Optical fiber ribbon manufacturing method

Abstract

To provide an optical fiber ribbon having a grating formed by a simpler method. The optical fiber ribbon includes a plurality of mono-coated optical fibers arranged in parallel, and a tape layer that covers the mono-coated optical fibers and partially connects adjacent mono-coated optical fibers. The mono-coated optical fibers have grating portions based on a plurality of strain portions formed at regular intervals in the tape layer in the longitudinal direction of the mono-coated optical fiber.

Description

[Technical field]

[0001] The present invention relates to an optical fiber ribbon and a method for manufacturing an optical fiber ribbon. [Background technology]

[0002] In recent years, data traffic has increased dramatically due to the spread of IoT (Internet of Things), the full-scale launch of 5G commercial services, and autonomous driving of automobiles, and there is a growing demand for the development and construction of high-speed, large-capacity optical fiber communication networks to support this. Among these, optical filters are widely used in WDM (Wavelength Division Multiplexing) transmission, which can transmit more information in optical communications. In addition, a technology using optical fiber gratings as optical filters has been proposed (see Patent Document 1).

[0003] Patent Document 1 discloses a method for manufacturing an optical fiber having a grating. The method for manufacturing an optical fiber described in Patent Document 1 applies resin to the coating of the optical fiber at predetermined intervals, and then hardens the resin. After that, stress is applied to the optical fiber at the intervals where the resin is applied, and the bend relative to the core is fixed, thereby manufacturing an optical fiber having a grating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-36340 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the optical fiber manufacturing method described in Patent Document 1, a relatively large amount of resin is applied to the coating, resulting in the formation of multiple relatively large protrusions on the surface of the optical fiber. Therefore, the optical fiber described in Patent Document 1 is not suitable for high-speed, large-capacity optical fiber communication networks because a large number of optical fibers cannot be accommodated in existing ducts. In addition, the multiple protrusions caused by the resin on the coating may exert lateral pressure on other optical fibers, which may affect them. Furthermore, the manufacturing process is complicated, resulting in high manufacturing costs.

[0006] An object of the present invention is to provide an optical fiber ribbon having a grating formed by a simpler method and a method for manufacturing the same. [Means for solving the problem]

[0007] In order to solve the above problems, according to one aspect of the present invention, there is provided a cable optical fiber cable having a plurality of mono-coated optical fibers arranged in parallel, and a tape layer covering the mono-coated optical fibers and partially connecting adjacent mono-coated optical fibers, the mono-coated optical fiber has a grating portion based on a plurality of strain portions formed at regular intervals in the tape layer in the longitudinal direction of the mono-coated optical fiber; An optical fiber ribbon is provided.

[0008] According to another aspect of the present invention, a method for manufacturing a ribbon-shaped core wire includes the steps of: preparing a ribbon-shaped core wire including a plurality of mono-coated optical fibers arranged in parallel; and a ribbon layer covering the mono-coated optical fibers and partially connecting adjacent mono-coated optical fibers; forming a grating by dropping a solution containing a volatile liquid at regular intervals or by cooling the tape layer at regular intervals in a longitudinal direction of the mono-coated optical fiber to form a plurality of distortion parts with a regular center distance in the tape layer; The present invention provides a method for producing an optical fiber ribbon, comprising the steps of: Effect of the Invention

[0009] According to the present invention, it is possible to provide an optical fiber ribbon having a grating portion formed by a simpler method and a method for manufacturing the same. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams showing an optical fiber ribbon according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flow chart for explaining the method for producing the optical fiber ribbon. [Diagram 3] FIG. 3 is a perspective view showing an example of an apparatus for producing an optical fiber ribbon. [Figure 4] FIG. 4 is a graph showing the relationship between the center distance of the strained portions and the optical transmission loss. [Diagram 5] FIG. 5 is a graph showing the relationship between the center-to-center distance of the strained portions, the wavelength of light incident on the optical fiber ribbon, and the optical transmission loss. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An optical fiber ribbon and a method for manufacturing the optical fiber ribbon according to an embodiment of the present invention will be described below. In this specification, the lower limit and upper limit of a numerical range are included in the numerical range.

[0012] (Configuration of optical fiber ribbon) Fig. 1A is a schematic plan view of an optical fiber ribbon 10. Fig. 1B is a cross-sectional view taken along line AA in Fig. 1A.

[0013] As shown in FIGS. 1A and 1B, the optical fiber ribbon 10 of this embodiment has a plurality of mono-coated optical fibers (hereinafter also simply referred to as “optical fibers”) 20 and a ribbon layer 40 including a plurality of connecting portions 30.

[0014] The optical fibers 20 are arranged in parallel. The number of the optical fibers 20 is not particularly limited as long as it is a plurality. The number of the optical fibers 20 included in one optical fiber ribbon 10 is appropriately selected depending on the application of the optical fiber ribbon 10. The number of the optical fibers 20 included in one optical fiber ribbon 10 is, for example, 2 to 12. In this embodiment, six optical fibers 20 are arranged in parallel in one optical fiber ribbon 10.

[0015] As shown in FIG. 1B, the optical fiber 20 has an optical fiber strand 21, a primary coating layer 22, and a secondary coating layer 23. The optical fiber strand 21, the primary coating layer 22, and the secondary coating layer 23 may be the same as the optical fiber strand, the first coating layer, and the second coating layer of a known optical fiber. A colored layer may be further formed on the second coating layer 23 of the optical fiber 20. The colors of the colored layers are preferably different from each other within the optical fiber ribbon 10. This allows multiple optical fibers 20 to be identified within one optical fiber ribbon 10. The optical fiber 20 also has a grating section 50.

[0016] The tape layer 40 covers the optical fibers 20 and intermittently connects adjacent optical fibers 20. In this embodiment, a region where the tape layer 40 is disposed between adjacent optical fibers 20 is referred to as a connection portion 30, and a region where the tape layer 40 is not disposed between adjacent optical fibers 20 is referred to as a separation portion 41. In the optical fiber ribbon 10 of this embodiment, the connection portions 30 and the separation portions 41 are alternately disposed between adjacent optical fibers 20 in the longitudinal direction of the optical fiber ribbon 10. In the short direction (width direction) of the optical fiber ribbon 10, the separation portions 41 are preferably disposed such that adjacent separation portions 41 partially overlap each other.

[0017] The width W of the connecting portion 30 when the optical fiber ribbon 10 is viewed in a plan view, i.e., the distance between adjacent optical fibers 20, is not particularly limited, and is, for example, within a range of more than 0 mm and 0.04 mm or less. The length L of the connecting portion 30 when the optical fiber ribbon 10 is viewed in a plan view is also not particularly limited, and is, for example, within a range of 10 mm or more and 47 mm or less. Furthermore, the thickness T of the connecting portion 30 is also not particularly limited, and is, for example, within a range of 0.2 mm or more and 0.3 mm or less. When the width W, length L, and thickness T of the connecting portion 30 are within the range, the strength of the connecting portion 30 is high, and the connecting portion 30 is not easily torn even when the optical fiber ribbon 10 is wound along the longitudinal direction or twisted as necessary. On the other hand, the length B of the separating portion 41 when the optical fiber ribbon 10 is viewed in a plan view is not particularly limited, and is, for example, within a range of 50 mm or more and 103 mm or less. If the length L of the separation portion 41 is within this range, the optical fiber ribbon 10 can be easily wound or twisted along the length direction when the optical fiber ribbon 10 is housed in a cable.

[0018] The grating section 50 is formed in the optical fiber 20. The position of the grating section 50 in the longitudinal direction of the optical fiber 20 is appropriately set depending on the use of the optical fiber 20. The grating section 50 may be formed in one place in one optical fiber 20, or in multiple places. The grating section 50 is formed based on multiple distortion sections 51 formed at regular intervals in the optical fiber 20 in the longitudinal direction of the optical fiber 20. Specifically, the grating section 50 is formed by applying stress to the core of the optical fiber 20 by strain sections 51 formed at regular intervals in a part of the outermost layer (the tape layer 40 in this embodiment) of the optical fiber 20. Preferably, the multiple strain sections 51 are formed in positions directly above the optical fiber 20 in each part of the tape layer 40.

[0019] The "strained portion 51" refers to a portion that is distorted to such an extent that stress is applied to the core of the optical fiber 20, and in this case, refers to a portion where the hardness differs between the strained portion 51 and an adjacent region (non-strained portion).

[0020] The shape of the strained portion 51 in a plan view is not particularly limited. The shape of the strained portion 51 in a plan view may be a circle, a polygon, or another shape. In the present embodiment, the multiple strained portions 51 are substantially circular and have the same size. The size of the strained portion 51 is set so that two adjacent strained portions 51 do not overlap in the longitudinal direction of the optical fiber 20. For example, the size of the strained portion 51 is about 0.25 mm.

[0021] The surface of the strained portion 51 may be colored. In the present embodiment, the strained portions 51 are arranged on only one side of the optical fiber ribbon 10, but they may be arranged on both sides of the optical fiber ribbon 10. A method for forming the grating portion 50 will be described later in detail.

[0022] The center-to-center distance of the strained portions 51 in the longitudinal direction of the optical fiber 20 is not particularly limited as long as it can exhibit the grating function. The center-to-center distance of two adjacent strained portions 51 is appropriately set according to the intended use of the optical fiber 20 having the grating portion 50. The center-to-center distance of the strained portions 51 does not necessarily have to be constant. For example, as long as the center-to-center distance of each of the strained portions 51 is within a range of ±0.05 mm of the average value of the centers of the strained portions 51, it can be said that the multiple strained portions 51 are formed at regular intervals. When the center of the distorted portion 51 cannot be determined based on the shape of the distorted portion 51 in a plan view, the center of gravity of the distorted portion 51 in a plan view is used.

[0023] For example, the multiple distortion sections 51 may be arranged so that the wavelength of light entering the optical fiber 20 does not overlap with the wavelength of light attenuated by the grating section 50 . In such a case, the wavelength of light used can be made to match the optical communication band while intentionally excluding the attenuated wavelength of light from the optical communication band (see the examples).

[0024] Conversely, the plurality of distortion sections 51 may be arranged so that the wavelength of light used entering the optical fiber 20 overlaps with the wavelength of light attenuated by the grating section 50. In this case, the wavelength of light used and the wavelength of light attenuated can be intentionally overlapped, and the optical fiber 20 in which the distortion section 51 is formed can exhibit a light filtering function (see Examples). For example, when light of a plurality of wavelengths is input to the optical fiber 20 as in WDM transmission and used as a wavelength filter on the output side, the plurality of distortion sections 51 are formed so that the wavelength of unnecessary light (the wavelength of light to be attenuated) among the wavelengths of light used entering the optical fiber 20 becomes the wavelength of light attenuated by the grating section 50. This makes it possible to block the wavelength of light to be attenuated, and therefore to filter the light passing through the grating section 50.

[0025] The plurality of strained portions 51 may be formed on all of the optical fibers 20 constituting the optical fiber ribbon 10 (see FIG. 1), on only one optical fiber 20, or on any number of optical fibers 20 in between (any between 2 and 5 in the example of FIG. 1). The number of strained portions 51 in each optical fiber 20 may be the same for all the optical fibers 20 (see FIG. 1), or may be different for each optical fiber 20.

[0026] (Method of manufacturing optical fiber ribbon) Next, a description will be given of a method for manufacturing the optical fiber ribbon 10. Fig. 2 is a flow chart for explaining a method for manufacturing the optical fiber ribbon 10. Fig. 3 is a perspective view showing an example of a manufacturing apparatus 100 for manufacturing the optical fiber ribbon 10. In this example, a method of forming the grating section 50 based on the distortion section 51 formed by dropping a solution containing a volatile liquid at regular intervals will be described.

[0027] As shown in FIG. 2, the method for producing the optical fiber ribbon 10 of the present embodiment includes a step (S110) of preparing the ribbon-shaped optical fiber 160, and a step (S120) of forming the grating section 50.

[0028] In the step (S110) of preparing the ribbon-shaped core wire 160, a ribbon-shaped core wire 160 having the above-mentioned optical fiber 20 is prepared. The ribbon-shaped core wire 160 may be manufactured by any method, and the ribbon-shaped core wire 160 may be prepared, for example, by using a manufacturing apparatus 100 shown in FIG. Specifically, while the optical fibers 20 are transported in the transport direction A, the tape die 120 applies uncured photocurable resin in a tape shape to the optical fibers 20 to form the tape layer 40. Thereafter, the separation needles 132, 134, 136 of the separation die 130 are raised and lowered relative to the tape layer 40 to remove parts of the tape layer 40 and form the above-mentioned separation portion 41 (and the connection portion 30). At the same time, the resin suction device 138 suctions the excess photocurable resin blocked by the descent of the separation needles 132, 134, 136. Next, the tape layer 40 is irradiated with light by the light irradiation device 140 to semi-cure the uncured photocurable resin, and finally, the semi-cured photocurable resin is completely cured by further irradiating with light by the light irradiation device 150. Note that the integrated irradiation amount of each of the upstream light irradiation device 140 and the downstream light irradiation device 150 is adjusted so that the integrated irradiation amount of the upstream light irradiation device 140 is smaller and the integrated irradiation amount of the downstream light irradiation device 150 is larger.

[0029] In the step (S120) of forming the grating section, as shown in Fig. 3, for example, the ribbon-shaped core wire 160 manufactured in the step (S110) of preparing the ribbon-shaped core wire 160 is further transported in the length direction (direction indicated by A in the figure) by the above-mentioned manufacturing apparatus 100. Then, the outermost layer of the optical fiber 20 is partially cooled in a predetermined region of the optical fiber 20 in the longitudinal direction of the optical fiber 20. The method of partially cooling the outermost layer of the optical fiber 20 is not particularly limited. Examples of the method for partially cooling the outermost layer of the optical fiber 20 include a method of dropping a solution containing a volatile liquid at regular intervals and a method of cooling at regular intervals by a predetermined method. In this embodiment, a solution containing a volatile liquid is dropped at regular intervals from the strain forming device 170. After that, the volatile liquid of the solution is vaporized. The strain forming device 170 is, for example, an inkjet type droplet ejection device. Examples of the volatile liquid include methyl ethyl ketone and ethanol. The solution containing the volatile liquid may also contain a dye or a pigment. At this time, the outermost layer of the optical fiber 20 is cooled and shrinks (distorted) due to the heat of vaporization generated when the volatile liquid is vaporized. At this time, the temperature of the outermost layer of the optical fiber 20 is, for example, within a range of 37.3°C or more, preferably within a range of 50°C or more, and the lower limit may be adjusted according to the type of volatile liquid. As a result, a strained portion 51 is formed in the optical fiber 20. In this way, based on the strained portion 51 formed in the optical fiber 20, stress is applied to the core of the optical fiber 20, and a grating portion 50 is formed.

[0030] When cooling at regular intervals, a device for partially cooling the optical fiber 20 is used as the strain forming device. In this case, the outermost layer of the optical fiber 20 is cooled and shrinks (strains). As a result, stress is applied to the core of the optical fiber 20 based on the strained portion 51 formed in the optical fiber 20, and the grating portion 50 is formed. In the device for partially cooling the optical fiber 20, the optical fiber 20 may be partially cooled by liquid nitrogen, for example.

[0031] In addition, in the process of forming the grating section, the grating section 50 based on the distortion section 51 may be shaped by dropping a solution containing a volatile liquid or by cooling so that the wavelength of light used to be incident on the optical fiber 20 does not overlap with the wavelength of light attenuated by the grating section 50.

[0032] In the above explanation, an example was given in which the device used in the process of preparing the ribbon-shaped core wire (S110) and the device used in the process of forming the grating section (S120) are integrated, but these may also be arranged on separate lines.

[0033] (effect) As described above, according to the present invention, the grating portion 50 is formed by the strain portion 51 caused by partially cooling the optical fiber 20, so that an optical fiber ribbon 10 having a grating portion 50 formed by a simple method can be obtained. EXAMPLES

[0034] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited by these examples, and the embodiments can be modified without departing from the spirit of the present invention.

[0035] (1) Preparation of samples A single-coated optical fiber with an outer diameter of 250 μm was prepared by applying a primary coating of urethane acrylate-based photocurable resin and a secondary coating of urethane acrylate-based photocurable resin to a silica glass-based SM optical fiber with an outer diameter of 125 μm. Then, while aligning 12 single-coated optical fibers, a urethane acrylate-based photocurable resin was applied to form a tape layer, and joints and separations were formed to obtain a ribbon-shaped core wire.

[0036] Furthermore, a solution containing a volatile liquid was dropped onto the 12 optical fibers of the ribbon-shaped core wire at a specified interval so that they overlapped with each other, and then the optical fibers were cooled by drying, forming a grating based on multiple distortion parts to produce an optical fiber ribbon. The distortion parts were roughly circular in shape and approximately 0.25 mm in size.

[0037] (2) Measurement of optical transmission loss at a wavelength of 1310 nm The optical transmission loss at a wavelength of 1310 nm was measured. Approximately 3000 m of the optical fiber ribbon was prepared and wound around a bobbin (assuming that it was packed or mounted at high density), and in this state, the transmission loss of light at a wavelength of 1310 nm was measured for each optical fiber in accordance with IEC 60793-1-40. The relationship between the center distance of the strained parts and the optical transmission loss is shown in Fig. 4. Fig. 4 is a graph showing the relationship between the center distance of the strained parts and the optical transmission loss. The horizontal axis of Fig. 4 shows the center distance of the strained parts (mm), and the vertical axis shows the optical transmission loss per km (dB / km). The center distance of the strained parts was set to 0.43 mm, 0.65 mm, 0.86 mm, or 1.29 mm (the minimum center distance of the strained parts was set to 0.43 mm because this was the lower limit for the manufacture of the strain forming device, and the other center distances were set to 1.5 times, 2 times, or 3 times that value). As shown in FIG. 4, it is understood that when the center distance between the distorted parts is 0.65 mm, the optical transmission loss of light with a wavelength of 1310 nm can be suppressed.

[0038] It can be seen from FIG. 4 that a grating portion based on a plurality of strain portions can be formed by dropping a solution containing a volatile liquid at predetermined intervals and cooling it.

[0039] Next, we investigated the relationship between the center-to-center distance of the strained parts, the wavelength of light incident on the optical fiber ribbon, and the optical transmission loss. Figure 5 shows the relationship between the center-to-center distance of the strained parts 24 hours after the manufacture of the optical fiber ribbon, the wavelength of light incident on the optical fiber ribbon, and the optical transmission loss per km. The upper row of the horizontal axis in Figure 5 shows the center-to-center distance of the strained parts (mm), the lower row shows the wavelength (nm) of light incident on the optical fiber ribbon, and the vertical axis shows the optical transmission loss per km (dB / km). The attenuation wavelength was measured using an OTDR (Optical Time Domain Reflectometer).

[0040] As shown in Figure 5, when the wavelength of the incident light was short (1310 nm, 1383 nm), the optical transmission loss was small when the center-to-center distance of the strained parts was 0.52 mm or more. On the other hand, when the center-to-center distance of the strained parts was 0.43 mm, the optical transmission loss was large. Also, as shown in Figure 5, when the wavelength of the incident light was long (1550 nm, 1625 nm), the optical transmission loss was small when the center-to-center distance of the strained parts was 0.65 mm or more or less than 0.43 mm. On the other hand, when the center-to-center distance of the strained parts was 0.52 mm, the optical transmission loss was large. In this way, it is understood that the attenuation wavelength can be adjusted by controlling the center distance of the strained portions. [Industrial Applicability]

[0041] The optical fiber ribbon obtained by the present invention is useful, for example, as an optical fiber for use in a high-speed, large-capacity optical fiber communication network. [Explanation of symbols]

[0042] 10 Optical fiber ribbon 20 Single-core coated optical fiber 21 Optical fiber 22 Primary coating layer 23 Secondary coating layer 30 Connecting part 40 Tape Layers 41 Separation section 50 Grating section 51 Strained part 100 Manufacturing equipment 120 Tape Dice 130 Separation Dice 132, 134, 136 Separation needle 138 Resin suction device 140 (Upstream) Light Irradiation Device 150 (Downstream) Light Irradiation Device 160 Ribbon-shaped core wire 170 Strain forming device

Claims

1. preparing a ribbon-shaped optical fiber having a plurality of mono-coated optical fibers arranged in parallel and a ribbon layer covering the mono-coated optical fibers and partially connecting adjacent mono-coated optical fibers; a step of forming a grating by dropping a solution containing a volatile liquid at regular intervals in the longitudinal direction of the mono-coated optical fiber or by cooling the mono-coated optical fiber at regular intervals to form a plurality of strained portions in the tape layer with a regular center-to-center distance; 2. A method for manufacturing an optical fiber ribbon, comprising:

2. 2. The method for producing an optical fiber ribbon according to claim 1, In the step of forming the grating portion, a solution containing a volatile liquid is dropped or cooled so that the wavelength of the light incident on the single-coated optical fiber does not overlap with the wavelength of the light attenuated by the grating portion. A manufacturing method for optical fiber ribbon.

3. 2. The method for producing an optical fiber ribbon according to claim 1, In the step of forming the grating portion, a solution containing a volatile liquid is dropped or cooled so that a wavelength of light incident on the single-coated optical fiber overlaps with a wavelength of light attenuated by the grating portion. A manufacturing method for optical fiber ribbon.

4. The method for producing an optical fiber ribbon according to any one of claims 1 to 3, The plurality of strained portions are formed so as to overlap each other in the mono-coated optical fiber. A manufacturing method for optical fiber ribbon.

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