JP4804796B2 - Manufacturing method of optical fiber preform - Google Patents

Manufacturing method of optical fiber preform Download PDF

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JP4804796B2
JP4804796B2 JP2005152053A JP2005152053A JP4804796B2 JP 4804796 B2 JP4804796 B2 JP 4804796B2 JP 2005152053 A JP2005152053 A JP 2005152053A JP 2005152053 A JP2005152053 A JP 2005152053A JP 4804796 B2 JP4804796 B2 JP 4804796B2
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base material
quartz glass
optical fiber
glass base
gas
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JP2006327858A (en
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智宏 布目
孝和 後藤
成敏 山田
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Fujikura Ltd
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    • 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

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  • Manufacture, Treatment Of Glass Fibers (AREA)

Description

本発明は、光ファイバ用母材など各種光学部品等の製造に用いられる石英ガラス母材の表面層に存在するＯＨ基を除去する光ファイバ用母材の製造方法に関する。 The present invention relates to a method of manufacturing an optical fiber preform that to remove the OH groups present in the surface layer of the quartz glass preform for use in the manufacture of various optical components such as optical fiber preform.

石英ガラス母材の加工を行う際に、酸水素火炎などで母材を加熱し、母材の変形、研削、清浄化する火炎研磨処理が行われている。
しかし、この火炎研磨処理では、石英ガラス母材を酸水素火炎など、水素を含む雰囲気下、高温で処理を行うため、母材の表面層に高濃度のＯＨ基が生成される。特許文献１には、前述したような加熱処理により、表面から０．２ｍｍの深さまで高濃度のＯＨ基が生成されるので、そのままオーバークラッド層を製造して光ファイバ用母材を製造し、更にその母材を紡糸して光ファイバを製造すると、ＯＨ基による損失、具体的には波長１．３８μｍ帯の損失が増加することが記載されている。
特許文献１では、母材の表面近傍に形成されるＯＨ基が高濃度の層をフッ酸でエッチングすることで取り除き、波長１．３８μｍ帯の損失を低減する方法が開示されている。
特開平１１−１３３９号公報 When processing a quartz glass base material, a flame polishing process is performed in which the base material is heated with an oxyhydrogen flame or the like to deform, grind and clean the base material.
However, in this flame polishing process, the quartz glass base material is processed at a high temperature in an atmosphere containing hydrogen, such as an oxyhydrogen flame, so that high-concentration OH groups are generated in the surface layer of the base material. In Patent Document 1, a high-concentration OH group is generated from the surface to a depth of 0.2 mm by the heat treatment as described above, so that an overcladding layer is produced as it is to produce an optical fiber preform, Furthermore, it is described that when an optical fiber is produced by spinning the base material, the loss due to OH groups, specifically, the loss in the wavelength band of 1.38 μm increases.
Patent Document 1 discloses a method of removing a layer having a high concentration of OH groups formed in the vicinity of the surface of a base material by etching with hydrofluoric acid to reduce a loss in a wavelength band of 1.38 μm.
JP-A-11-1339

しかしながら、特許文献１に開示されているように、石英ガラス母材をフッ酸でエッチングする場合、作業を行う上で危険を伴う問題がある。
また、石英ガラス母材の表面を除去するため、除去する分の石英ガラスをあらかじめ余分に製造しておく必要があり、製造コストの上昇を招く問題がある。
また、石英ガラス母材の表面をフッ酸によってエッチングすると、母材表面に凹凸を生じることがあり、石英ガラス母材の品質が低下する問題もある。
また、フッ酸は、エッチングを繰り返すと濃度が低下していくため、処理能力が変化する。そのため一定の削り量を維持することは難しかった。 However, as disclosed in Patent Document 1, when a quartz glass base material is etched with hydrofluoric acid, there is a problem with danger in performing the operation.
Further, in order to remove the surface of the quartz glass base material, it is necessary to produce in advance an extra amount of quartz glass to be removed, leading to a problem of an increase in production cost.
In addition, when the surface of the quartz glass base material is etched with hydrofluoric acid, irregularities may be generated on the surface of the base material, resulting in a problem that the quality of the quartz glass base material is deteriorated.
In addition, since the concentration of hydrofluoric acid decreases as etching is repeated, the processing capability changes. For this reason, it has been difficult to maintain a constant amount of cutting.

本発明は前記事情に鑑みてなされ、安全かつ簡単に母材表面近傍のＯＨ基を除去することができ、高品質の石英ガラス母材を低コストで製造することができる光ファイバ用母材の製造方法の提供を目的とする。 The present invention has been made in view of the above circumstances, safe and can easily be removed OH groups in the vicinity of the base material surface, the optical fiber preform which is Ru can manufacture higher-quality quartz glass preform at a low cost It aims at providing the manufacturing method of this.

前記目的を達成するため、本発明は、光ファイバ用母材のコアとなる石英ガラス母材に対して酸水素火炎による研磨を行い、この火炎研磨された石英ガラス母材の周りに、外付け法によりクラッドとなるスート微粒子を堆積し、このスート微粒子を焼結する光ファイバ用母材の製造方法であって、前記火炎研磨後の石英ガラス母材を炉心管内に収容し、前記石英ガラス母材を、塩素系ガス含有雰囲気下、１５００℃〜１７００℃の温度範囲で加熱して、前記火炎研磨によって前記石英ガラス母材の表面層に形成されたＯＨ基を減少させることを特徴とする光ファイバ用母材の製造方法を提供する。 In order to achieve the above object, the present invention performs polishing with an oxyhydrogen flame on a quartz glass base material that is a core of an optical fiber base material, and externally attaches around the flame-polished quartz glass base material. An optical fiber preform for depositing soot fine particles to be clad by a method and sintering the soot fine particles, the quartz glass preform after the flame polishing being accommodated in a furnace core tube, and the quartz glass preform The material is heated in a temperature range of 1500 ° C. to 1700 ° C. in a chlorine-containing gas-containing atmosphere to reduce OH groups formed on the surface layer of the quartz glass base material by the flame polishing. A method for manufacturing a fiber preform is provided.

本発明の光ファイバ用母材の製造方法において、塩素系ガス含有雰囲気が、塩素ガスとヘリウムガスなどの不活性ガスとの混合ガス雰囲気であり、かつその塩素ガス濃度が２〜４５％の範囲であることが好ましい。 In the optical fiber preform manufacturing method of the present invention, the chlorine-containing gas-containing atmosphere is a mixed gas atmosphere of chlorine gas and an inert gas such as helium gas, and the chlorine gas concentration is in the range of 2 to 45%. der Rukoto is preferable.

本発明の石英ガラス母材の処理方法は、石英ガラス母材を酸水素火炎で火炎研磨した後、該石英ガラス母材を塩素系ガス含有雰囲気下で加熱し、石英ガラス母材の表面層に存在するＯＨ基が減少した石英ガラス母材を得ることによって、従来のフッ酸による化学研磨でＯＨ基の減少を図る処理方法に比べ、安全かつ簡単に母材表面近傍のＯＨ基を除去することができ、高品質の石英ガラス母材を低コストで製造することができる。
また本発明の光ファイバ用母材の製造方法は、前述した本発明の石英ガラス母材の処理方法により得られた石英ガラス母材を用い、その表面に石英ガラスからなるスート微粒子を堆積し、さらに脱水焼結を行って光ファイバ用母材を製造するものなので、波長１３８３ｎｍ帯に現れるＯＨ基による損失を低減させた高品質の光ファイバを作製可能な光ファイバ用母材を製造することができる。また、石英ガラス母材とスート堆積後の外付け母材の外径比率を大きくすることができるので、光ファイバ用母材の製造コストを大幅に低減することができる。 In the method for treating a quartz glass base material of the present invention, after the quartz glass base material is flame polished with an oxyhydrogen flame, the quartz glass base material is heated in a chlorine-containing gas-containing atmosphere to form a surface layer of the quartz glass base material. By obtaining a quartz glass base material with reduced OH groups, it is possible to remove OH groups near the surface of the base material safely and easily compared to the conventional method of reducing OH groups by chemical polishing with hydrofluoric acid. It is possible to manufacture a high-quality quartz glass base material at a low cost.
Further, the method for manufacturing the optical fiber preform of the present invention uses the quartz glass preform obtained by the above-described method for treating a quartz glass preform of the present invention, deposits soot particles made of quartz glass on the surface thereof, Furthermore, since the optical fiber preform is manufactured by performing dehydration sintering, it is possible to manufacture an optical fiber preform capable of producing a high-quality optical fiber with reduced loss due to OH groups appearing in the wavelength 1383 nm band. it can. Moreover, since the outer diameter ratio of the quartz glass base material and the external base material after soot deposition can be increased, the manufacturing cost of the optical fiber base material can be greatly reduced.

以下、図面を参照して本発明を説明する。
本発明による石英ガラス母材の処理方法において、処理対象とする石英ガラス母材としては、純水石英（ＳｉＯ２）ガラスや石英ガラスに屈折率を変化させるドーパント（ＧｅＯ２，Ｆ，Ｂ２Ｏ３など）をドープした材料を円柱状、丸棒状などの形状に成形した母材であればよく、例えば、光ファイバを紡糸するための光ファイバ用母材を製造する際に、スート微粒子を堆積させる石英ガラス母材、コリメートレンズなどが挙げられるが、これに限定されない。 The present invention will be described below with reference to the drawings.
In the method for treating a quartz glass base material according to the present invention, as the quartz glass base material to be treated, pure water quartz (SiO 2 ) glass or a dopant (GeO 2 , F, B 2 O that changes the refractive index to quartz glass). 3 ) and the like may be used as long as the base material is formed into a cylindrical shape, a round bar shape, or the like. For example, soot fine particles are deposited when manufacturing an optical fiber base material for spinning an optical fiber. Examples thereof include, but are not limited to, a quartz glass base material and a collimating lens.

この石英ガラス母材の製造方法は限定されないが、例えば、ＶＡＤ（Ｖａｐｏｒ ｐｈａｓｅ Ａｘｉａｌ Ｄｅｐｏｓｉｔｉｏｎ）法などによって、石英ガラスを円筒状に形成し、これを脱水焼結して得られた石英ガラス母材を用いることができる。ＶＡＤ法によれば、光ファイバ用母材のコア部などとして好適なＧｅＯ２などのドーパントを含む石英ガラス母材を製造するのに好適である。 The method for producing the quartz glass base material is not limited. For example, a quartz glass base material obtained by forming quartz glass into a cylindrical shape by the VAD (Vapor Phase Axial Deposition) method and then dehydrating and sintering the quartz glass base material is used. Can be used. The VAD method is suitable for manufacturing a quartz glass base material containing a dopant such as GeO 2 suitable as a core part of an optical fiber base material.

ＶＡＤ法などで作製され、脱水焼結されて得られた石英ガラス母材は、スート微粒子を堆積させる前に、酸水素火炎などで火炎研磨し、表面の平滑化（火炎研磨）及び清浄化、あるいは形状修正などを行う。石英ガラス母材に前記火炎研磨を施すと、石英ガラス母材の表面近傍にＯＨ基が形成され、火炎研磨終了後に母材表面近傍にＯＨ基が残留する。   The quartz glass base material produced by the VAD method or the like and dehydrated and sintered is subjected to flame polishing with an oxyhydrogen flame or the like before depositing soot fine particles, and the surface is smoothed (flame polishing) and cleaned. Or shape correction is performed. When the flame polishing is performed on the quartz glass base material, OH groups are formed in the vicinity of the surface of the quartz glass base material, and OH groups remain in the vicinity of the base material surface after the completion of the flame polishing.

図１は、石英ガラス母材に酸水素火炎を吹き付けて火炎研磨を施した後の石英ガラス母材の直径方向のＯＨ基濃度分布を例示するグラフである。図１に示すように、酸水素火炎による火炎研磨を施すことにより、石英ガラス母材の表面近傍にＯＨ基が形成され、火炎研磨後にそのＯＨ基が高濃度で残存していることがわかる。このＯＨ基が残留した石英ガラス母材を用いて、外付け工程を経て光ファイバ用母材を製造し、これを紡糸して得られた光ファイバは、波長１３８３ｎｍ帯においてＯＨ基による損失が認められる。   FIG. 1 is a graph illustrating the OH group concentration distribution in the diameter direction of a quartz glass preform after oxyhydrogen flame is blown onto the quartz glass preform and subjected to flame polishing. As shown in FIG. 1, it is understood that OH groups are formed in the vicinity of the surface of the quartz glass base material by performing flame polishing with an oxyhydrogen flame, and the OH groups remain at a high concentration after flame polishing. Using this quartz glass base material in which the OH group remains, an optical fiber base material is manufactured through an external process, and an optical fiber obtained by spinning the optical fiber has a loss due to the OH group in a wavelength band of 1383 nm. It is done.

本発明の石英ガラス母材の処理方法は、石英ガラス母材を酸水素火炎で火炎研磨した後、その石英ガラス母材を塩素系ガス含有雰囲気下で加熱することにより、石英ガラス母材の表面層に存在するＯＨ基が減少した石英ガラス母材を得ることを特徴としている。表面近傍にＯＨ基が存在する石英ガラス母材を、高温下且つ塩素ガスを含む雰囲気下で処理することにより、表面近傍のＯＨ基を除去することができる。   The method for treating a quartz glass base material according to the present invention comprises: polishing the quartz glass base material with an oxyhydrogen flame; and then heating the quartz glass base material in a chlorine-containing gas-containing atmosphere to obtain a surface of the quartz glass base material. It is characterized by obtaining a quartz glass base material in which OH groups present in the layer are reduced. By treating a quartz glass base material having OH groups in the vicinity of the surface in an atmosphere containing high temperature and chlorine gas, the OH groups in the vicinity of the surface can be removed.

図２は、本発明の石英ガラス母材の処理方法を実施する処理装置の一例を示す構成図である。この処理装置１は、石英ガラス母材２を収容する炉心管３と、該炉心管３を囲んで設けられたカーボンヒータ４と、該カーボンヒータ４を囲んで設けられた断熱部５と、炉心管３のいずれか（図２では炉心管上端側）に設けられ、炉心管３内を排気する図示しない排気手段に接続される排気管６と、炉心管３上方から管内に挿通され、図示しない回転駆動手段に接続された石英ガラス母材２取付用の支持棒７と、炉心管３のいずれか（図２では炉心管下端側）に設けられ、図示しないガス供給手段から炉心管３内に塩素系ガスを含む雰囲気ガスを供給する給気管８とを備えて構成されている。   FIG. 2 is a block diagram showing an example of a processing apparatus for carrying out the method for processing a quartz glass base material of the present invention. The processing apparatus 1 includes a reactor core tube 3 that accommodates a quartz glass base material 2, a carbon heater 4 provided around the reactor core tube 3, a heat insulating portion 5 provided around the carbon heater 4, and a reactor core. An exhaust pipe 6 provided on one of the tubes 3 (in FIG. 2, the upper end side of the core tube) and connected to an exhaust means (not shown) for exhausting the inside of the core tube 3 is inserted into the tube from above the core tube 3 and is not shown. The support rod 7 for attaching the quartz glass base material 2 connected to the rotation driving means and the core tube 3 (in FIG. 2, the lower side of the core tube) are provided in the core tube 3 from a gas supply means (not shown). And an air supply pipe 8 for supplying an atmospheric gas containing a chlorine-based gas.

図２の装置を用いて、石英ガラス母材１のＯＨ基を減少させる処理を行うには、火炎研磨した後の石英ガラス母材２の一端を、炉心管３内の支持棒７に固定する。次いで、カーボンヒータ４に通電して炉心管３内を加熱するとともに、必要に応じて図示していない回転駆動手段により石英ガラス母材２を回転させる。次に、排気管６から炉心管３内の雰囲気ガスを排気するとともに、給気管８を通して炉心管３内に塩素系ガスとヘリウムガスなどの不活性ガスとの混合ガスを供給する。これによって、炉心管３内は塩素系ガス含有雰囲気となる。この塩素系ガス含有雰囲気下且つ高温下で石英ガラス母材２を処理することにより、石英ガラス母材２表面近傍のＯＨ基を除去する（ＯＨ基除去工程）。   In order to reduce the OH groups of the quartz glass base material 1 using the apparatus shown in FIG. 2, one end of the quartz glass base material 2 after flame polishing is fixed to the support rod 7 in the core tube 3. . Next, the carbon heater 4 is energized to heat the inside of the furnace core tube 3 and, if necessary, the quartz glass base material 2 is rotated by a rotation driving means (not shown). Next, the atmosphere gas in the furnace core tube 3 is exhausted from the exhaust pipe 6, and a mixed gas of a chlorine-based gas and an inert gas such as helium gas is supplied into the furnace core tube 3 through the air supply pipe 8. Thereby, the inside of the furnace core tube 3 becomes an atmosphere containing chlorine-based gas. By treating the quartz glass base material 2 in this chlorine-based gas-containing atmosphere and at a high temperature, OH groups near the surface of the quartz glass base material 2 are removed (OH group removal step).

ここで、塩素系ガスとしては、塩素（Ｃｌ２）ガス、三塩化ホウ素（ＢＣｌ３）ガス、四塩化炭素（ＣＣｌ４）ガス、四塩化ケイ素（ＳｉＣｌ４）ガスなどの各塩素系ガスの１種又は２種以上を用いることができるが、好ましくは塩素ガスが用いられる。また、塩素系ガスと混合して使用される不活性ガスとしては、ヘリウムガスの他、アルゴンガス、ネオンガスなどが挙げられる。 Here, as the chlorine-based gas, 1 of each chlorine-based gas such as chlorine (Cl 2 ) gas, boron trichloride (BCl 3 ) gas, carbon tetrachloride (CCl 4 ) gas, silicon tetrachloride (SiCl 4 ) gas or the like. Although a seed | species or 2 or more types can be used, Preferably chlorine gas is used. In addition, examples of the inert gas used by mixing with a chlorine-based gas include helium gas, argon gas, neon gas, and the like.

このＯＨ基除去工程において、雰囲気ガス中の塩素ガス濃度は、ガス全量に対する体積比で２〜４５％の範囲とすることが望ましい。雰囲気ガス中の塩素ガス濃度が２％未満であると、このＯＨ基除去工程において石英ガラス母材２表面近傍のＯＨ基を除去することが困難になる。一方、雰囲気ガス中の塩素ガス濃度が４５％を超えると、処理後の母材表面に残留する塩素量が多くなり、石英ガラス母材２の表面の屈折率などの光学特性が変化してしまう可能性がある。   In this OH group removal step, the chlorine gas concentration in the atmospheric gas is desirably in the range of 2 to 45% by volume ratio with respect to the total amount of gas. If the chlorine gas concentration in the atmospheric gas is less than 2%, it becomes difficult to remove OH groups near the surface of the quartz glass base material 2 in this OH group removal step. On the other hand, if the chlorine gas concentration in the atmospheric gas exceeds 45%, the amount of chlorine remaining on the surface of the base material after processing increases, and the optical characteristics such as the refractive index of the surface of the quartz glass base material 2 change. there is a possibility.

また、このＯＨ基除去工程において、処理温度は、１３００℃〜１７００℃の範囲とすることが望ましい。処理温度が１３００℃より低いと、このＯＨ基除去工程において石英ガラス母材２表面近傍のＯＨ基を除去することが困難になる。一方、処理温度が１７００℃を超えると、母材が変形してしまうおそれがある。   In this OH group removal step, it is desirable that the processing temperature be in the range of 1300 ° C to 1700 ° C. When the processing temperature is lower than 1300 ° C., it becomes difficult to remove OH groups near the surface of the quartz glass base material 2 in this OH group removal step. On the other hand, when the processing temperature exceeds 1700 ° C., the base material may be deformed.

このＯＨ基除去工程を数十分〜数十時間程度、好ましくは１時間〜１０時間程度施すことで、石英ガラス母材２の表面近傍のＯＨ基が除去される。図３は、ＯＨ基除去工程を行った後の石英ガラス母材の直径方向のＯＨ基濃度分布を例示するグラフである。図３に示すように、ＯＨ基除去工程を行った後の石英ガラス母材では、ＯＨ基が殆ど検出されなくなる。   By performing this OH group removal step for several tens of minutes to several tens of hours, preferably about 1 hour to 10 hours, OH groups near the surface of the quartz glass base material 2 are removed. FIG. 3 is a graph illustrating the OH group concentration distribution in the diameter direction of the quartz glass base material after the OH group removal step. As shown in FIG. 3, in the quartz glass base material after the OH group removal step, OH groups are hardly detected.

なお、図２に示す装置は、あくまでも一例であり、本発明の処理方法の実施のための装置は本例示に限定されず、種々の修正や変更が可能である。例えば、石英ガラス母材を移動させヒータにより加熱した領域を通過させる方式でもよい。また処理する本数も１本に限定されず、２本以上の母材を同時に処理することも可能である。   Note that the apparatus shown in FIG. 2 is merely an example, and the apparatus for carrying out the processing method of the present invention is not limited to this example, and various modifications and changes are possible. For example, a system in which a quartz glass base material is moved and passed through a region heated by a heater may be used. Further, the number of processing is not limited to one, and two or more base materials can be processed at the same time.

この石英ガラス母材の処理方法は、石英ガラス母材を酸水素火炎で火炎研磨した後、該石英ガラス母材を塩素系ガス含有雰囲気下で加熱し、石英ガラス母材の表面層に存在するＯＨ基が減少した石英ガラス母材を得ることによって、従来のフッ酸による化学研磨でＯＨ基の減少を図る処理方法に比べ、安全かつ簡単に母材表面近傍のＯＨ基を除去することができ、高品質の石英ガラス母材を低コストで製造することができる。   In this method of treating a quartz glass base material, the quartz glass base material is flame-polished with an oxyhydrogen flame, and then the quartz glass base material is heated in a chlorine-containing gas-containing atmosphere to be present on the surface layer of the quartz glass base material. By obtaining a quartz glass base material with reduced OH groups, OH groups near the surface of the base material can be removed safely and easily compared to conventional treatment methods that reduce OH groups by chemical polishing with hydrofluoric acid. High-quality quartz glass base material can be manufactured at low cost.

次に、本発明の光ファイバ用母材の製造方法を説明する。
本発明の光ファイバ用母材の製造方法は、前述した本発明の石英ガラス母材の処理方法により得られた石英ガラス母材を用い、その表面に石英ガラスからなるスート微粒子を堆積し、さらに脱水焼結を行って光ファイバ用母材を製造する。 Next, the manufacturing method of the optical fiber preform of the present invention will be described.
The optical fiber preform manufacturing method of the present invention uses the quartz glass preform obtained by the above-described method of processing a quartz glass preform of the present invention, deposits soot particles made of quartz glass on the surface, and An optical fiber preform is manufactured by dehydration sintering.

石英ガラス母材の表面に石英ガラスからなるスート微粒子を堆積する方法としては、例えば、ＯＶＤ（Ｏｕｔｓｉｄｅ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ）法などが好ましい。   As a method for depositing soot fine particles made of quartz glass on the surface of the quartz glass base material, for example, an OVD (Outside Vapor Deposition) method or the like is preferable.

本発明の光ファイバ用母材の製造方法は、前述した本発明の石英ガラス母材の処理方法により得られた石英ガラス母材を用い、その表面に石英ガラスからなるスート微粒子を堆積し、さらに脱水焼結を行って光ファイバ用母材を製造するものなので、波長１３８３ｎｍ帯に現れるＯＨ基による損失を低減させた高品質の光ファイバを作製可能な光ファイバ用母材を製造することができる。また、石英ガラス母材とスート堆積後の外付け母材の外径比率を大きくすることができるので、光ファイバ用母材の製造コストを大幅に低減することができる。   The optical fiber preform manufacturing method of the present invention uses the quartz glass preform obtained by the above-described method of processing a quartz glass preform of the present invention, deposits soot particles made of quartz glass on the surface, and Since the optical fiber preform is manufactured by performing dehydration and sintering, an optical fiber preform capable of producing a high-quality optical fiber with reduced loss due to OH groups appearing in the wavelength 1383 nm band can be manufactured. . Moreover, since the outer diameter ratio of the quartz glass base material and the external base material after soot deposition can be increased, the manufacturing cost of the optical fiber base material can be greatly reduced.

［実施例１］
図２に示す処理装置を用い、石英ガラス母材を炉内に設置し、回転させる。ヒータにより炉内を１５００℃に加熱し、給気管より塩素ガス及びヘリウムガスを流した。塩素ガスの濃度は体積比で４．０％とした。
この状態で６時間石英ガラス母材を処理し、その後の母材表面近傍のＯＨ基濃度を測定したところ、図３に示すように、ＯＨ基を除去することができた。
極表面近傍のＯＨ基濃度が最も高い位置における濃度は、処理前が３７８ｐｐｍあったところが、７ｐｐｍまで低下した。 [Example 1]
A quartz glass base material is placed in a furnace and rotated using the processing apparatus shown in FIG. The inside of the furnace was heated to 1500 ° C. with a heater, and chlorine gas and helium gas were supplied from the supply pipe. The concentration of chlorine gas was 4.0% by volume.
In this state, the quartz glass base material was treated for 6 hours, and then the OH group concentration in the vicinity of the surface of the base material was measured. As a result, OH groups could be removed as shown in FIG.
The concentration at the highest OH group concentration in the vicinity of the pole surface was 378 ppm before the treatment, but decreased to 7 ppm.

［実施例２］
実施例１の処理条件において、塩素ガス濃度を４．０％に固定したまま、処理温度を、１２２０℃、１３００℃、１５００℃、１６５０℃及び１７５０℃に変化させて処理を実施した。各温度で処理した母材の極表面近傍におけるＯＨ基濃度の最大値を測定した。その結果を図４に示す。
図４より、処理温度が高いほど、母材表面のＯＨ基を短時間で除去できることがわかる。ただし、１７５０℃のときは、高温で母材が変形してしまった。また、１２２０℃のときは、１４時間処理しても、ＯＨ基を除去することはできなかった。
図４に示した結果より、本発明における処理温度は１３００℃〜１７００℃の範囲とすることが好ましい。 [Example 2]
Under the processing conditions of Example 1, the processing temperature was changed to 1220 ° C., 1300 ° C., 1500 ° C., 1650 ° C., and 1750 ° C. while the chlorine gas concentration was fixed at 4.0%. The maximum value of the OH group concentration in the vicinity of the extreme surface of the base material treated at each temperature was measured. The result is shown in FIG.
FIG. 4 shows that the higher the treatment temperature, the faster the OH groups on the base material surface can be removed. However, at 1750 ° C., the base material was deformed at a high temperature. At 1220 ° C., the OH group could not be removed even after treatment for 14 hours.
From the results shown in FIG. 4, the treatment temperature in the present invention is preferably in the range of 1300 ° C. to 1700 ° C.

［実施例３］
実施例１の処理条件において、処理温度を１５００℃に固定したまま、塩素ガス濃度を１％、２％、４％、４５％、５０％と変えて処理を実施した。各塩素ガス濃度で処理した母材の極表面近傍におけるＯＨ基濃度の最大値を測定した。その結果を図５に示す。
図５より、塩素ガス濃度が高いほど、母材表面のＯＨ基を短時間で除去できる。ただし、塩素ガス濃度を５０％まで増加させると、母材表面に塩素が多く残存し、屈折率が変化する。そのため光学特性が変化するので、好ましくない。また、塩素ガス濃度が１％のときは、１４時間処理しても、ＯＨ基を除去することはできなかった。
図５に示した結果より、本発明における塩素ガス濃度は２〜４５％の範囲が好ましい。 [Example 3]
Under the processing conditions of Example 1, the processing temperature was fixed at 1500 ° C., and the chlorine gas concentration was changed to 1%, 2%, 4%, 45%, and 50%. The maximum value of the OH group concentration in the vicinity of the extreme surface of the base material treated with each chlorine gas concentration was measured. The result is shown in FIG.
As can be seen from FIG. 5, the higher the chlorine gas concentration, the shorter the OH groups on the surface of the base material can be removed. However, when the chlorine gas concentration is increased to 50%, a large amount of chlorine remains on the surface of the base material, and the refractive index changes. Therefore, the optical characteristics change, which is not preferable. Further, when the chlorine gas concentration was 1%, OH groups could not be removed even after treatment for 14 hours.
From the results shown in FIG. 5, the chlorine gas concentration in the present invention is preferably in the range of 2 to 45%.

［実施例４］
実施例１の処理条件と同じく、塩素ガス濃度４％、処理温度１５００℃、処理時間６時間の条件で処理した石英ガラス母材の外側に、ＳｉＯ２からなるスート微粒子を堆積し、脱水処理を行った（外付け工程）。このとき外付け工程前の母材外径と外付け工程後の母材外径の比率は１：４．０とした。この母材の直径方向のＯＨ基濃度分布を測定した結果、外付け前の母材と外付け後の母材の境界面のＯＨ基濃度は１ｐｐｍ以下であった。
外付け工程後、脱水、焼結（透明化）して光ファイバ用母材とし、さらにこの母材を紡糸して光ファイバを製造した。得られた光ファイバの波長１３８３ｎｍにおける損失を測定したところ、損失は０．２８ｄＢ／ｋｍと低かった。 [Example 4]
Similar to the processing conditions of Example 1, soot particles made of SiO 2 are deposited on the outside of the quartz glass base material processed under conditions of a chlorine gas concentration of 4%, a processing temperature of 1500 ° C., and a processing time of 6 hours, and dehydration processing is performed. (External process). At this time, the ratio of the outer diameter of the base material before the external process and the outer diameter of the base material after the external process was set to 1: 4.0. As a result of measuring the OH group concentration distribution in the diameter direction of the base material, the OH group concentration at the boundary surface between the base material before external attachment and the base material after external attachment was 1 ppm or less.
After the external attaching process, dehydration and sintering (transparency) were carried out to obtain an optical fiber preform, and this preform was spun to produce an optical fiber. When the loss at a wavelength of 1383 nm of the obtained optical fiber was measured, the loss was as low as 0.28 dB / km.

［比較例１］
ＯＨ基を除去する処理を施さない石英ガラス母材を用い、それ以外は実施例４と同様にして外付け工程を行った。このとき外付け工程前の母材外径と外付け工程後の母材外径の比率は１：４．０とした。この母材の直径方向のＯＨ基濃度分布を測定した結果、外付け前の母材と外付け後の母材の境界面のＯＨ基濃度は１１０ｐｐｍであった。
外付け工程後、脱水、焼結（透明化）して光ファイバ用母材とし、さらにこの母材を紡糸して光ファイバを製造した。得られた光ファイバの波長１３８３ｎｍにおける損失を測定したところ、損失は０．３９ｄＢ／ｋｍと高かった。 [Comparative Example 1]
The external attachment process was performed in the same manner as in Example 4 except that a quartz glass base material not subjected to the treatment for removing OH groups was used. At this time, the ratio of the outer diameter of the base material before the external process and the outer diameter of the base material after the external process was set to 1: 4.0. As a result of measuring the OH group concentration distribution in the diameter direction of the base material, the OH group concentration at the boundary surface between the base material before external attachment and the base material after external attachment was 110 ppm.
After the external attaching process, dehydration and sintering (transparency) were carried out to obtain an optical fiber preform, and this preform was spun to produce an optical fiber. When the loss at a wavelength of 1383 nm of the obtained optical fiber was measured, the loss was as high as 0.39 dB / km.

［比較例２］
ＯＨ基を除去する処理を施さない石英ガラス母材を用い、それ以外は実施例４と同様にして外付け工程を行った。このとき外付け工程前の母材外径と外付け工程後の母材外径の比率は１：３．０とした。この母材の直径方向のＯＨ基濃度分布を測定した結果、外付け前の母材と外付け後の母材の境界面のＯＨ基濃度は１１４ｐｐｍであった。
外付け工程後、脱水、焼結（透明化）して光ファイバ用母材とし、さらにこの母材を紡糸して光ファイバを製造した。得られた光ファイバの波長１３８３ｎｍにおける損失を測定したところ、損失は０．２９ｄＢ／ｋｍであった。 [Comparative Example 2]
The external attachment process was performed in the same manner as in Example 4 except that a quartz glass base material not subjected to the treatment for removing OH groups was used. At this time, the ratio of the outer diameter of the base material before the external process and the outer diameter of the base material after the external process was set to 1: 3.0. As a result of measuring the OH group concentration distribution in the diameter direction of this base material, the OH group concentration at the boundary surface between the base material before external attachment and the base material after external attachment was 114 ppm.
After the external attaching process, dehydration and sintering (transparency) were carried out to obtain an optical fiber preform, and this preform was spun to produce an optical fiber. When the loss at a wavelength of 1383 nm of the obtained optical fiber was measured, the loss was 0.29 dB / km.

実施例４、比較例１，２の結果から、石英ガラス母材に対して本発明に係るＯＨ基を除去する処理を行うことで、外付け後の母材と外付け前の母材との境界面のＯＨ基濃度を低減することができ、外付け後の母材を用いて光ファイバを製造することにより、波長１３８３ｎｍでの損失が少ない高品質の光ファイバを製造することができる。   From the results of Example 4 and Comparative Examples 1 and 2, by performing the treatment for removing the OH group according to the present invention on the quartz glass base material, the base material after external attachment and the base material before external attachment The OH group concentration at the interface can be reduced, and a high-quality optical fiber with little loss at a wavelength of 1383 nm can be manufactured by manufacturing an optical fiber using an externally attached base material.

また、別の観点から見ると、本発明による処理を行うことで、石英ガラス母材に外付け工程を経て光ファイバ母材を作製する場合に、石英ガラス母材外径に対する外付け母材の外径の比率を大きくすることができるので、光ファイバ用母材の製造コストを低減することができる。石英ガラス母材は、ＶＡＤ法で製造しており、コアを含むため、外付け工程で製造するよりもコストがかかっている。そのため、石英ガラス母材外径に対する外付け母材の外径の比率を大きくした方が、製造コストが安くなる。   Further, from another viewpoint, when an optical fiber preform is produced through an external process on the quartz glass preform by performing the treatment according to the present invention, the outer preform of the quartz glass preform is compared with the outer diameter of the quartz glass preform. Since the ratio of the outer diameter can be increased, the manufacturing cost of the optical fiber preform can be reduced. Since the quartz glass base material is manufactured by the VAD method and includes the core, it is more expensive than the external glass manufacturing process. Therefore, the manufacturing cost is reduced when the ratio of the outer diameter of the external base material to the outer diameter of the quartz glass base material is increased.

酸水素火炎研磨後の石英ガラス母材のＯＨ基濃度分布を示すグラフである。It is a graph which shows OH group concentration distribution of the quartz glass base material after oxyhydrogen flame polishing. 本発明の処理方法を実施するための処理装置の一例を示す構成図である。It is a block diagram which shows an example of the processing apparatus for enforcing the processing method of this invention. 本発明の処理方法によって処理した後の石英ガラス母材のＯＨ基濃度分布を示すグラフである。It is a graph which shows OH group concentration distribution of the quartz glass base material after processing by the processing method of the present invention. 実施例の結果を示し、各処理温度における処理時間とＯＨ基濃度の関係を示すグラフである。It is a graph which shows the result of an Example and shows the relationship between the processing time in each processing temperature, and OH group density | concentration. 実施例の結果を示し、各塩素ガス濃度における処理時間とＯＨ基濃度の関係を示すグラフである。It is a graph which shows the result of an Example and shows the relationship between the processing time in each chlorine gas concentration, and OH group concentration.

符号の説明Explanation of symbols

１…処理装置、２…石英ガラス母材、３…炉心管、４…カーボンヒータ、５…断熱部、６…排気管、７…支持棒、８…給気管。
DESCRIPTION OF SYMBOLS 1 ... Processing apparatus, 2 ... Quartz glass base material, 3 ... Core tube, 4 ... Carbon heater, 5 ... Heat insulation part, 6 ... Exhaust pipe, 7 ... Support rod, 8 ... Supply pipe.

Claims (2)

光ファイバ用母材のコアとなる石英ガラス母材に対して酸水素火炎による研磨を行い、この火炎研磨された石英ガラス母材の周りに、外付け法によりクラッドとなるスート微粒子を堆積し、このスート微粒子を焼結する光ファイバ用母材の製造方法であって、
前記火炎研磨後の石英ガラス母材を炉心管内に収容し、前記石英ガラス母材を、塩素系ガス含有雰囲気下、１５００℃〜１７００℃の温度範囲で加熱して、前記火炎研磨によって前記石英ガラス母材の表面層に形成されたＯＨ基を減少させることを特徴とする光ファイバ用母材の製造方法。 The silica glass base material that is the core of the optical fiber base material is polished with an oxyhydrogen flame, and the soot fine particles that become the cladding are deposited around the flame-polished quartz glass base material by an external method, A method for manufacturing an optical fiber preform for sintering the soot particles,
The quartz glass base material after the flame polishing is accommodated in a furnace core tube, the quartz glass base material is heated in a temperature range of 1500 ° C. to 1700 ° C. in a chlorine-containing gas-containing atmosphere , and the quartz glass is subjected to the flame polishing. A method for producing an optical fiber preform, wherein OH groups formed on a surface layer of the preform are reduced. 塩素系ガス含有雰囲気が、塩素ガスとヘリウムガスなどの不活性ガスとの混合ガス雰囲気であり、かつその塩素ガス濃度が２〜４５％の範囲であることを特徴とする請求項１に記載の光ファイバ用母材の製造方法。 Chlorine gas-containing atmosphere is a mixed gas atmosphere of inert gas such as chlorine gas and helium gas, and according to claim 1 where the chlorine gas concentration is characterized in that in the range of 2-45% Manufacturing method of optical fiber preform.
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JP3489104B2 (en) * 1993-05-24 2004-01-19 住友電気工業株式会社 Manufacturing method of polarization maintaining optical fiber
JP3169357B2 (en) * 1999-03-12 2001-05-21 信越化学工業株式会社 Apparatus and method for sintering porous glass base material
JP2001287925A (en) * 2000-04-05 2001-10-16 Shin Etsu Chem Co Ltd Method for producing porous preform and apparatus therefor
JP2003146687A (en) * 2001-11-13 2003-05-21 Furukawa Electric Co Ltd:The Method for manufacturing optical fiber preform
JP2003246639A (en) * 2002-02-22 2003-09-02 Sumitomo Electric Ind Ltd Method of manufacturing glass preform and glass preform

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