JP4413738B2 - Quartz glass tube for manufacturing optical fiber, quartz glass tube for manufacturing optical fiber, preform for manufacturing optical fiber, and method for manufacturing optical fiber - Google Patents
Quartz glass tube for manufacturing optical fiber, quartz glass tube for manufacturing optical fiber, preform for manufacturing optical fiber, and method for manufacturing optical fiber Download PDFInfo
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- JP4413738B2 JP4413738B2 JP2004291032A JP2004291032A JP4413738B2 JP 4413738 B2 JP4413738 B2 JP 4413738B2 JP 2004291032 A JP2004291032 A JP 2004291032A JP 2004291032 A JP2004291032 A JP 2004291032A JP 4413738 B2 JP4413738 B2 JP 4413738B2
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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
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
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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
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
- C03B37/01228—Removal of preform material
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Abstract
Description
本発明は、光ファイバ製造用石英ガラスチューブ、ならびに光ファイバ製造用プリフォームおよび光ファイバの製造方法に関し、更に詳細には、ロッドインチューブ法により石英ガラス系光ファイバの製造に使用されるジャケット用石英ガラスチューブ、ならびに光ファイバ製造用プリフォームおよび光ファイバの製造方法に関する。 The present invention relates to a quartz glass tube for manufacturing an optical fiber, a preform for manufacturing an optical fiber, and a method for manufacturing an optical fiber, and more particularly, for a jacket used for manufacturing a silica glass-based optical fiber by a rod-in-tube method. The present invention relates to a quartz glass tube, an optical fiber manufacturing preform, and an optical fiber manufacturing method.
近年インターネットの普及などに伴い大量の光ファイバが使用されるようになり、光ファイバの低コストでの量産が必要となっている。また、波長１．３８μｍにおけるＯＨ基の吸収を限りなく低減した光ファイバ（ＬＷＰＦ：Low water peak fiber）が、広帯域の利用に適したものとして、普及しつつある。
また、特開平７−１０９１３５号公報などで紹介されているように、光ファイバの低コスト大量生産に適した製造方法として、機械研削加工が施された大型の石英ガラスチューブを使用したロッドインチューブ法がある。この方法は、ＶＡＤ法などにより作成された、十分に脱水処理された石英ガラスコアまたはクラッドの一部をも含む石英ガラスコアロッドを使用する事により、同様のコアロッドにＯＶＤ法によりクラッド部を形成する方法では避けられないＯＶＤ時のコアロッドへのＯＨ基の汚染を避けられるため、ＬＷＰＦの製造に適した方法として注目されている。
In recent years, with the spread of the Internet and the like, a large amount of optical fibers have been used, and mass production of optical fibers at low cost is required. In addition, an optical fiber (LWPF: Low water peak fiber) in which absorption of OH groups at a wavelength of 1.38 μm is reduced as much as possible is becoming widespread as being suitable for use in a wide band.
Further, as introduced in Japanese Patent Application Laid-Open No. 7-109135, etc., a rod-in tube using a large quartz glass tube subjected to mechanical grinding as a manufacturing method suitable for low-cost mass production of optical fibers. There is a law. In this method, a quartz glass core rod that includes a sufficiently dehydrated quartz glass core or a part of a clad made by a VAD method or the like is used, and a clad portion is formed on a similar core rod by an OVD method. Since OH group contamination to the core rod at the time of OVD, which cannot be avoided by this method, can be avoided, it has been attracting attention as a method suitable for the production of LWPF.
ロッドインチューブ法においては、高価な光ファイバ用石英ガラスチューブを無駄なく使用するために、石英ガラスチューブの端部に廉価なダミーチューブまたはダミーロッド（以降合わせてダミーと記す）を溶接し、このダミーを把持して移動、溶着一体化等を行う方法が採用されている。機械研削された大型石英ガラスチューブの内表面は、コアロッドとの溶融一体化時に表面の凹凸に起因する泡の発生を防ぐ為に機械研磨加工が施されるが、従来は図２のように内表面及び外表面ともに仕上げた後でダミーの溶接を行っていた。
しかしながら、この従来方法によるダミー溶接された石英ガラスチューブを使用した場合、石英ガラスチューブとダミーの溶接箇所近傍部が、ジャケッティングされた光ファイバの破断頻度が高く、ＯＨ基の吸収も大きいという問題点があり、この部分の光ファイバを除去する必要があるため、ＭＦが悪化し、製造コスト上昇の原因となっていた。
In the rod-in-tube method, in order to use an expensive quartz glass tube for optical fiber without waste, an inexpensive dummy tube or dummy rod (hereinafter referred to as a dummy) is welded to the end of the quartz glass tube. A method is adopted in which a dummy is held and moved, welded and integrated. The inner surface of the machine-ground large quartz glass tube is mechanically polished to prevent the formation of bubbles due to surface irregularities when it is fused and integrated with the core rod. Conventionally, as shown in FIG. After finishing both the surface and the outer surface, dummy welding was performed.
However, when the quartz glass tube dummy-welded by this conventional method is used, the quartz glass tube and the dummy welded portion in the vicinity of the welded portion have a high frequency of breakage of the jacketed optical fiber and the absorption of OH groups is large. Since there is a point and it is necessary to remove the optical fiber in this portion, the MF deteriorates and causes an increase in manufacturing cost.
この問題の原因を調査したところ、ダミーとの溶接時に石英ガラスチューブの内表面が溶融状態となって表面荒れが発生し、また溶接用の熱源としてプロパン/酸素や水素/酸素などのバーナーを使用した場合には、ＯＨ基による汚染が発生している事が判明した。表面荒れが発生すると、コアロッドと石英ガラスチューブとの溶融一体化の際に泡を生じる原因となり、破断頻度悪化などの原因となる。また、バーナーから石英ガラスチューブの内表面に浸透したＯＨ基は、光ファイバ時の波長１．３８μｍの吸収の原因となる。
溶接用熱源を電気炉にすればＯＨ基による汚染をほとんど無くす事は可能だが、電気炉の場合は一般にヒートゾーンをバーナーのように狭くする事が困難なため、溶融部近傍の内表面の荒れの範囲はバーナーの場合よりも拡大する。
また、ＯＨ基に汚染された内表面の表層を、ＨＦ（フッ酸）エッチングなど化学的方法により除去すれば、ＯＨ基による汚染は除去出来るが、表面荒れは残留するか強調される。
As a result of investigating the cause of this problem, the inner surface of the quartz glass tube was melted during welding with the dummy, causing surface roughness, and burners such as propane / oxygen and hydrogen / oxygen were used as the heat source for welding. In this case, it was found that contamination with OH groups occurred. When the surface roughness occurs, bubbles are generated when the core rod and the quartz glass tube are fused and integrated, leading to deterioration of the fracture frequency. Moreover, the OH group which has penetrated from the burner into the inner surface of the quartz glass tube causes absorption at a wavelength of 1.38 μm during the optical fiber.
If an electric furnace is used as the heat source for welding, it is possible to eliminate contamination by OH groups. However, in the case of an electric furnace, it is generally difficult to narrow the heat zone like a burner. The range of is larger than that of the burner.
Further, if the surface layer of the inner surface contaminated with OH groups is removed by a chemical method such as HF (hydrofluoric acid) etching, contamination by OH groups can be removed, but it is emphasized that surface roughness remains.
そこで本発明は、内表面の全長に渡って凹凸が無く、ＯＨ基の汚染もないダミー付き石英ガラスチューブ、ならびに光ファイバ製造用プリフォームおよび光ファイバの製造方法を提供することを課題とする。 Accordingly, an object of the present invention is to provide a quartz glass tube with a dummy that has no unevenness over the entire length of the inner surface and is free from contamination with OH groups, a preform for manufacturing an optical fiber, and a method for manufacturing an optical fiber.
上記の課題は、本発明による下記（１）〜（６）の構成のいずれかにより達成される。
（１）
少なくとも片端にダミーチューブまたはダミーロッドが溶接された石英ガラスチューブにおいて、ダミーチューブまたはダミーロッドの溶接後に内表面を機械研磨のみあるいは機械研削及び機械研磨する事を特徴とする光ファイバ製造用石英ガラスチューブの製造方法。
（２）
機械研磨のみあるいは機械研削及び機械研磨によって除去された厚さが０．２ｍｍ以上である事を特徴とする上記（１）記載の光ファイバ製造用石英ガラスチューブの製造方法。
（３）
少なくとも片端にダミーチューブまたはダミーロッドが溶接された石英ガラスチューブにおいて、ダミーチューブまたはダミーロッドの溶接後に、この溶接による内表面のＯＨ基汚染および／または内面荒れを機械研磨のみあるいは機械研削及び機械研磨により除去する事を特徴とする光ファイバ製造用石英ガラスチューブの製造方法。
（４）
光ファイバ製造用プリフォームの製造方法において使用される石英ガラスチューブに関し、少なくとも片端にダミーチューブまたはダミーロッドが溶接された石英ガラスチューブであって、ダミーチューブまたはダミーロッドの溶接後に内表面を機械研磨のみあるいは機械研削及び機械研磨する光ファイバ製造用石英ガラスチューブに、コアのみ又はコアとクラッド部を含む石英ガラスロッドを挿入し、加熱溶融一体化のみあるいは同時に延伸を施す事により光ファイバ製造用プリフォームを得ることを特徴とする、光ファイバ製造用プリフォームの製造方法。
（５）
上記（４）の製造方法により製造されたプリフォームから線引機により光ファイバを得る光ファイバの製造方法。
（６）
光ファイバ製造用プリフォームの製造方法において使用される石英ガラスチューブに関し、少なくとも片端にダミーチューブまたはダミーロッドが溶接された石英ガラスチューブであって、ダミーチューブまたはダミーロッドの溶接後に内表面を機械研磨のみあるいは機械研削及び機械研磨する光ファイバ製造用石英ガラスチューブに、コアのみ又はコアとクラッド部を含む石英ガラスロッドを挿入し、加熱溶融一体化と同時に光ファイバの外径まで延伸して、直接光ファイバを得る事を特徴とする光ファイバの製造方法。
Said subject is achieved by either of the structure of following (1)-(6) by this invention.
(1)
At least one end of a quartz glass tube with a dummy tube or dummy rod welded, the inner surface of the quartz glass tube for optical fiber production is mechanically polished or mechanically ground and polished after the dummy tube or dummy rod is welded. Manufacturing method.
(2)
The method for producing a quartz glass tube for producing an optical fiber according to the above (1), wherein the thickness removed by mechanical polishing alone or by mechanical grinding and mechanical polishing is 0.2 mm or more.
(3)
In quartz glass tubes with a dummy tube or dummy rod welded to at least one end, after welding the dummy tube or dummy rod, OH group contamination and / or inner surface roughness of the inner surface due to this welding is either mechanical polishing only or mechanical grinding and mechanical polishing A method for producing a quartz glass tube for producing an optical fiber, characterized in that the glass glass tube is removed by a step.
(4)
Quartz glass tube used in a manufacturing method of optical fiber manufacturing preforms, which is a quartz glass tube with a dummy tube or dummy rod welded to at least one end, and the inner surface is mechanically polished after the dummy tube or dummy rod is welded only or mechanical grinding and mechanical polishing to an optical fiber manufacturing quartz glass tube, the core or only the core and the cladding portion inserted City quartz glass rod comprising, for optical fiber manufacture by applying a heat-melted integrated only or simultaneously stretched A method for producing a preform for producing an optical fiber, comprising obtaining a preform.
(5)
An optical fiber manufacturing method for obtaining an optical fiber from a preform manufactured by the manufacturing method according to the above (4) by a drawing machine.
(6)
Quartz glass tube used in a manufacturing method of optical fiber manufacturing preforms, which is a quartz glass tube with a dummy tube or dummy rod welded to at least one end, and the inner surface is mechanically polished after the dummy tube or dummy rod is welded only or mechanical grinding and mechanical polishing to an optical fiber manufacturing quartz glass tube, by stretching a quartz glass rod comprising a core alone or a core and a cladding portion inserted City, until the outer diameter of the heat melting integrated simultaneously with the optical fiber, An optical fiber manufacturing method characterized in that an optical fiber is obtained directly.
本発明によれば、石英ガラスチューブのダミーとの溶接部近傍の溶接に起因する内表面の凹凸及び、溶接にバーナーを使用した場合にはＯＨ基によって汚染された層を除去してからロッドインチューブ法に使用するため、石英ガラスチューブの端から端まで無駄なく使用する事が出来、ＭＦを向上させる事が出来る。
また、溶接後に溶接部近傍の内面荒れあるいはＯＨ基に汚染された部分のみを研削・研磨除去しても、本発明の効果に変わりはないが、ロッドインチューブ法に用いるジャケット管として問題になる内径や断面積の不連続が生じる恐れがあるため、全長に亘って研削／研磨を行うことが望ましい。
According to the present invention, the inner surface unevenness caused by the welding in the vicinity of the welded portion of the quartz glass tube dummy and the layer contaminated with OH groups when the burner is used for welding are removed before the rod-in. Since it is used for the tube method, it can be used without waste from the end of the quartz glass tube, and the MF can be improved.
Further, even if only the portion of the inner surface roughened near the welded portion or the portion contaminated by the OH group is ground and polished after welding, the effect of the present invention is not changed, but it becomes a problem as a jacket tube used in the rod-in tube method. Since discontinuity of the inner diameter and the cross-sectional area may occur, it is desirable to perform grinding / polishing over the entire length.
以下、添付図面を参照して本発明の実施の形態について説明する。
図１を参照して、本発明の実施の形態によるダミー付き石英ガラスチューブの製造方法について説明する。
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
With reference to FIG. 1, the manufacturing method of the quartz glass tube with a dummy by embodiment of this invention is demonstrated.
まず、ＯＶＤ法により、外径１００〜２５０ｍｍ、内径４０〜９０ｍｍ、長さ６００〜３５００ｍｍ程度のスート体を作成し、これを脱水処理、ガラス化を行ってマザーインゴットを作成する。
次に、このマザーインゴットの外表面および内表面に荒研削加工を施して、ある程度の寸法合わせを行い、この後、外表面の研削仕上げを行って石英ガラスチューブを作成する。
次に、ダミーチューブまたはダミーロッド（以降ダミーチューブを代表させて説明する）を上記石英ガラスチューブの少なくとも一端に溶接する。ダミーチューブの外径は、石英ガラスチューブの外径ほぼ同程度あるいはそれ以下の寸法のものとすることが好ましい。溶接の熱源には、プロパン/酸素バーナーが好ましいが、異なったバーナーあるいは従来の溶接技術のいずれを用いてもよい。
First, a soot body having an outer diameter of 100 to 250 mm, an inner diameter of 40 to 90 mm, and a length of about 600 to 3500 mm is prepared by OVD method, and this is dehydrated and vitrified to prepare a mother ingot.
Next, rough grinding is performed on the outer surface and the inner surface of the mother ingot to adjust the dimensions to some extent, and thereafter, the outer surface is ground and finished to produce a quartz glass tube.
Next, a dummy tube or a dummy rod (hereinafter, a dummy tube will be described as a representative) is welded to at least one end of the quartz glass tube. The outer diameter of the dummy tube is preferably approximately the same as or smaller than the outer diameter of the quartz glass tube. The welding heat source is preferably a propane / oxygen burner, although either a different burner or a conventional welding technique may be used.
このダミーチューブの溶接後、内表面の機械研削および研磨仕上げを行う。なお、ダミーチューブの溶接前に機械研削及び研磨まで行った石英ガラスチューブを使用しても本発明の効果には影響は無いが、溶接前には荒研削までにとどめておく事が、石英ガラスチューブの加工工程の重複とならず、好ましい。
また、この研削・研磨時に削り落とされる厚みは０．２ｍｍ以上が好ましい。これはここで述べる寸法の石英ガラスチューブをバーナーにより溶接加工した際のＯＨ基汚染層を除去出来る値であるが、溶接条件等の違いにより加減すれば良い。ＯＨ基を問題としない場合の削り落とす厚みは、内表面の凹凸が十分に除去できる値とすれば良い。
各研削には一般的な研削装置、外周であればダイヤモンド回転砥石付きの外周研削機、内周であれば、やはりダイヤモンド砥石付きのホーニングマシンを使用すればよい。内周の研磨には、酸化セリューム砥粒を使用しても良いが、より好ましくは特開２００４−２４３４３３号公報で紹介しているダイヤモンドペーパーによる研磨方法を使用すると良い。
After the dummy tube is welded, the inner surface is mechanically ground and polished. Note that the use of a quartz glass tube that has been mechanically ground and polished before welding of the dummy tube does not affect the effect of the present invention. This is preferable because it does not overlap the tube processing steps.
Further, the thickness scraped off during the grinding / polishing is preferably 0.2 mm or more. This is a value that can remove the OH-based contaminated layer when the quartz glass tube having the dimensions described here is welded by a burner, but it may be adjusted depending on the welding conditions and the like. When the OH group is not a problem, the thickness to be scraped off may be a value that can sufficiently remove the irregularities on the inner surface.
For each grinding, a general grinding apparatus, an outer peripheral grinding machine with a diamond rotating grindstone for the outer periphery, and a honing machine with a diamond grindstone for the inner periphery may be used. For polishing the inner periphery, oxidized cerium abrasive grains may be used, but more preferably, a polishing method using diamond paper introduced in Japanese Patent Application Laid-Open No. 2004-243433 may be used.
光ファイバ製造用プリフォームの製造は、コアのみ又はコアとクラッド部を含む石英ガラスロッドを上記のダミー付き石英ガラスチューブに挿入し、電気炉などの熱源により加熱溶融一体化のみあるいは同時に延伸を施す事により行われる。
光ファイバの製造は、上記のようにして製造されたプリフォームを線引機により線引きすることにより行われる。あるいは、コアのみ又はコアとクラッド部を含む石英ガラスロッドを上記のダミーチューブ付き石英ガラスチューブに挿入し、加熱溶融一体化と同時に光ファイバの外径まで延伸して、直接光ファイバを得る事により行われる。
The optical fiber manufacturing preform is manufactured by inserting a quartz glass rod including only the core or the core and the clad into the above-mentioned quartz glass tube with a dummy, and heating or melting and integration with a heat source such as an electric furnace or stretching simultaneously. Done by things.
The optical fiber is manufactured by drawing the preform manufactured as described above with a drawing machine. Alternatively, by inserting a quartz glass rod containing only the core or the core and the clad into the quartz glass tube with a dummy tube, and heating and melting and simultaneously extending to the outer diameter of the optical fiber to obtain an optical fiber directly. Done.
本発明によれば、外径１００〜２５０ｍｍ、内径４０〜９０ｍｍ、長さ６００〜３５００ｍｍ程度のＯＶＤ法により作成した石英ガラスチューブに対して、石英ガラスチューブと同程度あるいはそれ以下の寸法のダミーチューブを、バーナーを熱源として溶接を行って、ロッドインチューブ法に使用しても、石英ガラスチューブの全長に渡ってＯＨ基による汚染や破断の多発しない良好な光ファイバを得る事が出来る。なお、コアロッド挿入後の加熱溶融一体化時のスタート側に、ロッド形状のダミーを溶接して使用したり、石英ガラスチューブ自体の先端を封止加工したりする場合があるが、その場合でも熱加工を施された石英ガラスチューブの内表面に対する本発明の効果には変わりは無い。 According to the present invention, a dummy tube having the same or smaller dimensions as a quartz glass tube compared to a quartz glass tube having an outer diameter of 100 to 250 mm, an inner diameter of 40 to 90 mm, and a length of about 600 to 3,500 mm. Even if welding is performed using a burner as a heat source and used in the rod-in-tube method, it is possible to obtain a good optical fiber that does not frequently cause contamination and breakage due to OH groups over the entire length of the quartz glass tube. In some cases, a rod-shaped dummy is welded and used on the start side of the heat-melt integration after inserting the core rod, or the tip of the quartz glass tube itself is sealed. The effect of the present invention on the inner surface of the processed quartz glass tube remains unchanged.
なお本件出願人らは、特開２０００−１２８５５９号において、予め石英ガラスチューブまたはダミーチューブの双方の内径端部に面取りを施しておく事により、溶接時の内径の縮小を防ぐ方法を提示したが、この方法を併用する事により、ダミーチューブ溶接前に石英ガラスチューブの内表面の研削加工までを行い、溶接後には研磨加工のみを行っても良いとしている。この特開２０００−１２８５５９号の方法を併用しないと溶接時に縮小した溶接部の内径を拡大するための研削が必要となる。これにより、ダミーチューブが付いたために全長が長く且つ重量が増加した石英ガラスチューブのハンドリングの困難や、より大型の研削装置が必要となる事を、避ける事が出来る。 In addition, although the present applicants disclosed in Japanese Patent Application Laid-Open No. 2000-128559, a method for preventing the reduction of the inner diameter during welding by chamfering the inner diameter ends of both the quartz glass tube and the dummy tube in advance. By using this method in combination, the inner surface of the quartz glass tube is ground before the dummy tube welding, and only the polishing process may be performed after the welding. If the method of Japanese Patent Laid-Open No. 2000-128559 is not used in combination, grinding is required to enlarge the inner diameter of the welded portion that has been reduced during welding. As a result, it is possible to avoid difficulty in handling the quartz glass tube having a long overall length and increased weight due to the dummy tube, and the need for a larger grinding apparatus.
ＯＶＤ法を用いて外径３００ｍｍのスート体を作成し、脱水処理後にゾーンメルト法により焼結ガラス化を行ってマザーインゴットを作成した。このマザーインゴットの外周はＮＣ旋盤により回転ダイヤモンド砥石を用いて、内周はホーニングマシンにより回転ダイヤモンド砥石を用いて研削し、外径１８０ｍｍで内径４４ｍｍ、長さ２．６ｍの真直な石英ガラスチューブに仕上げた。 この石英ガラスチューブの片側に、外径１８０ｍｍで内径８５ｍｍ、長さ１．２ｍの天然石英ガラス製ダミーチューブをプロパン／酸素バーナーを用いて溶接した。その後、内周をホーニングマシンによって、まず回転ダイヤモンド砥石によって内径を４４．６ｍｍ（肉厚で片側０．３ｍｍ研削除去）まで研削し、ダイヤモンドペーパーにより鏡面研磨仕上げを施した。
このダミーチューブ付き石英ガラスチューブにＶＡＤ法により作成したコア部とクラッドの一部を含むコアロッドを挿入し、ロッドインチューブ法により加熱溶融一体化と同時に延伸して外径８０ｍｍのプリフォームを作成し、そのプリフォームから線引機により外径１２５μｍのシングルモード光ファイバを得た。
この結果得られた光ファイバは、全長に渡って１．３８μｍの伝送損失は０．２８ｄＢ／ｋｍ以下であり、線引中の破断は一度も無かった。
A soot body having an outer diameter of 300 mm was prepared by using the OVD method, and after the dehydration treatment, a sintered glass was formed by a zone melt method to prepare a mother ingot. The outer circumference of this mother ingot is ground with a rotating diamond grindstone using an NC lathe, and the inner circumference is ground with a rotating diamond grindstone using a honing machine, and is formed into a straight quartz glass tube with an outer diameter of 180 mm, an inner diameter of 44 mm, and a length of 2.6 m. Finished. A natural quartz glass dummy tube having an outer diameter of 180 mm, an inner diameter of 85 mm, and a length of 1.2 m was welded to one side of the quartz glass tube using a propane / oxygen burner. Thereafter, the inner circumference was ground to a diameter of 44.6 mm (thickened and removed by 0.3 mm on one side) with a rotating diamond grindstone using a honing machine, and mirror-polished with diamond paper.
Insert a core rod containing a core part and a part of the clad made by the VAD method into this dummy glass tube with a dummy tube, and draw it at the same time as heat-melt integration by the rod-in-tube method to make a preform with an outer diameter of 80 mm. A single mode optical fiber having an outer diameter of 125 μm was obtained from the preform by a drawing machine.
The optical fiber obtained as a result had a transmission loss of 1.38 μm over the entire length of 0.28 dB / km or less, and there was no break during drawing.
実施例１と同様にＯＶＤ法を用いて作成したマザーインゴットを機械研削して外径２００ｍｍで内径４８．５ｍｍ、長さ３ｍの真直な石英ガラスチューブに仕上げた。この石英ガラスチューブの片側に、外径２００ｍｍで内径１００ｍｍ、長さ１．２ｍの天然石英ガラス製ダミーチューブを、プロパン／酸素バーナーを熱源として溶接した。また石英ガラスチューブの反対側の端部は、やはりプロパン／酸素バーナーを用いて円錐形状に溶融成型し、先端を封止した。その後、内周をホーニングマシンによって、まず回転ダイヤモンド砥石によって内径を４９．０ｍｍまで拡大し（肉厚で片側０．２５ｍｍ研削除去）、ダイヤモンドペーパーにより鏡面研磨仕上げを施した。
この片端封止のダミーチューブ付き石英ガラスチューブにＶＡＤ法により作成したコア部とクラッドの一部を含むコアロッドを挿入し、ロッドインチューブ法により加熱溶融一体化と同時に線引して直接外径１２５μｍのシングルモード光ファイバを得た。
この結果得られた光ファイバは、全長に渡って１．３８μｍの伝送損失が０．２８ｄＢ／ｋｍ以下であり、線引中の破断は一度も無かった。
A mother ingot produced using the OVD method in the same manner as in Example 1 was mechanically ground into a straight quartz glass tube having an outer diameter of 200 mm, an inner diameter of 48.5 mm, and a length of 3 m. A natural quartz glass dummy tube having an outer diameter of 200 mm, an inner diameter of 100 mm, and a length of 1.2 m was welded to one side of the quartz glass tube using a propane / oxygen burner as a heat source. The opposite end of the quartz glass tube was melt-formed into a conical shape using a propane / oxygen burner, and the tip was sealed. Thereafter, the inner circumference was first enlarged to 49.0 mm with a honing machine using a rotating diamond grindstone (thickness was removed by grinding 0.25 mm on one side), and mirror polishing was performed with diamond paper.
A core rod including a core part and a part of a clad made by a VAD method is inserted into this one-end sealed quartz glass tube with a dummy tube, and the outer diameter 125 μm is directly drawn by heating and fusion integration by a rod-in-tube method. A single mode optical fiber was obtained.
The optical fiber obtained as a result had a transmission loss of 1.38 μm over the entire length of 0.28 dB / km or less, and there was no breakage during drawing.
実施例１と同様にＯＶＤ法を用いて作成したマザーインゴットに機械研削を施し、外径１８０ｍｍで内径４４ｍｍ、長さ２．２ｍの真直な石英ガラスチューブに仕上げ、内周をホーニングマシンによりダイヤモンドペーパーを使用して鏡面に研磨仕上げた。
この石英ガラスチューブの片側に、外径１８０ｍｍで内径８５ｍｍ、長さ１．２ｍの天然石英ガラス製ダミーチューブをプロパン／酸素バーナーを熱源として、溶接した。
このダミーチューブ付き石英ガラスチューブにＶＡＤ法により作成したコア部とクラッドの一部を含むコアロッドを挿入し、ロッドインチューブ法により加熱溶融一体化と同時に延伸して外径８０ｍｍのプリフォームを作成した。そのプリフォームから線引機により外径１２５μｍのシングルモード光ファイバを得た。
この結果得られた光ファイバの内、使用した石英ガラスチューブのダミーとの溶接面から７ｃｍ以内の部位がジャケッティングされたものは、１．３８μｍの伝送損失が０．３４ｄＢ／ｋｍ以上となりＬＷＰＦとして不適当であり、線引中の破断が１１回も発生した。
以上により本発明の効果が明らかである。
As in Example 1, the mother ingot produced using the OVD method was mechanically ground, finished to a straight quartz glass tube with an outer diameter of 180 mm, an inner diameter of 44 mm, and a length of 2.2 m, and the inner circumference was diamond paper with a honing machine. Was polished to a mirror surface.
A natural quartz glass dummy tube having an outer diameter of 180 mm, an inner diameter of 85 mm, and a length of 1.2 m was welded to one side of the quartz glass tube using a propane / oxygen burner as a heat source.
A core rod including a core part and a part of the clad prepared by the VAD method was inserted into this quartz glass tube with a dummy tube, and was stretched simultaneously with heat melting and integration by a rod-in-tube method to prepare a preform having an outer diameter of 80 mm. . A single mode optical fiber having an outer diameter of 125 μm was obtained from the preform by a drawing machine.
Of the optical fibers obtained as a result, the one within 7 cm from the weld surface with the quartz glass tube dummy used was jacketed, and the 1.38 μm transmission loss was 0.34 dB / km or more as LWPF. Inappropriate and 11 breaks during drawing occurred.
The effects of the present invention are apparent from the above.
Claims (6)
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