WO2019031070A1 - Production method for single core optical fiber base material and production method for single core optical fiber - Google Patents

Production method for single core optical fiber base material and production method for single core optical fiber Download PDF

Info

Publication number
WO2019031070A1
WO2019031070A1 PCT/JP2018/023340 JP2018023340W WO2019031070A1 WO 2019031070 A1 WO2019031070 A1 WO 2019031070A1 JP 2018023340 W JP2018023340 W JP 2018023340W WO 2019031070 A1 WO2019031070 A1 WO 2019031070A1
Authority
WO
WIPO (PCT)
Prior art keywords
rods
optical fiber
clad
rod
glass
Prior art date
Application number
PCT/JP2018/023340
Other languages
French (fr)
Japanese (ja)
Inventor
淑通 安間
良平 福本
Original Assignee
株式会社フジクラ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社フジクラ filed Critical 株式会社フジクラ
Publication of WO2019031070A1 publication Critical patent/WO2019031070A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers

Definitions

  • the present invention relates to a method of manufacturing a single core optical fiber preform and a method of manufacturing a single core optical fiber.
  • a single core optical fiber having a rare earth element added to its core is used.
  • a double clad structure is generally applied in order to allow more excitation light to be incident on the core.
  • a double clad single core optical fiber generally has a core doped with a rare earth element, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding, the outer cladding having a lower refractive index than the inner cladding. The excitation light incident on the inner cladding is reflected to the core side at the interface between the inner cladding and the outer cladding and is incident on the core to excite the rare earth element added to the core.
  • the excitation light when the cross-sectional shape perpendicular to the longitudinal direction of the inner cladding is circular, the excitation light continues to be reflected at a certain angle at the interface between the inner and outer claddings.
  • the excitation light may propagate through the inner cladding without being incident on the core.
  • skew light When skew light is generated, the amount of excitation light incident on the core decreases, so that it is difficult to excite the rare earth element added to the core.
  • Patent Document 1 discloses a single-core optical fiber in which the cross-sectional shape perpendicular to the longitudinal direction of the inner cladding is a polygon. As described above, by making the cross-sectional shape of the inner cladding non-circular, it is considered that the excitation light propagating through the inner cladding repeats reflection while changing the reflection angle on the outer peripheral surface of the inner cladding and easily enters the core.
  • the base material for a single-core optical fiber for manufacturing the single-core optical fiber has a non-cross-sectional shape perpendicular to the longitudinal direction. It needs to be round.
  • the machineable length of the glass rod is It tends to be restricted.
  • the present invention provides a method for producing a single core optical fiber preform that can produce a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction and having a large length, and a single core optical fiber
  • the purpose is to provide a manufacturing method.
  • a method of manufacturing a base material for a single core optical fiber according to the present invention for solving the above problems includes a plurality of glass rods including a core rod having a core portion to be a core and a plurality of clad rods to be a part of a clad.
  • the soot By depositing soot on the outer peripheral surface of the plurality of bundled glass rods, the soot tends to be deposited along the outer peripheral surface of the bundle of the plurality of glass rods. Therefore, by depositing the soot in the state where the plurality of clad rods are disposed around the core rod as described above, in the cross section perpendicular to the longitudinal direction of the core rod, the outer peripheral shape of the portion where the soot is deposited surrounds the core rod. It can be a rounded corner of the polygon. That is, in a cross section perpendicular to the longitudinal direction of the core rod, the soot can be deposited in a non-circular area surrounding the core rod.
  • the soot thus deposited and integrating it with a plurality of glass rods it is possible to manufacture a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction. Furthermore, since the length of the single core optical fiber preform can be adjusted by adjusting the length of the glass rod, the length of the single core optical fiber preform can be increased. Therefore, it is possible to manufacture a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction and a large length.
  • each of the cladding rods may have the same diameter, and in the bundling step, each of the cladding rods may be disposed at an overlapping position with each vertex of a regular polygon centered on the center of the core rod. preferable.
  • soot By depositing soot in this manner with the plurality of clad rods arranged, the soot can be deposited in a region centered on the core rod in a cross section perpendicular to the longitudinal direction of the core rod. Further, by sintering the soot thus deposited and integrating it with a plurality of glass rods, it is possible to manufacture a base material for a single core optical fiber in which the central axis coincides with the portion formed by the core portion of the core rod. By using such a single-core optical fiber preform, a single-core optical fiber in which the core is disposed at the center of the clad can be manufactured.
  • the core rod has a clad glass layer which becomes a part of the clad on the outer peripheral surface of the core portion.
  • the core rod having the clad glass layer can suppress damage to the core portion of the core rod in the bundle process.
  • outer circumferential surfaces of the clad rods adjacent to each other be in contact with each other.
  • the respective clad rods are compared to the case where the plurality of clad rods are arranged to be separated from each other
  • the diameter of the can be increased.
  • single core optical fibers with thick cladding may be manufactured. That is, a single core optical fiber having a large distance from the center of the core to the outer peripheral surface of the cladding can be manufactured. In such a single core optical fiber, bending loss and loss due to microbent can be suppressed.
  • outer peripheral surfaces of the clad rods adjacent to each other be separated.
  • the filling glass rods having a refractive index lower than that of the core portion and a diameter smaller than that of the cladding rods surround the plurality of cladding rods by tangent lines contacting the outer peripheral surface of the cladding rods adjacent to each other. It is preferable to be disposed inside the polygon formed as such.
  • the cross-sectional shape perpendicular to the longitudinal direction of the single core optical fiber base material can be approximated to a polygon.
  • the filling glass rod is preferably arranged to be in contact with the outer peripheral surface of at least one of the clad rods.
  • the filling glass rod is disposed in contact with the outer peripheral surface of the core rod.
  • a plurality of the filling glass rods be disposed between the adjacent clad rods, and the outer peripheral surfaces of the filling glass rods adjacent to each other be in contact.
  • the filling glass rods are preferably arranged to be in contact with the respective outer peripheral surfaces of the clad rods adjacent to each other.
  • an active element is added to the core portion.
  • a single core optical fiber manufactured using a single core optical fiber base material can be used as an amplification optical fiber.
  • the refractive index of the other part of the cladding made of the soot may be lower than the refractive index of the cladding rod after the sintering step.
  • the portion made of the cladding rod in the base material for a single core optical fiber becomes a portion that becomes a part of the inner cladding and made of soot.
  • the portion may be a portion to be an outer cladding having a lower refractive index than the inner cladding.
  • a method of producing a single core optical fiber according to the present invention for solving the above problems comprises a wire for drawing a single core optical fiber preform produced by the method of producing a single core optical fiber preform according to the present invention. It is characterized by including a pulling step.
  • a base material for a single core optical fiber of the present invention it is possible to manufacture a base material for a single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction and a large length. Therefore, by using the single-core optical fiber base material, it is possible to manufacture a long single-core optical fiber in which the cross-sectional shape of the clad is noncircular.
  • a method of manufacturing a single core optical fiber base material capable of manufacturing a single core optical fiber base material having a non-circular cross section perpendicular to the longitudinal direction and having a large length, A method of manufacturing a single core optical fiber is provided.
  • FIG. 1 It is a figure showing the section perpendicular to the longitudinal direction of the single core optical fiber concerning the embodiment of the present invention. It is a flowchart which shows the manufacturing method of the single core optical fiber of FIG. It is a perspective view showing a bundle of a plurality of glass rods. It is a figure which shows the cross section perpendicular
  • FIG. 1 is a view showing a cross section perpendicular to the longitudinal direction of a single core optical fiber according to an embodiment of the present invention.
  • the single-core optical fiber 1 of the present embodiment mainly includes a core 10, a clad 20 surrounding the outer peripheral surface of the core 10 without a gap, and a protective layer 30 covering the outer peripheral surface of the clad 20.
  • the core 10 is disposed at the center of the cladding 20.
  • the cladding 20 includes an inner cladding 21 surrounding the outer peripheral surface of the core 10 without a gap, and an outer cladding 22 covering the outer peripheral surface of the inner cladding 21.
  • the single core optical fiber 1 has a so-called double cladding structure. .
  • the refractive index of the inner cladding 21 is lower than the refractive index of the core 10, and the refractive index of the outer cladding 22 is lower than the refractive index of the inner cladding 21.
  • the outer shape of the inner cladding 21 is non-circular. Specifically, in the cross section of the inner cladding 21 perpendicular to the longitudinal direction of the single core optical fiber 1, the apexes of the regular hexagon are rounded and chamfered, and the respective sides are rounded inward. It has a curved shape.
  • a material which comprises such an inner clad 21 pure quartz to which no dopant is added can be mentioned, for example.
  • An element such as fluorine (F) that lowers the refractive index may be added to the material forming the inner cladding 21.
  • the outer cladding 22 of the present embodiment is made of a resin, and an example of the resin is an ultraviolet curable resin.
  • the single core optical fiber 1 of the present embodiment is an amplification optical fiber. Therefore, as a material which comprises the core 10, the quartz to which active elements, such as ytterbium (Yb), were added is mentioned, for example.
  • active elements include rare earth elements. Examples of rare earth elements include thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), erbium (Er), etc. in addition to Yb. It can be mentioned. In addition to the rare earth elements, bismuth (Bi) and the like can be mentioned as the active element.
  • elements, such as germanium (Ge) which raises a refractive index may be added to the material which comprises the core 10.
  • the ultraviolet curable resin different from resin which comprises the outer side clad 22 is mentioned, for example.
  • FIG. 2 is a flowchart showing a method of manufacturing the single core optical fiber of FIG.
  • the method of manufacturing the single-core optical fiber 1 mainly includes a bundle process P1, an external process P2, a sintering process P3, and a drawing process P4.
  • FIG. 3 is a perspective view showing a bundle of a plurality of glass rods.
  • FIG. 4 is a figure which shows the cross section perpendicular
  • the plurality of glass rods are the core rod 2, the plurality of clad rods 3, and the plurality of filling glass rods 4.
  • the core rod 2 is a cylindrical glass rod having a core portion 10R to be the core 10 of the single core optical fiber 1 of FIG. 1 and a clad glass layer 20R to be a part of the inner cladding 21 covering the outer peripheral surface of the core portion 10R. It is.
  • the core 10 R of the core rod 2 is made of the same material as the core 10 because it becomes the core 10. Further, since the clad glass layer 20R is a part of the inner clad 21, it is made of the same material as the inner clad 21.
  • Each of the plurality of clad rods 3 is a cylindrical glass rod which is a part of the inner clad 21.
  • six clad rods 3 are prepared.
  • each clad rod 3 is a cylindrical glass rod having the same diameter as each other, and is made of the same material. Further, since each clad rod 3 is a part of the inner clad 21, it is made of the same material as the inner clad 21. Therefore, the refractive index of each clad rod 3 is also lower than the refractive index of the core portion 10R.
  • Each of the plurality of filling glass rods 4 is a cylindrical glass rod which is a part of the inner clad 21.
  • six filling glass rods 4 are prepared.
  • the respective filling glass rods 4 are cylindrical glass rods having the same diameter as each other and smaller in diameter than the clad rod 3.
  • each filling glass rod 4 is made of the same material and is made of the same material as the inner cladding 21 to be a part of the inner cladding 21. Therefore, the refractive index of each of the filling glass rods 4 is lower than the refractive index of the core portion 10R.
  • the clad glass layer 20R, the clad rod 3, and the filling glass rod 4 are made of the same silica glass.
  • each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a regular hexagon surrounding the core rod 2 with the center of the core rod 2 as a center.
  • the clad rods 3 adjacent to each other are separated from each other in the outer peripheral surface, and the glass rod 4 for filling is disposed between the clad rods 3 adjacent to each other.
  • the respective filling glass rods 4 arranged in this manner are arranged so as to be accommodated inside the regular hexagon formed by the tangent lines in contact with the respective outer peripheral surfaces of the adjacent clad rods 3.
  • the regular hexagon is indicated by a broken line in FIG.
  • Each filling glass rod 4 is disposed in contact with the outer peripheral surface of the core rod 2 and in contact with the respective outer peripheral surfaces of the clad rods 3 adjacent to each other.
  • the binding band 51 may be made of resin or metal, but it is preferable to be made of resin from the viewpoint of preventing the outer peripheral surface of the glass rod from being scratched, and it is high heat resistance. It is preferably made of metal. Thus, as shown in FIG. 3, a plurality of glass rods are bound.
  • FIG. 5 is a view showing how a plurality of glass rods are thus fixed.
  • one dummy glass rod 52 is fixed to one end of each glass rod in a state where the plurality of glass rods are bound by the binding band 51.
  • one other dummy glass rod 52 is fixed to the other end of each glass rod. From the viewpoint of suppressing the adhesion of impurities to the glass rod, this fixing is preferably performed by welding.
  • the binding band 51 binding the respective glass rods is removed.
  • a plurality of glass rods are bundled.
  • the dummy glass rods 52 are welded to the respective glass rods, but such a procedure is not necessarily required.
  • the dummy glass rods 52 are fixed at appropriate positions at both ends of one glass rod.
  • one other glass rod is arranged adjacent to the glass rod already fixed to the dummy glass rod 52, and both ends of the other arranged glass rod are fixed to the respective dummy glass rod 52 Do. This is repeated to fix all the glass rods to the dummy glass rods 52 at appropriate positions. As described above, even if each glass rod is fixed to the dummy glass rod 52, a plurality of glass rods are bundled as shown in FIG.
  • FIG. 6 is a view showing the appearance of the external attachment process P2.
  • the external attachment process P2 is performed, for example, by the outside vapor deposition method (OVD), and deposits soot to be a part of the inner cladding 21 on the outer peripheral surface of the plurality of glass rods bundled in the bundle process P1.
  • ODD outside vapor deposition method
  • each dummy glass rod 52 is fixed to a chuck of a lathe (not shown), and a plurality of bundled glass rods are rotated about the axis of the dummy glass rod 52. Then, while rotating a plurality of glass rods as shown in FIG. 6, soot to be the inner clad 21 is deposited.
  • FIG. 7 is a view showing a state after the external attachment process P2.
  • the vaporized SiCl 4 is introduced into the flame of the oxyhydrogen burner 53 by the carrier gas whose flow rate is controlled to change it from SiCl 4 to SiO 2 (silica glass).
  • the SiO 2 soot 5 is deposited so as to cover the outer peripheral surface of each glass rod.
  • the deposition of the soot 5 forms a porous glass body that becomes a part of the inner cladding 21.
  • the soot 5 is made of the same glass glass as the clad glass layer 20R, the clad rod 3, and the filling glass rod 4.
  • the soot 5 is deposited without adding any dopant.
  • the dopant is added to the soot 5.
  • a gas containing a controlled amount of dopant is introduced into the flame of the oxyhydrogen burner together with the vaporized SiCl 4 .
  • SiF 4 vaporized together with the vaporized SiCl 4 is put into the flame of the oxyhydrogen burner Introduce.
  • the soot 5 is deposited on the outer peripheral surfaces of the plurality of glass rods bundled as shown in FIG.
  • the apex of the regular hexagon centered on the center of the core rod 2 is rounded and chamfered and the respective sides are rounded inward Is deposited on the curved and curved area.
  • ⁇ Sintering process P3> After the soot 5 is deposited as shown in FIG. 7, dehydration treatment is performed as needed prior to the sintering step P3.
  • the said dehydration process is performed by being provided with a heater and being aged for a predetermined time in the furnace filled with gas, such as Ar and He.
  • the sintering step P3 is a step of heating the plurality of glass rods in which the soot 5 is deposited on the outer peripheral surface to make the soot 5 and the respective glass rods into an integral glass body.
  • sintering is performed until the temperature of the inside of the furnace is made higher than in the case of performing the above-described dehydration treatment so that the porous glass body of the soot 5 deposited becomes a transparent glass body.
  • the furnace used at this time may be a furnace used for the above-mentioned dehydration processing, and may be a furnace different from the furnace used for the above-mentioned dehydration processing.
  • a single core optical fiber preform 1P shown in FIG. 8 is obtained.
  • the core rod 2 the clad rod 3, the glass rod 4 for filling and the soot 5 become the base material 1 P for single core optical fiber
  • the core portion 10 R of the core rod 2 hardly deforms the base material for single core optical fiber It becomes base material core part 10P of 1P.
  • each of the clad glass layer 20R of the core rod 2, the plurality of clad rods 3, the plurality of filling glass rods 4 and the suit 5 is a part of the base clad part 20P of the single core optical fiber base material 1P.
  • the outer shape of the cross section perpendicular to the longitudinal direction of the single core optical fiber preform 1P thus obtained is non-circular.
  • the outer shape of the cross section perpendicular to the longitudinal direction of the single core optical fiber preform 1P is a shape resulting from the outer shape of the cross section perpendicular to the longitudinal direction of the bundle of the plurality of glass rods.
  • each of the plurality of cladding rods 3 is disposed at a position overlapping each vertex of the regular hexagon, and each of the plurality of filling glass rods 4 is disposed inside the regular hexagon surrounding the plurality of cladding rods 3. Ru.
  • the apex of the regular hexagon centered on the center of the base material core portion 10P is rounded and chamfered, and each side is curved inward and curved. It will be shaped.
  • the clad glass layer 20R, the clad rod 3, and the filling glass rod 4 are made of silica glass to which fluorine is added as described above, this process may be performed in an atmosphere containing a fluorine-based gas. Specifically, a fluorine-based gas such as SiF 4 , CF 4 , C 2 F 6 or the like is introduced into a furnace for performing this step. In such a process, when the glass porous body made of soot 5 causes viscous flow, fluorine tends to be added to the glass body derived from the soot 5.
  • a fluorine-based gas such as SiF 4 , CF 4 , C 2 F 6 or the like
  • FIG. 9 is a diagram showing the drawing process P4.
  • the single core optical fiber preform 1P manufactured by the above step is installed in the spinning furnace 110.
  • the heating unit 111 of the spinning furnace 110 is caused to generate heat to heat the single core optical fiber preform 1P.
  • the lower end of the single-core optical fiber base material 1P is heated to, for example, 2000 ° C. to be in a molten state.
  • the glass is melted from the single core optical fiber base material 1P, and the glass is drawn.
  • the drawn glass in the molten state is solidified immediately upon leaving the spinning furnace 110, and the base material core portion 10P becomes the core 10, and the base material clad portion 20P becomes the cladding 20. It becomes a single core optical fiber strand composed of the clad 20.
  • this single core optical fiber strand passes through the cooling device 120 and is cooled to an appropriate temperature.
  • the temperature of the single-core optical fiber strand is, for example, about 1800 ° C, but when leaving the cooling device 120, the temperature of the single-core optical fiber strand is, for example, 40 ° C to 50 ° C. It becomes.
  • the single core optical fiber strand coming out of the cooling device 120 passes through the coating device 131 containing the ultraviolet curable resin to be the outer clad 22 and is coated with this ultraviolet curable resin. Furthermore, by passing through the ultraviolet irradiation device 132 and being irradiated with ultraviolet light, the ultraviolet curable resin is cured to form the outer clad 22.
  • the multi-core fiber coated with the outer cladding 22 passes through the coating device 133 containing the ultraviolet curable resin to be the protective layer 30, and is coated with the ultraviolet curable resin. Furthermore, by passing through the ultraviolet irradiation device 134 and being irradiated with ultraviolet light, the ultraviolet curable resin is cured to form the protective layer 30, and the single core optical fiber 1 shown in FIG.
  • the direction of the single core optical fiber 1 is converted by the turn pulley 141, and the single core optical fiber 1 is wound by the reel 142.
  • the single core optical fiber 1 shown in FIG. 1 is manufactured.
  • the core rod 2 having the core portion 10R to be the core 10 and a part of the inner clad 21 which is a part of the clad 20.
  • a sintering step P3 in which the plurality of glass rods on which the soot 5 is deposited are heated to make the soot 5 and the respective glass rods into an integral glass body.
  • the plurality of clad rods 3 are disposed in contact with the outer peripheral surface of the core rod 2 and at positions overlapping respective apexes of regular hexagons surrounding the core rod 2.
  • the soot 5 By depositing the soot 5 on the outer peripheral surface of the plurality of bundled glass rods, the soot 5 is easily deposited along the outer peripheral surface of the bundle of the plurality of glass rods. Therefore, by depositing the soot 5 in a state where the plurality of clad rods 3 are disposed around the core rod 2 as described above, the outer periphery of the portion where the soot 5 is deposited in the cross section perpendicular to the longitudinal direction of the core rod 2
  • the shape may be a shape obtained by rounding the corners of a regular hexagon surrounding the core rod 2. That is, in a cross section perpendicular to the longitudinal direction of the core rod 2, the soot 5 can be deposited in a non-circular area surrounding the core rod 2.
  • the soot 5 deposited in this way by sintering the soot 5 deposited in this way and integrating it with a plurality of glass rods, it is possible to manufacture a single core optical fiber preform 1P having a non-circular cross-sectional shape perpendicular to the longitudinal direction. . Furthermore, since the length of the single core optical fiber preform 1P can be adjusted by adjusting the length of the glass rod, the length of the single core optical fiber preform 1P can be increased. Accordingly, it is possible to manufacture a single core optical fiber preform 1P having a non-circular cross-sectional shape perpendicular to the longitudinal direction and a large length.
  • the respective clad rods 3 have the same diameter, and in the bundle process P1, the respective clad rods 3 are disposed at positions overlapping respective apexes of the regular hexagon centered on the center of the core rod 2 Be done.
  • the soot 5 can be deposited in a region centered on the core rod 2 in a cross section perpendicular to the longitudinal direction of the core rod 2.
  • Base material 1P can be manufactured.
  • a single-core optical fiber preform 1P a single-core optical fiber 1 in which the core 10 is disposed at the center of the clad 20 can be manufactured.
  • the bundle process P1 in the bundle process P1, it arrange
  • the diameter is larger than that in the case where the plurality of clad rods 3 are arranged to be in contact with each other.
  • the core rod 2 can be used. Therefore, the single core optical fiber 1 having a large diameter of the core 10 can be manufactured when compared with the same fiber diameter.
  • the glass rod 4 for filling is disposed in contact with the outer peripheral surface of the clad rod 3 in the bundle process P1.
  • the filling glass rod 4 is arranged to be in contact with the outer peripheral surface of at least one clad rod 3 in this manner, deformation of the filling glass rod 4 and the clad rod 3 can be suppressed in the sintering step P3.
  • the glass rod 4 for filling is disposed in contact with the outer peripheral surface of the core rod 2 in the bundle process P1.
  • the filling glass rods 4 are disposed in contact with the respective outer peripheral surfaces of the clad rods 3 adjacent to each other.
  • the filling glass rod in the sintering step P3 is compared to the case where the filling glass rod 4 contacts only one of the clad rods 3 adjacent to each other. The deformation of 4 and the clad rod 3 can be further suppressed.
  • the core rod 2 has a clad glass layer 20R which is a part of the clad 20 on the outer peripheral surface of the core portion 10R.
  • the core rod 2 having the clad glass layer 20R can prevent the core portion 10R of the core rod 2 from being damaged in the bundling process P1.
  • the clad glass layer 20R is not an essential component.
  • a plurality of filling glass rods 4 having a refractive index lower than that of the core portion 10R and a diameter smaller than that of the clad rods 3 contact a plurality of tangents to the outer peripheral surface of the clad rods 3 adjacent to each other. Is disposed inside a regular hexagon formed to surround the clad rods 3 of the above.
  • the method of manufacturing the single core optical fiber 1 of the present embodiment is a drawing step P4 of drawing the single core optical fiber base material 1P manufactured by the method of manufacturing the single core optical fiber base material 1P of the above embodiment. Equipped with As described above, according to the method of manufacturing the base material 1P for a single core optical fiber of the present embodiment, the base material 1P for a single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction and a large length is manufactured obtain. Therefore, by using the single-core optical fiber preform 1P, as described above, the long single-core optical fiber 1 can be manufactured in which the cross-sectional shape of the inner cladding 21 is noncircular.
  • the clad rods 3 are described as being disposed at the positions overlapping the respective apexes of the regular hexagon centered on the center of the core rod 2, but the present invention It is not limited to this.
  • the plurality of clad rods 3 may be disposed at positions overlapping the respective apexes of the polygon surrounding the core rod 2, and the number of clad rods 3 is not particularly limited as long as it is three or more. That is, in the bundle process P1, each clad rod 3 may be disposed at a position overlapping with each vertex of the polygon surrounding the core rod 2 with the same number of angles as the number of the clad rods 3.
  • the said polygon is a polygon centering on the center of the core rod 2, and it is preferable that the said polygon is a regular polygon.
  • the polygon will approach a circle. Therefore, in a cross section perpendicular to the longitudinal direction of the core rod 2, the area where the soot 5 is deposited approaches a circle, and the cross-sectional shape of the inner cladding 21 also approaches a circle.
  • the number of clad rods 3 is preferably eight or less from the viewpoint of making the shape of the inner cladding 21 effective to suppress the generation of skew light. That is, the polygon is preferably a polygon having eight or less corners.
  • FIG. 10 is a view showing a cross section perpendicular to the longitudinal direction of the bundle of the plurality of glass rods after the bundle process P1 according to the modification of the present invention.
  • three clad rods 3 are arranged around the core rod 2.
  • Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of an equilateral triangle surrounding the core rod 2.
  • two filling glass rods 4 are disposed between the clad rods 3 adjacent to each other.
  • Each filling glass rod 4 is disposed inside an equilateral triangle formed so as to surround a plurality of cladding rods 3 by a tangent line in contact with the outer peripheral surface of the adjacent cladding rods 3.
  • the equilateral triangle is shown by a broken line in FIG.
  • the glass rods 4 for filling which adjoin mutually are arrange
  • the plurality of filling glass rods 4 are disposed between the clad rods 3 adjacent to each other in the bundling step P1, and the outer peripheral surfaces of the filling glass rods 4 adjacent to each other are in contact. The deformation of the filling glass rod 4 can be suppressed.
  • FIG. 11 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundling process P1 according to another modification of the present invention.
  • four clad rods 3 are arranged around the core rod 2.
  • Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a square surrounding the core rod 2.
  • one filling glass rod 4 is disposed between the clad rods 3 adjacent to each other.
  • Each filling glass rod 4 is disposed inside a square formed so as to surround a plurality of cladding rods 3 by a tangent line contacting the outer peripheral surface of the adjacent cladding rods 3. The square is indicated by a broken line in FIG.
  • FIG. 12 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention.
  • four clad rods 3 are arranged around the core rod 2.
  • Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a square surrounding the core rod 2. Further, the outer peripheral surfaces of the clad rods 3 adjacent to each other are in contact with each other.
  • a single core optical fiber 1 having a thick cladding 20 can be manufactured. That is, a single core optical fiber 1 having a large distance from the center of the core 10 to the outer peripheral surface of the cladding 20 can be manufactured. In such a single core optical fiber 1, bending loss and loss due to microbent can be suppressed.
  • FIG. 13 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention.
  • five clad rods 3 are arranged around the core rod 2.
  • Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each apex of the regular pentagon surrounding the core rod 2.
  • one filling glass rod 4 is disposed between the clad rods 3 adjacent to each other.
  • Each filling glass rod 4 is disposed inside a regular pentagon formed so as to surround a plurality of cladding rods 3 by tangent lines contacting the outer circumferential surface of the adjacent cladding rods 3.
  • the regular pentagon is indicated by a broken line in FIG.
  • FIG. 14 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention.
  • six clad rods 3 are arranged around the core rod 2.
  • Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a regular hexagon surrounding the core rod 2. Further, the outer peripheral surfaces of the clad rods 3 adjacent to each other are in contact with each other.
  • the filling glass rod 4 for filling are in contact with the outer peripheral surfaces of the adjacent clad rods 3 in the bundle process P1 .
  • the filling glass rod 4 may be separated from the outer peripheral surface of the clad rod 3.
  • the filling glass rod 4 is preferably arranged to be in contact with the outer peripheral surface of at least one clad rod 3.
  • each clad rod 3 mentioned and demonstrated the example made into mutually the same diameter the diameters of each clad rod 3 may mutually differ.
  • the glass glass rods 4 for filling showed and demonstrated the example made into mutually the same diameter, the diameters of the glass rods 4 for filling may mutually differ.
  • the outer cladding 22 may be made of silica glass.
  • the outer cladding 22 can be formed by the soot 5 by making the refractive index of a part of the cladding 20 made of the soot 5 lower than the refractive index of the cladding rod 3.
  • the part made of the clad rod 3 becomes a part that becomes a part of the inner clad 21 and the part made of the soot 5 becomes A single core optical fiber preform 1P can be manufactured which is a portion to be the outer cladding 22 having a lower refractive index than the inner cladding 21.
  • the externally attached step P2 be performed a plurality of times.
  • the soot 5 it is preferable to deposit the soot 5 to be the inner cladding 21 in the first one or several initial external application processes P2, and to deposit the soot 5 to be the outer cladding 22 in the remaining external application processes P2.
  • the base material 1P for a single core optical fiber manufactured in this manner, it is possible to manufacture a single core optical fiber 1 of a double clad structure suitable for an amplification optical fiber.
  • the single core optical fiber 1 may be an optical fiber in which no active element is added to the core 10. Good.
  • the single core optical fiber 1 can be used as a delivery fiber connected to an amplification optical fiber such as the single core optical fiber 1 of the above embodiment.
  • a method of manufacturing a single core optical fiber base material capable of manufacturing a single core optical fiber base material having a non-circular cross section perpendicular to the longitudinal direction and a large length is provided and is expected to be used in the field of fiber laser devices and the like.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

The present invention comprises: a bundling step (P1) in which a plurality of glass rods are bundled that include a core rod (2) having a core section (10R) being a core (10) and a plurality of cladding rods (3) arranged in contact with an outer circumferential surface of the core rod (2) and becoming part of a cladding (20); an external attachment step (P2) in which soot (5), which becomes another part of the cladding (20), is deposited upon the outer circumferential surface of the bundled plurality of glass rods; and a sintering step (P3) in which the plurality of glass rods having the soot (5) deposited thereupon are heated and the soot (5) and each glass rod form an integrated glass body. In the bundling step (P1), the plurality of cladding rods (3) are arranged at positions at which same overlap each of the apexes of a polygon encircling the core rod (2).

Description

シングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法Method of manufacturing base material for single core optical fiber and method of manufacturing single core optical fiber
　本発明は、シングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法に関する。 The present invention relates to a method of manufacturing a single core optical fiber preform and a method of manufacturing a single core optical fiber.
　レーザ加工機として使用されるファイバレーザ装置では、コアに希土類元素が添加されたシングルコア光ファイバが用いられる。また、このようなシングルコア光ファイバでは、コアにより多くの励起光を入射させるため、一般的にダブルクラッド構造が適用される。ダブルクラッド構造のシングルコア光ファイバは、一般的に、希土類元素が添加されたコアとコアを囲う内側クラッドと内側クラッドを囲う外側クラッドとを有し、外側クラッドは内側クラッドより屈折率が低い。内側クラッドに入射される励起光は、内側クラッドと外側クラッドとの界面においてコア側に反射されてコアに入射し、コアに添加される希土類元素を励起する。しかし、このようなダブルクラッド構造のシングルコア光ファイバにおいて、内側クラッドの長手方向に垂直な断面形状が円形である場合、励起光が内側クラッドと外側クラッドとの界面において一定の角度で反射し続け、励起光がコアに入射せずに内側クラッドを伝搬する場合がある。このように、コアを通過せずにクラッドを伝搬する光をスキュー光という。スキュー光が生じると、コアに入射する励起光が少なくなるため、コアに添加される希土類元素が励起され難くなる。 In a fiber laser device used as a laser processing machine, a single core optical fiber having a rare earth element added to its core is used. In addition, in such a single core optical fiber, a double clad structure is generally applied in order to allow more excitation light to be incident on the core. A double clad single core optical fiber generally has a core doped with a rare earth element, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding, the outer cladding having a lower refractive index than the inner cladding. The excitation light incident on the inner cladding is reflected to the core side at the interface between the inner cladding and the outer cladding and is incident on the core to excite the rare earth element added to the core. However, in such a double-clad single-core optical fiber, when the cross-sectional shape perpendicular to the longitudinal direction of the inner cladding is circular, the excitation light continues to be reflected at a certain angle at the interface between the inner and outer claddings. The excitation light may propagate through the inner cladding without being incident on the core. Thus, light propagating in the cladding without passing through the core is referred to as skew light. When skew light is generated, the amount of excitation light incident on the core decreases, so that it is difficult to excite the rare earth element added to the core.
　スキュー光の発生を抑制するための技術として、例えば下記特許文献１には、内側クラッドの長手方向に垂直な断面形状を多角形とするシングルコア光ファイバが開示されている。このように内側クラッドの断面形状が非円形とされることによって、内側クラッドを伝搬する励起光は内側クラッドの外周面において反射角を変えながら反射を繰り返し、コアに入射し易くなると考えられる。 As a technique for suppressing the generation of skew light, for example, Patent Document 1 below discloses a single-core optical fiber in which the cross-sectional shape perpendicular to the longitudinal direction of the inner cladding is a polygon. As described above, by making the cross-sectional shape of the inner cladding non-circular, it is considered that the excitation light propagating through the inner cladding repeats reflection while changing the reflection angle on the outer peripheral surface of the inner cladding and easily enters the core.
国際公開第２００９－０２８６１４号公報International Publication No. 2009-028614
　上記のようなクラッドの断面形状が非円形であるシングルコア光ファイバを製造する場合、当該シングルコア光ファイバを製造するためのシングルコア光ファイバ用母材は、長手方向に垂直な断面形状が非円形とされる必要がある。しかし、長手方向に垂直な断面形状が円形のガラスロッドを当該断面形状が非円形となるように切削してシングルコア光ファイバ用母材として用いる場合、機械でガラスロッドを切削可能な長さは制限される傾向にある。ところで、製造コスト低減等の要請により、１つのシングルコア光ファイバ用母材から長尺のシングルコア光ファイバを製造することが求められている。しかし、上記のように機械でガラスロッドを切削可能な長さは制限される傾向にあるため、長手方向に垂直な断面形状が非円形で長さの大きなシングルコア光ファイバ用母材を作製することは難しい。このため、長手方向に垂直な断面形状が非円形で長尺のシングルコア光ファイバを作製することも難しい。 When manufacturing a single-core optical fiber in which the cross-sectional shape of the cladding as described above is non-circular, the base material for a single-core optical fiber for manufacturing the single-core optical fiber has a non-cross-sectional shape perpendicular to the longitudinal direction. It needs to be round. However, when using a glass rod with a circular cross-sectional shape perpendicular to the longitudinal direction so that the cross-sectional shape becomes non-circular and using it as a base material for a single core optical fiber, the machineable length of the glass rod is It tends to be restricted. By the way, there is a demand for manufacturing a long single core optical fiber from one single core optical fiber base material due to a request for reduction in manufacturing cost and the like. However, as described above, since the machineable length of the glass rod tends to be limited, a base material for single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction and a large length is manufactured. Things are difficult. For this reason, it is also difficult to produce a long single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction.
　そこで、本発明は、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材を製造し得るシングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法を提供することを目的とする。 Therefore, the present invention provides a method for producing a single core optical fiber preform that can produce a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction and having a large length, and a single core optical fiber The purpose is to provide a manufacturing method.
　上記課題を解決するための本発明のシングルコア光ファイバ用母材の製造方法は、コアとなるコア部を有するコアロッド、及び、クラッドの一部となる複数のクラッドロッド、を含む複数のガラスロッドを束ねるバンドル工程と、束ねられた前記複数のガラスロッドの外周面上に前記クラッドの他の一部となるスートを堆積する外付工程と、前記スートが堆積した前記複数のガラスロッドを加熱して前記スートとそれぞれの前記ガラスロッドとを一体のガラス体とする焼結工程と、を備え、前記バンドル工程において、それぞれの前記クラッドロッドは、前記コアロッドの外周面に接すると共に前記コアロッドを囲う多角形のそれぞれの頂点と重なる位置に配置されることを特徴とする。 A method of manufacturing a base material for a single core optical fiber according to the present invention for solving the above problems includes a plurality of glass rods including a core rod having a core portion to be a core and a plurality of clad rods to be a part of a clad. A bundle process of bundling, an external application process of depositing a soot to be another part of the cladding on the outer peripheral surface of the plurality of glass rods bundled, and heating the plurality of glass rods on which the soot is deposited A sintering step in which the soot and each of the glass rods are integrated into a single glass body, and in the bundling step, each of the clad rods is in contact with the outer peripheral surface of the core rod and surrounds the core rod. It is characterized in that it is disposed at a position overlapping with each vertex of the square.
　束ねられた複数のガラスロッドの外周面上にスートを堆積することによって、スートは複数のガラスロッドの束の外周面に沿って堆積し易い。このため、上記のようにコアロッドの周りに複数のクラッドロッドが配置された状態でスートを堆積させることにより、コアロッドの長手方向に垂直な断面において、スートが堆積した部分の外周形状はコアロッドを囲う多角形の角を丸めた形状と成り得る。すなわち、コアロッドの長手方向に垂直な断面において、スートはコアロッドを囲う非円形の領域に堆積され得る。また、このように堆積したスートを焼結させて複数のガラスロッドと一体化させることによって、長手方向に垂直な断面形状が非円形のシングルコア光ファイバ用母材を製造することができる。さらに、このシングルコア光ファイバ用母材の長さはガラスロッドの長さを調整することで調整され得るため、シングルコア光ファイバ用母材の長さを大きくし得る。よって、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材を製造し得る。 By depositing soot on the outer peripheral surface of the plurality of bundled glass rods, the soot tends to be deposited along the outer peripheral surface of the bundle of the plurality of glass rods. Therefore, by depositing the soot in the state where the plurality of clad rods are disposed around the core rod as described above, in the cross section perpendicular to the longitudinal direction of the core rod, the outer peripheral shape of the portion where the soot is deposited surrounds the core rod. It can be a rounded corner of the polygon. That is, in a cross section perpendicular to the longitudinal direction of the core rod, the soot can be deposited in a non-circular area surrounding the core rod. Further, by sintering the soot thus deposited and integrating it with a plurality of glass rods, it is possible to manufacture a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction. Furthermore, since the length of the single core optical fiber preform can be adjusted by adjusting the length of the glass rod, the length of the single core optical fiber preform can be increased. Therefore, it is possible to manufacture a single core optical fiber preform having a non-circular cross-sectional shape perpendicular to the longitudinal direction and a large length.
　また、それぞれの前記クラッドロッドは互いに同じ直径とされ、前記バンドル工程において、それぞれの前記クラッドロッドは、前記コアロッドの中心を中心とする正多角形のそれぞれの頂点と重なる位置に配置されることが好ましい。 Also, each of the cladding rods may have the same diameter, and in the bundling step, each of the cladding rods may be disposed at an overlapping position with each vertex of a regular polygon centered on the center of the core rod. preferable.
　このように複数のクラッドロッドが配置された状態でスートを堆積させることにより、コアロッドの長手方向に垂直な断面において、スートはコアロッドを中心とする領域に堆積され得る。また、このように堆積したスートを焼結させて複数のガラスロッドと一体化させることによって、コアロッドのコア部からなる部位と中心軸とが一致するシングルコア光ファイバ用母材を製造し得る。このようなシングルコア光ファイバ用母材を用いることによって、クラッドの中心にコアが配置されたシングルコア光ファイバを製造し得る。 By depositing soot in this manner with the plurality of clad rods arranged, the soot can be deposited in a region centered on the core rod in a cross section perpendicular to the longitudinal direction of the core rod. Further, by sintering the soot thus deposited and integrating it with a plurality of glass rods, it is possible to manufacture a base material for a single core optical fiber in which the central axis coincides with the portion formed by the core portion of the core rod. By using such a single-core optical fiber preform, a single-core optical fiber in which the core is disposed at the center of the clad can be manufactured.
　また、前記コアロッドは、前記コア部の外周面に前記クラッドの一部となるクラッドガラス層を有することが好ましい。 Further, it is preferable that the core rod has a clad glass layer which becomes a part of the clad on the outer peripheral surface of the core portion.
　このようにコアロッドがクラッドガラス層を有することによって、バンドル工程においてコアロッドのコア部が傷つくことが抑制され得る。 Thus, the core rod having the clad glass layer can suppress damage to the core portion of the core rod in the bundle process.
　また、前記バンドル工程において、互いに隣り合う前記クラッドロッドの外周面が接することが好ましい。 Further, in the bundling step, it is preferable that outer circumferential surfaces of the clad rods adjacent to each other be in contact with each other.
　同じ数のクラッドロッドが用いられる場合において、上記のように複数のクラッドロッドが互いに接するように配置されると、複数のクラッドロッドが互いに離間するように配置される場合に比べてそれぞれのクラッドロッドの直径を大きくすることができる。そのため、厚いクラッドを有するシングルコア光ファイバが製造され得る。すなわち、コアの中心からクラッドの外周面までの距離が大きなシングルコア光ファイバが製造され得る。このようなシングルコア光ファイバでは、曲げ損失やマイクロベントによる損失が抑制され得る。 When the same number of clad rods are used, when the plurality of clad rods are arranged to be in contact with each other as described above, the respective clad rods are compared to the case where the plurality of clad rods are arranged to be separated from each other The diameter of the can be increased. As such, single core optical fibers with thick cladding may be manufactured. That is, a single core optical fiber having a large distance from the center of the core to the outer peripheral surface of the cladding can be manufactured. In such a single core optical fiber, bending loss and loss due to microbent can be suppressed.
　また、前記バンドル工程において、互いに隣り合う前記クラッドロッドの外周面が離間することが好ましい。 Further, in the bundling step, it is preferable that outer peripheral surfaces of the clad rods adjacent to each other be separated.
　同じ数のクラッドロッドが用いられる場合において、上記のように複数のクラッドロッドが互いに離間するように配置されると、複数のクラッドロッドが互いに接するように配置される場合よりも直径が大きなコアロッドを用いることができる。そのため、同一のファイバ径で比較した場合にコアの直径が大きなシングルコア光ファイバが製造され得る。 In the case where the same number of cladding rods are used, when the plurality of cladding rods are arranged to be separated from each other as described above, core rods having a larger diameter than in the case where the plurality of cladding rods are arranged to be in contact with each other It can be used. Therefore, a single core optical fiber having a large core diameter can be manufactured when compared with the same fiber diameter.
　また、前記バンドル工程において、前記コア部よりも屈折率が低く前記クラッドロッドよりも直径が小さい充填用ガラスロッドが、互いに隣り合う前記クラッドロッドの外周面に接する接線によって前記複数のクラッドロッドを囲うように形成される多角形の内側に配置されることが好ましい。 Further, in the bundling step, the filling glass rods having a refractive index lower than that of the core portion and a diameter smaller than that of the cladding rods surround the plurality of cladding rods by tangent lines contacting the outer peripheral surface of the cladding rods adjacent to each other. It is preferable to be disposed inside the polygon formed as such.
　このように充填用ガラスロッドが配置されることによって、シングルコア光ファイバ用母材の長手方向に垂直な断面形状が多角形に近付けられ得る。 By arranging the filling glass rods in this manner, the cross-sectional shape perpendicular to the longitudinal direction of the single core optical fiber base material can be approximated to a polygon.
　また、前記バンドル工程において、前記充填用ガラスロッドは、少なくとも１本の前記クラッドロッドの外周面に接するように配置されることが好ましい。 Further, in the bundling step, the filling glass rod is preferably arranged to be in contact with the outer peripheral surface of at least one of the clad rods.
　このように充填用ガラスロッド及びクラッドロッドが配置されることによって、焼結工程において充填用ガラスロッド及びクラッドロッドの変形が抑制され得る。 By arranging the filling glass rod and the cladding rod in this manner, deformation of the filling glass rod and the cladding rod can be suppressed in the sintering process.
　また、前記バンドル工程において、前記充填用ガラスロッドは、前記コアロッドの外周面に接するように配置されることが好ましい。 Further, in the bundling step, preferably, the filling glass rod is disposed in contact with the outer peripheral surface of the core rod.
　このように充填用ガラスロッド及びコアロッドが配置されることによって、焼結工程において充填用ガラスロッド及びコアロッドの変形が抑制され得る。 By arranging the filling glass rod and the core rod in this manner, deformation of the filling glass rod and the core rod can be suppressed in the sintering process.
　また、前記バンドル工程において、互いに隣り合う前記クラッドロッドの間に複数の前記充填用ガラスロッドが配置され、互いに隣り合う前記充填用ガラスロッドの外周面が接することが好ましい。 Further, in the bundle step, it is preferable that a plurality of the filling glass rods be disposed between the adjacent clad rods, and the outer peripheral surfaces of the filling glass rods adjacent to each other be in contact.
　このように充填用ガラスロッドが配置されることによって、焼結工程において充填用ガラスロッドの変形が抑制され得る。 By arranging the filling glass rod in this manner, deformation of the filling glass rod can be suppressed in the sintering step.
　また、前記バンドル工程において、前記充填用ガラスロッドは、互いに隣り合う前記クラッドロッドのそれぞれの外周面に接するように配置されることが好ましい。 Further, in the bundling step, the filling glass rods are preferably arranged to be in contact with the respective outer peripheral surfaces of the clad rods adjacent to each other.
　このように充填用ガラスロッド及びクラッドロッドが配置されることによって、互いに隣り合うクラッドロッドの一方にのみ充填用ガラスロッドが接する場合に比べて、焼結工程において充填用ガラスロッド及びクラッドロッドの変形がより抑制され得る。 By arranging the filler glass rod and the clad rod in this way, deformation of the filler glass rod and the clad rod in the sintering step is made as compared to the case where the filler glass rod contacts only one of the clad rods adjacent to each other. Can be more suppressed.
　また、前記コア部に活性元素が添加されることが好ましい。 Preferably, an active element is added to the core portion.
　コア部に活性元素が添加されることによって、シングルコア光ファイバ用母材を用いて製造されるシングルコア光ファイバを増幅用光ファイバとして用いることができる。 By adding an active element to the core portion, a single core optical fiber manufactured using a single core optical fiber base material can be used as an amplification optical fiber.
　また、前記焼結工程後に前記スートからなる前記クラッドの他の一部の屈折率が前記クラッドロッドの屈折率よりも低くされてもよい。 In addition, the refractive index of the other part of the cladding made of the soot may be lower than the refractive index of the cladding rod after the sintering step.
　スートからなるクラッドの一部の屈折率がクラッドロッドの屈折率より低くされることによって、シングルコア光ファイバ用母材におけるクラッドロッドからなる部位を内側クラッドの一部となる部位とすると共にスートからなる部位を内側クラッドより屈折率が低い外側クラッドとなる部位とし得る。このようなシングルコア光ファイバ用母材を用いることによって、ダブルクラッド構造のシングルコア光ファイバを製造し得る。 By making the refractive index of a part of the cladding made of soot lower than the refractive index of the cladding rod, the portion made of the cladding rod in the base material for a single core optical fiber becomes a portion that becomes a part of the inner cladding and made of soot. The portion may be a portion to be an outer cladding having a lower refractive index than the inner cladding. By using such a single core optical fiber preform, a double clad single core optical fiber can be manufactured.
　また、上記課題を解決するための本発明のシングルコア光ファイバの製造方法は、上記本発明のシングルコア光ファイバ用母材の製造方法により製造されるシングルコア光ファイバ用母材を線引きする線引工程を備えることを特徴とする。 Further, a method of producing a single core optical fiber according to the present invention for solving the above problems comprises a wire for drawing a single core optical fiber preform produced by the method of producing a single core optical fiber preform according to the present invention. It is characterized by including a pulling step.
　上記のように、上記本発明のシングルコア光ファイバ用母材の製造方法によれば、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材を製造し得る。よって、当該シングルコア光ファイバ用母材を用いることによって、クラッドの断面形状が非円形で長尺のシングルコア光ファイバを製造し得る。 As described above, according to the method of manufacturing a base material for a single core optical fiber of the present invention, it is possible to manufacture a base material for a single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction and a large length. Therefore, by using the single-core optical fiber base material, it is possible to manufacture a long single-core optical fiber in which the cross-sectional shape of the clad is noncircular.
　以上のように、本発明によれば、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材を製造し得るシングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法が提供される。 As described above, according to the present invention, a method of manufacturing a single core optical fiber base material capable of manufacturing a single core optical fiber base material having a non-circular cross section perpendicular to the longitudinal direction and having a large length, A method of manufacturing a single core optical fiber is provided.
本発明の実施形態に係るシングルコア光ファイバの長手方向に垂直な断面を示す図である。It is a figure showing the section perpendicular to the longitudinal direction of the single core optical fiber concerning the embodiment of the present invention. 図１のシングルコア光ファイバの製造方法を示すフローチャートである。It is a flowchart which shows the manufacturing method of the single core optical fiber of FIG. 複数のガラスロッドの束を示す斜視図である。It is a perspective view showing a bundle of a plurality of glass rods. 複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods. 複数のガラスロッドの束の端面にダミーガラスロッドが固定された様子を示す斜視図である。It is a perspective view which shows a mode that the dummy glass rod was fixed to the end surface of the bundle | flux of several glass rods. 外付工程の様子を示す図である。It is a figure which shows the mode of an external attachment process. 外付工程後の様子を示す図である。It is a figure which shows the mode after an external attachment process. 本発明の実施形態に係るシングルコア光ファイバ用母材の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the preform | base_material for single core optical fiber which concerns on embodiment of this invention. 線引工程の様子を示す図である。It is a figure which shows the mode of a drawing process. 本発明の変形例に係るバンドル工程後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods after the bundle process which concerns on the modification of this invention. 本発明の他の変形例に係るバンドル工程後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods after the bundle process which concerns on the other modification of this invention. 本発明のさらに他の変形例に係るバンドル工程後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods after the bundle process which concerns on the other modification of this invention. 本発明のさらに他の変形例に係るバンドル工程後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods after the bundle process which concerns on the further another modification of this invention. 本発明のさらに他の変形例に係るバンドル工程後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods after the bundle process which concerns on the other modification of this invention.
　以下、本発明に係るシングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法の好適な実施形態について図面を参照しながら詳細に説明する。 BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for producing a single-core optical fiber preform and the method for producing a single-core optical fiber according to the present invention will be described in detail below with reference to the drawings.
　図１は、本発明の実施形態に係るシングルコア光ファイバの長手方向に垂直な断面を示す図である。図１に示すように、本実施形態のシングルコア光ファイバ１は、コア１０と、コア１０の外周面を隙間なく囲むクラッド２０と、クラッド２０の外周面を被覆する保護層３０とを主な構成として備える。本実施形態のシングルコア光ファイバ１では、コア１０は、クラッド２０の中心に配置されている。また、クラッド２０は、コア１０の外周面を隙間なく囲む内側クラッド２１と内側クラッド２１の外周面を被覆する外側クラッド２２とを備え、シングルコア光ファイバ１は、いわゆるダブルクラッド構造とされている。内側クラッド２１の屈折率はコア１０の屈折率よりも低く、外側クラッド２２の屈折率は内側クラッド２１の屈折率よりも低くされている。 FIG. 1 is a view showing a cross section perpendicular to the longitudinal direction of a single core optical fiber according to an embodiment of the present invention. As shown in FIG. 1, the single-core optical fiber 1 of the present embodiment mainly includes a core 10, a clad 20 surrounding the outer peripheral surface of the core 10 without a gap, and a protective layer 30 covering the outer peripheral surface of the clad 20. Prepare as a configuration. In the single core optical fiber 1 of the present embodiment, the core 10 is disposed at the center of the cladding 20. Further, the cladding 20 includes an inner cladding 21 surrounding the outer peripheral surface of the core 10 without a gap, and an outer cladding 22 covering the outer peripheral surface of the inner cladding 21. The single core optical fiber 1 has a so-called double cladding structure. . The refractive index of the inner cladding 21 is lower than the refractive index of the core 10, and the refractive index of the outer cladding 22 is lower than the refractive index of the inner cladding 21.
　また、シングルコア光ファイバ１の長手方向に垂直な断面において、内側クラッド２１の外形は非円形とされる。具体的には、内側クラッド２１の外形は、シングルコア光ファイバ１の長手方向に垂直な断面において、正六角形の各頂点が丸みを帯びて面取りされると共にそれぞれの辺が内側に丸みを帯びて湾曲した形状とされる。このような内側クラッド２１を構成する材料としては、例えば、何らドーパントが添加されていない純粋石英を挙げることができる。なお、内側クラッド２１を構成する材料には、屈折率を低下させるフッ素（Ｆ）等の元素が添加されてもよい。 Further, in the cross section perpendicular to the longitudinal direction of the single core optical fiber 1, the outer shape of the inner cladding 21 is non-circular. Specifically, in the cross section of the inner cladding 21 perpendicular to the longitudinal direction of the single core optical fiber 1, the apexes of the regular hexagon are rounded and chamfered, and the respective sides are rounded inward. It has a curved shape. As a material which comprises such an inner clad 21, pure quartz to which no dopant is added can be mentioned, for example. An element such as fluorine (F) that lowers the refractive index may be added to the material forming the inner cladding 21.
　本実施形態の外側クラッド２２は、樹脂から成り、樹脂としては例えば紫外線硬化性樹脂が挙げられる。 The outer cladding 22 of the present embodiment is made of a resin, and an example of the resin is an ultraviolet curable resin.
　また、本実施形態のシングルコア光ファイバ１は、増幅用光ファイバとされる。よって、コア１０を構成する材料としては、例えば、イッテルビウム（Ｙｂ）等の活性元素が添加された石英が挙げられる。このような活性元素としては、希土類元素が挙げられ、希土類元素としては、上記Ｙｂの他にツリウム（Ｔｍ）、セリウム（Ｃｅ）、ネオジウム（Ｎｄ）、ユーロピウム（Ｅｕ）、エルビウム（Ｅｒ）等が挙げられる。さらに活性元素として、希土類元素の他に、ビスマス（Ｂｉ）等を挙げることができる。また、コア１０を構成する材料には、屈折率を上昇させるゲルマニウム（Ｇｅ）等の元素が添加されてもよい。 Further, the single core optical fiber 1 of the present embodiment is an amplification optical fiber. Therefore, as a material which comprises the core 10, the quartz to which active elements, such as ytterbium (Yb), were added is mentioned, for example. Examples of such active elements include rare earth elements. Examples of rare earth elements include thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), erbium (Er), etc. in addition to Yb. It can be mentioned. In addition to the rare earth elements, bismuth (Bi) and the like can be mentioned as the active element. Moreover, elements, such as germanium (Ge) which raises a refractive index, may be added to the material which comprises the core 10. FIG.
　保護層３０を構成する材料としては、例えば、外側クラッド２２を構成する樹脂とは異なる紫外線硬化性樹脂が挙げられる。 As a material which comprises the protective layer 30, the ultraviolet curable resin different from resin which comprises the outer side clad 22 is mentioned, for example.
　次に、シングルコア光ファイバ１の製造方法について説明する。 Next, a method of manufacturing the single core optical fiber 1 will be described.
　図２は、図１のシングルコア光ファイバの製造方法を示すフローチャートである。図２に示すように、シングルコア光ファイバ１の製造方法は、バンドル工程Ｐ１、外付工程Ｐ２、焼結工程Ｐ３、線引工程Ｐ４を主な工程として備える。 FIG. 2 is a flowchart showing a method of manufacturing the single core optical fiber of FIG. As shown in FIG. 2, the method of manufacturing the single-core optical fiber 1 mainly includes a bundle process P1, an external process P2, a sintering process P3, and a drawing process P4.
　＜バンドル工程Ｐ１＞
　本工程は、複数のガラスロッドを束ねる工程である。図３は、複数のガラスロッドの束を示す斜視図である。また、図４は、複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本実施形態において、当該複数のガラスロッドは、コアロッド２、複数のクラッドロッド３、及び複数の充填用ガラスロッド４である。 <Bundle process P1>
This process is a process of bundling a plurality of glass rods. FIG. 3 is a perspective view showing a bundle of a plurality of glass rods. Moreover, FIG. 4 is a figure which shows the cross section perpendicular | vertical to the longitudinal direction of the bundle | flux of several glass rods. In the present embodiment, the plurality of glass rods are the core rod 2, the plurality of clad rods 3, and the plurality of filling glass rods 4.
　コアロッド２は、図１のシングルコア光ファイバ１のコア１０となるコア部１０Ｒとコア部１０Ｒの外周面を被覆する内側クラッド２１の一部となるクラッドガラス層２０Ｒとを有する円柱状のガラスロッドである。コアロッド２のコア部１０Ｒは、コア１０となるためコア１０と同じ材料から構成される。また、クラッドガラス層２０Ｒは内側クラッド２１の一部となるため内側クラッド２１と同じ材料から構成される。 The core rod 2 is a cylindrical glass rod having a core portion 10R to be the core 10 of the single core optical fiber 1 of FIG. 1 and a clad glass layer 20R to be a part of the inner cladding 21 covering the outer peripheral surface of the core portion 10R. It is. The core 10 R of the core rod 2 is made of the same material as the core 10 because it becomes the core 10. Further, since the clad glass layer 20R is a part of the inner clad 21, it is made of the same material as the inner clad 21.
　複数のクラッドロッド３は、それぞれ内側クラッド２１の一部となる円柱状のガラスロッドである。本実施形態では、６本のクラッドロッド３が用意される。また、それぞれのクラッドロッド３は、互いに同じ直径とされる円柱状のガラスロッドであり、同じ材料で構成される。また、それぞれのクラッドロッド３は、内側クラッド２１の一部となるため、内側クラッド２１と同様の材料から構成される。したがって、それぞれのクラッドロッド３の屈折率は、コア部１０Ｒの屈折率よりも屈折率も低い。 Each of the plurality of clad rods 3 is a cylindrical glass rod which is a part of the inner clad 21. In the present embodiment, six clad rods 3 are prepared. Further, each clad rod 3 is a cylindrical glass rod having the same diameter as each other, and is made of the same material. Further, since each clad rod 3 is a part of the inner clad 21, it is made of the same material as the inner clad 21. Therefore, the refractive index of each clad rod 3 is also lower than the refractive index of the core portion 10R.
　複数の充填用ガラスロッド４は、それぞれ内側クラッド２１の一部となる円柱状のガラスロッドである。本実施形態では、６本の充填用ガラスロッド４が用意される。また、それぞれの充填用ガラスロッド４は、互いに同じ直径とされ、クラッドロッド３よりも小径の円柱状のガラスロッドである。また、それぞれの充填用ガラスロッド４は、同じ材料で構成され、内側クラッド２１の一部となるため内側クラッド２１と同様の材料から構成される。したがって、それぞれの充填用ガラスロッド４の屈折率は、コア部１０Ｒの屈折率よりも低い。また、本実施形態では、クラッドガラス層２０Ｒ、クラッドロッド３、及び、充填用ガラスロッド４は、同じシリカガラスから構成される。 Each of the plurality of filling glass rods 4 is a cylindrical glass rod which is a part of the inner clad 21. In the present embodiment, six filling glass rods 4 are prepared. Further, the respective filling glass rods 4 are cylindrical glass rods having the same diameter as each other and smaller in diameter than the clad rod 3. Further, each filling glass rod 4 is made of the same material and is made of the same material as the inner cladding 21 to be a part of the inner cladding 21. Therefore, the refractive index of each of the filling glass rods 4 is lower than the refractive index of the core portion 10R. Further, in the present embodiment, the clad glass layer 20R, the clad rod 3, and the filling glass rod 4 are made of the same silica glass.
　上記複数のガラスロッドを用意し、次にこれらのガラスロッドを束ねる位置に配置する。図３及び図４に示すように、それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共に、コアロッド２の中心を中心としてコアロッド２を囲う正六角形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３は外周面が離間しており、互いに隣り合うクラッドロッド３の間に充填用ガラスロッド４が配置される。このように配置されるそれぞれの充填用ガラスロッド４は、互いに隣り合うクラッドロッド３のそれぞれの外周面に接する接線で形成される正六角形の内側に収まるように配置される。当該正六角形は、図４において破線で示される。また、それぞれの充填用ガラスロッド４は、コアロッド２の外周面に接すると共に互いに隣り合うクラッドロッド３のそれぞれの外周面に接するように配置される。 The above plurality of glass rods are prepared, and then placed at the bundling position. As shown in FIGS. 3 and 4, each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a regular hexagon surrounding the core rod 2 with the center of the core rod 2 as a center. . Further, the clad rods 3 adjacent to each other are separated from each other in the outer peripheral surface, and the glass rod 4 for filling is disposed between the clad rods 3 adjacent to each other. The respective filling glass rods 4 arranged in this manner are arranged so as to be accommodated inside the regular hexagon formed by the tangent lines in contact with the respective outer peripheral surfaces of the adjacent clad rods 3. The regular hexagon is indicated by a broken line in FIG. Each filling glass rod 4 is disposed in contact with the outer peripheral surface of the core rod 2 and in contact with the respective outer peripheral surfaces of the clad rods 3 adjacent to each other.
　そして、上記のように束ねられる位置に配置された複数のガラスロッドを結束バンド５１により結束する。結束バンド５１は、樹脂製であっても金属製であっても良いが、ガラスロッドの外周面に傷がつくことを抑制する観点では樹脂製であることが好ましく、耐熱性が高い点においては金属製であることが好ましい。こうして、図３に示すように複数のガラスロッドが結束された状態となる。 Then, the plurality of glass rods arranged at the bundling position as described above are bound by the binding band 51. The binding band 51 may be made of resin or metal, but it is preferable to be made of resin from the viewpoint of preventing the outer peripheral surface of the glass rod from being scratched, and it is high heat resistance. It is preferably made of metal. Thus, as shown in FIG. 3, a plurality of glass rods are bound.
　次に結束された複数のガラスロッドの両端部にダミーガラスロッドを固定する。図５は、このように複数のガラスロッドが固定された様子を示す図である。まず、複数のガラスロッドが結束バンド５１で結束された状態で、それぞれのガラスロッドの一方の端部に１つのダミーガラスロッド５２を固定する。次に、それぞれのガラスロッドの他方の端部に他の１つのダミーガラスロッド５２を固定する。ガラスロッドに不純物が付着することを抑制する観点からは、この固定は溶着によって行われることが好ましい。このようにそれぞれのガラスロッドの両端にダミーガラスロッド５２を固定することで、それぞれのガラスロッドが束ねられた状態を維持することができる。次に、それぞれのガラスロッドを結束していた結束バンド５１を外す。こうして、図５に示すように複数のガラスロッドが束ねられた状態となる。 Next, dummy glass rods are fixed to both ends of the plurality of glass rods bound together. FIG. 5 is a view showing how a plurality of glass rods are thus fixed. First, one dummy glass rod 52 is fixed to one end of each glass rod in a state where the plurality of glass rods are bound by the binding band 51. Next, one other dummy glass rod 52 is fixed to the other end of each glass rod. From the viewpoint of suppressing the adhesion of impurities to the glass rod, this fixing is preferably performed by welding. By fixing the dummy glass rods 52 at both ends of the respective glass rods in this manner, the state in which the respective glass rods are bundled can be maintained. Next, the binding band 51 binding the respective glass rods is removed. Thus, as shown in FIG. 5, a plurality of glass rods are bundled.
　なお、本工程は結束バンド５１を用いてそれぞれのガラスロッドを束ねた後、ダミーガラスロッド５２をそれぞれのガラスロッドに溶着したが、必ずしもこのような手順とする必要はない。例えば、１つのガラスロッドの両端にダミーガラスロッド５２を適切な位置に固定する。次に他の１つのガラスロッドを既にダミーガラスロッド５２に固定されているガラスロッドと隣り合うように配置して、配置された他の１つのガラスロッドの両端をそれぞれのダミーガラスロッド５２に固定する。これを繰り返して全てのガラスロッドを適切な位置でダミーガラスロッド５２に固定する。このようにそれぞれのガラスロッドをダミーガラスロッド５２に固定しても、図５に示すように複数のガラスロッドが束ねられた状態となる。 In this process, after bundling the respective glass rods with the use of the binding band 51, the dummy glass rods 52 are welded to the respective glass rods, but such a procedure is not necessarily required. For example, the dummy glass rods 52 are fixed at appropriate positions at both ends of one glass rod. Then, one other glass rod is arranged adjacent to the glass rod already fixed to the dummy glass rod 52, and both ends of the other arranged glass rod are fixed to the respective dummy glass rod 52 Do. This is repeated to fix all the glass rods to the dummy glass rods 52 at appropriate positions. As described above, even if each glass rod is fixed to the dummy glass rod 52, a plurality of glass rods are bundled as shown in FIG.
　＜外付工程Ｐ２＞
　図６は外付工程Ｐ２の様子を示す図である。外付工程Ｐ２は、例えば、ＯＶＤ（Outside vapor deposition method）法により行い、バンドル工程Ｐ１で束ねられた複数のガラスロッドの外周面上に内側クラッド２１の一部となるスートを堆積する。 <External attachment process P2>
FIG. 6 is a view showing the appearance of the external attachment process P2. The external attachment process P2 is performed, for example, by the outside vapor deposition method (OVD), and deposits soot to be a part of the inner cladding 21 on the outer peripheral surface of the plurality of glass rods bundled in the bundle process P1.
　まず、それぞれのダミーガラスロッド５２を不図示の旋盤のチャックに固定して、束ねられた複数のガラスロッドをダミーガラスロッド５２の軸中心に回転させる。そして、図６に示すように複数のガラスロッドを回転させながら、内側クラッド２１となるスートを堆積する。図７は、外付工程Ｐ２後の様子を示す図である。 First, each dummy glass rod 52 is fixed to a chuck of a lathe (not shown), and a plurality of bundled glass rods are rotated about the axis of the dummy glass rod 52. Then, while rotating a plurality of glass rods as shown in FIG. 6, soot to be the inner clad 21 is deposited. FIG. 7 is a view showing a state after the external attachment process P2.
　本工程で堆積するスート５は、流量が制御されたキャリアガスにより、気化されたＳｉＣｌ４を酸水素バーナ５３の火炎中に導入してＳｉＣｌ４からＳｉＯ２（シリカガラス）とする。これと共に、酸水素バーナ５３をガラスロッドの長手方向に複数回往復移動させながら、ＳｉＯ２のスート５をそれぞれのガラスロッドの外周面を被覆するように堆積する。このスート５の堆積により、内側クラッド２１の一部となるガラス多孔体が形成される。なお、本実施形態では、スート５はクラッドガラス層２０Ｒ、クラッドロッド３、充填用ガラスロッド４と同様のシリカガラスから構成される。従って、内側クラッド２１が上記のように何らドーパントが添加されないシリカガラスにより構成される場合には、特にドーパントを加えずにスート５を堆積する。また、内側クラッド２１がドーパントが添加されたシリカガラスとされる場合には、スート５にドーパントを添加する。この場合、気化されたＳｉＣｌ４と共に添加量がコントロールされたドーパントを含有するガスを酸水素バーナの火炎内に導入する。上記のように内側クラッド２１がフッ素が添加されたシリカガラスにより構成され、スート５にもフッ素を添加する場合には、気化されたＳｉＣｌ４と共に気化されたＳｉＦ４を酸水素バーナの火炎内に導入する。 In the soot 5 deposited in this step, the vaporized SiCl 4 is introduced into the flame of the oxyhydrogen burner 53 by the carrier gas whose flow rate is controlled to change it from SiCl 4 to SiO 2 (silica glass). At the same time, while reciprocating the oxyhydrogen burner 53 in the longitudinal direction of the glass rod a plurality of times, the SiO 2 soot 5 is deposited so as to cover the outer peripheral surface of each glass rod. The deposition of the soot 5 forms a porous glass body that becomes a part of the inner cladding 21. In the present embodiment, the soot 5 is made of the same glass glass as the clad glass layer 20R, the clad rod 3, and the filling glass rod 4. Therefore, when the inner cladding 21 is composed of silica glass to which no dopant is added as described above, the soot 5 is deposited without adding any dopant. When the inner cladding 21 is made of silica glass to which a dopant is added, the dopant is added to the soot 5. In this case, a gas containing a controlled amount of dopant is introduced into the flame of the oxyhydrogen burner together with the vaporized SiCl 4 . As described above, when the inner cladding 21 is made of fluorine-doped silica glass, and fluorine is also added to the soot 5, SiF 4 vaporized together with the vaporized SiCl 4 is put into the flame of the oxyhydrogen burner Introduce.
　こうして図７に示すように束ねられた複数のガラスロッドの外周面上にスート５が堆積された状態となる。本実施形態では、スート５は、複数のガラスロッドの長手方向に垂直な断面において、コアロッド２の中心を中心とする正六角形の頂点が丸みを帯びて面取りされると共にそれぞれの辺が内側に丸みを帯びて湾曲した領域に堆積される。 Thus, the soot 5 is deposited on the outer peripheral surfaces of the plurality of glass rods bundled as shown in FIG. In the present embodiment, in the cross section perpendicular to the longitudinal direction of the plurality of glass rods, the apex of the regular hexagon centered on the center of the core rod 2 is rounded and chamfered and the respective sides are rounded inward Is deposited on the curved and curved area.
　＜焼結工程Ｐ３＞
　図７に示すようにスート５が堆積した後、焼結工程Ｐ３に先立って、必要に応じて脱水処理を行う。当該脱水処理は、ヒータが設けられ、Ａｒ、Ｈｅ等のガスが充填された炉内で所定時間エージングされることで行われる。 <Sintering process P3>
After the soot 5 is deposited as shown in FIG. 7, dehydration treatment is performed as needed prior to the sintering step P3. The said dehydration process is performed by being provided with a heater and being aged for a predetermined time in the furnace filled with gas, such as Ar and He.
　次に焼結工程Ｐ３を行う。焼結工程Ｐ３は、外周面上にスート５が堆積した複数のガラスロッドを加熱してスート５とそれぞれのガラスロッドとを一体のガラス体とする工程である。焼結工程Ｐ３では、上記脱水処理を行う場合よりも炉内の温度を更に高くして堆積されたスート５から成るガラス多孔体が透明なガラス体となるまで焼結を行う。このとき用いる炉は上記脱水処理に用いる炉であっても良く、上記脱水処理に用いる炉と異なる炉であっても良い。こうして、図８に示すシングルコア光ファイバ用母材１Ｐを得る。なお、コアロッド２、クラッドロッド３、充填用ガラスロッド４及びスート５がシングルコア光ファイバ用母材１Ｐになる際に、コアロッド２のコア部１０Ｒは殆ど変形することなくシングルコア光ファイバ用母材１Ｐの母材コア部１０Ｐとなる。また、コアロッド２のクラッドガラス層２０Ｒ、複数のクラッドロッド３、複数の充填用ガラスロッド４及びスート５のそれぞれがシングルコア光ファイバ用母材１Ｐの母材クラッド部２０Ｐの一部となる。 Next, the sintering step P3 is performed. The sintering step P3 is a step of heating the plurality of glass rods in which the soot 5 is deposited on the outer peripheral surface to make the soot 5 and the respective glass rods into an integral glass body. In the sintering step P3, sintering is performed until the temperature of the inside of the furnace is made higher than in the case of performing the above-described dehydration treatment so that the porous glass body of the soot 5 deposited becomes a transparent glass body. The furnace used at this time may be a furnace used for the above-mentioned dehydration processing, and may be a furnace different from the furnace used for the above-mentioned dehydration processing. Thus, a single core optical fiber preform 1P shown in FIG. 8 is obtained. When the core rod 2, the clad rod 3, the glass rod 4 for filling and the soot 5 become the base material 1 P for single core optical fiber, the core portion 10 R of the core rod 2 hardly deforms the base material for single core optical fiber It becomes base material core part 10P of 1P. Further, each of the clad glass layer 20R of the core rod 2, the plurality of clad rods 3, the plurality of filling glass rods 4 and the suit 5 is a part of the base clad part 20P of the single core optical fiber base material 1P.
　こうして得られたシングルコア光ファイバ用母材１Ｐの長手方向に垂直な断面の外形は非円形とされる。具体的には、シングルコア光ファイバ用母材１Ｐの長手方向に垂直な断面の外形は、複数のガラスロッドの束の長手方向に垂直な断面の外形に起因する形状とされる。本実施形態では、複数のクラッドロッド３のそれぞれが正六角形の各頂点と重なる位置に配置されると共に複数の充填用ガラスロッド４のそれぞれが複数のクラッドロッド３を囲う正六角形の内側に配置される。そのため、シングルコア光ファイバ用母材１Ｐの外形は、母材コア部１０Ｐの中心を中心とする正六角形の頂点が丸みを帯びて面取りされると共にそれぞれの辺が内側に丸みを帯びて湾曲した形状とされる。 The outer shape of the cross section perpendicular to the longitudinal direction of the single core optical fiber preform 1P thus obtained is non-circular. Specifically, the outer shape of the cross section perpendicular to the longitudinal direction of the single core optical fiber preform 1P is a shape resulting from the outer shape of the cross section perpendicular to the longitudinal direction of the bundle of the plurality of glass rods. In the present embodiment, each of the plurality of cladding rods 3 is disposed at a position overlapping each vertex of the regular hexagon, and each of the plurality of filling glass rods 4 is disposed inside the regular hexagon surrounding the plurality of cladding rods 3. Ru. Therefore, in the outer shape of the single core optical fiber base material 1P, the apex of the regular hexagon centered on the center of the base material core portion 10P is rounded and chamfered, and each side is curved inward and curved. It will be shaped.
　なお、クラッドガラス層２０Ｒ、クラッドロッド３、充填用ガラスロッド４が上記のようにフッ素が添加されたシリカガラスから成る場合には、本工程をフッ素系ガスを含む雰囲気で行っても良い。具体的には、本工程を行う炉内にＳｉＦ４，ＣＦ４，Ｃ２Ｆ６等のフッ素系ガスを導入する。このような工程とすることで、スート５から成るガラス多孔体が粘性流動を起こす際にスート５内に由来するガラス体にフッ素が添加される傾向にある。 When the clad glass layer 20R, the clad rod 3, and the filling glass rod 4 are made of silica glass to which fluorine is added as described above, this process may be performed in an atmosphere containing a fluorine-based gas. Specifically, a fluorine-based gas such as SiF 4 , CF 4 , C 2 F 6 or the like is introduced into a furnace for performing this step. In such a process, when the glass porous body made of soot 5 causes viscous flow, fluorine tends to be added to the glass body derived from the soot 5.
　＜線引工程Ｐ４＞
　図９は、線引工程Ｐ４の様子を示す図である。まず、線引工程Ｐ４を行う準備段階として、上記工程により製造されるシングルコア光ファイバ用母材１Ｐを紡糸炉１１０に設置する。 <Drawing process P4>
FIG. 9 is a diagram showing the drawing process P4. First, as a preparatory step of performing the drawing step P4, the single core optical fiber preform 1P manufactured by the above step is installed in the spinning furnace 110.
　次に、紡糸炉１１０の加熱部１１１を発熱させて、シングルコア光ファイバ用母材１Ｐを加熱する。このときシングルコア光ファイバ用母材１Ｐの下端は、例えば２０００℃に加熱され溶融状態となる。そして、シングルコア光ファイバ用母材１Ｐからガラスが溶融して、ガラスが線引きされる。そして、線引きされた溶融状態のガラスは、紡糸炉１１０から出ると、すぐに固化して、母材コア部１０Ｐがコア１０となり、母材クラッド部２０Ｐがクラッド２０となることで、コア１０とクラッド２０とから構成されるシングルコア光ファイバ素線となる。なお、図８には空隙が非形成のシングルコア光ファイバ用母材１Ｐを例示しているが、シングルコア光ファイバ用母材１Ｐに空隙が形成されている場合、本工程において減圧したり溶融ガラスの表面張力を利用したりして当該空隙が潰されることが好ましい。 Next, the heating unit 111 of the spinning furnace 110 is caused to generate heat to heat the single core optical fiber preform 1P. At this time, the lower end of the single-core optical fiber base material 1P is heated to, for example, 2000 ° C. to be in a molten state. Then, the glass is melted from the single core optical fiber base material 1P, and the glass is drawn. Then, the drawn glass in the molten state is solidified immediately upon leaving the spinning furnace 110, and the base material core portion 10P becomes the core 10, and the base material clad portion 20P becomes the cladding 20. It becomes a single core optical fiber strand composed of the clad 20. Although FIG. 8 exemplifies the single core optical fiber base material 1P in which no air gap is formed, when the air gap is formed in the single core optical fiber base material 1P, the pressure is reduced or melted in this process. It is preferable that the space is crushed by utilizing the surface tension of glass.
　上記のようにシングルコア光ファイバ素線が作製された後、このシングルコア光ファイバ素線は、冷却装置１２０を通過して、適切な温度まで冷却される。冷却装置１２０に入る際、シングルコア光ファイバ素線の温度は、例えば１８００℃程度であるが、冷却装置１２０を出る際には、シングルコア光ファイバ素線の温度は、例えば４０℃～５０℃となる。 After the single core optical fiber strand is manufactured as described above, this single core optical fiber strand passes through the cooling device 120 and is cooled to an appropriate temperature. When entering the cooling device 120, the temperature of the single-core optical fiber strand is, for example, about 1800 ° C, but when leaving the cooling device 120, the temperature of the single-core optical fiber strand is, for example, 40 ° C to 50 ° C. It becomes.
　冷却装置１２０から出たシングルコア光ファイバ素線は、外側クラッド２２となる紫外線硬化性樹脂が入ったコーティング装置１３１を通過し、この紫外線硬化性樹脂で被覆される。更に紫外線照射装置１３２を通過し、紫外線が照射されることで、紫外線硬化性樹脂が硬化して外側クラッド２２が形成される。次に外側クラッド２２で被覆されたマルチコアファイバは、保護層３０となる紫外線硬化性樹脂が入ったコーティング装置１３３を通過し、この紫外線硬化性樹脂で被覆される。更に紫外線照射装置１３４を通過し、紫外線が照射されることで、紫外線硬化性樹脂が硬化して保護層３０が形成され、図１に示すシングルコア光ファイバ１となる。 The single core optical fiber strand coming out of the cooling device 120 passes through the coating device 131 containing the ultraviolet curable resin to be the outer clad 22 and is coated with this ultraviolet curable resin. Furthermore, by passing through the ultraviolet irradiation device 132 and being irradiated with ultraviolet light, the ultraviolet curable resin is cured to form the outer clad 22. Next, the multi-core fiber coated with the outer cladding 22 passes through the coating device 133 containing the ultraviolet curable resin to be the protective layer 30, and is coated with the ultraviolet curable resin. Furthermore, by passing through the ultraviolet irradiation device 134 and being irradiated with ultraviolet light, the ultraviolet curable resin is cured to form the protective layer 30, and the single core optical fiber 1 shown in FIG.
　そして、シングルコア光ファイバ１は、ターンプーリー１４１により方向が変換され、リール１４２により巻取られる。 Then, the direction of the single core optical fiber 1 is converted by the turn pulley 141, and the single core optical fiber 1 is wound by the reel 142.
　このようにして、図１に示すシングルコア光ファイバ１が製造される。 Thus, the single core optical fiber 1 shown in FIG. 1 is manufactured.
　以上説明したように、本実施形態のシングルコア光ファイバ用母材１Ｐの製造方法は、コア１０となるコア部１０Ｒを有するコアロッド２、及び、クラッド２０の一部である内側クラッド２１の一部となる複数のクラッドロッド３、を含む複数のガラスロッドを束ねるバンドル工程Ｐ１と、束ねられた複数のガラスロッドの外周面上に内側クラッド２１の他の一部となるスート５を堆積する外付工程Ｐ２と、スート５が堆積した複数のガラスロッドを加熱してスート５とそれぞれのガラスロッドとを一体のガラス体とする焼結工程Ｐ３と、を備える。また、バンドル工程Ｐ１において、複数のクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正六角形のそれぞれの頂点と重なる位置に配置される。 As described above, in the method of manufacturing the base material 1P for a single core optical fiber according to this embodiment, the core rod 2 having the core portion 10R to be the core 10 and a part of the inner clad 21 which is a part of the clad 20. A bundle process P1 for bundling a plurality of glass rods including a plurality of clad rods 3 and an outer attachment for depositing a soot 5 to be another part of the inner cladding 21 on the outer peripheral surface of the plurality of glass rods bundled. And a sintering step P3 in which the plurality of glass rods on which the soot 5 is deposited are heated to make the soot 5 and the respective glass rods into an integral glass body. Further, in the bundle process P1, the plurality of clad rods 3 are disposed in contact with the outer peripheral surface of the core rod 2 and at positions overlapping respective apexes of regular hexagons surrounding the core rod 2.
　束ねられた複数のガラスロッドの外周面上にスート５を堆積することによって、スート５は複数のガラスロッドの束の外周面に沿って堆積し易い。このため、上記のようにコアロッド２の周りに複数のクラッドロッド３が配置された状態でスート５を堆積させることにより、コアロッド２の長手方向に垂直な断面において、スート５が堆積した部分の外周形状はコアロッド２を囲う正六角形の角を丸めた形状と成り得る。すなわち、コアロッド２の長手方向に垂直な断面において、スート５はコアロッド２を囲う非円形の領域に堆積され得る。また、このように堆積したスート５を焼結させて複数のガラスロッドと一体化させることによって、長手方向に垂直な断面形状が非円形のシングルコア光ファイバ用母材１Ｐを製造することができる。さらに、このシングルコア光ファイバ用母材１Ｐの長さはガラスロッドの長さを調整することで調整され得るため、シングルコア光ファイバ用母材１Ｐの長さを大きくし得る。よって、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材１Ｐを製造し得る。 By depositing the soot 5 on the outer peripheral surface of the plurality of bundled glass rods, the soot 5 is easily deposited along the outer peripheral surface of the bundle of the plurality of glass rods. Therefore, by depositing the soot 5 in a state where the plurality of clad rods 3 are disposed around the core rod 2 as described above, the outer periphery of the portion where the soot 5 is deposited in the cross section perpendicular to the longitudinal direction of the core rod 2 The shape may be a shape obtained by rounding the corners of a regular hexagon surrounding the core rod 2. That is, in a cross section perpendicular to the longitudinal direction of the core rod 2, the soot 5 can be deposited in a non-circular area surrounding the core rod 2. Further, by sintering the soot 5 deposited in this way and integrating it with a plurality of glass rods, it is possible to manufacture a single core optical fiber preform 1P having a non-circular cross-sectional shape perpendicular to the longitudinal direction. . Furthermore, since the length of the single core optical fiber preform 1P can be adjusted by adjusting the length of the glass rod, the length of the single core optical fiber preform 1P can be increased. Accordingly, it is possible to manufacture a single core optical fiber preform 1P having a non-circular cross-sectional shape perpendicular to the longitudinal direction and a large length.
　また、本実施形態では、それぞれのクラッドロッド３は互いに同じ直径とされ、バンドル工程Ｐ１において、それぞれのクラッドロッド３は、コアロッド２の中心を中心とする正六角形のそれぞれの頂点と重なる位置に配置される。このように複数のクラッドロッド３が配置された状態でスート５を堆積させることにより、コアロッド２の長手方向に垂直な断面において、スート５はコアロッド２を中心とする領域に堆積され得る。また、このように堆積したスート５を焼結させて複数のガラスロッドと一体化させることによって、コアロッド２のコア部１０Ｒからなる母材コア部１０Ｐと中心軸とが一致するシングルコア光ファイバ用母材１Ｐを製造し得る。このようなシングルコア光ファイバ用母材１Ｐを用いることによって、クラッド２０の中心にコア１０が配置されたシングルコア光ファイバ１を製造し得る。 Further, in the present embodiment, the respective clad rods 3 have the same diameter, and in the bundle process P1, the respective clad rods 3 are disposed at positions overlapping respective apexes of the regular hexagon centered on the center of the core rod 2 Be done. By depositing the soot 5 with the plurality of clad rods 3 arranged in this manner, the soot 5 can be deposited in a region centered on the core rod 2 in a cross section perpendicular to the longitudinal direction of the core rod 2. Moreover, by sintering the soot 5 deposited in this way and integrating it with a plurality of glass rods, for a single core optical fiber in which the base material core portion 10P consisting of the core portion 10R of the core rod 2 coincides with the central axis. Base material 1P can be manufactured. By using such a single-core optical fiber preform 1P, a single-core optical fiber 1 in which the core 10 is disposed at the center of the clad 20 can be manufactured.
　また、本実施形態では、バンドル工程Ｐ１において、互いに隣り合うクラッドロッド３の外周面が離間するように配置される。同じ数のクラッドロッド３が用いられる場合において、このように複数のクラッドロッド３が互いに離間するように配置されると、複数のクラッドロッド３が互いに接するように配置される場合よりも直径が大きなコアロッド２を用いることができる。そのため、同一のファイバ径で比較した場合にコア１０の直径が大きなシングルコア光ファイバ１が製造され得る。 Moreover, in this embodiment, in the bundle process P1, it arrange | positions so that the outer peripheral surface of the clad rod 3 which adjoins each other may space apart. In the case where the same number of clad rods 3 are used, when the plurality of clad rods 3 are arranged to be separated from each other in this manner, the diameter is larger than that in the case where the plurality of clad rods 3 are arranged to be in contact with each other. The core rod 2 can be used. Therefore, the single core optical fiber 1 having a large diameter of the core 10 can be manufactured when compared with the same fiber diameter.
　また、本実施形態では、バンドル工程Ｐ１において、充填用ガラスロッド４がクラッドロッド３の外周面に接するように配置される。このように充填用ガラスロッド４が少なくとも１本のクラッドロッド３の外周面に接するように配置されることによって、焼結工程Ｐ３において充填用ガラスロッド４及びクラッドロッド３の変形が抑制され得る。 Further, in the present embodiment, the glass rod 4 for filling is disposed in contact with the outer peripheral surface of the clad rod 3 in the bundle process P1. By arranging the filling glass rod 4 to be in contact with the outer peripheral surface of at least one clad rod 3 in this manner, deformation of the filling glass rod 4 and the clad rod 3 can be suppressed in the sintering step P3.
　また、本実施形態では、バンドル工程Ｐ１において、充填用ガラスロッド４はコアロッド２の外周面に接するように配置される。このように充填用ガラスロッド４及びコアロッド２が配置されることによって、焼結工程Ｐ３において充填用ガラスロッド４及びコアロッド２の変形が抑制され得る。 Further, in the present embodiment, the glass rod 4 for filling is disposed in contact with the outer peripheral surface of the core rod 2 in the bundle process P1. By arranging the filling glass rod 4 and the core rod 2 in this manner, deformation of the filling glass rod 4 and the core rod 2 can be suppressed in the sintering step P3.
　また、本実施形態では、バンドル工程Ｐ１において、充填用ガラスロッド４は互いに隣り合うクラッドロッド３のそれぞれの外周面に接するように配置される。このように充填用ガラスロッド４及びクラッドロッド３が配置されることによって、互いに隣り合うクラッドロッド３の一方にのみ充填用ガラスロッド４が接する場合に比べて、焼結工程Ｐ３において充填用ガラスロッド４及びクラッドロッド３の変形がより抑制され得る。 Further, in the present embodiment, in the bundling step P1, the filling glass rods 4 are disposed in contact with the respective outer peripheral surfaces of the clad rods 3 adjacent to each other. By arranging the filling glass rod 4 and the clad rod 3 in this manner, the filling glass rod in the sintering step P3 is compared to the case where the filling glass rod 4 contacts only one of the clad rods 3 adjacent to each other. The deformation of 4 and the clad rod 3 can be further suppressed.
　また、本実施形態では、コアロッド２は、コア部１０Ｒの外周面にクラッド２０の一部となるクラッドガラス層２０Ｒを有する。このようにコアロッド２がクラッドガラス層２０Ｒを有することによって、バンドル工程Ｐ１においてコアロッド２のコア部１０Ｒが傷つくことが抑制され得る。ただし、クラッドガラス層２０Ｒは必須の構成ではない。 Further, in the present embodiment, the core rod 2 has a clad glass layer 20R which is a part of the clad 20 on the outer peripheral surface of the core portion 10R. As described above, the core rod 2 having the clad glass layer 20R can prevent the core portion 10R of the core rod 2 from being damaged in the bundling process P1. However, the clad glass layer 20R is not an essential component.
　また、本実施形態では、バンドル工程Ｐ１において、コア部１０Ｒよりも屈折率が低くクラッドロッド３よりも直径が小さい充填用ガラスロッド４が、互いに隣り合うクラッドロッド３の外周面に接する接線によって複数のクラッドロッド３を囲うように形成される正六角形の内側に配置される。このように充填用ガラスロッド４が配置されることによって、シングルコア光ファイバ用母材１Ｐの長手方向に垂直な断面形状が正六角形に近付けられ得る。 Further, in the present embodiment, in the bundle process P1, a plurality of filling glass rods 4 having a refractive index lower than that of the core portion 10R and a diameter smaller than that of the clad rods 3 contact a plurality of tangents to the outer peripheral surface of the clad rods 3 adjacent to each other. Is disposed inside a regular hexagon formed to surround the clad rods 3 of the above. By arranging the filling glass rods 4 in this manner, the cross-sectional shape perpendicular to the longitudinal direction of the single-core optical fiber preform 1P can be made close to a regular hexagon.
　また、本実施形態のシングルコア光ファイバ１の製造方法は、上記実施形態のシングルコア光ファイバ用母材１Ｐの製造方法により製造されるシングルコア光ファイバ用母材１Ｐを線引きする線引工程Ｐ４を備える。上記のように、本実施形態のシングルコア光ファイバ用母材１Ｐの製造方法によれば、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材１Ｐを製造し得る。よって、当該シングルコア光ファイバ用母材１Ｐを用いることによって、上記のように内側クラッド２１の断面形状が非円形で長尺のシングルコア光ファイバ１を製造し得る。 Further, the method of manufacturing the single core optical fiber 1 of the present embodiment is a drawing step P4 of drawing the single core optical fiber base material 1P manufactured by the method of manufacturing the single core optical fiber base material 1P of the above embodiment. Equipped with As described above, according to the method of manufacturing the base material 1P for a single core optical fiber of the present embodiment, the base material 1P for a single core optical fiber having a non-circular cross section perpendicular to the longitudinal direction and a large length is manufactured obtain. Therefore, by using the single-core optical fiber preform 1P, as described above, the long single-core optical fiber 1 can be manufactured in which the cross-sectional shape of the inner cladding 21 is noncircular.
　以上、本発明について、上記実施形態を例に説明したが、本発明はこれらに限定されるものではない。 As mentioned above, although the said embodiment was described to the example about this invention, this invention is not limited to these.
　例えば、上記実施形態では、バンドル工程Ｐ１において、それぞれのクラッドロッド３がコアロッド２の中心を中心とする正六角形のそれぞれの頂点と重なる位置に配置される例を挙げて説明したが、本発明はこれに限定されない。複数のクラッドロッド３は、コアロッド２を囲う多角形のそれぞれの頂点と重なる位置に配置されればよく、クラッドロッド３の数は３本以上であれば特に限定されない。すなわち、バンドル工程Ｐ１において、それぞれのクラッドロッド３は、クラッドロッド３の数と同じ数の角を有してコアロッド２を囲う多角形の各頂点と重なる位置に配置されればよい。ただし、当該多角形は、コアロッド２の中心を中心とする多角形であることが好ましく、また当該多角形は正多角形であることが好ましい。なお、クラッドロッド３の数が増えると当該多角形は円形に近付くこととなる。そのため、コアロッド２の長手方向に垂直な断面においてスート５が堆積される領域が円形に近付き、内側クラッド２１の断面形状も円形に近付く。内側クラッド２１の形状をスキュー光の発生を抑制するために効果的な形状とする観点から、クラッドロッド３の数は８本以下であることが好ましい。すなわち、上記多角形は、角の数が８以下の多角形であることが好ましい。 For example, in the above-described embodiment, in the bundle process P1, the clad rods 3 are described as being disposed at the positions overlapping the respective apexes of the regular hexagon centered on the center of the core rod 2, but the present invention It is not limited to this. The plurality of clad rods 3 may be disposed at positions overlapping the respective apexes of the polygon surrounding the core rod 2, and the number of clad rods 3 is not particularly limited as long as it is three or more. That is, in the bundle process P1, each clad rod 3 may be disposed at a position overlapping with each vertex of the polygon surrounding the core rod 2 with the same number of angles as the number of the clad rods 3. However, it is preferable that the said polygon is a polygon centering on the center of the core rod 2, and it is preferable that the said polygon is a regular polygon. When the number of clad rods 3 increases, the polygon will approach a circle. Therefore, in a cross section perpendicular to the longitudinal direction of the core rod 2, the area where the soot 5 is deposited approaches a circle, and the cross-sectional shape of the inner cladding 21 also approaches a circle. The number of clad rods 3 is preferably eight or less from the viewpoint of making the shape of the inner cladding 21 effective to suppress the generation of skew light. That is, the polygon is preferably a polygon having eight or less corners.
　図１０は、本発明の変形例に係るバンドル工程Ｐ１後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本変形例では、コアロッド２の周りに３本のクラッドロッド３が配置される。それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正三角形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３の間には２本の充填用ガラスロッド４が配置される。それぞれの充填用ガラスロッド４は、互いに隣り合うクラッドロッド３の外周面に接する接線によって複数のクラッドロッド３を囲うように形成される正三角形の内側に配置される。当該正三角形は、図１０において破線で示される。また、互いに隣り合う充填用ガラスロッド４は、外周面が接するように配置される。このように互いに隣り合うクラッドロッド３の間に複数の充填用ガラスロッド４が配置されることによって、互いに隣り合うクラッドロッド３の間の隙間が大きい場合でも当該隙間を充填用ガラスロッド４で埋めることができる。そのため、シングルコア光ファイバ用母材１Ｐの長手方向に垂直な断面形状が多角形に近付けられ得る。また、このようにバンドル工程Ｐ１において互いに隣り合うクラッドロッド３の間に複数の充填用ガラスロッド４が配置され、互いに隣り合う充填用ガラスロッド４の外周面が接することによって、焼結工程Ｐ３において充填用ガラスロッド４の変形が抑制され得る。 FIG. 10 is a view showing a cross section perpendicular to the longitudinal direction of the bundle of the plurality of glass rods after the bundle process P1 according to the modification of the present invention. In this modification, three clad rods 3 are arranged around the core rod 2. Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of an equilateral triangle surrounding the core rod 2. Further, two filling glass rods 4 are disposed between the clad rods 3 adjacent to each other. Each filling glass rod 4 is disposed inside an equilateral triangle formed so as to surround a plurality of cladding rods 3 by a tangent line in contact with the outer peripheral surface of the adjacent cladding rods 3. The equilateral triangle is shown by a broken line in FIG. Moreover, the glass rods 4 for filling which adjoin mutually are arrange | positioned so that an outer peripheral surface may contact | connect. By arranging a plurality of filling glass rods 4 between adjacent clad rods 3 as described above, even when the gap between adjacent clad rods 3 is large, the gap is filled with filling glass rods 4. be able to. Therefore, the cross-sectional shape perpendicular to the longitudinal direction of the single-core optical fiber preform 1P can be approximated to a polygon. In addition, as described above, the plurality of filling glass rods 4 are disposed between the clad rods 3 adjacent to each other in the bundling step P1, and the outer peripheral surfaces of the filling glass rods 4 adjacent to each other are in contact. The deformation of the filling glass rod 4 can be suppressed.
　図１１は、本発明の他の変形例に係るバンドル工程Ｐ１後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本変形例では、コアロッド２の周りに４本のクラッドロッド３が配置される。それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正方形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３の間には１本の充填用ガラスロッド４が配置される。それぞれの充填用ガラスロッド４は、互いに隣り合うクラッドロッド３の外周面に接する接線によって複数のクラッドロッド３を囲うように形成される正方形の内側に配置される。当該正方形は、図１１において破線で示される。 FIG. 11 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundling process P1 according to another modification of the present invention. In the present modification, four clad rods 3 are arranged around the core rod 2. Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a square surrounding the core rod 2. Further, one filling glass rod 4 is disposed between the clad rods 3 adjacent to each other. Each filling glass rod 4 is disposed inside a square formed so as to surround a plurality of cladding rods 3 by a tangent line contacting the outer peripheral surface of the adjacent cladding rods 3. The square is indicated by a broken line in FIG.
　図１２は、本発明のさらに他の変形例に係るバンドル工程Ｐ１後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本変形例では、コアロッド２の周りに４本のクラッドロッド３が配置される。それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正方形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３の外周面が接している。同じ数のクラッドロッド３が用いられる場合において、このように複数のクラッドロッド３が互いに接するように配置されると、複数のクラッドロッド３が互いに離間するように配置される場合に比べてそれぞれのクラッドロッド３の直径を大きくすることができる。そのため、厚いクラッド２０を有するシングルコア光ファイバ１が製造され得る。すなわち、コア１０の中心からクラッド２０の外周面までの距離が大きなシングルコア光ファイバ１が製造され得る。このようなシングルコア光ファイバ１では、曲げ損失やマイクロベントによる損失が抑制され得る。 FIG. 12 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention. In the present modification, four clad rods 3 are arranged around the core rod 2. Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a square surrounding the core rod 2. Further, the outer peripheral surfaces of the clad rods 3 adjacent to each other are in contact with each other. In the case where the same number of clad rods 3 are used, when the plurality of clad rods 3 are arranged to be in contact with each other in this manner, compared to the case where the plurality of clad rods 3 are arranged to be separated from each other. The diameter of the clad rod 3 can be increased. Therefore, a single core optical fiber 1 having a thick cladding 20 can be manufactured. That is, a single core optical fiber 1 having a large distance from the center of the core 10 to the outer peripheral surface of the cladding 20 can be manufactured. In such a single core optical fiber 1, bending loss and loss due to microbent can be suppressed.
　図１３は、本発明のさらに他の変形例に係るバンドル工程Ｐ１後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本変形例では、コアロッド２の周りに５本のクラッドロッド３が配置される。それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正五角形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３の間には１本の充填用ガラスロッド４が配置される。それぞれの充填用ガラスロッド４は、互いに隣り合うクラッドロッド３の外周面に接する接線によって複数のクラッドロッド３を囲うように形成される正五角形の内側に配置される。当該正五角形は、図１３において破線で示される。 FIG. 13 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention. In this modification, five clad rods 3 are arranged around the core rod 2. Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each apex of the regular pentagon surrounding the core rod 2. Further, one filling glass rod 4 is disposed between the clad rods 3 adjacent to each other. Each filling glass rod 4 is disposed inside a regular pentagon formed so as to surround a plurality of cladding rods 3 by tangent lines contacting the outer circumferential surface of the adjacent cladding rods 3. The regular pentagon is indicated by a broken line in FIG.
　図１４は、本発明のさらに他の変形例に係るバンドル工程Ｐ１後における複数のガラスロッドの束の長手方向に垂直な断面を示す図である。本変形例では、コアロッド２の周りに６本のクラッドロッド３が配置される。それぞれのクラッドロッド３は、コアロッド２の外周面に接すると共にコアロッド２を囲う正六角形のそれぞれの頂点と重なる位置に配置される。また、互いに隣り合うクラッドロッド３の外周面が接している。 FIG. 14 is a view showing a cross section perpendicular to the longitudinal direction of a bundle of a plurality of glass rods after a bundle process P1 according to still another modification of the present invention. In the present modification, six clad rods 3 are arranged around the core rod 2. Each clad rod 3 is disposed in contact with the outer peripheral surface of the core rod 2 and at a position overlapping each vertex of a regular hexagon surrounding the core rod 2. Further, the outer peripheral surfaces of the clad rods 3 adjacent to each other are in contact with each other.
　また、上記実施形態では、バンドル工程Ｐ１において、充填用ガラスロッド４が互いに隣り合うクラッドロッド３のそれぞれの外周面に接する例を挙げて説明した。しかし、充填用ガラスロッド４は、クラッドロッド３の外周面から離間していてもよい。ただし、バンドル工程Ｐ１において、充填用ガラスロッド４は、少なくとも１本のクラッドロッド３の外周面に接するように配置されることが好ましい。 In the above-described embodiment, the example in which the glass rods 4 for filling are in contact with the outer peripheral surfaces of the adjacent clad rods 3 in the bundle process P1 has been described. However, the filling glass rod 4 may be separated from the outer peripheral surface of the clad rod 3. However, in the bundling process P1, the filling glass rod 4 is preferably arranged to be in contact with the outer peripheral surface of at least one clad rod 3.
　また、上記実施形態では、それぞれのクラッドロッド３は互いに同じ直径とされる例を挙げて説明したが、それぞれのクラッドロッド３の直径は互いに異なっていてもよい。また、上記実施形態では、それぞれの充填用ガラスロッド４は互いに同じ直径とされる例を挙げて説明したが、それぞれの充填用ガラスロッド４の直径は互いに異なっていてもよい。 Moreover, in the said embodiment, although each clad rod 3 mentioned and demonstrated the example made into mutually the same diameter, the diameters of each clad rod 3 may mutually differ. Moreover, in the said embodiment, although the glass glass rods 4 for filling showed and demonstrated the example made into mutually the same diameter, the diameters of the glass rods 4 for filling may mutually differ.
　また、上記実施形態では、外側クラッド２２が樹脂からなる例を挙げて説明したが、外側クラッド２２はシリカガラスで構成されてもよい。この場合、例えば、スート５からなるクラッド２０の一部の屈折率をクラッドロッド３の屈折率よりも低くすることによって、スート５によって外側クラッド２２を形成することができる。スート５からなるクラッド２０の一部の屈折率がクラッドロッド３の屈折率より低くされることによって、クラッドロッド３からなる部位が内側クラッド２１の一部となる部位とされ、スート５からなる部位が内側クラッド２１より屈折率が低い外側クラッド２２となる部位とされるシングルコア光ファイバ用母材１Ｐを製造し得る。このようにスート５によって外側クラッド２２を形成する場合、外付工程Ｐ２は複数回行われることが好ましい。すなわち、最初の１回または最初から数回の外付工程Ｐ２では内側クラッド２１となるスート５を堆積させ、残りの外付工程Ｐ２では外側クラッド２２となるスート５を堆積させることが好ましい。このようにして製造されるシングルコア光ファイバ用母材１Ｐを用いることによって、増幅用光ファイバに好適なダブルクラッド構造のシングルコア光ファイバ１を製造し得る。 In the above embodiment, although the example in which the outer cladding 22 is made of resin is described, the outer cladding 22 may be made of silica glass. In this case, for example, the outer cladding 22 can be formed by the soot 5 by making the refractive index of a part of the cladding 20 made of the soot 5 lower than the refractive index of the cladding rod 3. By setting the refractive index of a part of the clad 20 made of soot 5 to be lower than the refractive index of the clad rod 3, the part made of the clad rod 3 becomes a part that becomes a part of the inner clad 21 and the part made of the soot 5 becomes A single core optical fiber preform 1P can be manufactured which is a portion to be the outer cladding 22 having a lower refractive index than the inner cladding 21. In the case where the outer cladding 22 is formed by the soot 5 as described above, it is preferable that the externally attached step P2 be performed a plurality of times. That is, it is preferable to deposit the soot 5 to be the inner cladding 21 in the first one or several initial external application processes P2, and to deposit the soot 5 to be the outer cladding 22 in the remaining external application processes P2. By using the base material 1P for a single core optical fiber manufactured in this manner, it is possible to manufacture a single core optical fiber 1 of a double clad structure suitable for an amplification optical fiber.
　また、上記実施形態では、シングルコア光ファイバ１が増幅用光ファイバである例を挙げて説明したが、シングルコア光ファイバ１は、コア１０に活性元素が添加されていない光ファイバとされてもよい。例えば、コア１０に活性元素が添加されていない場合、シングルコア光ファイバ１は、上記実施形態のシングルコア光ファイバ１のような増幅用光ファイバに接続されるデリバリファイバとして用いることができる。 In the above embodiment, although the example in which the single core optical fiber 1 is the amplification optical fiber has been described, the single core optical fiber 1 may be an optical fiber in which no active element is added to the core 10. Good. For example, when the active element is not added to the core 10, the single core optical fiber 1 can be used as a delivery fiber connected to an amplification optical fiber such as the single core optical fiber 1 of the above embodiment.
　以上説明したように、本発明によれば、長手方向に垂直な断面形状が非円形で長さが大きなシングルコア光ファイバ用母材を製造し得るシングルコア光ファイバ用母材の製造方法、及び、シングルコア光ファイバの製造方法が提供され、ファイバレーザ装置等の分野で利用することが期待される。 As described above, according to the present invention, a method of manufacturing a single core optical fiber base material capable of manufacturing a single core optical fiber base material having a non-circular cross section perpendicular to the longitudinal direction and a large length, and A single core optical fiber manufacturing method is provided and is expected to be used in the field of fiber laser devices and the like.
１・・・シングルコア光ファイバ
１Ｐ・・・シングルコア光ファイバ用母材
２・・・コアロッド
３・・・クラッドロッド
４・・・充填用ガラスロッド
５・・・スート
１０・・・コア
１０Ｒ・・・コア部
２０・・・クラッド
２０Ｒ・・・クラッドガラス層
２１・・・内側クラッド
２２・・・外側クラッド
Ｐ１・・・バンドル工程
Ｐ２・・・外付工程
Ｐ３・・・焼結工程
Ｐ４・・・線引工程

  DESCRIPTION OF SYMBOLS 1 ... Single core optical fiber 1P ... Base material for single core optical fiber 2 .. Core rod 3 ... Clad rod 4 ... Glass rod 5 for filling 5 ... Soot 10 ... Core 10R .. Core 20: clad 20R: clad glass layer 21: inner clad 22: outer clad P1: bundle process P2: external process P3: sintering process P4 ..Wire drawing process

Claims (13)

  1. 　コアとなるコア部を有するコアロッド、及び、クラッドの一部となる複数のクラッドロッド、を含む複数のガラスロッドを束ねるバンドル工程と、
    　束ねられた前記複数のガラスロッドの外周面上に前記クラッドの他の一部となるスートを堆積する外付工程と、
    　前記スートが堆積した前記複数のガラスロッドを加熱して前記スートとそれぞれの前記ガラスロッドとを一体のガラス体とする焼結工程と、
    を備え、
    　前記バンドル工程において、それぞれの前記クラッドロッドは、前記コアロッドの外周面に接すると共に前記コアロッドを囲う多角形のそれぞれの頂点と重なる位置に配置される
    ことを特徴とするシングルコア光ファイバ用母材の製造方法。     A bundling step of bundling a plurality of glass rods including a core rod having a core portion to be a core and a plurality of clad rods to be a part of a clad;
    An external applying step of depositing a soot to be another part of the cladding on the outer peripheral surface of the plurality of bundled glass rods;
    A sintering step of heating the plurality of glass rods on which the soot has been deposited to form the soot and the respective glass rods into an integral glass body;
    Equipped with
    In the bundling step, each of the clad rods is disposed in a position in contact with the outer peripheral surface of the core rod and at a position overlapping with each vertex of a polygon surrounding the core rod. Production method.
  2. 　それぞれの前記クラッドロッドは互いに同じ直径とされ、
    　前記バンドル工程において、それぞれの前記クラッドロッドは、前記コアロッドの中心を中心とする正多角形のそれぞれの頂点と重なる位置に配置される
    ことを特徴とする請求項１に記載のシングルコア光ファイバ用母材の製造方法。     Each of the cladding rods has the same diameter as one another,
    2. The single-core optical fiber according to claim 1, wherein in the bundling step, each of the clad rods is disposed at a position overlapping each vertex of a regular polygon centered on the center of the core rod. Method of manufacturing base material.
  3. 　前記コアロッドは、前記コア部の外周面に前記クラッドの一部となるクラッドガラス層を有する
    ことを特徴とする請求項１または２に記載のシングルコア光ファイバ用母材の製造方法。     The method for manufacturing a base material for a single core optical fiber according to claim 1 or 2, wherein the core rod has a clad glass layer which becomes a part of the clad on an outer peripheral surface of the core portion.
  4. 　前記バンドル工程において、互いに隣り合う前記クラッドロッドの外周面が接する
    ことを特徴とする請求項１から３のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     The manufacturing method of a base material for a single core optical fiber according to any one of claims 1 to 3, wherein outer peripheral surfaces of the clad rods adjacent to each other are in contact in the bundling step.
  5. 　前記バンドル工程において、互いに隣り合う前記クラッドロッドの外周面が離間する
    ことを特徴とする請求項１から３のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     The manufacturing method of a base material for a single core optical fiber according to any one of claims 1 to 3, wherein outer peripheral surfaces of the clad rods adjacent to each other are separated in the bundling step.
  6. 　前記バンドル工程において、前記コア部よりも屈折率が低く前記クラッドロッドよりも直径が小さい充填用ガラスロッドが、互いに隣り合う前記クラッドロッドの外周面に接する接線によって前記複数のクラッドロッドを囲うように形成される多角形の内側に配置される
    ことを特徴とする請求項１から５のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     In the bundling step, the filling glass rods having a refractive index lower than that of the core portion and a diameter smaller than that of the cladding rods surround the plurality of cladding rods by tangent lines contacting the outer peripheral surface of the cladding rods adjacent to each other. The method of manufacturing a base material for a single core optical fiber according to any one of claims 1 to 5, wherein the method is disposed inside a polygon to be formed.
  7. 　前記バンドル工程において、前記充填用ガラスロッドは、少なくとも１本の前記クラッドロッドの外周面に接するように配置される
    ことを特徴とする請求項６に記載のシングルコア光ファイバ用母材の製造方法。     The method of manufacturing a base material for a single core optical fiber according to claim 6, wherein in the bundling step, the filling glass rod is disposed in contact with the outer peripheral surface of at least one of the clad rods. .
  8. 　前記バンドル工程において、前記充填用ガラスロッドは、前記コアロッドの外周面に接するように配置される
    ことを特徴とする請求項６または７に記載のシングルコア光ファイバ用母材の製造方法。     The method of manufacturing a base material for a single core optical fiber according to claim 6 or 7, wherein in the bundling step, the filling glass rod is disposed in contact with the outer peripheral surface of the core rod.
  9. 　前記バンドル工程において、互いに隣り合う前記クラッドロッドの間に複数の前記充填用ガラスロッドが配置され、互いに隣り合う前記充填用ガラスロッドの外周面が接する
    ことを特徴とする請求項６から８のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     9. The bundling process according to any one of claims 6 to 8, wherein a plurality of the filling glass rods are disposed between the clad rods adjacent to each other, and outer peripheral surfaces of the filling glass rods adjacent to each other are in contact with each other. The manufacturing method of the preform | base_material for single core optical fibers of 1 or 2 item.
  10. 　前記バンドル工程において、前記充填用ガラスロッドは、互いに隣り合う前記クラッドロッドのそれぞれの外周面に接するように配置される
    ことを特徴とする請求項６から８のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     The single core according to any one of claims 6 to 8, wherein, in the bundle step, the filling glass rods are disposed in contact with the outer peripheral surfaces of the adjacent cladding rods adjacent to each other. Method of manufacturing base material for optical fiber.
  11. 　前記コア部に活性元素が添加される
    ことを特徴とする請求項１から１０のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     The method according to any one of claims 1 to 10, wherein an active element is added to the core portion.
  12. 　前記焼結工程後に前記スートからなる前記クラッドの他の一部の屈折率が前記クラッドロッドの屈折率よりも低くされる
    ことを特徴とする請求項１から１１のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法。     The single core according to any one of claims 1 to 11, wherein the refractive index of the other part of the cladding made of soot after the sintering step is lower than the refractive index of the cladding rod. Method of manufacturing base material for optical fiber.
  13. 　請求項１から１２のいずれか１項に記載のシングルコア光ファイバ用母材の製造方法により製造されるシングルコア光ファイバ用母材を線引きする線引工程を備える
    ことを特徴とするシングルコア光ファイバの製造方法。

          A single core optical fiber comprising a drawing step of drawing a single core optical fiber base material manufactured by the method of manufacturing a single core optical fiber base material according to any one of claims 1 to 12. Fiber manufacturing method.

PCT/JP2018/023340 2017-08-09 2018-06-19 Production method for single core optical fiber base material and production method for single core optical fiber WO2019031070A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017-154333 2017-08-09
JP2017154333A JP6666882B2 (en) 2017-08-09 2017-08-09 Method of manufacturing single-core optical fiber preform and method of manufacturing single-core optical fiber

Publications (1)

Publication Number Publication Date
WO2019031070A1 true WO2019031070A1 (en) 2019-02-14

Family

ID=65272183

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/023340 WO2019031070A1 (en) 2017-08-09 2018-06-19 Production method for single core optical fiber base material and production method for single core optical fiber

Country Status (2)

Country Link
JP (1) JP6666882B2 (en)
WO (1) WO2019031070A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003226540A (en) * 2002-02-04 2003-08-12 Mitsubishi Cable Ind Ltd Method for manufacturing double clad fiber
JP2007137753A (en) * 2005-11-18 2007-06-07 Korea Electronics Telecommun Optical fiber preform using vad method, method of manufacturing optical fiber preform and optical fiber using optical fiber preform
JP2012025625A (en) * 2010-07-23 2012-02-09 Hitachi Cable Ltd Method for producing optical fiber
JP2016017029A (en) * 2014-07-11 2016-02-01 株式会社フジクラ Method of manufacturing base material for multi-core fiber, and method of manufacturing multi-core fiber using the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003226540A (en) * 2002-02-04 2003-08-12 Mitsubishi Cable Ind Ltd Method for manufacturing double clad fiber
JP2007137753A (en) * 2005-11-18 2007-06-07 Korea Electronics Telecommun Optical fiber preform using vad method, method of manufacturing optical fiber preform and optical fiber using optical fiber preform
JP2012025625A (en) * 2010-07-23 2012-02-09 Hitachi Cable Ltd Method for producing optical fiber
JP2016017029A (en) * 2014-07-11 2016-02-01 株式会社フジクラ Method of manufacturing base material for multi-core fiber, and method of manufacturing multi-core fiber using the same

Also Published As

Publication number Publication date
JP2019031423A (en) 2019-02-28
JP6666882B2 (en) 2020-03-18

Similar Documents

Publication Publication Date Title
US8031999B2 (en) Photonic band-gap fiber
EP2140294B1 (en) Optical fiber article for handling higher power and method of fabricating or using
CN110954988A (en) Laser transmission optical fiber and manufacturing method thereof
JP6396821B2 (en) Method for manufacturing base material for multi-core fiber, and method for manufacturing multi-core fiber using the same
JP5676152B2 (en) Optical fiber and manufacturing method thereof
CN112028468B (en) Active and passive alternate optical fiber, preparation method thereof and optical fiber laser
EP4123349A1 (en) Multicore fiber, multicore fiber ribbon, multicore fiber production method and multicore fiber processing method
US8381548B2 (en) Method of manufacturing photonic band gap fiber base material and fiber
WO2019031070A1 (en) Production method for single core optical fiber base material and production method for single core optical fiber
EP2261181A1 (en) Method for fabricating and processing a preform, preform and optical fiber
JP6010587B2 (en) Method for manufacturing base material for multi-core fiber, and method for manufacturing multi-core fiber using the same
WO2013031484A1 (en) Fiber
CN115477469A (en) Method for manufacturing preform of multicore optical fiber and method for manufacturing multicore optical fiber
JP6517583B2 (en) Method of manufacturing base material for multi-core fiber, and method of manufacturing multi-core fiber using the same
JP6681306B2 (en) Method for manufacturing base material for multicore fiber, and method for manufacturing multicore fiber using the same
JP6216263B2 (en) Multi-core fiber preform, multi-core fiber using the same, multi-core fiber preform manufacturing method, and multi-core fiber manufacturing method using the same
JP6085788B2 (en) Light shielding fiber, bundle fiber, light shielding fiber manufacturing method, and bundle fiber manufacturing method
JP6623146B2 (en) Method for manufacturing base material for multi-core fiber, and method for manufacturing multi-core fiber using the same
JP2007153697A (en) Method of producing preform for double clad optical fiber and method of producing double clad optical fiber
WO2020004238A1 (en) Multi-clad optical fiber and method for manufacturing same
WO2012111436A1 (en) Method for manufacturing optical fibers
RU2543006C2 (en) Production of preforms with preset refractive index profile, preform and optic fibre
JP5329347B2 (en) Optical fiber for ultraviolet transmission and method for manufacturing the same
JPH0557215B2 (en)
JPS6033234A (en) Correction of surface defect of quartz preform

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18844567

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18844567

Country of ref document: EP

Kind code of ref document: A1