WO2004101457A1 - 光ファイバ用ガラス母材の製造方法 - Google Patents
光ファイバ用ガラス母材の製造方法 Download PDFInfo
- Publication number
- WO2004101457A1 WO2004101457A1 PCT/JP2004/006631 JP2004006631W WO2004101457A1 WO 2004101457 A1 WO2004101457 A1 WO 2004101457A1 JP 2004006631 W JP2004006631 W JP 2004006631W WO 2004101457 A1 WO2004101457 A1 WO 2004101457A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- glass
- preform
- optical fiber
- producing
- core
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Definitions
- the present invention relates to a method for producing a glass preform for optical fibers, which sinters a porous preform for optical fibers produced by an OVD method and turns it into a transparent glass.
- a glass preform for optical fibers As a method of manufacturing a glass preform for optical fibers (hereinafter, simply referred to as a glass preform), glass fine particles produced by supplying a glass material to an oxyhydrogen flame parner around a glass rod serving as a core are known. There is known a method of forming a porous preform for optical fiber (hereinafter simply referred to as a porous preform) by depositing the porous preform and sintering the transparent preform at a high temperature to form a vitreous glass.
- a porous preform for optical fiber
- a glass particle generation parner is placed perpendicular to the core glass rod, commonly called the external CVD method (OVD method), and the parner is reciprocated along the glass rod.
- OTD method external CVD method
- a method of moving and depositing glass particles is adopted.
- heat treatment is performed at a high temperature in an atmosphere of halogen gas, and then, in an atmosphere of only He, 0 and He, below the transparent vitrification temperature.
- Patent Document 2 A method of processing at the above high temperature is generally known (see Patent Document 2).
- Patent Documents 4 and 5 In order to solve the problem of air bubbles remaining in the glass base material, there is a method of performing vitrification under a vacuum as shown in Patent Documents 4 and 5.
- Patent Document 1 Patent Publication No. 2612949
- Patent Document 2 JP-A-61-270232
- Patent Document 3 Japanese Patent Application Laid-Open No. 05-319848
- Patent Document 4 JP-A-56-63833
- Patent Document 5 JP-A-63-201025
- the present inventors have prepared a porous base material by depositing glass particles around a core glass rod having a core and a part of a clad by an OVD method, and prepared the porous base material in a chlorine gas-containing atmosphere. After the heat treatment, a transparent vitrification treatment was performed under vacuum or reduced pressure to produce a glass base material. As shown in FIG. 1, the refractive index distribution was uneven in the radial direction.
- FIG. 2 is an enlarged view of the refractive index distribution near the boundary of the core glass rod of FIG. 1, and the outer layer has an inner layer with a higher refractive index, particularly the refractive index near the boundary is lower. Is allowed. An optical fiber obtained by drawing such a glass base material has poor dispersion characteristics.
- an object of the present invention is to reduce the difference in refractive index between a glass rod for a core (starting rod) having a core and a part of a clad by an OVD method and a glass layer deposited thereon. Smaller and diameter An object of the present invention is to provide a method for producing a glass base material having a uniform refractive index distribution in the direction. Means for solving the problem
- the method for producing a glass preform of the present invention includes a method for producing a glass preform for an optical fiber by sintering a porous preform for an optical fiber produced by the OVD method and turning it into a transparent glass. After the porous preform is heat-treated in an atmosphere containing a dehydrating gas, cooled for at least 10 hours, the dehydrating gas is replaced with an inert gas, and then the glass is transparently vitrified under vacuum or reduced pressure. I have.
- the replacement of the dehydration gas with the inert gas may be performed after the porous base material is heat-treated in an atmosphere containing the dehydration gas, preferably after cooling for at least 24 hours.
- a core glass rod having a core and a part of a clad is used as a starting rod, and the start positions of the reciprocating motion are sequentially determined by a plurality of parners arranged at regular intervals along the glass rod. Glass particles are deposited while moving.
- the sintering furnace has a furnace tube made of quartz glass, and it is preferable that the length of the heating and soaking region be equal to or longer than the length of the porous base material.
- the vitrification performed after the heat treatment is preferably performed in a different sintering furnace.
- the glass base material of the present invention is manufactured by the above-described manufacturing method.
- This glass base material preferably has a uniform refractive index when it is made transparent.
- This glass preform is formed by depositing glass fine particles around a core glass rod having a core and a part of a clad, and has a refractive index substantially equal to that of the core glass rod when it is made transparent. More preferably,
- the present inventors have conducted intensive studies to achieve the above object, and as a result, after a heat treatment step of dehydrating and drying the porous base material in an atmosphere containing a dehydrating gas such as chlorine gas, the inert gas was removed from the inert gas.
- the timing of the replacement was found to be extremely important.
- the introduction of the inert gas is performed after the porous base material has been cooled for at least 10 hours, and preferably after cooling for at least 24 hours.
- the present inventors have found that the difference in the refractive index near the boundary with the glass layer deposited thereon becomes small, and that a glass base material having a uniform refractive index distribution in the radial direction can be obtained, and the present invention has been completed.
- the temperature of the sintering furnace is lowered immediately after the heat treatment, and an inert gas is introduced into the furnace simultaneously with the start of the temperature reduction. At this time, even if the temperature in the furnace is lowered, the inside of the porous preform is not sufficiently cooled and the temperature is high. The reverse reaction occurs, and the bonded Si'C1 is replaced with Si • ⁇ H again.
- the residual amount of C1 having an effect of increasing the refractive index in the glass decreases, and the refractive index decreases. Since the temperature of the central portion of the porous base material is hardly lowered, a portion having a low refractive index in the radial direction is generated in the inside where the C1 re-displacement phenomenon easily occurs.
- the porous base material is a force obtained by depositing glass particles around a starting rod by the OVD method.
- the starting rod uses a glass rod for a core having a core and a part of a clad.
- the porous mother body is extremely efficiently and at a high speed. Materials can be manufactured.
- the furnace tube disposed in the sintering furnace is preferably made of quartz glass because it is less affected by contamination.
- the heating unit performs processing while moving the heating region or the porous base material in which the conventional heating region is short, by setting the length of the heating soaking region to be equal to or longer than the length of the porous base material. Heat treatment can be performed in a shorter time than in the zone heating method.
- ten deposition parners are arranged at 150mm intervals along a core glass rod with an outer diameter of 50mm, which has a core and a part of a clad, and reciprocate. While moving the starting position sequentially, the glass particles are deposited, and the outer diameter is 300 mm,
- a 1500 mm porous base material was produced.
- the porous preform 1 is inserted into a heat treatment furnace 3 having a quartz furnace tube 2 having a total length of 4 m and an inner diameter of 400 mm ⁇ , and is suspended by being held by the holding section 6, with chlorine gas 2 Nl / min, nitrogen gas 24 Nl.
- the heater 5 was used to raise the temperature in the furnace from room temperature to 1000 ° C over 2 hours. After that, the furnace temperature was maintained at 1000 ° C and heat treatment was performed for 15 hours. 24 hours after the start of natural cooling, the supply of chlorine gas, which had been supplying the above amount, was stopped. Then, an inert gas was introduced into the furnace tube.
- the dehydrated and dried porous base material was transferred to a different sintering furnace and subjected to a transparent vitrification process under reduced pressure to produce a glass base material having an outer diameter of 150 mm. After stretching and reducing the diameter of the glass base material to an outer diameter of 60 mm, the refractive index distribution in the radial direction was measured.
- a porous preform of the same size was prepared in the same manner as in Example 1, and this porous preform was inserted into a heat treatment furnace 3 having a quartz furnace tube 2 having a total length of 4 m and an inner diameter of 400 mm ⁇ , and chlorine gas 2 Nl
- the temperature inside the furnace was raised from room temperature to 1000 ° C. over 2 hours while introducing / N1 and nitrogen gas 24Nl / min from the gas supply pipe 4 provided at the lower part of the furnace tube 2. Thereafter, heat treatment was performed for 15 hours while maintaining the furnace temperature at 1000 ° C. Immediately after the heating, the supply of chlorine gas was stopped, and the atmosphere in the furnace tube was replaced with an inert gas.
- the heat-treated porous base material was transferred to a different sintering furnace and subjected to a transparent vitrification process under reduced pressure to produce a glass base material having an outer diameter of 150 mm. After stretching and shrinking the glass base material to an outer diameter of 60 mm ⁇ , the refractive index distribution in the radial direction was measured.
- the measurement results are as shown in FIGS. 1 and 2, and a change in the refractive index distribution in the radial direction was observed. In particular, there was a tendency that the refractive index was higher on the outer side and lower on the inner side. Further, there was a difference in the refractive index near the boundary with the starting rod.
- a porous preform of the same size was prepared in the same manner as in Example 1, and this porous preform was inserted into a heat treatment furnace 3 having a quartz furnace core tube 2 with a total length of 4 m and an inner diameter of 400 mm ⁇ , and chlorine gas 2 Nl
- the temperature inside the furnace was raised from room temperature to 1000 ° C. over 2 hours while introducing / N1 and nitrogen gas 24Nl / min from the gas supply pipe 4 provided at the lower part of the furnace tube 2. After that, the furnace temperature was maintained at 1000 ° C and heat treatment was performed for 15 hours.
- the heat-treated porous base material was transferred to a different sintering furnace, and reduced pressure was applied to a transparent vitrification process to produce a glass base material having an outer diameter of 150 mm. After stretching and reducing the diameter of the glass base material to an outer diameter of 60 mm ⁇ , the refractive index distribution in the radial direction was measured.
- the refractive index difference is not recognized near the boundary between the starting rod and the glass layer deposited thereon, and the variation in the refractive index in the radial direction is extremely small and the refractive index difference in the glass base material is small.
- a glass base material having an extremely small amount of H groups can be obtained. This glass preform can be used for manufacturing optical fibers.
- FIG. 1 is a schematic cross-sectional view showing a radial refractive index distribution of a glass base material manufactured by a conventional method.
- FIG. 2 is an enlarged view showing a refractive index distribution near a boundary of a core glass rod of FIG. 1.
- FIG. 3 is a schematic sectional view showing a sintering furnace used in an example of the present invention.
- FIG. 4 is a schematic cross-sectional view showing a radial refractive index distribution of a glass base material obtained in an example of the present invention.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003-140749 | 2003-05-19 | ||
JP2003140749A JP2004345869A (ja) | 2003-05-19 | 2003-05-19 | 光ファイバ用ガラス母材の製造方法 |
Publications (1)
Publication Number | Publication Date |
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WO2004101457A1 true WO2004101457A1 (ja) | 2004-11-25 |
Family
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Family Applications (1)
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PCT/JP2004/006631 WO2004101457A1 (ja) | 2003-05-19 | 2004-05-17 | 光ファイバ用ガラス母材の製造方法 |
Country Status (3)
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JP (1) | JP2004345869A (ja) |
TW (1) | TW200500310A (ja) |
WO (1) | WO2004101457A1 (ja) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP4501850B2 (ja) * | 2005-12-07 | 2010-07-14 | 住友電気工業株式会社 | ガラス体製造方法 |
JPWO2019107557A1 (ja) | 2017-12-01 | 2020-11-19 | 古河電気工業株式会社 | ガラス体の製造装置、ガラス体の製造方法、スート搬送機構、及びスート加熱機構 |
WO2023112967A1 (ja) * | 2021-12-14 | 2023-06-22 | 住友電気工業株式会社 | ガラス母材の製造方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05319848A (ja) * | 1992-05-18 | 1993-12-03 | Tosoh Corp | 石英ガラスの製造方法 |
JPH11292557A (ja) * | 1998-04-13 | 1999-10-26 | Sumitomo Electric Ind Ltd | 光ファイバ多孔質母材の透明化方法 |
JP2003137584A (ja) * | 2001-11-01 | 2003-05-14 | Furukawa Electric Co Ltd:The | 光ファイバ母材の熱処理装置および方法 |
-
2003
- 2003-05-19 JP JP2003140749A patent/JP2004345869A/ja active Pending
-
2004
- 2004-05-17 WO PCT/JP2004/006631 patent/WO2004101457A1/ja active Application Filing
- 2004-05-18 TW TW093113910A patent/TW200500310A/zh unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05319848A (ja) * | 1992-05-18 | 1993-12-03 | Tosoh Corp | 石英ガラスの製造方法 |
JPH11292557A (ja) * | 1998-04-13 | 1999-10-26 | Sumitomo Electric Ind Ltd | 光ファイバ多孔質母材の透明化方法 |
JP2003137584A (ja) * | 2001-11-01 | 2003-05-14 | Furukawa Electric Co Ltd:The | 光ファイバ母材の熱処理装置および方法 |
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Publication number | Publication date |
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TW200500310A (en) | 2005-01-01 |
JP2004345869A (ja) | 2004-12-09 |
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