Method for producing Anti-resonant fiber preform and method for producing Anti-resonant fiber

Abstract

A method for producing an anti-resonant fiber preform including an outer tube, a plurality of first capillaries joined to the inner wall of the outer tube and arranged in a first positional relationship with each other, and an air hole core formed in a region surrounded by the plurality of first capillaries, the method comprising a first step for positioning each of the first capillaries in each of a plurality of first positioning holes provided in a first positioning member and a second step for inserting the plurality of first capillaries into the outer tube, the first positioning holes provided in the first positioning member being arranged to correspond to the first positional relationship of the first capillaries in the outer tube.

Description

Method for manufacturing antiresonant fiber preform and method for manufacturing antiresonant fiber

[0001] The present invention relates to a method for manufacturing an antiresonant fiber preform and a method for manufacturing an antiresonant fiber.

[0002] An antiresonant fiber is an optical fiber that uses the antiresonance phenomenon to confine and propagate light in an air-hole core, and has been actively studied in recent years. For example, Patent Document 1 discloses a method for manufacturing an antiresonant fiber preform for manufacturing an antiresonant fiber, in which a capillary is fixed to the inner wall of an outer tube by locally irradiating it with laser light.

[0003] US Patent Publication No. 2020 / 0156987

[0004] However, the method of Patent Document 1 has a problem in that the process is extremely complicated because the capillaries are fixed one by one using a laser beam.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a method for manufacturing an antiresonant fiber preform and a method for manufacturing an antiresonant fiber that can be realized through simple steps.

[0006] In order to solve the above-mentioned problems and achieve the object, one aspect of the present invention is a method for manufacturing an antiresonant fiber preform comprising an outer tube and a plurality of first capillaries joined to the inner wall of the outer tube and arranged in a first positional relationship relative to each other, wherein an air hole core is formed in an area surrounded by the plurality of first capillaries, the method comprising: a first step of positioning each of the plurality of first capillaries in a respective one of a plurality of first positioning holes provided in a first positioning member; and a second step of inserting the plurality of first capillaries into the outer tube, wherein the plurality of first positioning holes provided in the first positioning member are arranged to correspond to the first positional relationship of the plurality of first capillaries within the outer tube.

[0007] In the first step, the plurality of first capillaries may be inserted into the plurality of first positioning holes, respectively.

[0008] The outer tube, the first capillary, and the first positioning member may be made of glass.

[0009] The number of the first positioning holes in the first positioning member may be equal to the number of the first capillaries.

[0010] The method for manufacturing the antiresonant fiber preform may include a third step of fixing the first positioning member and the outer tube.

[0011] Two of the first positioning members may be arranged to sandwich the outer tube in the longitudinal direction.

[0012] The method for manufacturing the antiresonant fiber preform may include, after the first step, a fourth step of fixing the first positioning member and the first capillary.

[0013] In the fourth step, the first positioning member and the first capillary may be fixed by reducing the diameter of the first positioning hole.

[0014] The first positioning member may have a first communication hole that communicates with a region surrounded by the first capillary when the first positioning member is attached to the outer tube.

[0015] The antiresonant fiber preform may include a plurality of second capillaries each having an outer diameter smaller than the inner diameter of the first capillary and each disposed inside one of the plurality of first capillaries, and the manufacturing method for the antiresonant fiber preform may include a fifth step of positioning each of the plurality of second capillaries in a respective one of a plurality of second positioning holes provided in a second positioning member, and a sixth step of inserting each of the plurality of second capillaries into each of the first capillaries, and the plurality of second positioning holes provided in the second positioning member may be arranged to correspond to a second positional relationship of the plurality of second capillaries within the outer tube.

[0016] The second positioning member may have a second communication hole that communicates with the inside of the first capillary when the second positioning member is attached to the first positioning member.

[0017] The second positioning member may be disposed so that the first positioning member is sandwiched between the outer tube and the second positioning member.

[0018] The method for manufacturing the antiresonant fiber preform may include a seventh step of fixing the first positioning member, the second positioning member, and the outer tube.

[0019] The method for manufacturing the antiresonant fiber preform may include an eighth step of fixing the second positioning member and the second capillary.

[0020] In the eighth step, the second positioning member and the second capillary may be fixed by reducing the diameter of the second positioning hole.

[0021] The first positioning member may have a first communication hole that communicates with the area surrounded by the first capillary when attached to the outer tube, and the second positioning member may have a third communication hole that communicates with the area surrounded by the first capillary via the first communication hole when attached to the first positioning member.

[0022] The manufacturing method of the antiresonant fiber preform may include a ninth step of providing a tapered section on the first end side of the outer tube, the outer diameter of which decreases with increasing distance from the outer tube, and attaching a pressurizing member for pressurizing at least the inside of the first capillary on the second end side of the outer tube opposite the first end.

[0023] One aspect of the present invention is a method for manufacturing an antiresonant fiber, comprising: an antiresonant fiber preform manufacturing process for carrying out the method for manufacturing an antiresonant fiber preform; and a drawing process for drawing an antiresonant fiber from the manufactured antiresonant fiber preform.

[0024] According to the present invention, a method for manufacturing an antiresonant fiber preform and a method for manufacturing an antiresonant fiber can be realized through simple steps.

[0025] FIG. 1 is a schematic cross-sectional view of an antiresonant fiber preform manufactured by a manufacturing method according to the first embodiment. FIG. 2 is a flow diagram of the manufacturing method according to the first embodiment. FIG. 3 is an explanatory diagram of the manufacturing method according to the first embodiment. FIG. 4 is an explanatory diagram of the manufacturing method according to the first embodiment. FIG. 5 is an explanatory diagram of the manufacturing method according to the first embodiment. FIG. 6 is a flow diagram of the manufacturing method according to the second embodiment. FIG. 7 is an explanatory diagram of the manufacturing method according to the third embodiment. FIG. 8 is an explanatory diagram of the manufacturing method according to the fourth embodiment. FIG. 9 is an explanatory diagram of the manufacturing method according to the fourth embodiment. FIG. 10 is a schematic cross-sectional view of an antiresonant fiber manufactured using a manufacturing method according to the fifth embodiment. FIG. 11 is an explanatory diagram of the manufacturing method according to the fifth embodiment. FIG. 12 is an explanatory diagram of the manufacturing method according to the fifth embodiment. FIG. 13 is an explanatory diagram of the manufacturing method according to the fifth embodiment. FIG. 14 is an explanatory diagram of the manufacturing method according to the fifth embodiment. FIG. 15 is an explanatory diagram of the manufacturing method according to the sixth embodiment. FIG. 16 is an explanatory diagram of the manufacturing method according to the sixth embodiment. FIG. 17 is a flow diagram of a method for manufacturing an antiresonant fiber according to the seventh embodiment.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below. Furthermore, in each drawing, the same or corresponding components are appropriately designated by the same reference numerals, and redundant explanations are appropriately omitted.

[0027] 1 is a schematic cross-sectional view of an antiresonant fiber preform manufactured by a manufacturing method according to embodiment 1, taken along a cross section perpendicular to the longitudinal direction. The antiresonant fiber preform 1000 is made of silica-based glass and includes five first capillaries 110 and one outer tube 120. The five first capillaries 110 are an example of a plurality of first capillaries.

[0028] The five first capillaries 110 are cylindrical and arranged to form a pentagonal lattice in cross section. The pentagonal lattice is, for example, a regular pentagonal lattice. The first capillaries 110 are, for example, silica-based glass tubes having a predetermined thickness. Arranging the first capillaries 110 to form the pentagonal lattice is an example of the first capillaries 110 being arranged in a first positional relationship with each other.

[0029] The outer tube 120 has a circular tubular shape. The outer tube 120 is, for example, a silica glass tube having a predetermined thickness. The outer tube 120 houses the first capillary 110. Specifically, the first capillary 110 is joined to an inner wall 121 of the outer tube 120 by welding or the like.

[0030] An air hole core 1001 is formed in the region surrounded by the five first capillaries 110. The five first capillaries 110 have the effect of confining light in the air hole core 1001 by an antiresonant phenomenon. As a result, light is confined and propagated in the air hole core 1001 by an antiresonant light confinement effect. For example, 80% or more of the field of light propagating through each air hole core 1001 is present, and the remaining 20% ​​or less of the field of light is present in the first capillaries 110, etc.

[0031] The wavelength of the light propagating through the hole core 1001 can be changed by adjusting the thickness of the first capillary 110. That is, the thickness of the first capillary 110 is set according to the wavelength of the light propagating through the hole core 1001. The wavelength of the light propagating through the hole core 1001 is, for example, a wavelength included in a communication wavelength band such as the 1.55 μm band, but is not particularly limited. For example, the light propagating through the hole core 1001 and its wavelength may be light and its wavelength used for power transmission such as optical power feeding.

[0032] The first capillaries 110 are arranged with appropriate gaps between them. If there are no gaps and the first capillaries 110 are in contact with each other, light propagating through the hole cores 1001 may leak through the contacting portions of the first capillaries 110. If the gaps are too large, the leakage of light from the gaps will be excessively large.

[0033] [Manufacturing Method] Next, a manufacturing method according to the first embodiment for manufacturing the antiresonant fiber preform 1000 will be described. FIG. 2 is a flow diagram of the manufacturing method according to the first embodiment. First, in step S101, a first capillary, an outer tube, and a first positioning member are prepared. Next, in step S102, the first capillary is inserted into a first positioning hole of the first positioning member. Next, in step S103, the first capillary is inserted into the outer tube. Next, in step S104, the first positioning member and the outer tube are fixed. Next, in step S105, a tapered member and a pressure member are attached. In this way, an antiresonant fiber preform is manufactured.

[0034] Each step will be specifically described below with reference to FIGS.

[0035] First, in step S101, five first capillaries 110 as shown in FIG. 1, one outer tube 120, and one first positioning member 100 as shown in FIG. 3 are prepared. The first positioning member 100 is a cylindrical member made of, for example, silica-based glass. Five first positioning holes 101 are formed in the first positioning member 100 so as to penetrate it in the thickness direction (left-right direction in the drawing). The first positioning holes 101 are preferably parallel to each other. The five first positioning holes 101 are an example of a plurality of first positioning holes.

[0036] The five first positioning holes 101 are arranged to correspond to a first positional relationship of the first capillaries 110 in the outer tube 120. That is, in this embodiment, the five first positioning holes 101 are arranged to form a pentagonal lattice such as a regular pentagonal lattice in a cross section perpendicular to the thickness direction of the first positioning member 100. Also, in this embodiment, the number of first positioning holes 101 in the first positioning member 100 is equal to the number of first capillaries 110.

[0037] The first capillary 110, outer tube 120, and first positioning member 100 can be formed by drilling holes in a glass rod manufactured using a method such as Vapor Axial Deposition (VAD) or Modified Chemical Vapor Deposition (MCVD). Alternatively, a synthetic silica tube may be used as the first capillary 110 or the outer tube 120. The first positioning hole 101 has an appropriate clearance relative to the outer diameter of the first capillary 110 so that the first capillary 110 can be inserted.

[0038] Next, in step S102, the first capillaries 110 are inserted into the first positioning holes 101 of the first positioning member 100, respectively. This positions the first capillaries 110 in the first positioning holes 101, respectively. Step S102 is an example of a first process.

[0039] Next, in step S103, the first capillary 110 positioned in the first positioning hole 101 is inserted into the hole 122 of the outer tube 120. Fig. 4 is a diagram showing the first capillary 110 being inserted into the outer tube 120. As a result, the first capillary 110 is positioned along the inner wall 121 of the outer tube 120. Step S103 is an example of the second step.

[0040] Next, in step S104, the first positioning member 100 and the outer tube 120 are fixed together by, for example, welding. Step S104 is an example of a third step.

[0041] FIG. 5 is a cross-sectional view of the antiresonant fiber preform 1000 completed by performing step S105, taken along a plane including the central axis extending in the longitudinal direction of the outer tube 120. In step S105, as shown in FIG. 5, a tapered member 130 is attached to the first end side of the outer tube 120 (the right side of the drawing, the side where the first positioning member 100 is not attached). The tapered member 130 has a conical shape whose outer diameter decreases with increasing distance from the outer tube 120. Also, in step S105, a pressurizing member 140 is attached to the second end side (the left side of the drawing, the side where the first positioning member 100 is attached) opposite the first end side. However, in this embodiment, the pressurizing member 140 is attached with the first positioning member 100 interposed therebetween. Here, the pressurizing member 140 is made of a highly heat-resistant material, such as silica-based glass or metal. The pressurizing member 140 also has a through-hole 141. The through hole 141 communicates with the inside of the first capillary 110 when the pressurizing member 140 is attached to the first positioning member 100. The through hole 141 is also connected to an external pressurizing device. The pressurized state generated by the pressurizing device extends to the first capillary 110 through the through hole 141. Step S105 is an example of a ninth step. In this way, the antiresonant fiber preform 1000 is manufactured.

[0042] According to the manufacturing method of the first embodiment as described above, the first positioning hole 101 of the first positioning member 100 is arranged to correspond to the arrangement of the first capillary 110 inside the outer tube 120. As a result, by inserting the first capillary 110 into the first positioning hole 101 and positioning it, and then inserting it into the outer tube 120, the first capillary 110 can be easily arranged in a desired positional relationship (first positional relationship) inside the outer tube 120. As a result, according to the manufacturing method of the first embodiment, the antiresonant fiber preform 1000 can be manufactured through a simple process.

[0043] Furthermore, according to the manufacturing method of the first embodiment, the tapered member 130 is provided, which makes it easier to start drawing an antiresonant fiber from the antiresonant fiber preform 1000 .

[0044] Furthermore, according to the manufacturing method of embodiment 1, a pressurizing member 140 is attached to apply pressure to the inside of the first capillary 110, so that pressure can be applied to the inside of the first capillary 110 during drawing, thereby suppressing or preventing deformation of the first capillary 110.

[0045] In the above steps S102 and S103, all of the first capillaries 110 may be inserted into the first positioning holes 101, and then all of the first capillaries 110 may be inserted into the outer tube 120 at once. Furthermore, the step of inserting the first capillaries 110 into the outer tube 120 at once may be started before the step of inserting the first capillaries 110 into the first positioning holes 101 is completed. Furthermore, for example, three of the five first capillaries 110 may be inserted into the first positioning holes 101, and then these three first capillaries 110 may be inserted into the outer tube 120 at once, and then the remaining two first capillaries 110 may be inserted into the first positioning holes 101 and further into the outer tube 120. Furthermore, for example, the order of step S102, which is an example of the first step, and step S103, which is an example of the second step, may be reversed. That is, at least one of the first capillaries 110 may be inserted into the hole 122 of the outer tube 120, and then the at least one first capillary 110 may be inserted into at least one of the first positioning holes 101 of the first positioning member 100 to position it.

[0046] Furthermore, if the outer tube 120 is placed horizontally or tilted relative to the vertical direction and the above manufacturing method is performed, the first capillary 110 may tilt downward due to its own weight in step S102. Such tilting makes it difficult to perform step S103. Therefore, a thick first positioning member 100 is preferable because it makes the first capillary 110 less likely to tilt downward. However, if the first positioning member 100 is too thick, the portion of the first capillary 110 used to manufacture the antiresonant fiber will be reduced. Therefore, for example, the thickness of the first positioning member 100, i.e., the length of the first positioning hole 101, is preferably approximately 10% to 40% of the first capillary 110.

[0047] Furthermore, it is preferable to perform at least steps S102 and S103 with the first capillary 110 and the outer tube 120 standing vertically, for example, since this will prevent the first capillary 110 from tilting due to its own weight.

[0048] Furthermore, after the first step such as step S102, a fourth step of fixing the first positioning member 100 and the first capillary 110 may be performed. This is preferable because it stabilizes the posture of the first capillary 110 when inserting the first capillary 110 into the outer tube 120. Note that in this fourth step, the first positioning member 100 and the first capillary 110 may be fixed by, for example, reducing the diameter of the first positioning hole 101. In this case, the first positioning member 100 may be heated to reduce the diameter of the first positioning hole 101.

[0049] 6 is a flow chart of a manufacturing method according to a second embodiment for manufacturing an antiresonant fiber preform 1000. First, in step S201, similar to step S101, the first capillary 110, the outer tube 120, and the first positioning member 100 are prepared. Next, in step S202, the first positioning member 100 is fixed to the outer tube 120. Next, in step S203, the first capillary 110 is inserted into the first positioning hole 101 of the first positioning member 100 and the hole 122 of the outer tube 120. Next, in step S204, the first capillary 110 and the first positioning member 100 are fixed together. Next, in step S205, the tapered member 130 and the pressurizing member 140 are attached. Here, step S202 is an example of the third step, step S203 is an example of the first and second steps, step S204 is an example of the fourth step, and step S205 is an example of the ninth step.

[0050] According to the manufacturing method of the second embodiment described above, the same effects as those of the first embodiment can be obtained, and for example, the antiresonant fiber preform 1000 can be manufactured through a simple process.

[0051] 7 is an explanatory diagram of a manufacturing method according to a third embodiment, showing an antiresonant fiber preform 2000 manufactured by the manufacturing method according to the third embodiment cut along a plane including the central axis extending in the longitudinal direction of the outer tube 120. As shown in FIG. 7, in the manufacturing method according to the third embodiment, two first positioning members 100 are arranged to sandwich the outer tube 120 in the longitudinal direction.

[0052] When manufacturing such an antiresonant fiber preform 2000, for example, two first positioning members 100 are prepared in step S101 of embodiment 1. Next, in step S102, the first capillaries 110 are inserted into the first positioning holes 101 of one of the first positioning members 100, and the one first positioning member 100 is disposed on the second end side of the outer tube 120. Then, in step S103, the first capillaries 110 positioned by the first positioning member 100 disposed on the second end side are inserted into the holes 122 of the outer tube 120. During this insertion, a first positioning member 100 is also disposed on the first end side of the outer tube 120. Then, the first capillaries 110 that have passed through the holes 122 of the outer tube 120 are inserted into the first positioning holes 101 of the first positioning member 100 on the first end side, and are positioned in the first positioning holes 101. Thereafter, step S104 is carried out, and in step S105, the tapered member 130 is attached to the first positioning member 100 on the first end side.

[0053] According to the manufacturing method of the third embodiment described above, the same effects as those of the first embodiment can be obtained, and for example, the antiresonant fiber preform 3000 can be manufactured through a simple process. Furthermore, by supporting the first capillary 110 at both ends of the outer tube 120 with the two first positioning members 100, the posture of the first capillary 110 within the hole 122 of the outer tube 120 can be more stabilized.

[0054] Furthermore, when manufacturing the antiresonant fiber preform 2000, for example, two first positioning members 100 may be prepared in step S201 of the second embodiment, and the first positioning members 100 may be fixed to both ends of the outer tube 120 in step S202. Then, in step S203, the first capillary 110 may be inserted into the first positioning hole 101 of the first positioning member 100 on the second end side, then into the hole 122 of the outer tube 120, and then into the first positioning hole 101 of the first positioning member 100 on the first end side. In this case, too, by supporting the first capillary 110 at both ends of the outer tube 120 with the two first positioning members 100, the posture of the first capillary 110 in the hole 122 of the outer tube 120 can be more stabilized.

[0055] (Embodiment 4) In the antiresonant fiber preform manufactured according to the above embodiment, the first positioning member 100 and the pressurizing member 140 are configured so that pressure can be applied inside the first capillary 110. In contrast, the antiresonant fiber preform manufactured according to embodiment 4 is configured so that pressure can also be applied to the region of the hole 122 in the outer tube 120 that is surrounded by the first capillary 110.

[0056] 8 is an explanatory diagram of a manufacturing method according to embodiment 4, and is a schematic diagram of a first positioning member 100A used in the manufacturing. This first positioning member 100A has a configuration in which one first communication hole 102 is further provided in addition to the first positioning member 100 shown in FIG. 3. The first communication hole 102 is, for example, a through-hole provided in an area surrounded by five first positioning holes 101 and parallel to the first positioning holes 101.

[0057] In the manufacturing method of embodiment 4, for example, in the manufacturing method of embodiment 1 described with reference to Figure 2, a first positioning member 100A is used instead of the first positioning member 100, and another pressing member is used instead of the pressing member 140.

[0058] 9 is an explanatory diagram of the manufacturing method according to the fourth embodiment, showing the antiresonant fiber preform 3000 completed by performing step S105, cut along a plane including the central axis extending in the longitudinal direction of the outer tube 120. As shown in FIG. 9 , when the first positioning member 100A is attached to the outer tube 120, the first communication hole 102 communicates with the region surrounded by the first capillary 110 at the hole 122 of the outer tube 120. Furthermore, the pressurizing member 140A, which replaces the pressurizing member 140, has a through hole 142. When attached to the first positioning member 100A, the through hole 142 communicates with the interior of the first capillary 110 via the first communication hole 102. Furthermore, the through hole 142 is connected to an external pressurizing device. That is, in a state in which the first positioning member 100A is attached to the outer pipe 120, the first communication hole 102 is connected to an external pressure device via the through hole 142.

[0059] According to the manufacturing method of the fourth embodiment described above, the same effects as those of the first embodiment can be obtained, and for example, it is possible to manufacture the antiresonant fiber preform 3000 through a simple process. Furthermore, according to the manufacturing method of the fourth embodiment, during drawing, the inside of the first capillary 110 and the region surrounded by the first capillary 110 in the hole 122 of the outer tube 120 can be pressurized separately, thereby more precisely controlling the structure of the first capillary 110 and the region.

[0060] 10 is a schematic cross-sectional view of an antiresonant fiber preform manufactured by a manufacturing method according to a fifth embodiment, taken along a cross section perpendicular to the longitudinal direction. The antiresonant fiber preform 4000 has a configuration in which five second capillaries 160 are added to the antiresonant fiber preform 1000 shown in FIG. 1 . Each of the five second capillaries 160 has an outer diameter smaller than the inner diameter of the first capillary 110, and is disposed inside each of the five first capillaries 110. That is, the five second capillaries 160 are disposed so as to form a pentagonal lattice, such as a regular pentagonal lattice, in the cross section. The second capillaries 160 are disposed so as to form the pentagonal lattice, which is an example of the second capillaries 160 being disposed in a second positional relationship with respect to each other. The thickness of the second capillary 160 is also set according to the wavelength of the light propagating through the air hole core 1001 so as to achieve antiresonant optical confinement.

[0061] In an antiresonant fiber manufactured using such an antiresonant fiber preform 4000, the structure formed by the first capillary 110 and the second capillary 160 realizes an antiresonant double optical confinement structure for the air hole core of the antiresonant fiber. As a result, such an antiresonant fiber may be able to reduce the confinement loss of the air hole core more than an antiresonant fiber using an antiresonant fiber preform manufactured by the manufacturing method according to the first embodiment, for example.

[0062] Next, a manufacturing method according to the fifth embodiment will be specifically described with reference to Fig. 2 and Fig. 11 to Fig. 14. In the manufacturing method according to the fifth embodiment, first, for example, in step S101 of the manufacturing method according to the first embodiment shown in Fig. 2, five second capillaries 160 and the second positioning member 150 shown in Fig. 11 are prepared together with the first capillary 110, the outer tube 120, and the first positioning member 100.

[0063] The second positioning member 150 is a cylindrical member made of, for example, silica-based glass. Five second positioning holes 151 are formed in the second positioning member 150 so as to penetrate the member in the thickness direction. The second positioning holes 151 are preferably parallel to one another. The five second positioning holes 151 are an example of a plurality of second positioning holes.

[0064] The five second positioning holes 151 are arranged to correspond to the second positional relationship of the second capillaries 160 in the outer tube 120. That is, in the fifth embodiment, the five second positioning holes 151 are arranged to form a pentagonal lattice such as a regular pentagonal lattice in a cross section perpendicular to the thickness direction. In the fifth embodiment, the number of second positioning holes 151 in the second positioning member 150 is equal to the number of second capillaries 160.

[0065] The second positioning member 150 is also provided with one second communication hole 153. The second communication hole 152 is a through hole provided in a region surrounded by five second positioning holes 151 and parallel to the second positioning holes 151, for example.

[0066] The second capillary 160 can be manufactured in the same manner as the first capillary 110 , and the second positioning member 150 can be manufactured in the same manner as the first positioning member 100 .

[0067] Next, in the manufacturing method according to the fifth embodiment, steps S102 to S104 shown in Fig. 2 are performed to fabricate a structure as shown in Fig. 12. In this case, for example, the first positioning member 100 and the first capillary 110 may be fixed together by reducing the diameter of the first positioning hole 101.

[0068] Next, the second positioning member 150 is arranged so that the first positioning member 100 is sandwiched between the outer tube 120 and the second positioning member 150, and the second positioning member 150 is fixed to the first positioning member 100. This fixes the first positioning member 100, the second positioning member 150, and the outer tube 120 (an example of the seventh step). In this case, when viewed from the longitudinal direction of the outer tube 120, the positional relationship between the position of the second positioning hole 151 of the second positioning member 150 and the first positioning hole 101 of the first positioning member 100 is set to be the same as the positional relationship between the second capillary 160 and the first capillary 110 as shown in FIG.

[0069] Next, the second capillaries 160 are inserted into the second positioning holes 151, respectively, thereby positioning the second capillaries 160 in the second positioning holes 151, respectively (an example of a fifth step).

[0070] Next, each of the positioned second capillaries 160 is inserted into each of the first capillaries 110 (an example of a sixth step). At this time, the second capillaries 160 are also inserted into the holes 122 of the outer tube 120. Fig. 13 is a diagram showing the state after the second capillaries 160 have been inserted into the first capillaries 110. Note that the example of the fifth step and the example of the sixth step may be performed in reverse order.

[0071] As shown in FIG. 13, when the second positioning member 150 is attached to the first positioning member 100 , the second communication hole 153 communicates with the inside of the first capillary 110 .

[0072] Thereafter, for example, the diameter of the second positioning hole 151 may be reduced to fix the second positioning member 150 and the second capillary 160 (an example of an eighth step).

[0073] Next, step S105 shown in Fig. 2 is executed, and an antiresonant fiber preform 4000 as shown in Fig. 14 is completed. As shown in Fig. 14, the second communication hole 153 of the second positioning member 150 also communicates with the through hole 141 of the pressurizing member 140. Therefore, the second communication hole 153 communicates with the inside of the first capillary 110 and is connected to an external pressurizing device via the through hole 141. This pressurizing device may be configured to simultaneously pressurize the inside of the first capillary 110 and the inside of the second capillary 160 with the same pressure, or may be configured to independently pressurize the inside of the first capillary 110 and the inside of the second capillary 160 with different pressures.

[0074] The manufacturing method according to the fifth embodiment as described above provides the same effects as those of the first embodiment. Furthermore, since the second positioning hole 151 of the second positioning member 150 is disposed in a position corresponding to the position of the second capillary 160 inside the outer tube 120, the second capillary 160 can be easily disposed in the desired positional relationship (second positional relationship) inside the outer tube 120 by inserting the second capillary 160 into the second positioning hole 151 and positioning it, and then inserting the second capillary 160 into the outer tube 120. As a result, the manufacturing method according to the fifth embodiment allows the antiresonant fiber preform 4000 to be manufactured through a simple process.

[0075] Furthermore, according to the manufacturing method of embodiment 5, the pressure applying member 140 can apply pressure to the inside of the first capillary 110 and the inside of the second capillary 160 using the same pressure applying device or separate pressure applying devices during drawing, thereby suppressing or preventing deformation of the first capillary 110 and the second capillary 160.

[0076] As a first modification of the manufacturing method according to the fifth embodiment, the antiresonant fiber preform 4000 may be manufactured using a manufacturing flow as shown in Fig. 6. In this case, for example, in step S201 of Fig. 6, five second capillaries 160 and the second positioning member 150 shown in Fig. 11 are prepared in addition to the first capillary 110, the outer tube 120, and the first positioning member 100.

[0077] Next, after performing steps S202 to S204 shown in Figure 6, the second positioning member 150 is positioned so that the first positioning member 100 is sandwiched between the outer tube 120 and the second positioning member 150, and the second positioning member 150 is fixed to the first positioning member 100.

[0078] Next, the second capillaries 160 are inserted into the second positioning holes 151, respectively. At this time, the second capillary 160 inserted into a certain second positioning hole 151 is subsequently inserted into one of the first capillaries 110.

[0079] Next, step S205 is executed, and the antiresonant fiber preform 4000 is completed.

[0080] As a second modification of the manufacturing method according to embodiment 5, two first positioning members 100 and two second positioning members 150 may be used, as in the manufacturing method according to embodiment 3. In the case of the second modification, for example, a first positioning member 100 is disposed on each of the first end side and the second end side of the outer tube 120. In this case, the first positioning member 100 may be fixed to the outer tube 120.

[0081] Next, the first capillary 110 is inserted so that it passes through the first positioning hole 101 of one of the first positioning members 100, the outer tube 120, and the first positioning hole 101 of the other first positioning member 100 in that order. Thereafter, it is preferable to fix the first capillary 110 to the two first positioning members 100.

[0082] Next, two second positioning members 150 are fixed to the first positioning member 100 at the first end side and the second end side of the outer tube 120, respectively, so that the first positioning member 100 is sandwiched between the second positioning member 150 and the outer tube 120.

[0083] Next, the second capillary 160 is inserted so that it passes through the second positioning hole 151 of one second positioning member 150, the first positioning hole 101 of one first positioning member 100, the outer tube 120, the first positioning hole 101 of the other first positioning member 100, and the second positioning hole 151 of the other second positioning member 150 in that order. Thereafter, it is preferable to fix the second capillary 160 to the two second positioning members 150.

[0084] Next, for example, step S205 in FIG. 6 is executed, and the antiresonant fiber preform 4000 is completed.

[0085] (Embodiment 6) The antiresonant fiber preform 4000 manufactured by the above-described embodiment 5 and its modified examples is configured with a first positioning member 100, a second positioning member 150, and a pressurizing member 140 so as to be able to apply pressure to the inside of the first capillary 110 and the inside of the second capillary 160. In contrast, the antiresonant fiber preform manufactured by embodiment 6 is configured so as to be able to apply pressure to the region of the hole 122 of the outer tube 120 that is surrounded by the first capillary 110.

[0086] 15 is an explanatory view of a manufacturing method according to embodiment 6 and is a schematic diagram of a second positioning member 150A used in the manufacturing. This second positioning member 150A has a configuration in which the second communication holes 153 in the configuration of the second positioning member 150 shown in FIG. 11 are replaced with second communication holes 153A and third communication holes 152A are further provided. The second communication holes 153A are through holes provided in the vicinity of each of the five second positioning holes 151 and parallel to the second positioning holes 151. The third communication holes 152A are through holes provided in the area surrounded by the five second communication holes 153A and parallel to the first positioning holes 101.

[0087] In the manufacturing method of embodiment 6, in the manufacturing method of embodiment 5 or its modified example, a first positioning member 100A (see Figures 8 and 9) is used instead of the first positioning member 100, a second positioning member 150A is used instead of the second positioning member 150, and a pressure applying member 140A is used instead of the pressure applying member 140.

[0088] 16 is an explanatory diagram of the manufacturing method according to the sixth embodiment, showing the completed antiresonant fiber preform 5000 cut along a plane including the central axis extending in the longitudinal direction of the outer tube 120. As shown in Fig. 16, when the second positioning member 150A is attached to the first positioning member 100A, the second communication hole 153A communicates with the interior of the first capillary 110 and is connected to an external pressurizing device via the through hole 141 of the pressurizing member 140A. Furthermore, when the second positioning member 150A is attached to the first positioning member 100A, the third communication hole 152A communicates with the region surrounded by the first capillary 110 in the hole 122 of the outer tube 120 via the first communication hole 102 of the first positioning member 100A and is connected to an external pressurizing device via the through hole 142 of the pressurizing member 140A.

[0089] According to the manufacturing method of the sixth embodiment described above, the same effects as those of the first embodiment can be obtained, and for example, it is possible to manufacture the antiresonant fiber preform 5000 through a simple process. Furthermore, according to the manufacturing method of the sixth embodiment, during drawing, pressure can be applied to the inside of the first capillary 110, the inside of the second capillary 160, and the region surrounded by the first capillary 110 in the hole 122 of the outer tube 120, thereby further suppressing or preventing deformation of the first capillary 110, the second capillary 160, and the region.

[0090] (Embodiment 7) Fig. 17 is a flow diagram of a method for manufacturing an antiresonant fiber according to embodiment 7. In embodiment 7, in step S301, an antiresonant fiber preform manufacturing process is performed using the method for manufacturing an antiresonant fiber preform according to any of the above embodiments, thereby manufacturing an antiresonant fiber preform. Subsequently, in step S302, a drawing process is performed in which the manufactured antiresonant fiber preform is drawn. The drawing process can be performed using a known drawing device.

[0091] According to the seventh embodiment described above, an antiresonant fiber can be easily manufactured using an antiresonant fiber preform manufactured by a simple process.

[0092] (Example) As an example, an antiresonant fiber preform was manufactured based on the fifth embodiment. A commercially available synthetic silica tube was prepared as the outer tube. The synthetic silica tube had an outer diameter of 45 mm, an inner diameter of 33 mm, and a length of 1,000 mm.

[0093] A first capillary and a second capillary were prepared by stretching commercially available synthetic silica tubes. The first capillary had an outer diameter of 11 mm, an inner diameter of 10 mm, and a length of 1,600 mm. The second capillary had an outer diameter of 5 mm, an inner diameter of 4 mm, and a length of 2,200 mm.

[0094] A cylindrical silica glass piece having a diameter of 45 mm and a length of 300 mm was prepared, and a first positioning hole was drilled in it to fabricate two first positioning members. The inner diameter of the first positioning hole was 0.5 mm larger than the outer diameter of the first capillary. A cylindrical silica glass piece having a diameter of 45 mm and a length of 300 mm was prepared, and a second positioning hole and a second communicating hole were drilled in it to fabricate two second positioning members. The inner diameter of the second positioning hole was 0.5 mm larger than the outer diameter of the second capillary. The inner diameter of the second communicating hole was 17 mm.

[0095] Next, first positioning members were welded to both ends of the outer tube using oxyhydrogen flame. Next, five first capillaries were inserted sequentially so that the first capillaries passed through one first positioning member, the outer tube, and the other first positioning member in that order. After the five first capillaries had been inserted, second positioning members were welded to each of the first positioning members using oxyhydrogen flame. During this welding, the first positioning members were also heated to reduce the diameter of the first positioning holes. This fixed the first capillaries to the first positioning members and stabilized their positions.

[0096] Next, five first capillaries were inserted sequentially so that the second capillaries passed through one second positioning member, one first positioning member, the first capillary, the other first positioning member, and the other second positioning member in that order. Then, a pressurizing member was welded to one of the second positioning members using oxyhydrogen flame. A tapered member was also welded to the other second positioning member using oxyhydrogen flame. During this welding, the second positioning member was also heated to reduce the diameter of the second positioning hole. This fixed the second capillaries to the second positioning members, stabilizing their positions. Then, the tapered member and pressurizing member were attached.

[0097] As described above, it was confirmed that an antiresonant fiber preform can be manufactured without any complicated steps.

[0098] In each of the above embodiments, the tapered member 130 is attached, but the tapered portion may be provided by, for example, heating and melting the first capillary 110, the outer tube 120, or other members with a flame or the like to form a tapered shape.

[0099] Furthermore, for example, in the above-mentioned embodiment 5, an antiresonant fiber preform having a double capillary structure is manufactured, but by further using a third positioning member and a fourth positioning member, an antiresonant fiber preform having a triple or quadruple capillary structure may also be manufactured.

[0100] Furthermore, the present invention is not limited to the above-described embodiments. The present invention also includes configurations in which the above-described components are appropriately combined. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

[0101] The present invention can be used to manufacture antiresonant fibers.

[0102] 100, 100A: First positioning member 101: First positioning hole 102: First communicating hole 110: First capillary 120: Outer tube 121: Inner wall 122: Hole 130: Tapered member 140, 140A: Pressurizing member 141, 142: Through hole 150, 150A: Second positioning member 151: Second positioning hole 152A: Third communicating hole 153, 153A: Second communicating hole 160: Second capillary 1000, 2000, 3000, 4000, 5000: Antiresonant fiber preform 1001: Hole core

Claims

1. A method for manufacturing an antiresonant fiber preform comprising an outer tube and a plurality of first capillaries joined to the inner wall of the outer tube and arranged in a first positional relationship relative to each other, wherein an air hole core is formed in an area surrounded by the plurality of first capillaries, the method comprising: a first step of positioning each of the plurality of first capillaries in each of a plurality of first positioning holes provided in a first positioning member; and a second step of inserting the plurality of first capillaries into the outer tube, wherein the plurality of first positioning holes provided in the first positioning member are arranged to correspond to the first positional relationship of the plurality of first capillaries within the outer tube.

2. A method for manufacturing an antiresonant fiber preform according to claim 1, wherein in the first step, each of the plurality of first capillaries is inserted into each of the plurality of first positioning holes.

3. The method for manufacturing an antiresonant fiber preform according to claim 1, wherein the outer tube, the first capillary, and the first positioning member are made of glass.

4. A method for manufacturing an antiresonant fiber preform as described in claim 1, wherein the number of the first positioning holes in the first positioning member is equal to the number of the first capillaries.

5. A method for manufacturing an antiresonant fiber preform according to claim 1, further comprising a third step of fixing the first positioning member and the outer tube.

6. The method for manufacturing an antiresonant fiber preform according to claim 1, wherein the two first positioning members are arranged so as to sandwich the outer tube in the longitudinal direction.

7. A method for manufacturing an antiresonant fiber preform according to claim 1, further comprising a fourth step of fixing the first positioning member and the first capillary after the first step.

8. A method for manufacturing an antiresonant fiber preform as described in claim 7, wherein in the fourth step, the first positioning member and the first capillary are fixed by reducing the diameter of the first positioning hole.

9. A method for manufacturing an antiresonant fiber preform as described in claim 1, wherein the first positioning member has a first communication hole that communicates with the area surrounded by the first capillary when attached to the outer tube.

10. A method for manufacturing an antiresonant fiber preform as described in claim 1, wherein the antiresonant fiber preform comprises a plurality of second capillaries each having an outer diameter smaller than the inner diameter of the first capillary and each being disposed inside each of the plurality of first capillaries, the method comprising: a fifth step of positioning each of the plurality of second capillaries in each of a plurality of second positioning holes provided in a second positioning member; and a sixth step of inserting each of the plurality of second capillaries into each of the first capillaries, wherein the plurality of second positioning holes provided in the second positioning member are arranged to correspond to a second positional relationship of the plurality of second capillaries within the outer tube.

11. A method for manufacturing an antiresonant fiber preform as described in claim 10, wherein the second positioning member has a second communication hole that communicates with the inside of the first capillary when attached to the first positioning member.

12. The method for manufacturing an antiresonant fiber preform according to claim 10, wherein the second positioning member is disposed so as to sandwich the first positioning member between the outer tube and the second positioning member.

13. A method for manufacturing an antiresonant fiber preform according to claim 10, comprising a seventh step of fixing the first positioning member, the second positioning member and the outer tube.

14. The method for manufacturing an antiresonant fiber preform according to claim 10, further comprising an eighth step of fixing the second positioning member and the second capillary.

15. A method for manufacturing an antiresonant fiber preform as described in claim 14, wherein in the eighth step, the second positioning member and the second capillary are fixed together by reducing the diameter of the second positioning hole.

16. A method for manufacturing an antiresonant fiber preform as described in claim 10, wherein the first positioning member has a first communication hole that communicates with the area surrounded by the first capillary when attached to the outer tube, and the second positioning member has a third communication hole that communicates with the area surrounded by the first capillary via the first communication hole when attached to the first positioning member.

17. A method for manufacturing an antiresonant fiber preform described in any one of claims 1 to 16, comprising a ninth step of providing a tapered section on the first end side of the outer tube whose outer diameter decreases with increasing distance from the outer tube, and attaching a pressurizing member for pressurizing at least the inside of the first capillary on the second end side of the outer tube opposite the first end.

18. A method for manufacturing an antiresonant fiber, comprising: an antiresonant fiber preform manufacturing process for carrying out the method for manufacturing an antiresonant fiber preform according to any one of claims 1 to 16; and a drawing process for drawing an antiresonant fiber from the manufactured antiresonant fiber preform.

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