WO2005090247A1

WO2005090247A1 - Process for producing glass parent material for hollow fiber, hollow fiber and process for producing the same

Info

Publication number: WO2005090247A1
Application number: PCT/JP2005/003919
Authority: WO
Inventors: Tetsuya Otosaka
Original assignee: Shin-Etsu Chemical Co., Ltd.
Priority date: 2004-03-19
Filing date: 2005-03-07
Publication date: 2005-09-29
Also published as: KR101164672B1; JP4252005B2; TW200533618A; JP2005263576A; KR20050093709A

Abstract

A process for producing a glass parent material for hollow fiber, in which a glass parent material for hollow fiber being of large size and low impurity content, suited to production of hollow fiber can be produced at low cost; a hollow fiber; and a process for producing the same. There is provided a process for producing a glass parent material for hollow fiber having multiple hollows made over the entire length in the axial direction thereof, characterized by depositing glass microparticles on a revolving starting member bar to thereby obtain a porous glass parent material, subsequently making multiple hollows in the axial direction from an end of the porous glass parent material, heating the porous glass parent material in an atmosphere containing chlorine or fluorine, and thereafter heating the same at a temperature suitable for transparentization of the porous glass parent material.

Description

Specification

FIELD OF THE INVENTION

The present invention relates to a method of manufacturing a glass preform for a holey fiber in which the purity of an optical fiber having a plurality of holes over its entire length (hereinafter, simply referred to as a holey fiber) is improved, a holey fiber, and a method of manufacturing the same. . This application is also related to the following Japanese patent application. For those designated States for which incorporation by reference to the literature is permitted, the contents described in the following application are incorporated into this application by reference and are incorporated as part of the description of this application.

Patent application 2004—080456 Application filed March 19, 2004

Background art

[0002] Optical fibers that are widely used generally have a solid structure in which a central portion of quartz glass or the like has a high refractive index region called a core. On the other hand, optical fibers having holes inside, such as the photonic crystal fiber and holey fiber disclosed in Patent Document 1, are currently receiving attention. A photonic crystal fiber forms a photonic band gap by providing regularly arranged holes in the fiber, and guides light by providing defects in the band.

[0003] The holey fiber is provided with a hole in the cladding to reduce the effective refractive index of the cladding to give a refractive index difference between the hole and the core. Is used for total reflection. In addition, a hole-added type fino having a shape in which a hole is formed around the core of a conventional optical fiber has been proposed. These fibers also have holes in the gap, and their shape, size, arrangement, and the like greatly affect the transmission characteristics.

[0004] To manufacture these fibers, a method of drawing a bundle of glass tubules (capillaries) as disclosed in Patent Document 2 (a method using a cable or a stack and draw method) and a method disclosed in Patent Document 2 There is a method of making a hole in a glass rod and drawing (a method of making a hole) as disclosed in 3 and 4. Optical fibers having holes, such as photonic crystal fiber optical fibers and hole-added fibers, are hereinafter generally referred to as hole fibers.

As shown in Fig. 1, the hole-drilling method involves synthesizing a porous glass base material, making it transparent, and then opening it. This is what you do.

[0005] Patent Document 1: Japanese Patent Publication No. 2002-506533

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-97034

Patent Document 3: JP-A-2002-293562

Patent Document 4: JP 2002-145634 A

Disclosure of the invention

Problems to be solved by the invention

[0006] While applying force, the cavitary method has a problem that voids remain in the fiber and the shape of the hole is easily collapsed when drawing. Furthermore, the use of cavities causes a problem that OH-based Z impurities are contaminated on the outer surface of the cavities and it is difficult to reduce the loss immediately.

[0007] On the other hand, in the hole making method, it is very difficult to make a very deep hole in the quartz glass, and a special method such as ultrasonic vibration grinding must be used. Furthermore, the production of fibers with a large number of holes requires extremely high processing costs and long processing times. Quartz glass is a difficult-to-cut material, so it is necessary to rotate the grinding tool at high speeds. There is a problem of disappearing.

[0008] The present invention has been made in view of the above circumstances, and it is possible to manufacture a large-sized and low-impurity glass preform for a holey fiber suitable for the manufacture of a holey fiber at low cost. It is an object of the present invention to provide a method of manufacturing a glass preform for a holey fiber, a holey fiber, and a method of manufacturing the same.

Means for solving the problem

[0009] In the method for producing a glass preform for a holey fiber of the present invention, the method for producing a glass preform for an optical fiber having a plurality of holes extending in the axial direction over the entire length thereof rotates glass fine particles. A porous glass preform is formed by depositing on a starting member rod to be formed, and a plurality of holes are formed in an axial direction from an end of the porous glass preform, and then heated to a temperature at which the porous glass preform becomes transparent. It is characterized by doing. In this case, after a plurality of holes are formed in the porous glass base material, heat treatment may be performed in an atmosphere containing chlorine or fluorine, preferably at 700 to 1200 ° C. In addition, a porous glass base material is formed by depositing on the starting member rod, and the porous glass is formed. A plurality of holes may be formed in the axial direction of the end portion of the lath base material and heated to a temperature at which it becomes transparent after dehydration treatment with chlorine and treatment with fluorine.

[0010] For the starting member rod, high-purity quartz glass or quartz glass containing a dopant is used, and glass fine particles generated by supplying the dopant material together with the glass material are deposited thereon. The deposition of the glass particles may be caused by the tip force of the starting member rod being also directed in the axial direction, axially along the side surface of the starting member bar, or on the side surface of the starting member bar in a direction perpendicular to the axis of the starting member bar. The force V applied toward the surface may be accumulated in the direction of the deviation.

[0011] Further, prior to the step of forming a plurality of holes, a step of adjusting the density of the porous glass base material to 0.25-0.80 g / cm ³ by heating at 1100-1450 ° C is provided. Good. This density adjustment is preferably performed in an atmosphere containing chlorine or fluorine.

[0012] In this case, the heating time in the step of adjusting the density of the porous glass base material to 0.25 to 0.80 g / cm ³ is such that the porous glass base material is heated to a transparent temperature. The heating time in the process may be shorter. Alternatively, the heating temperature in the step of adjusting the density of the porous glass preform to 0. 25-0. 80g / cm ³ is lower than the heating temperature in the step where the porous glass preform is heated to a temperature of clearing Is also good. In the step of adjusting the density, the heating time may be shortened and the heating temperature may be lowered as compared with the step of performing transparency. Alternatively, the heating temperature may be substantially the same, and the heating time may be shortened. Alternatively, the heating time may be substantially the same and the heating temperature may be lowered. In the step of adjusting these densities, the heating temperature and Z or the heating time are set so that the bulk density of the porous glass base material increases while the porous glass base material remains opaque. Yeah.

[0013] Further, prior to the step of forming a plurality of holes, the end of the porous glass base material may be cut off, and the end face may be cut into a plane perpendicular to the central axis before the holes are formed.

[0014] Transparency of the porous glass base material may be performed in an atmosphere containing a dopant.

In addition, it is preferable that the inner surface of the hole of the transparent glass base material is mirror-polished. By heating and drawing the glass preform for hole fiber manufactured in this way, a hole fiber is obtained.

The invention's effect According to the present invention, since the power hole is formed by adjusting the density of the porous glass base material to a density suitable for drilling, deeper and deeper holes are formed as compared with a method of forming a hole in a hard glass rod. It can be easily opened, and it is possible to easily produce a large-sized glass fiber preform for a hole fiber at low cost. Furthermore, since the high purity treatment is performed after the perforating process is performed at the stage of the porous glass preform, the purity of the glass preform for the holey fiber can be improved.

Brief Description of Drawings

FIG. 1 is a process flow chart for explaining a conventional drilling process.

FIG. 2 is a process flow chart for explaining a drilling process according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments do not limit the invention according to the scope of the claims, and all combinations of features described in the embodiments are described. Is not necessarily essential to the solution of the invention! / ,.

In the method for producing a glass preform for a holey fiber of the present invention, for example, a porous glass preform is produced by depositing glass fine particles generated by a flame hydrolysis decomposition reaction of a glass raw material, and obtained. The porous glass base material is heated at 1100-145 0 ° C during or after dehydration treatment as necessary to shrink the porous glass base material, and its bulk density is suitable for drilling. After adjusting the pressure to 0.80 g / cm ³ , the porous glass base material is perforated in the axial direction, and then subjected to dehydration / purification treatment and transparency treatment.

In the present invention, as shown in FIG. 2, the method for producing a glass preform for a holey fiber includes: (1) a step of producing a porous glass preform, (2) a density adjusting step, and (3) a hole making. It also has five process capabilities: processing, (4) dehydration, high-purification, and (5) transparency. In addition, (6) a hole polishing step is added as necessary. Thereafter, the holey fiber is manufactured in the (7) drawing step. Hereinafter, these steps will be described in order.

[0020] First, (1) the manufacturing process of the porous glass base material includes the following steps: the porous glass base material is conventionally known as a gas phase shafting method (VAD method), an external VAD method, Attachment method (OVD method) t These methods are used to produce glass fine particles by flame hydrolysis of a glass material in a Pana flame and then rotate the glass material. It is deposited on the member bar. [0021] The VAD method is a method in which the tip force of a starting member rod is deposited and grown in the axial direction. In the external VAD method, glass particles are deposited on the side of the starting member rod while moving the wrench in one direction in parallel with the axial end force of the starting member rod, so that the wrench moves along the side of the starting member rod. Grow the base material. In the OVD method, while depositing glass particles toward the side of the starting member bar, the wrench is reciprocated in parallel with the axis of the starting member bar, and the base material is placed on the side of the starting member bar in the direction perpendicular to this axis. Grow.

[0022] At the time of deposition, by supplying a dopant material together with a glass material, or by using a high-purity quartz glass or a quartz glass containing a dopant for a starting member rod, various properties such as a refractive index and photosensitivity of the glass are obtained. Can be changed.

[0023] The porous glass base material thus obtained is subjected to a heat treatment in a furnace heated to 1100-1450 ° C in order to adjust the density to a level suitable for cutting before the punching force. It is adjusted to a density of 0.25 one 0. 80gZcm ^3. In the density is less than 0. 25gZcm ^3, damaged or immediately other during cutting too brittle, too hard exceeds 0. 80gZcm ^3, since the machining crack easily enter becomes difficult at the time of cutting, the density Is adjusted to the above range. A particularly preferable range is around 0.4, because dehydration with chlorine can be performed efficiently and processability is good.

[0024] When adjusting the density of the porous glass base material, the glass particles are slightly melted and fused together, so that OH groups and impurities mainly present on the surface of the glass particles can be taken into the glass. There is. To prevent this, OH groups and impurities can be removed by heating in an atmosphere containing chlorine or a fluorinated compound in the density adjusting step. The density adjustment step can be omitted by adjusting the density in the manufacturing process of the porous glass base material and keeping the density within the above range in advance.

Next, the porous glass base material adjusted to have a density suitable for processing is subjected to a boring process by mechanical grinding. When drilling is used for hard-to-cut materials such as carbide drills and diamond drills, the tool life is long and the blade replacement interval can be lengthened, improving workability and processing accuracy. The processing speed at this time varies depending on the hole diameter ゃ depth, bulk density, etc., but can be 0.1 mm to several tens of mmZ seconds or more, which is much faster than that of hard transparent glass. Drill at speed. [0026] Even if the porous glass base material is made by any of the VAD method, the external VAD method, and the OVD method, its end is not a plane perpendicular to the axis. For this reason, by cutting the end of the porous glass base material perpendicular to the axis and providing a flat surface in advance at the end, it becomes easy to make a hole thereafter. As a result, the depths of the holes can be made uniform, thereby improving the position accuracy of the holes and improving the yield.

[0027] When the end is cut without a transparent glass rod in the center, a metal saw, a thread saw, a saw for woodworking, a rotary cutting whetstone, a wire saw, a band saw, etc., metal, wood, new building materials, glass Etc. can be used. In the case where a transparent glass rod is provided at the center, the transparent glass rod may be cut or cut off after removing the porous portion using these cutting means.

The perforated porous glass base material is subjected to dehydration and high-purity treatment by heating to 700 to 1200 ° C. in an atmosphere containing a chlorine or fluorine compound as necessary. Thereafter, the temperature is raised to a temperature at which the glass becomes transparent, whereby a transparent glass base material having pores is obtained.

The dehydration, high-purification treatment and clarification process can be performed simultaneously in a heating furnace provided with a temperature gradient. Further, by making the atmosphere containing a dopant at the time of transparency, various characteristics such as the refractive index and the photosensitivity of the obtained glass can be changed.

[0029] Depending on the density of the porous glass preform before the perforation processing / the perforation processing method, the inner surface of the hole of the obtained transparent glass preform may be roughened. In such a case, the inner surface of the hole is mirror-polished using an abrasive, whereby the scattering of light from the glass base material can be suppressed, and the transmission loss of the hole fiber obtained therefrom can be reduced. In order to mirror-polish the inner surface of the hole, for example, a method of polishing IJ using a material that can be used for polishing and polishing ordinary glass, such as silicon carbide or cerium oxide powder, may be mentioned. Can be

Industrial applicability

By using the glass preform for hole fiber of the present invention, a hole fiber with high purity can be obtained at low cost.

Claims

The scope of the claims

[I] In a method for manufacturing a glass preform for an optical fiber having a plurality of holes in the axial direction over its entire length, glass fine particles are deposited on a rotating starting member rod to form a porous glass preform. A method for producing a glass preform for a holey fiber, comprising: forming a plurality of holes in an axial direction, and heating the porous glass preform to a temperature at which the porous glass preform becomes transparent.

[2] A method for producing a glass preform for a holey fiber, wherein a heat treatment is performed in an atmosphere containing chlorine or fluorine after the step of forming a plurality of holes.

[3] Prior to making the porous glass base material transparent, 700- 12 under an atmosphere containing chlorine or fluorine.

The method for producing a glass preform for a holey fiber according to claim 1 or 2, wherein the heat treatment is performed at 00 ° C.

4. The method according to claim 1, wherein the starting member rod is a high-purity quartz glass.

5. The method according to claim 1, wherein the starting member rod is a quartz glass containing a dopant.

6. The method for producing a glass preform for a holey fiber according to claim 1, wherein the glass fine particles are generated by supplying a dopant raw material together with a glass raw material.

7. The method for producing a glass preform for a holey fiber according to claim 1, wherein the deposition of the glass fine particles is performed from the tip of the starting member rod toward the axial direction.

8. The method according to claim 1, wherein the deposition of the glass particles is performed in the axial direction along a side surface of the starting member rod.

[9] The glass mother for a holey fiber according to any one of claims 1 to 6, wherein the deposition of the glass particles is performed on a side surface of the starting member rod in a direction perpendicular to an axis of the starting member rod. The method of manufacturing the material.

[10] Prior to the step of forming the plurality of holes, a heat treatment at 1100-1450 ° C. is performed to adjust the density of the porous glass base material to 0.25-0.80 gZcm ³ . 10. The method for producing a glass preform for a holey fiber according to claim 1.

[II] pressure in the porous 0. The density of the glass preform 25-0. 80gZcm ³ step of adjusting the 11. The method for producing a glass preform for a holey fiber according to claim 10, wherein the heating time is shorter than the heating time in the step of heating to a temperature at which the porous glass preform becomes transparent.

[12] The heating temperature in the step of adjusting the density of the porous glass base material to 0.25 to 0.80 gZcm ³ is higher than the heating temperature in the step of heating to a temperature at which the porous glass base material becomes transparent. 11. The method for producing a glass preform for a holey fiber according to claim 10, which is low.

13. The method for producing a glass preform for a holey fiber according to claim 10, wherein the step of adjusting the density is performed in an atmosphere containing chlorine or fluorine.

14. The empty space according to claim 1, wherein prior to the step of forming the plurality of holes, an end of the porous glass base material is cut off, and the end surface is a plane perpendicular to a central axis. Manufacturing method of glass base material for hole fiber.

15. The method for producing a glass preform for a holey fiber according to claim 1, wherein the transparentization of the porous glass preform is performed in an atmosphere containing a dopant.

16. The method for producing a glass preform for a holey fiber according to any one of claims 1 to 15, wherein an inner surface of the hole of the glass preform that has been made transparent is mirror-polished.

[17] A method for manufacturing a holey fiber, comprising heating and drawing a glass preform for a holey fiber manufactured using the method according to any one of claims 1 to 16.

[18] A holey fiber manufactured using the manufacturing method according to claim 17.