JP2017019675A - Optical fiber manufacturing method, and optical fiber manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber manufacturing method capable of accurately forming a base material of an optical fiber of a complicated structure and manufacturing the optical fiber of a complicated structure more easily than in the past.SOLUTION: In an optical fiber manufacturing method, an organic resin is added to a silica powder, a raw material of a cladding, to form a pelletizing powder. One or more capillary tubes or glass rods are inserted into a jacket tube having a closed bottom. The pelletizing powder is filled in a gap in the jacket tube and pressured to form a base material. The base material is gradually introduced into a heating furnace having two independent heat sources at an upper part and a lower part of the furnace. The heat source at an upper part serves to defat the organic resin added to the silica powder in the base material, while the heat source at a lower part serves to sinter the base material and draw the base material to a desired diameter.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical fiber manufacturing method and manufacturing apparatus.

  Currently, the production method of optical fiber preforms for long distances is mainly based on the gas phase method, and the process up to the completion of the fiber is roughly divided into the production of porous preforms and sintering of the preforms (transparency) 3) Fiber drawing.

There are the following four methods for producing a base material by a vapor phase method.
{1} OVD method (Outside Vapor Deposition Method)
{2} MCVD method (Modified Chemical Vapor Deposition Method)
{3} PCVD method (Plasma Chemical Vapor Deposition Method)
{4} VAD method (Vapor-phase Axial Deposition Method)

Among these, the manufacturing method of an optical fiber preform will be described by taking the {4} VAD method, which is the mainstream at present, as an example (FIG. 1). The raw material gas (SiCl ₄ , GeCl ₄ ) supplied from the raw material supply system is guided into the flame of the oxyhydrogen burner and is generated by the combustion in the burner combustion section at the burner combustion section, SiCl ₄ + 2H ₂ O-> SiO ₂ + 4HCl.
_{GeCl 4 + 2H 2 O ->} GeO 2 + 4HCl
Subject to flame hydrolysis. Upon undergoing this flame hydrolysis, quartz glass fine particles (soot) are formed. The fine particles are deposited on the tip of the starting material. Since the glass fine particles are deposited in the axial direction, the starting material is pulled upward while rotating in accordance with the growth rate, and a porous base material is formed. Next, when the porous base material is put in a heating furnace and heated to a high temperature, the sintering proceeds, the volume shrinks, and the voids in the base material are connected to reach outside the base material. When the temperature is further increased, a complete transparent glass body (base material) is obtained. Furthermore, this transparent glass body is inserted into an optical fiber drawing device, and drawing is performed (Non-Patent Document 1).

  As shown in Non-Patent Document 2, a general optical fiber drawing apparatus includes a heating furnace, a fiber outer diameter measuring device, a die (coating (resin) coating), and a coating (resin) curing device (heating furnace, UV irradiator). Etc.), a capstan, a winding device, a base material feeding device that holds the drawing base material and feeds the base material to the heating furnace in accordance with the drawing amount (FIG. 2). The transparent glass base material is heated in an electric furnace at about 2000 ° C., and the locally softened glass is reduced in diameter to a desired fiber outer diameter (generally 125 μm). The optical fiber drawn from the lower end of the heating furnace passes through the outer diameter measuring device, the resin coats the fiber surface with a resin applicator, and the resin is cured by a resin curing device (UV light source). Further, the optical fiber is drawn out by a capstan and wound around a bobbin by a winding device. Based on the measurement result of the outer diameter measuring device, the capstan speed is adjusted so that the outer diameter of the fiber is constant.

  On the other hand, in the manufacturing method of a multi-core optical fiber (MCF) that has been rapidly researched and developed in recent years, the drawing process of the optical fiber is basically the same as that of the conventional fiber described above. However, since it is necessary to form a plurality of cores, the manufacturing process of the base material requires a more complicated process than the conventional method described above. Examples of methods for producing these base materials include a stack and draw method and a rod-in-tube method. In the stack and draw method, a plurality of core glass rods and clad glass rods produced by a vapor phase method or the like are inserted into a jacket tube and integrated to produce a base material. On the other hand, in the rod-in-tube method, a core glass rod is inserted into a large-diameter clad glass rod that has been drilled with a drill or the like and integrated to produce a base material.

Shojiro Kawakami, Kazuo Shiraishi, Masaharu Ohashi, “Optical Fiber and Fiber-Type Device”, issued July 10, 1996, p. 11-13 Tetsuya Miki, Shoichi Sudo, “Optical Communication Handbook”, Optronics, published on January 30, 2002, p. 244 T. T. Yajima et al. "OH-Free, Low loss single-mode fiber fabricated by slurry casting / Rod-in-tube method", ECOC2014, Th. 2.4.4 2014.

  However, in the vapor phase method, which is a general base material manufacturing method, it is theoretically difficult to manufacture a base material of a complex structure MCF having a large number of cores in a clad in a series of steps. Even when this is realized, the number of processes increases, and it is difficult to manufacture an MCF base material having a complicated cross-sectional structure with high accuracy, and there is also a problem from the viewpoint of economy. As a method for avoiding these difficulties, the above-described stack and draw method or rod-in-tube method is used. However, in the stack and draw method, it is necessary to combine a large number of rods, and there is a problem that the arrangement of the core is almost limited to a structure in which the rods can be filled finely without gaps. In addition, due to the fact that the drilling process is necessary in the rod-in-tube method, the number of processes is increased, the length of the base material that can be drilled is limited, the base material is destroyed during drilling, and the positional accuracy is deteriorated. There is a problem that there is a possibility of doing.

  In addition to these methods, there is a study example (Non-Patent Document 3) that realizes an increase in the size of the base material by using a powder material as a cladding material, but the study is limited to a single core base material, and the MCF. The example applied to is not known. Further, as shown in the literature, even if it is limited to the production of a base material, it requires a complicated process process that is very finely divided into seven stages, and then an optical fiber drawing process is further added. In addition, when applied to MCF, a plurality of cores are arranged in addition to the center of the base material, and the base material is degreased (removal of organic chemicals as a binder) and contraction during sintering. There is also concern about deterioration of position accuracy from the assumed core position. Also in the MCF, it is possible to suppress bending loss and signal crosstalk between a plurality of cores by arranging holes in the cladding. However, any of the above manufacturing methods has the same problem as the problem related to the arrangement of the cores.

  The present invention has been made in view of the above circumstances. An optical fiber manufacturing method and an optical device capable of forming a base material of an optical fiber having a complicated structure with high accuracy and easily manufacturing an optical fiber having a complicated structure than before. An object is to provide a fiber manufacturing apparatus.

  In order to achieve the above-described object, the optical fiber manufacturing method according to the present invention adds one or more organic resins to silica powder as a raw material for the cladding part to form a granulated powder, and at least one jacket tube having a closed bottom part. A capillary tube or glass rod is inserted, a granulated powder is filled in the gap in the jacket tube and pressed to form a base material, and the base material is gradually introduced into a heating furnace having two independent heating sources. The organic resin added to the silica powder in the base material was degreased by the upper heating source, and the base material was sintered by the lower heating source and simultaneously stretched to a desired outer diameter.

Specifically, in the first optical fiber manufacturing method according to the present invention, a glass tube is closed at one end, a jacket tube that is the outermost periphery of the cladding portion of the optical fiber, and a capillary tube that is a hole of the optical fiber or An optical fiber manufacturing method for manufacturing an optical fiber using a glass rod that is a core part of an optical fiber,
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
Inserting the at least one or more capillary tubes or at least one or more glass rods into the jacket tube;
After the insertion step, the granulated powder formed in the granulated powder forming step is filled into the gap between the capillary tubes or between the glass rods and the gap between the capillary tube or the glass rod and the jacket tube. A granulated powder charging process,
After the granulated powder charging step, the granulated powder solidifying step of pressurizing and solidifying the granulated powder filling the gap from the other end of the jacket tube,
An optical fiber is manufactured from the columnar base material formed.

  By placing capillary tubes or glass rods at precise positions in the jacket tube, filling these gaps with granulated powder and pressing them together, it is possible to form an optical fiber preform with a complicated structure with high accuracy. . If drawing is performed using this base material, an optical fiber having a complicated structure can be easily manufactured.

  Therefore, the present invention can provide an optical fiber manufacturing method capable of forming a base material of an optical fiber having a complicated structure with high accuracy and more easily manufacturing an optical fiber having a complicated structure than before.

Specifically, the second optical fiber manufacturing method according to the present invention includes a jacket tube that is the outermost periphery of the clad portion of the optical fiber, and a capillary tube that is a hole of the optical fiber, with one end of the glass tube closed. An optical fiber manufacturing method for manufacturing an optical fiber using a glass rod that is a core part of an optical fiber,
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. An insertion step of inserting into the tube;
After the insertion step, the granulated powder formed in the granulated powder forming step in the gap between the capillary tubes or between the glass rods and in the gap between the capillary tube or the glass rod and the jacket tube A granulated powder charging process for filling;
A fixing jig installation step of fitting the hole of the other fixing jig formed in the fixing jig forming step to the other end of the capillary tube or the other end of the glass rod after the granulated powder charging step; ,
After the fixing jig installation step, pressurize the other fixing jig, and a granulated powder solidifying step for solidifying the granulated powder filling the gap,
An optical fiber is manufactured from the columnar base material formed.

  If the capillary tube or the glass rod is fixed using a fixing jig prepared in advance with granulated powder, the displacement of the capillary tube or the glass rod can be greatly reduced in the subsequent steps. If drawing is performed using this base material, an optical fiber having a complicated structure can be easily manufactured.

  Therefore, the present invention can provide an optical fiber manufacturing method capable of forming a base material of an optical fiber having a complicated structure with high accuracy and more easily manufacturing an optical fiber having a complicated structure than before.

  The second optical fiber manufacturing method according to the present invention is characterized in that the granulated powder injection step and the fixing jig installation step are repeated. By repeating these steps, it is possible to significantly reduce the displacement of the capillary tube or the glass rod even when a long base material is produced.

Specifically, the third optical fiber manufacturing method according to the present invention includes a jacket tube that is the outermost periphery of the cladding portion of the optical fiber, and a capillary tube that is a hole of the optical fiber, with one end of the glass tube closed. An optical fiber manufacturing method for manufacturing an optical fiber using a glass rod that is a core part of an optical fiber,
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. Inserted into a tube, and the other end of the capillary tube or the other end of the glass rod is fitted into the hole of the other fixing jig formed in the fixing jig forming step, and a plurality of the fixing jigs are stacked, or ,
The capillary tube or the glass rod is passed through the holes of the plurality of fixing jigs formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the plurality of fixing jigs is used as the jacket. An insertion step of inserting into the tube;
An optical fiber is manufactured from the columnar base material formed.

  By continuously fitting a plurality of fixing jigs previously made of granulated powder into the capillary tube or glass rod, the displacement of the capillary tube or glass rod can be greatly reduced in subsequent steps. If drawing is performed using this base material, an optical fiber having a complicated structure can be easily manufactured.

  Therefore, the present invention can provide an optical fiber manufacturing method capable of forming a base material of an optical fiber having a complicated structure with high accuracy and more easily manufacturing an optical fiber having a complicated structure than before.

  In the first to third optical fiber manufacturing methods according to the present invention, the base material is sequentially heated in the longitudinal direction at a first temperature and a second temperature, and the silica powder is added to the silica powder by heating at the first temperature. A fiber drawing step is further performed in which the organic resin is degreased and the silica powder is sintered by heating at a second temperature and the diameter is reduced by stretching to a desired outer diameter.

  This optical fiber manufacturing method can degrease the organic resin added to the silica powder in the base material, sinter the base material, and at the same time perform drawing to a desired outer diameter in one step.

  At this time, in the fiber drawing step, the second temperature is preferably higher than the first temperature.

  The fiber drawing step is preferably performed in a vacuum or in a state where the pressure is reduced from atmospheric pressure.

An optical fiber manufacturing apparatus capable of realizing the above optical fiber manufacturing method is:
At least one or more glass used as a core part of at least one capillary tube used as a hole of an optical fiber, or a jacket tube used as the outermost circumference of a cladding part of an optical fiber which closed one end of a glass tube Insert the rod,
A granulated powder obtained by adding an organic resin to silica powder, which is a raw material for the clad part of an optical fiber, is a gap between the capillary tubes or between the glass rods, and between the capillary tube or the glass rod and the jacket tube. Columnar base material formed by filling the gap between
The first and second temperatures are sequentially heated in the longitudinal direction, the organic resin added to the silica powder is degreased by heating at the first temperature, and the silica powder is sintered by heating at the second temperature. And a heating furnace for reducing the diameter by stretching to a desired outer diameter.

  Therefore, the present invention can provide an optical fiber manufacturing apparatus that can form a base material of an optical fiber having a complicated structure with high precision and can easily manufacture an optical fiber having a complicated structure.

  The present invention can provide an optical fiber manufacturing method and an optical fiber manufacturing apparatus that can form a base material of an optical fiber having a complicated structure with high accuracy and can easily manufacture an optical fiber having a complicated structure.

It is explanatory drawing regarding base material preparation. It is a block diagram of the optical fiber manufacturing apparatus which concerns on this invention. It is explanatory drawing regarding the 1st optical fiber manufacturing method which concerns on this invention. It is explanatory drawing regarding the fiber drawing process of the optical fiber manufacturing method which concerns on this invention. It is explanatory drawing regarding the 2nd and 3rd optical fiber manufacturing method which concerns on this invention. It is explanatory drawing regarding the fiber drawing process of the optical fiber manufacturing method which concerns on this invention. It is explanatory drawing regarding the fiber drawing process of the optical fiber manufacturing method which concerns on this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Outline of the embodiment)
The optical fiber manufacturing method described in the following embodiment includes a step of forming silica powder that is a raw material for the cladding portion of the glass base material,
Adding an organic resin to the silica powder to form a granulated powder;
Put a capillary tube or at least one glass rod that becomes at least one core into a jacket tube that is closed at the bottom, which is the outermost part of the cladding, and then fill the gap in the jacket tube with the granulated powder and pressurize it further. Forming a base material,
Silica powder when passing through the vicinity of the upper heating source while gradually introducing the base material into a heating furnace having two independent heating sources on the upper and lower sides and different temperature control for each heating source. Degreasing the organic resin added to the process, sintering the vicinity of the lower heating source at the time of passing, and simultaneously reducing the diameter by stretching to the desired outer diameter, and performing the fiber drawing all at once;
It is comprised from these.

  Since the granulated powder can be introduced into the clad in a large amount at once, productivity can be greatly improved as compared with the vapor phase method. The use of granulated powder necessitates a degreasing process, but the degreasing, sintering, and drawing processes can be combined to eliminate the disadvantages, and the sintering process is also incorporated, so the number of processes is substantially reduced. Decrease than before.

  In this optical fiber manufacturing method, the lower heating source is higher in temperature than the upper heating source in the heating furnace. This means that the degreasing process is performed with the upper heating source, and the sintering / drawing process is performed with the lower heating source.

  In this optical fiber manufacturing method, a device for depressurization or vacuum degassing from the upper part of the base material during drawing is installed at the upper end of the base material. As a result, the organic gas generated by degreasing can be efficiently discharged.

  Further, the present optical fiber manufacturing method includes a step of inserting a capillary tube or at least one glass rod to be a core portion into a jacket tube having a closed bottom portion, or a step of adding granulated powder to be a cladding portion thereafter. The core rod (glass rod) or capillary tube is fixed using a fixing jig that has been granulated powder in advance so that the rod or capillary tube is not displaced. It is characterized by containing granulated powder.

(Embodiment 1)
FIG. 3 is a diagram for explaining the basic flow of the optical fiber manufacturing method of the present embodiment. FIG. 3 shows a case where the core is a single core fiber for simplification. For comparison, the flow of the optical fiber manufacturing method described in Non-Patent Document 3 is also shown.

This optical fiber manufacturing method uses a jacket tube that is the outermost periphery of the cladding portion of the optical fiber, with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes the core portion of the optical fiber. An optical fiber manufacturing method for manufacturing an optical fiber,
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
Inserting the at least one or more capillary tubes or at least one or more glass rods into the jacket tube;
After the insertion step, the granulated powder formed in the granulated powder forming step is filled into the gap between the capillary tubes or between the glass rods and the gap between the capillary tube or the glass rod and the jacket tube. A granulated powder charging process,
After the granulated powder charging step, the granulated powder solidifying step of pressurizing and solidifying the granulated powder filling the gap from the other end of the jacket tube,
An optical fiber is manufactured from the columnar base material formed.

  Step S11 in FIG. 3 is a granulated powder forming step. In the granulated powder forming step, an organic resin such as a binder (binder) is put into a silica powder having a diameter of several to several tens of micrometers to produce a granulated powder having an order of several hundred micrometers. The reason for preparing granulated powder by adding not only silica powder but also binder is to increase the particle size and improve the introduction into the jacket tube, and granulate uniformly without generating voids etc. It becomes possible to introduce powder.

  Step S12 in FIG. 3 is an insertion process and a granulated powder charging process. A glass rod is put into the jacket tube in the insertion process, and a gap between the glass rod and the jacket tube is filled with the granulated powder in the granulated powder charging process. In order to improve the filling property, it is possible to use ultrasonic waves or centrifugal force. In addition, the method using granulated powder can fill the clad material into the desired clad shape at a time, so it can greatly improve the production efficiency compared with the vapor deposition method, especially for large base materials. It seems to grow.

  Step S13 in FIG. 3 is a granulated powder solidifying step. In the granulated powder solidifying step, a pressure jig is fitted into the upper part of the jacket tube, and a pressure device (hydrostatic pressure device or the like) is used to apply a pressure of several tens to several hundreds of MPa to the granulated powder. As a result, a porous base material is formed.

  The completed porous base material is installed in the drawing apparatus shown in FIG. 2, and various processes are performed. In the present embodiment, the base material is sequentially heated in the longitudinal direction at the first temperature and the second temperature, and the organic resin added to the silica powder by heating at the first temperature is degreased at the second temperature. A fiber drawing step is further performed in which the silica powder is sintered by heating and the diameter is reduced by stretching to a desired outer diameter. Step S14 in FIG. 3 is a fiber drawing process.

FIG. 2 is also an optical fiber manufacturing apparatus that realizes the optical fiber manufacturing method of the present embodiment. This optical fiber manufacturing equipment
At least one or more glass used as a core part of at least one capillary tube used as a hole of an optical fiber, or a jacket tube used as the outermost circumference of a cladding part of an optical fiber which closed one end of a glass tube Insert the rod,
A granulated powder obtained by adding an organic resin to silica powder, which is a raw material for the clad part of an optical fiber, is a gap between the capillary tubes or between the glass rods, and between the capillary tube or the glass rod and the jacket tube. Columnar base material formed by filling the gap between
The first and second temperatures are sequentially heated in the longitudinal direction, the organic resin added to the silica powder is degreased by heating at the first temperature, and the silica powder is sintered by heating at the second temperature. And a heating furnace for reducing the diameter by stretching to a desired outer diameter.

  FIG. 4 is a diagram illustrating the structure of the heating furnace 101 that performs the fiber drawing process. The heating furnace 101 has two upper and lower heating sources, and the heating temperature can be adjusted respectively. In the fiber drawing process, Ar gas is purged into the heating furnace, degreased with an upper gas burner set at a relatively low temperature (first temperature: 500-1000 ° C.), and degreased to complete the porous preform. Is introduced into the lower gas burner, heated at about 2000 ° C. (second temperature), and drawn simultaneously with sintering. Since a series of processes are continuously performed while introducing the porous base material into the heating furnace at a constant speed, degreasing, sintering, and drawing can be performed in a batch process, which can greatly simplify the process. It becomes.

  Compared with the manufacturing process of Non-Patent Document 3 shown in FIG. 3, the optical fiber manufacturing method of the present embodiment can shorten steps S04 to S06 of Non-Patent Document 3. The outer diameter of the fiber is determined by the ratio of the size of the base material and the feed speed of the base material to the heating furnace and the take-up speed of the fiber. The propagation loss of the fiber manufactured by the optical fiber manufacturing method of the embodiment was 0.19 dB / km (λ = 1550 nm), which was equivalent to a commercially available fiber.

  The fiber drawing step may be performed in a vacuum or in a state where the pressure is reduced from atmospheric pressure. As shown in FIG. 4, when a jig for vacuum (decompression) deaeration is installed at the upper end of the base material, the degreasing speed increases, so that the base material speed can be increased. We succeeded in increasing the drawing speed by about twice.

(Embodiment 2)
FIG. 5 is a diagram for explaining the optical fiber manufacturing method of the present embodiment. In this embodiment, there are two processes (A process and B process). In this embodiment, a method in the case of using a plurality of glass rods will be described. When using multiple glass rods, it is difficult to precisely match the positional relationship between the cores, and if the granulated powder is pressed while the positional relationship is slightly shifted, the positional shift will be even greater. There is a concern that Therefore, in the present embodiment, as shown in FIG. 5, a jig in which granulated powder for fixing each glass rod is hardened is produced, and each glass rod is inserted into the jig and fixed to avoid a shift at the time of pressurization. .

First, the A process will be described. In the A process, an optical fiber is formed by using a jacket tube that is the outermost periphery of the clad portion of the optical fiber with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes the core portion of the optical fiber. An optical fiber manufacturing method for manufacturing
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. An insertion step of inserting into the tube;
After the insertion step, the granulated powder formed in the granulated powder forming step in the gap between the capillary tubes or between the glass rods and in the gap between the capillary tube or the glass rod and the jacket tube A granulated powder charging process for filling;
A fixing jig installation step of fitting the hole of the other fixing jig formed in the fixing jig forming step to the other end of the capillary tube or the other end of the glass rod after the granulated powder charging step; ,
After the fixing jig installation step, pressurize the other fixing jig, and a granulated powder solidifying step for solidifying the granulated powder filling the gap,
An optical fiber is manufactured from the columnar base material formed.
Moreover, you may repeat the said granulated powder injection | throwing-in process and the said fixing jig installation process.

  The granulated powder forming step is the same as described in the first embodiment. Steps S21 and S22 in FIG. 5 are fixing jig forming steps. In the fixing jig forming step, the granulated powder is put into a mold (a hole is formed in the core insertion portion) shaped like the fixing jig (step S21), and this is pressurized at several tens to several hundreds of MPa (step S22). . In the insertion step, each glass rod is inserted and fixed into the produced fixing jig, and is inserted into the jacket tube (steps S23 and S24A). In the granulated powder charging step, the granulated powder is put and a second fixing jig is put (step S24A). The granulated powder is put again, a third fixing jig is put in the process jig setting step, and the pressure is applied at several tens to several hundreds of MPa in the granulated powder solidifying step (similar to step S13 in the first embodiment).

  One fixing jig may be provided at the bottom and the upper end of the jacket tube, but the fixing accuracy of the glass rod can be improved by installing a fixing jig at an intermediate position of the base material as shown in FIG. It is also possible to further increase the fixing accuracy by increasing the number of fixing jigs.

Next, the B process will be described. In the B process, an optical fiber is formed by using a jacket tube that is the outermost periphery of a clad portion of an optical fiber with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes a core portion of the optical fiber. An optical fiber manufacturing method for manufacturing
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. Inserted into a tube, and the other end of the capillary tube or the other end of the glass rod is fitted into the hole of the other fixing jig formed in the fixing jig forming step, and a plurality of the fixing jigs are stacked, or ,
The capillary tube or the glass rod is passed through the holes of the plurality of fixing jigs formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the plurality of fixing jigs is used as the jacket. An insertion step of inserting into the tube;
An optical fiber is manufactured from the columnar base material formed.

  The B process is an example in which the base material is assembled only with a fixed jig in which the granulated powder is hardened. The B process is the same as the A process until the fixing jig forming step (step S22). In the insertion step, a plurality of fixing jigs are stacked and skewered with a glass rod (step S24B). The fixing jig may be inserted into the jacket tube after skewering, or the glass rod is inserted into one fixing jig as in the A process, and after this is placed on the jacket tube, the fixing jig is continuously inserted. It may be fitted. There is a possibility that the formation accuracy may be higher when the granulated powder is pressure-formed in small increments than when the granulated powder is solidified after the granulated powder is put in the jacket tube as in the A process. Furthermore, since the fixing jig and the base material can be assembled in parallel at the same time, work efficiency can be improved.

  FIG. 6 is a diagram illustrating the heating furnace 102 of the present embodiment. The heating furnace 102 performs a fiber drawing process using a multi-core base material manufactured by the A process or the B process of FIG. The heating furnace 102 uses an electric furnace equipped with a carbon heater, and has a two-zone heating source as in the first embodiment. In this embodiment, a single-mode 6-core type multi-core base material is produced and drawn. As a result, the average optical propagation loss of 6 cores was 0.20 dB / km (λ = 1550 nm).

(Embodiment 3)
In the optical fiber manufacturing methods of Embodiments 1 and 2, the method of manufacturing an optical fiber with a glass rod serving as a core has been described. The optical fiber manufacturing method of this embodiment is a method in the case of using a plurality of capillary tubes instead of glass rods. A photonic crystal optical fiber (PCF) can be manufactured by forming a base material using a capillary tube and performing a fiber drawing process.

  First, as described in the second embodiment, a plurality of capillaries are inserted into a process jig by A process or B process to form a base material. Since pressurization of the granulated powder using a capillary may cause foreign matter to enter the capillary, the pressurization was performed with the capillary sealed.

FIG. 7 is a diagram illustrating the heating furnace 103 of the present embodiment. The heating furnace 103 performs the fiber drawing process of this embodiment. The heating furnace 103 uses an electric furnace equipped with a carbon heater, and has a two-zone heating source as in the first embodiment. The specification of the base material used in this example is 2LP mode PCF. As a result of drawing, the optical propagation loss was 0.23 dB / km (λ = 1550 nm) in the LP ₀₁ mode and 0.5 dB / km (λ = 1550 nm) in the LP ₁₁ mode.

[Appendix]
The following describes the optical fiber manufacturing method and the optical fiber manufacturing apparatus of the present embodiment.

(the purpose)
By filling the clad part with the powder material, it is possible to economically manufacture the MCF base material having a complex structure having a plurality of cores. In addition, by setting two heating sources for the base material in the process direction, the process from filling the powder material to degreasing, sintering, and drawing is a series of steps, and the manufacturing process is reduced, and a highly accurate core and It aims at realization of the position accuracy of the hole.

(1):
Forming a silica powder as a raw material for the clad portion of the glass base material;
Adding an organic resin to the silica powder to form a granulated powder;
Put a capillary tube or at least one glass rod that becomes at least one core into a jacket tube that is closed at the bottom, which is the outermost part of the cladding, and then fill the gap in the jacket tube with the granulated powder and pressurize it further. The manufacturing method of the base material comprised from the process of forming a base material.

(2):
Forming a silica powder as a raw material for the clad portion of the glass base material;
Adding an organic resin to the silica powder to form a granulated powder;
Put a capillary tube or at least one glass rod that becomes at least one core into a jacket tube that is closed at the bottom, which is the outermost part of the cladding, and then fill the gap in the jacket tube with the granulated powder and pressurize it further. Forming a base material,
Silica powder when passing through the vicinity of the upper heating source while gradually introducing the base material into a heating furnace having two independent heating sources on the upper and lower sides and different temperature control for each heating source. Degreasing the organic resin added to the process, sintering the vicinity of the lower heating source at the time of passing, and simultaneously reducing the diameter by stretching to the desired outer diameter, and performing the fiber drawing all at once;
An optical fiber manufacturing method comprising:

(3):
The method for producing an optical fiber according to (2) above, wherein the lower heating source has a higher temperature than the upper heating source.

(4):
The method for producing an optical fiber as described in (2) above, wherein a device for depressurization or vacuum degassing from the upper part during drawing is installed on the upper end side of the base material.

(5):
The position of the glass rod or capillary tube in the step of inserting the capillary tube or at least one glass rod (core rod) that becomes at least one core into the jacket tube closed at the bottom, or the step of subsequently adding granulated powder that becomes the cladding The core rod or capillary tube is fixed in a state where the core rod or capillary tube is fixed using a fixing jig in which the granulated powder is hardened in advance, so that the core rod or capillary tube and the granulated powder that becomes the cladding portion are put into the jacket tube. The manufacturing method of the optical fiber of any one of said (2)-(4) to do.

(6):
A granulated powder in which a capillary tube or at least one glass rod serving as a core portion is inserted into a jacket tube whose bottom portion is the outermost portion of the cladding portion, and an organic resin is added to silica powder in a gap in the jacket tube In the vicinity of the upper heating source, the base material formed by satisfying the above is gradually introduced into a heating furnace having two independent heating sources on the upper and lower sides, each of which can be controlled at different temperatures. The organic resin added to the silica powder is degreased when passing through, and the vicinity of the lower heating source is sintered at the time of passing, and at the same time, the diameter is reduced to the desired outer diameter, and the fiber drawing is performed all at once. An optical fiber manufacturing apparatus, characterized in that

(effect)
According to the present invention, in a method for producing a multi-core optical fiber, a powder material is used for a clad part, and a process from forming a base material to drawing is performed all at once, thereby reducing the number of manufacturing processes and various cores and holes. An optical fiber having an arrangement can be manufactured with high accuracy.

101-103: Heating furnace

Claims (8)

Light that manufactures an optical fiber using a jacket tube that is the outermost periphery of the cladding portion of the optical fiber with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes the core portion of the optical fiber A fiber manufacturing method comprising:
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
Inserting the at least one or more capillary tubes or at least one or more glass rods into the jacket tube;
After the insertion step, the granulated powder formed in the granulated powder forming step is filled into the gap between the capillary tubes or between the glass rods and the gap between the capillary tube or the glass rod and the jacket tube. A granulated powder charging process,
After the granulated powder charging step, the granulated powder solidifying step of pressurizing and solidifying the granulated powder filling the gap from the other end of the jacket tube,
The optical fiber manufacturing method which manufactures an optical fiber from the columnar preform | base_material formed by performing. Light that manufactures an optical fiber using a jacket tube that is the outermost periphery of the cladding portion of the optical fiber with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes the core portion of the optical fiber A fiber manufacturing method comprising:
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. An insertion step of inserting into the tube;
After the insertion step, the granulated powder formed in the granulated powder forming step in the gap between the capillary tubes or between the glass rods and in the gap between the capillary tube or the glass rod and the jacket tube A granulated powder charging process for filling;
A fixing jig installation step of fitting the hole of the other fixing jig formed in the fixing jig forming step to the other end of the capillary tube or the other end of the glass rod after the granulated powder charging step; ,
After the fixing jig installation step, pressurize the other fixing jig, and a granulated powder solidifying step for solidifying the granulated powder filling the gap,
The optical fiber manufacturing method which manufactures an optical fiber from the columnar preform | base_material formed by performing.   The optical fiber manufacturing method according to claim 2, wherein the granulated powder charging step and the fixing jig setting step are repeated. Light that manufactures an optical fiber using a jacket tube that is the outermost periphery of the cladding portion of the optical fiber with one end of the glass tube closed, and a capillary tube that becomes a hole of the optical fiber or a glass rod that becomes the core portion of the optical fiber A fiber manufacturing method comprising:
A granulated powder forming step of forming an agglomerated powder by adding an organic resin to the silica powder as a raw material of the cladding portion of the optical fiber;
The granulated powder formed in the granulated powder forming step is filled into a mold and pressed and hardened, and is a disk whose diameter is the inner diameter of the jacket tube, and the outer diameter of the capillary tube or the glass rod is the diameter A fixing jig forming step for forming a fixing jig in which at least one or more holes are formed at predetermined positions on the disk;
One end of the capillary tube or one end of the glass rod is inserted into the hole of the fixing jig formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the fixing jig is inserted into the jacket. Inserted into a tube, and the other end of the capillary tube or the other end of the glass rod is fitted into the hole of the other fixing jig formed in the fixing jig forming step, and a plurality of the fixing jigs are stacked, or ,
The capillary tube or the glass rod is passed through the holes of the plurality of fixing jigs formed in the fixing jig forming step, and the capillary tube or the glass rod fixed by the plurality of fixing jigs is used as the jacket. An insertion step of inserting into the tube;
The optical fiber manufacturing method which manufactures an optical fiber from the columnar preform | base_material formed by performing.   The base material is heated in the longitudinal direction in order at a first temperature and a second temperature, the organic resin added to the silica powder is degreased by heating at the first temperature, and the silica is heated by heating at a second temperature. The optical fiber manufacturing method according to any one of claims 1 to 4, further comprising a fiber drawing step of reducing the diameter by sintering powder and stretching to a desired outer diameter.   The optical fiber manufacturing method according to claim 5, wherein in the fiber drawing step, the second temperature is higher than the first temperature.   The optical fiber manufacturing method according to claim 5, wherein the fiber drawing step is performed in a vacuum or in a state where pressure is reduced from atmospheric pressure. At least one or more glass used as a core part of at least one capillary tube used as a hole of an optical fiber, or a jacket tube used as the outermost circumference of a cladding part of an optical fiber which closed one end of a glass tube Insert the rod,
A granulated powder obtained by adding an organic resin to silica powder, which is a raw material for the clad part of an optical fiber, is a gap between the capillary tubes or between the glass rods, and between the capillary tube or the glass rod and the jacket tube. Columnar base material formed by filling the gap between
The first and second temperatures are sequentially heated in the longitudinal direction, the organic resin added to the silica powder is degreased by heating at the first temperature, and the silica powder is sintered by heating at the second temperature. And an optical fiber manufacturing apparatus provided with the heating furnace which reduces in diameter by extending | stretching to a desired outer diameter.