JP2003160353A - Optical fiber glass preform and method of manufacturing the same and optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical fiber preform capable of obtaining the preform stably and easily, the eccentricity of which is ≤0.2 μm, by holding a starting preform for securing easiness of working, operability of a burner, and easy deposition of glass fine grains. <P>SOLUTION: The porous glass preform is manufactured in such a way that a gaseous glass raw material is led into an oxyhydrogen flame burner 5, and is subjected to hydrolysis reaction while generating fine glass grains which deposit on the surface of the preform 1, thereby the porous glass preform is manufactured. The method of manufacturing the optical fiber glass preform is that it is obtained by vitrifying the porous glass preform into transparent glass. A starter preform 3 obtained by connecting a glass preform for a core 1 with a dummy rod 2, is horizontally placed, a part of or whole of which is heated with oxyhydrogen flame, while rotating it so as to straighten it by a correction, thereafter, the porous starter preform 3 is manufactured by depositing the glass fine grains on the starter preform 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical fiber glass base material, and more particularly, an optical fiber glass base material capable of stably and easily manufacturing an optical fiber glass base material having an eccentricity of 0.2 μm or less. And a fiber optic glass preform and an optical fiber obtained therefrom.

[0002]

2. Description of the Related Art A single mode type optical fiber used for long-distance optical transmission has a small core diameter, which makes it difficult to connect the fibers, and a high level technique is required for the connection. Further, in recent years, a method of collectively connecting by tape connection or the like has been performed, and various fibers for wavelength division multiplexing transmission represented by a dispersion shift fiber have been developed, and the chances of connecting different kinds of fibers are increasing, The eccentricity of the core part is required to be extremely small.

By the way, in manufacturing an optical fiber glass preform, a starting preform having dummy loads connected to both ends of a core glass preform manufactured by a known method such as a VAD method, an MCVD method, and a PCVD method is used. The glass was placed horizontally on a glass lathe in the reaction vessel, the gaseous glass raw material was introduced into an oxyhydrogen flame burner that moved relative to the starting base material, and the glass produced by hydrolysis with an oxyhydrogen flame from this burner. A so-called external attachment method is generally used in which fine particles are deposited on a starting base material to form a porous glass base material, which is heated and melted to form a transparent glass.

[0004]

In view of the ease of work, the workability of the burner, and the ease of depositing glass particles, the above-mentioned method is usually a horizontal reaction vessel in which the starting base material is placed horizontally. It has been installed at. However, when the target optical fiber becomes longer and larger, the horizontally placed starting base material bends due to its own weight, and center deviation easily occurs between its both ends and the central part. However, there is a problem that the optical glass base material obtained by this becomes eccentric. As a method for solving this problem, Japanese Patent No. 251795 proposes a method of vertically installing a starting base material. However, this method is not preferable from the viewpoints of workability, burner workability, and glass particulate deposition, as described above.

The present invention has been made in view of the above circumstances, and an object of the present invention is to horizontally set the starting base material in order to ensure workability, burner workability, and glass particulate deposition. And a method for producing an optical fiber glass preform capable of stably and easily obtaining an optical fiber glass preform having an eccentricity of 0.2 μm or less, and an optical fiber glass preform obtained therefrom. And providing an optical fiber.

[0006]

In the method for producing an optical fiber glass preform according to the present invention, a gaseous glass raw material is introduced into an oxyhydrogen flame burner to undergo flame hydrolysis, and the produced glass fine particles are used as a core glass preform. A porous glass preform is manufactured by uniformly depositing on the surface, and an optical fiber glass preform is manufactured by producing a transparent glass into a glass fiber preform, and a dummy rod is added to the core glass preform. The connected starting base material is installed horizontally, and then part or all of the starting base material is heated and softened with an oxyhydrogen flame while rotating the starting base material to correct the bending of the starting base material. The method of solving the above problems was to deposit fine glass particles on the starting base material to produce a porous glass base material.

According to this method for producing an optical fiber glass preform, the starting preform is placed horizontally and is softened by heating to correct its bending, and thereafter glass fine particles are deposited on the starting preform. Therefore, by correcting the bend and depositing the glass particles in a state where the starting base material is installed horizontally, the workability, burner workability, and glass particle deposition are improved. The optical fiber glass preform having an eccentricity amount of, for example, 0.2 μm or less can be stably and easily obtained by the bending correction process.

The optical fiber glass preform of the present invention is manufactured by using the above-mentioned manufacturing method, which is a means for solving the above-mentioned problems. According to this optical fiber glass preform, since it is manufactured by the manufacturing method described above, it is possible to secure ease of work during manufacturing, workability of a burner, and ease of depositing fine glass particles, and also to prevent bending. The eccentricity amount becomes, for example, 0.2 μm or less by the correction processing of.

The optical fiber of the present invention is obtained by drawing the optical fiber glass preform and has an eccentricity of 0.
It was set as 2 μm or less as a means for solving the above problems. According to this optical fiber, the production of the optical fiber glass preform, which is easy to work, workability of the burner, and easy to deposit glass particles, is facilitated, and the optical fiber glass base material is easy to bend. The eccentricity is 0.2 μm due to the use of the modified optical fiber glass preform.
The following are good results.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
In the method for producing an optical fiber glass preform of the present invention, first,
As shown in FIG. 1, dummy rods 2 are connected to both ends of a glass base material 1 for core to form a starting base material 3. And
This is put in the reaction container 4, both ends thereof are attached to attachment portions (not shown), and this is installed horizontally.

Next, a driving unit (not shown) connected to the mounting unit is actuated to rotate the starting base material 3, and part or all of the starting base material 3 is heated and softened by the oxyhydrogen flame burner 5. Then, the bending of the starting base material 3 is corrected. Here, as the oxyhydrogen flame burner 5 used for heating and softening, a general one that has been conventionally used can be used, and the oxyhydrogen flame burner 5 is configured to be horizontally movable along the axial direction of the starting base material 3. Things are used. The oxyhydrogen flame burner 5 is connected to supply pipes (not shown) for supplying oxygen, hydrogen, and a gaseous glass raw material, and these supply pipes are provided with oxygen, hydrogen, and a gaseous glass raw material, respectively. Each source of is connected.

Regarding the heating and softening of the starting base material 3, it is not necessary to heat and soften it over its entire length, and it is possible to obtain a sufficient bending correction effect only by heating and softening one end. Therefore, when the bending is corrected by the heat softening, the oxyhydrogen flame burner 5 is added to the starting base material 3.
It is not necessary to move them relative to each other by moving them in the axial direction, and this can be done in a fixed state. Since the oxyhydrogen flame burner 5 can be fixed in this manner, the bending correction process by the heating and softening has good workability.

Regarding the oxyhydrogen flame ejected from the burner 5, the amount of hydrogen supplied to the burner 5 (hydrogen flow rate) is 1
If it is less than 10 [L / min], it takes time to remove the bend from the starting base material 3, and the effect of reducing the eccentricity may not be sufficiently obtained. Regarding the amount of hydrogen gas supply,
It is preferably 10 [L / min] or more.

Further, the supply amount (flow rate) of hydrogen gas to the oxyhydrogen flame burner 5 is V [L / min], and the glass base material for core 1
[Mm], the heating time for softening by heating is T
When [seconds] is set, it is desirable to perform so as to satisfy 15 ≦ VT / D ² ≦ 100. If VT / D ² is less than 15, the correction effect for removing the bend cannot be expected sufficiently,
This is because if VT / D ² is greater than 100, the starting base material 3 may be excessively softened. In addition, about 5 minutes at the most, it suffices that the bending correction process due to the heat softening does not take a long time. In addition, it is preferable to perform the bending correction by the heat softening while confirming the correction state using, for example, an outer diameter measuring device using a laser beam.

After the bending is corrected in this manner, the glass base particles 3 are deposited on the starting base material 3 after the bending correction without removing the starting base material 3 from the reaction vessel 4 while the bending correction is continued. That is, in the same manner as in the prior art, the gaseous glass raw material is also introduced into the oxyhydrogen flame burner 5 and flame-hydrolyzed in the oxyhydrogen flame to generate the generated glass fine particles for the core of the starting base material 3. It is deposited uniformly on the surface of the glass base material 1.

Subsequently, glass fine particles are deposited on the surface of the glass base material for core 1 in this manner, and the dummy rods 2 and 2 are removed from the starting base material 3 to obtain a porous glass base material. After that, the obtained porous glass preform is made into transparent glass in the same manner as in the prior art to obtain the optical fiber glass preform of the present invention. Further, the porous glass preform thus obtained is drawn in the same manner as in the prior art, and particularly the eccentricity is set to 0.2 μm or less to obtain the optical fiber of the present invention.

In such a method for producing an optical fiber glass preform, the starting preform 3 is placed horizontally and is softened by heating to correct the bending, and then the starting preform 3 is formed. Since the glass particles are deposited, the correction of the bend and the deposition of the glass particles are both performed with the starting base material 3 being horizontally installed, thereby facilitating the work and the workability of the burner. It is possible to ensure the ease of depositing the glass particles. Further, by performing the bending correction process, it is possible to stably and easily obtain the optical fiber glass preform having an eccentricity amount of, for example, 0.2 μm or less. Further, since the starting base material 3 after the bend is corrected is not taken out from the reaction vessel 4 and the glass particles are deposited on the bend-corrected state, the treatment should be continuously performed. By doing so, the good optical fiber glass preform described above can be manufactured without significantly reducing productivity.

Further, in the optical fiber glass preform manufactured by the above manufacturing method, as described above, the workability at the time of manufacturing, the workability of the burner, and the easiness of depositing glass particles are secured. In addition, since the amount of eccentricity is reduced to, for example, 0.2 μm or less by the bending correction process, a good optical fiber with a small amount of eccentricity can be easily manufactured. Further, in the optical fiber of the present invention obtained by drawing the optical fiber glass preform, the eccentricity amount is 0.2 μm or less, so that for example, good fiber connection can be achieved. become.

[0019]

The present invention will be described in more detail with reference to the following examples. Needless to say, the present invention is not limited to this embodiment. (Example 1) A starting base material in which a dummy rod having a diameter of 35 mm and a length of 450 mm was connected to both ends of a glass base material for a core having a diameter of 30 mm and a length of 1200 mm was placed horizontally in a reaction vessel. Next, an oxyhydrogen flame burner was set at a position 120 mm from one end of the starting base material, and the hydrogen supply amount (flow rate) was 160 [L / L in that state.
Min], the oxygen supply amount (flow rate) was set to 80 [L / min], an oxyhydrogen flame was jetted, and the starting base material was heated and softened for 200 seconds to perform bending correction processing. The rotation speed of the starting base material at this time was 24 rotations / minute. Subsequently, without removing the modified starting base material from the reaction vessel, glass fine particles are deposited by the conventional method in the same state,
A porous glass base material was obtained. Then, the obtained porous glass preform was sintered to obtain an optical fiber glass preform.

(Example 2) Diameter 26 mm, length 1000
A starting base material, in which dummy rods having a diameter of 30 mm and a length of 400 mm were connected to both ends of a glass base material for core of mm, was horizontally installed in a reaction vessel. Next, an oxyhydrogen flame burner was set at a position 100 mm from one end of the starting base material, and in that state, the hydrogen supply rate (flow rate) was 150 [L / min] and the oxygen supply rate ( Flow rate) to 75 [L /
Min.], An oxyhydrogen flame was ejected, and the starting base material was heated and softened for 90 seconds to perform bending correction processing. The rotation speed of the starting base material at this time was 24 rotations / minute. Subsequently, without removing the modified starting base material from the reaction vessel, glass particles were deposited by the conventional method as it was, to obtain a porous glass base material. Then, the obtained porous glass preform was sintered to obtain an optical fiber glass preform.

(Example 3) Diameter 12 mm, length 850 m
20 mm in diameter and 4 in length at both ends of the glass base material for core of m.
The starting base material to which a dummy rod of 00 mm was connected was placed horizontally in the reaction vessel. Next, an oxyhydrogen flame burner was set at a position 100 mm from one end of the starting base material, and the hydrogen supply amount (flow rate) was set to 1 in that state.
50 [L / min], oxygen supply amount (flow rate) is 75 [L / min]
Min.], An oxyhydrogen flame was ejected, and the starting base material was heated and softened for 90 seconds to perform bending correction processing. The rotation speed of the starting base material at this time was 24 rotations / minute. Subsequently, without removing the modified starting base material from the reaction vessel, glass particles were deposited by the conventional method as it was, to obtain a porous glass base material. Then, the obtained porous glass preform was sintered to obtain an optical fiber glass preform.

(Comparative Example 1) The same starting base material as that shown in Example 1 was used, and glass fine particles were deposited by a conventional method without heat softening treatment for removing bending, and thus obtained. The porous glass preform was sintered to obtain an optical fiber glass preform. (Comparative Example 2) The same starting base material as that shown in Example 2 was used, and the heat softening treatment for removing the bending was not performed,
Glass fine particles were deposited by a conventional method, and the obtained porous glass preform was sintered to obtain an optical fiber glass preform. (Comparative Example 3) The same starting base material as that shown in Example 3 was used, and the heat softening treatment for removing the bending was not performed,
Glass fine particles were deposited by a conventional method, and the obtained porous glass preform was sintered to obtain an optical fiber glass preform.

When each of Examples 1 to 3 and Comparative Examples 1 to 3 was tried 20 times, the eccentricity of the optical fiber glass preform was as shown below. The following values of the eccentricity amount are all average values obtained by 20 trials. "Eccentricity" -Example 1; 0.18 µm-Example 2; 0.17 µm-Example 3; 0.14 µm-Comparative Example 1; 0.44 µm-Comparative Example 2; 0.38 µm-Comparative Example 3; 0 From the results of .24 μm or more, Examples 1 to 3 of the present invention have a significantly larger amount of eccentricity than Comparative Examples 1 to 3 based on the conventional method in which the bending correction processing (heat softening processing for removing the bending) is not performed. It was confirmed that it was getting smaller. In addition, Examples 1 to 1
When the optical fiber glass preforms of No. 3 were used to draw optical fibers from these, optical fibers were produced, and the resulting optical fibers all had an eccentricity of 0.2 μm or less.

[0024]

As described above, the manufacturing method of the optical fiber glass preform of the present invention corrects the bending by heating and softening the starting preform in a state where it is installed horizontally, and thereafter,
Since the glass microparticles are deposited on the starting base material, the bending is corrected and the glass microparticles are deposited in the state where the starting base material is horizontally installed. It is possible to secure the workability and the ease of depositing glass particles. Further, by performing the bending correction process, it is possible to stably and easily obtain the optical fiber glass preform having an eccentricity amount of, for example, 0.2 μm or less.

Since the optical fiber glass preform of the present invention is manufactured by the above-mentioned manufacturing method, it is easy to work during manufacturing, burner workability, and easy deposition of glass particles. In addition, the eccentricity amount becomes favorable, for example, 0.2 μm or less by the bending correction process.

Since the optical fiber of the present invention is obtained by drawing the optical fiber glass preform, easiness of work, workability of the burner, and easiness of depositing glass particles are ensured. The use of the optical fiber glass base material facilitates its manufacture, and the use of the optical fiber glass base material subjected to the bending correction treatment provides a good eccentricity of 0.2 μm or less. Further, since the eccentricity amount is 0.2 μm or less, the connection between the fibers can be particularly well performed.

[Brief description of drawings]

FIG. 1 is a side sectional view for explaining a method for manufacturing an optical fiber glass preform according to the present invention.

[Explanation of symbols]

1 ... Glass base material for core, 2 ... Dummy rod, 3 ... Starting base material, 4 ... Reaction vessel, 5 ... Oxygen hydrogen flame burner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Horikoshi             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office F-term (reference) 4G021 EA03 EB01 EB13

Claims (8)

[Claims] 1. A porous glass preform is manufactured by introducing a gaseous glass raw material into an oxyhydrogen flame burner to cause flame hydrolysis and uniformly depositing the produced glass fine particles on the surface of the glass preform for the core. In the method for producing an optical fiber glass preform by vitrifying vitreous glass, a starting preform having a dummy rod connected to the core glass preform is horizontally installed, and then rotated. While part of or all of the starting base material is heated and softened with an oxyhydrogen flame to correct the bending of the starting base material, glass fine particles are deposited on the starting base material to produce a porous glass base material. A method of manufacturing an optical fiber glass preform, characterized by: 2. The starting base material is heat-softened in a reaction vessel, and the glass particles are deposited on the starting base material continuously without being taken out from the reaction vessel. The method for producing an optical fiber glass preform according to claim 1. 3. A burner for ejecting an oxyhydrogen flame and a starting base material, when a part or the whole of the starting base material is heated and softened by an oxyhydrogenation flame, in a relative direction in the axial direction of the starting base material. The method for producing an optical fiber glass preform according to claim 1 or 2, which is performed without moving. 4. The production of an optical fiber glass preform according to claim 1, wherein the supply amount of hydrogen gas to the oxyhydrogen flame burner is 110 [L / min] or more. Method. 5. The supply amount of hydrogen gas to the oxyhydrogen flame burner is V [L / min], and the diameter of the glass base material for the core is D.
When [mm] and heating time at the time of heat softening are set to T [second], these are performed so that these may satisfy 15 ≦ VT / D ² ≦ 100. Manufacturing method of optical fiber glass preform. 6. An optical fiber glass preform manufactured by using the manufacturing method according to claim 1. 7. The optical fiber glass preform according to claim 6, wherein the amount of eccentricity is 0.2 μm or less. 8. An optical fiber obtained by drawing the optical fiber glass preform according to claim 6 or 7, wherein the amount of eccentricity is 0.2 μm or less.