cladding 12 covering the core 11, and a coating 14 covering the cladding 12. The core 11 has a refractive index higher than that of the cladding 12 and can guide light. The coating 14 includes, for example, two layers of an ultraviolet curing resin layer and a coloring layer.

[0048] More specifically, the core 11 is made of pure quartz. The smaller the amount of dopant added to the core 11, the faster the light propagation speed. Therefore, as described above, by making the core 11 of pure quartz, the light propagation speed can be increased compared to the case where the core 11 contains a material other than quartz such as germanium. In addition, since the core 11 does not contain a dopant, the variation in the amount of dopant added can be substantially eliminated, and thus the light propagation speed can be easily made uniform.

[0049] In addition, the twelve cores 11 and the cladding 12 in the optical fiber ribbon 1 are formed using the same preform. This can reduce the difference in refractive index between the twelve optical fiber cores 10 and reduce the time delay which is the difference in propagation speed of light.

[0050] Furthermore, when the 12 optical fiber cores 10 are formed into the optical fiber ribbon 1, the tension of the plurality of optical fiber cores 10 is controlled to be equal. Hereinafter, controlling the tension to be equal to the set value is referred to as "tension control". By performing such tension control, the difference in line length of the 12 optical fiber cores 10 included in the same optical fiber ribbon 1 can be suppressed, and as a result, the time lag can be further reduced.

[0051] Figure 2 It is shown Figure 1 FIG. 1 is a diagram showing the structure of the optical fiber core 10. Figure 2In the embodiment, the outer diameter D1 of the cladding 12 is formed to be, for example, less than 100 μm. By reducing the cladding diameter (glass diameter of the optical fiber core), breakage due to bending can be suppressed. In addition, the outer diameter D2 of the optical fiber core 10 is formed to be, for example, less than 200 μm. With such a structure, the optical fiber core 10 can be made high-density.

[0052] It should be noted that the optical fiber ribbon 1 is not limited to the structure including 12 optical fiber core wires 10 , and may include, for example, 24 optical fiber core wires 10 or 4 optical fiber core wires 10 .

[0053] In addition, the connecting member 20 is not limited to Figure 1 The structure shown in which the entire twelve optical fiber cores 10 are covered may be a structure in which, for example, parts of the optical fiber cores 10 adjacent to each other are connected to each other.

[0054] (Variant 1)

[0055] Figure 3 FIG. 1 is a diagram showing an example of a modification of the optical fiber ribbon according to the embodiment of the present disclosure. Figure 3 In the diagram, the extending direction of the optical fiber core wire 10 is defined as the Y direction, and the arrangement direction of the plurality of optical fiber core wires 10 is defined as the X direction.

[0056] The optical fiber ribbon involved in the embodiment of the present disclosure is not limited to Figure 1 For example, adjacent optical fiber cores in the optical fiber ribbon may also be intermittently combined with each other. Specifically, Figure 3 As shown, in the optical fiber ribbon 2 according to the modified example, the adjacent optical fiber cores 10 are replaced by a plurality of coupling members 13 intermittently provided in a part of the Y direction, for example. Figure 1 The connecting member 20 shown is combined.

[0057] Figure 4 It shows that the Figure 3 FIG. 2 is a diagram showing an example of an optical cable of the optical fiber ribbon 2 shown. Figure 4 The optical cable 100, for example, includes two optical fiber ribbons 2 including twelve optical fiber cores 10, a cable sheath 3 covering the two optical fiber ribbons 2, and a plurality of tensile members 15 formed by a collection of aramid fibers or the like.

[0058] As described above, according to the structure in which the adjacent optical fiber cores 10 are intermittently connected to each other, the flexibility of the optical fiber ribbon 2 can be improved. Figure 4 As shown, even if the optical fiber ribbon 2 is rolled into a circle or bundled in cross-sectional view, the transmission loss does not deteriorate, and thus a high-density optical fiber cable 100 can be formed.

[0059] It should be noted that the plurality of adjacent optical fiber cores 10 are not limited to the structure in which the optical fiber cores are intermittently connected. For example, the connecting member 13 may be intermittently connected between some of the optical fiber cores. Figure 3 The optical cable 100 is provided as a whole in the Y direction shown. In addition, the optical cable 100 may also be a structure without the tensile member 15 .

[0060] (Variant 2)

[0061] The optical fiber core wire involved in the embodiment of the present disclosure is not limited to Figure 2 SCF shown. Figure 5 and Figure 6 FIG. 1 is a diagram showing an example of a modification of the optical fiber core wire according to the embodiment of the present disclosure. Figure 5 and Figure 6 The optical fiber cores 30 and 40 may also be a structure including a plurality of fiber cores 11 , namely a multi-core optical fiber (MCF (Multi Core Fiber)).

[0062] For example, Figure 5 As shown, the optical fiber core wire 30 may also be a structure including four cores 11 inside the cladding 12. Figure 6 As shown, the optical fiber core wire 40 may also be a structure including 12 cores 11 inside the cladding 12. In this way, by using the optical fiber core wires 30 and 40 as MCF, the length of the core 11 in the same optical fiber core wires 30 and 40 is the same, the line length difference of the core can be reduced (almost zero), and the transmission amount can be increased. In addition, by using MCF to form an optical cable, the core can be installed at a higher density.

[0063] (Variant 3)

[0064] Figure 7 FIG. 1 is a diagram showing an example of another modification of the optical fiber core wire involved in the embodiment of the present disclosure. Figure 7 As shown, the core 11 in the optical fiber core wire 50 may also be formed as a hollow core instead of being formed of pure quartz. Figure 7 , as an example, a PBGF (Photonic Band Gap Fiber) is shown in which holes 16 are regularly arranged around a core 11 which is a hollow core. By forming the core 11 as a hollow core in this way, the propagation speed can be further increased.

[0065] (Measurement of the difference in light propagation time between optical fiber cores)

[0066] Next, the results of measuring the propagation time difference of light between optical fiber cores using the optical fibers in the optical fiber ribbon according to the embodiment of the present disclosure and the optical fibers according to the comparative example will be described. Figure 8: is a diagram showing an overview of a measurement system used in the present measurement. Hereinafter, the optical fiber ribbon or optical fiber used in the measurement is also referred to as a "measurement object".

[0067] exist Figure 8 In the measurement system shown, one end of the measurement object is connected to a light source emitting light of a wavelength of 1550nm via an FC connector, and the other end of the measurement object is connected to a light receiver via an FC connector. Furthermore, the light source is connected to a modulator, and the light receiver is connected to a vector voltmeter. The modulator is electrically connected to the vector voltmeter to transmit a reference signal.

[0068] Fig. 9 This is a diagram showing an overview of the measurement objects and measurement results of this measurement. In this measurement, measurement objects 1 to 5, which are measurement objects that meet the standards of ITU-T G.652.D and G657.A1, were used. Each of measurement objects 1 to 5 has 12 optical fiber cores, and the core included in each optical fiber core is formed of pure quartz. Measurement objects 1 and 2 are optical fibers involved in the comparative example, and measurement objects 3 to 5 are included in the optical fiber ribbon of the present disclosure.

[0069] More specifically, the measurement object 1 is an optical fiber formed by twisting 12 optical fiber cores as SCF. The multiple cores and claddings (hereinafter referred to as glass fibers) in the measurement object 1 are not sorted when formed from a preform. That is, at least two of the multiple glass fibers are formed using different preforms. In the measurement object 1, the difference between the maximum value and the minimum value of the propagation time of light in the 12 optical fiber cores is 0.23% of the average value of the propagation time of light in the 12 optical fiber cores.

[0070] The measurement object 2 is an optical fiber formed by twisting 12 optical fiber cores as SCF, similarly to the measurement object 1. In addition, the multiple glass fibers in the measurement object 2 are sorted when they are formed from the preform rod, unlike the measurement object 1. That is, these multiple glass fibers are formed using the same preform rod. In the measurement object 2, the difference between the maximum value and the minimum value of the propagation time of the light in the 12 optical fiber cores is 0.15% of the average value of the propagation time of the light in the optical fiber cores.

[0071] By comparing the measurement object 1 and the measurement object 2, it was confirmed that the time skew between the plurality of optical fiber cores can be reduced by forming the glass fibers in the respective optical fiber cores from the same preform.

[0072] The measurement object 3 is to use 12 optical fiber cores as SCF as Figure 3 The optical fiber ribbon is formed by connecting in parallel as shown. Multiple optical fiber cores adjacent to each other are as shown in FIG. Figure 3In addition, the plurality of glass fibers in the measurement object 3 were sorted when formed from the preform. It should be noted that when the 12 optical fiber cores in the measurement object 3 were formed into an optical fiber ribbon, tension control was not performed to make the tension of the plurality of optical fiber cores equal. In the measurement object 3, the difference between the maximum value and the minimum value of the propagation time of the light in the 12 optical fiber cores was 0.10% of the average value of the propagation time of the light in the optical fiber cores.

[0073] It was confirmed that, compared with the measurement object 2 in which 12 optical fiber cores were twisted, in the measurement object 3 in which the optical fiber ribbon including 12 optical fiber cores was adopted, the time skew between the optical fiber cores could be further reduced.

[0074] The measurement object 4 is a fiber ribbon formed by connecting 12 optical fiber cores in parallel as SCF, similarly to the measurement object 3. Multiple optical fiber cores adjacent to each other are intermittently combined. In addition, the multiple glass fibers in the measurement object 4 are sorted when formed from the preform rod. Furthermore, the 12 optical fiber cores in the measurement object 4 are different from the measurement object 3 in that the tension is controlled when they are formed into the optical fiber ribbon. In the measurement object 4, the difference between the maximum value and the minimum value of the propagation time of the light in the 12 optical fiber cores is 0.05% of the average value of the propagation time of the light in the optical fiber cores.

[0075] By comparing the measurement object 3 with the measurement object 4, it was confirmed that the time lag between the optical fiber cores can be further reduced by controlling the tension of the optical fiber cores when forming the optical fiber ribbon.

[0076] The measurement object 5 is an optical fiber ribbon formed by connecting 12 optical fiber cores in parallel as an MCF including 4 cores. Multiple optical fiber cores adjacent to each other are intermittently combined. In addition, the multiple glass fibers in the measurement object 5 are sorted when formed from the preform rod. Furthermore, the 12 optical fiber cores in the measurement object 5 are tension-controlled when formed into the optical fiber ribbon. In the measurement object 5, the difference between the maximum value and the minimum value of the propagation time of light in the multiple cores included in the 12 optical fiber cores is 0.04% of the average value of the propagation time of light in these multiple cores.

[0077] Comparing the measurement object 4 with the measurement object 5, it was confirmed that the use of MCF can further reduce the time delay between optical fiber cores compared to the use of SCF. In addition, in the measurement object 5, it was confirmed that the time delay between multiple cores in the same optical fiber core was also reduced. It should be noted that the core included in each optical fiber core is replaced by pure quartz. Figure 7 In the case of forming a hollow core of quartz, the same results as those in the case of using a pure quartz core are obtained.

[0078] As mentioned above, although this disclosure was described based on the specific embodiment, this disclosure is not limited to these examples, but is shown by a claim, and intends to include all changes within the meaning and scope equivalent to a claim.

[0079] Description of Reference Numerals

[0080] 1.2 Fiber Optic Ribbon

[0081] 3 Cable sheath

[0082] 10, 30, 40, 50 fiber cores

[0083] 11 Core

[0084] 12 Cladding

[0085] 13 Combination parts

[0086] 14 Coating

[0087] 15 Tension body

[0088] 16 empty holes

[0089] 20 Connecting parts

[0090] 100 Fiber Optic Cable

[0091] D1: outer diameter of the cladding

[0092] D2 The outer diameter of the optical fiber core.

Claims

1. An optical fiber ribbon is an optical fiber ribbon having a plurality of optical fiber cores including a core and a cladding, The fiber core is formed of pure quartz or is formed as a hollow fiber core, The optical fiber cores arranged in parallel and adjacent to each other among the plurality of optical fiber cores are connected to each other. A difference between a maximum value and a minimum value of propagation time of light in the plurality of optical fibers is equal to or less than 0.1% of an average value of propagation time of light in the optical fibers.

2. The optical fiber ribbon according to claim 1, wherein: The difference is less than 0.05% of the average value.

3. The optical fiber ribbon according to claim 1 or 2, wherein: A plurality of adjacent optical fiber core wires are intermittently coupled to each other.

4. The optical fiber ribbon according to claim 1 or 2, wherein: Each of the optical fiber cores includes a plurality of the fiber cores.

5. The optical fiber ribbon according to claim 1 or 2, wherein: The outer diameter of the optical fiber core is less than 200 μm, The outer diameter of the cladding in each of the optical fiber cores is 100 μm or less.

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