JP2000109333A - Production of optical fiber preform - Google Patents
Production of optical fiber preformInfo
- Publication number
- JP2000109333A JP2000109333A JP10284245A JP28424598A JP2000109333A JP 2000109333 A JP2000109333 A JP 2000109333A JP 10284245 A JP10284245 A JP 10284245A JP 28424598 A JP28424598 A JP 28424598A JP 2000109333 A JP2000109333 A JP 2000109333A
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- glass
- soot
- external
- preform
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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
-
- 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
- C03B37/0146—Furnaces therefor, e.g. muffle tubes, furnace linings
-
- 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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、コア用ガラスロッ
ドの周辺に外スス付けを行い、これを透明ガラス化する
ことによる光ファイバ用母材の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a preform for an optical fiber by forming an external soot around a glass rod for a core and turning the glass rod into a transparent glass.
【０００２】[0002]
【従来の技術】従来、光ファイバ用母材の製造方法とし
てコア用ガラスロッドを作製し、該コア用ガラスロッド
の周囲に外付け法によるスス付けを行って外付けスス体
とし、このスス体を加熱透明化して光ファイバ用母材と
する方法がある。ここで外付けスス体の作製方法として
は、コア用ガラスロッドを回転させながら軸方向にガラ
ス微粒子合成用バーナに対し相対的に往復移動させ、ガ
ラス微粒子合成用バーナで合成されたガラス微粒子をガ
ラスロッドの外周に吹き付けて層状に堆積させるＯＶＤ
法（層状外付け法）、鉛直方向に配置したコア用ガラス
ロッドを回転させながら軸方向にガラス微粒子合成用バ
ーナを移動させ、コア用ガラスロッドの上部から下方に
向かって徐々にガラス微粒子を堆積させて行くＶＡＤ法
が行われている。これらの方法により作製した外付けス
ス体を、ゾーン加熱炉を使用して前記外付けスス体を一
端から徐々に加熱ゾーンを通過させ、一端から徐々に透
明化していく方法、均熱炉を使用して前記外付けスス体
の全体を均一に加熱し透明化する方法などによって加熱
透明化し、光ファイバ用母材とする。2. Description of the Related Art Conventionally, a glass rod for a core is manufactured as a method of manufacturing a preform for an optical fiber, and a soot is formed around the core glass rod by an external method to form an external soot body. Is made transparent by heating to obtain a base material for an optical fiber. Here, as a method for manufacturing the external soot body, the glass fine particles synthesized by the glass fine particle synthesis burner are reciprocated in the axial direction while rotating the glass rod for the core, and the glass fine particles synthesized by the burner for glass fine particle synthesis are turned into glass. OVD sprayed around the rod and deposited in layers
Method (layered external method), the burner for synthesizing glass fine particles is moved in the axial direction while rotating the glass rod for the core arranged in the vertical direction, and the glass fine particles are gradually deposited downward from the upper part of the glass rod for the core. The VAD method is performed. A method in which the external soot body produced by these methods is gradually passed through the heating zone from one end of the external soot body using a zone heating furnace and gradually becomes transparent from one end, using a soaking furnace. Then, the whole external soot body is heated and made transparent by a method of uniformly heating and making the whole transparent soot body to be a preform for an optical fiber.
【０００３】[0003]
【発明が解決しようとする課題】前記方法においては、
外付けスス体を加熱透明化する際にコア用ガラスロッド
と外付けしたススとの境界面に気泡が残りやすいという
問題点がある。これは、外付け技術では透明化時に大き
く収縮する外付けススと収縮しないコア用ガラスロッド
との間で引張力が生じ、ガラス構造内に空隙を作りやす
い状態となっている、外側から加熱するために表面から
透明化が進む傾向があり、母材全体の表面で透明化が先
に進んでしまうと空隙内に存在する残存ガスの逃げ道が
なくなり、気泡として残存する、などの理由による。な
お、両端の非有効部では熱源からの距離が遠くなるの
で、傾斜部分の表面からの熱と母材内部から伝導する熱
とのバランスで若干様子が異なる場合もある。特にＶＡ
Ｄ法による外付けスス体の場合には、上方のスス付け開
始部分ではススとガラスを密着させるため、円柱状の有
効部に比較してススのかさ密度を高くしていることが多
く、この部分が先に透明化してしまい、気泡となるガス
の逃げ道を閉止してしまう場合があり、ゾーン加熱炉に
よる透明化の際に加熱終了側の非有効部近傍に気泡が多
く残りやすくなっている。このような気泡の残留は、光
ファイバとした際の光の伝送特性上好ましくなく、極力
取り除く必要がある。In the above method,
When the external soot body is heated and made transparent, there is a problem that air bubbles are likely to remain on the boundary surface between the core glass rod and the external soot. This is because, in the external technology, a tensile force is generated between the external soot that greatly shrinks during transparency and the glass rod for the core that does not shrink, and it is in a state where it is easy to create a void in the glass structure, heating from the outside For this reason, the surface tends to be transparent, and if the surface of the entire base material is transparent, the escape path of the residual gas existing in the voids disappears and remains as bubbles. In addition, since the distance from the heat source is longer in the ineffective portions at both ends, the appearance may slightly differ depending on the balance between the heat from the surface of the inclined portion and the heat conducted from inside the base material. Especially VA
In the case of an external soot body by the D method, the soot and the glass are brought into close contact with each other at the upper sooting start portion, so that the bulk density of the soot is often higher than that of the columnar effective portion. In some cases, the part becomes transparent first, closing the escape path of gas that becomes bubbles, and when transparentizing with a zone heating furnace, many bubbles are likely to remain near the ineffective part on the heating end side . Such residual bubbles are not preferable in terms of light transmission characteristics when used as an optical fiber, and must be removed as much as possible.
【０００４】特開昭４９−９５２３号公報には、高品質
の光学的導波管、レンズなどに用いられるブランク（ｂ
ｌａｎｋ）の形の、水を含有しない光学的高品質の溶融
シリカを製造する方法として、芯材上に珪素含有ススを
付着させてプリフォームを形成し、前記ススを焼結する
のに十分な速度でかつ前記ススが焼結して芯の周りに収
縮するとき、取り込まれていたガスが炉の厚い区域に未
だきていないススの部分を通って逃げることが可能な速
度で、ススの層を徐々に炉中へ挿入していく方法が開示
されている。この方法では、ゾーン加熱法を用いること
により円柱状となる有効部分においてはガスの脱出経路
を維持できるが、加熱を終了する非有効部では気泡が閉
じ込められやすいという問題がある。また、特開昭５３
−６７４４７号公報には、ガラス形成用気相原料を酸化
あるいは加水分解してガラススートを合成し、これを回
転し移動する棒状出発部材上に積層させ、このスート積
層体を焼結し、透明ガラス体を得、これを光ファイバ用
母材とする方法において、前記スートを棒状出発部材上
に積層させた後の個所に集光された赤外線（ＣＯ2 レー
ザー）を照射しながらガラス膜を形成していくことを特
徴とする光ファイバ用母材の製造方法が開示されてい
る。この方法は本発明の方法と若干技術内容が異なるも
のであるが、この方法ではレーザーによる透明化が工程
の速度を決めることになり、生産性（堆積速度）の向上
が難しい。Japanese Patent Application Laid-Open No. 49-9523 discloses a blank (b) used for a high-quality optical waveguide, a lens or the like.
As a method of producing water-free, optically high quality fused silica in the form of rank (lank), silicon-containing soot is deposited on a core material to form a preform and sufficient to sinter the soot. A layer of soot at a rate and at such a rate that when the soot sinters and shrinks around the wick, the entrained gas can escape through the portion of the soot that has not yet entered the thick section of the furnace. Is gradually introduced into a furnace. In this method, a gas escape route can be maintained in a columnar effective portion by using the zone heating method, but there is a problem that air bubbles are easily trapped in an ineffective portion where heating is completed. Also, Japanese Unexamined Patent Publication No.
JP-67-4747 discloses that a glass soot is synthesized by oxidizing or hydrolyzing a gas-phase raw material for forming a glass, and the glass soot is laminated on a rotating and moving rod-shaped starting member. In a method of obtaining a glass body and using the glass body as a base material for an optical fiber, a glass film is formed while irradiating a focused infrared ray (CO 2 laser) to a portion after the soot is laminated on a rod-shaped starting member. A method of manufacturing a preform for an optical fiber, which is characterized in that it is performed, is disclosed. This method has a slightly different technical content from the method of the present invention. However, in this method, transparency by a laser determines the process speed, and it is difficult to improve productivity (deposition speed).
【０００５】本発明はこのような従来技術の実状に鑑
み、外付けスス体からの気泡の残留が少ない光ファイバ
用母材の製造方法を提供しようとするものである。The present invention has been made in view of the above circumstances of the prior art, and has as its object to provide a method of manufacturing a preform for an optical fiber in which bubbles are less likely to remain from an external soot body.
【０００６】[0006]
【課題を解決するための手段】本発明は、前記課題を解
決する手段として次の（１）〜（６）の態様を含むもの
である。 （１）コア用ガラスロッドの周囲に外付け法によりスス
付けを行い、得られた外付けスス体を熱処理して透明ガ
ラス化する光ファイバ用母材の製造方法において、透明
ガラス化の際に、光ファイバ用母材の両端の非有効部の
いずれか一方又は両方の少なくとも一部分を不透明ガラ
ス状態で残すことを特徴とする光ファイバ用母材の製造
方法。 （２）外付け法によるスス付けを、外付け法によるスス
付けを、鉛直方向にコア用ガラスロッドを配置し、縦方
向にススを成長させるＶＡＤ法により行うことを特徴と
する前記（１）の光ファイバ用母材の製造方法。 （３）不透明ガラス状態部分を残す非有効部として、上
方に位置するスス付け開始部分を選択することを特徴と
する前記（２）の光ファイバ用母材の製造方法。 （４）外付け法によるスス付けを、コア用ガラスロッド
の周囲に、層状にスス付けを行うＯＶＤ法により行うこ
とを特徴とする前記（１）の光ファイバ用母材の製造方
法。 （５）外付けスス体の透明ガラス化をゾーン加熱炉を用
いて行い、前記外付けスス体の加熱終了位置を調整する
ことにより不透明ガラス状態部分を形成させることを特
徴とする前記（１）〜（４）のいずれか１つの光ファイ
バ用母材の製造方法。 （６）外付けスス体の透明ガラス化を均熱炉を用いて行
い、両端の非有効部のいずれか一方又は両方の少なくと
も一部分が、均熱範囲に入らないようにすることによ
り、該非有効部に不透明ガラス状態部分を形成させるこ
とを特徴とする前記（１）〜（４）のいずれか１つの光
ファイバ用母材の製造方法。The present invention includes the following aspects (1) to (6) as means for solving the above-mentioned problems. (1) In a method of manufacturing a preform for optical fiber, a soot is formed around the core glass rod by an external method, and the obtained external soot body is heat-treated to obtain a transparent glass. A method for manufacturing an optical fiber preform, wherein at least a part of one or both of the ineffective portions at both ends of the optical fiber preform is left in an opaque glass state. (2) The method of (1), wherein the sooting by the external method is performed by the VAD method in which a glass rod for a core is arranged in a vertical direction and soot is grown in a vertical direction. A method for producing a preform for an optical fiber. (3) The method for manufacturing a preform for an optical fiber according to the above (2), wherein a sooting start portion located above is selected as an ineffective portion that leaves an opaque glass state portion. (4) The method of manufacturing an optical fiber preform according to the above (1), wherein the sooting by the external method is performed by an OVD method in which soot is formed in a layer around the core glass rod. (5) Transparent vitrification of the external soot body is performed using a zone heating furnace, and an opaque glass state portion is formed by adjusting a heating end position of the external soot body. (4) The method for producing a preform for an optical fiber according to any one of (4) to (4). (6) Transparent vitrification of the external soot body is performed by using a soaking furnace, and at least a part of one or both of the ineffective portions at both ends is prevented from entering the soaking range, thereby making the ineffective soot. The method for producing a preform for an optical fiber according to any one of (1) to (4), wherein an opaque glass state portion is formed in the portion.
【０００７】[0007]
【発明の実施の形態】本発明においては、先ずコア用ガ
ラスロッドを作製し、その表面に（ガラスロッドの周囲
に）ＶＡＤ法、ＯＶＤ法などの外付け法によりガラス微
粒子合成用バーナで合成したガラス微粒子を堆積させる
スス付けを行う。得られる外付けスス体（ガラス微粒子
堆積体）は図１に模式的に示すようにコア用ガラスロッ
ド２の周囲にガラス微粒子の堆積層（スス層）３が形成
されている。この外付けスス体１は中央部の有効部（光
ファイバとした際に製品として使用可能な部分）の両端
に非有効部（光ファイバとした際に特性が不安定で製品
として使用できない部分）が形成される。DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first, a glass rod for a core is prepared, and the surface thereof (around the glass rod) is synthesized by a burner for synthesizing glass fine particles by an external method such as a VAD method or an OVD method. A soot for depositing glass particles is provided. In the obtained external soot body (glass fine particle deposit), a deposition layer (soot layer) 3 of glass fine particles is formed around the core glass rod 2 as schematically shown in FIG. This external soot body 1 has an ineffective portion (a portion where characteristics are unstable when used as an optical fiber and cannot be used as a product) at both ends of a central effective portion (a portion that can be used as a product when formed into an optical fiber). Is formed.
【０００８】次にこの外付けスス体１をゾーン加熱炉あ
るいは均熱炉などの加熱炉を用いて加熱し、透明ガラス
化して光ファイバ母材とするが、この際に図２に示すよ
うにコア用ガラスロッド２の周囲の透明ガラス層４との
境界部分に気泡５が残留しやすい。なお、図２には光フ
ァイバ母材の全長にわたって気泡が残存する例を示した
が、ゾーン加熱炉を使用する場合には加熱終了端部の非
有効部の近傍に集中する傾向がある。本発明の方法にお
いては、このような気泡の残留を抑制するため、外付け
スス体の両端部の非有効部のいずれか一方又は両方の少
なくとも一部分を不透明ガラス状態で残すことを特徴と
する。これにより透明化の最終段階まで残存ガスの逃げ
道が確保でき、気泡の残留を抑制することができる。こ
こで不透明ガラス状態とはスス付けままの状態から、一
部焼結は進行しているが残存ガスは通過できる程度に多
孔質性を残した状態までを意味する。また、不透明ガラ
ス状態で残す部分の割合は、厳密に規定する必要はなく
残存ガスが排出できる量とすればよいが、目安としては
非有効部体積の０．５〜５０％、好ましくは５〜３０％
程度の範囲である。Next, the external soot body 1 is heated by using a heating furnace such as a zone heating furnace or a soaking furnace, and is vitrified to form an optical fiber preform, as shown in FIG. Bubbles 5 are likely to remain at the boundary between the core glass rod 2 and the transparent glass layer 4. FIG. 2 shows an example in which bubbles remain over the entire length of the optical fiber preform. However, when a zone heating furnace is used, the bubbles tend to concentrate near the ineffective portion at the end of heating. The method of the present invention is characterized in that at least a part of one or both of the ineffective portions at both ends of the external soot body is left in an opaque glass state in order to suppress such bubbles from remaining. As a result, an escape path for the residual gas can be ensured until the final stage of the transparency, and the remaining of bubbles can be suppressed. Here, the opaque glass state means a state from a state in which soot is attached to a state in which sintering is partially progressed but remains porous enough to allow a residual gas to pass. The ratio of the portion left in the opaque glass state does not need to be strictly defined and may be set to an amount that allows the residual gas to be discharged. 30%
Range.
【０００９】非有効部に不透明ガラス状態部分を残すパ
ターンの例を図３に模式的に示す。図３において２はコ
ア用ガラスロッド、４は透明ガラス層、６は不透明ガラ
ス状態部分である。なお、不透明ガラス状態部分の形状
は加熱方法、スス体の半径方向密度分布などによって異
なり、ここには典型的な例を示した。図３（ａ）は一方
の非有効部の表面付近を透明ガラス化せずに不透明ガラ
ス状態で残したものである。このパターンはゾーン加熱
炉を使用し、外付けスス体の下端部から徐々に加熱ゾー
ン内に挿入して加熱ゾーンを通過させる方法の際に、上
端の非有効部を十分透明ガラス化せずに残す場合などに
形成される。具体的には、従来技術のように非有効部を
含む外付けスス体全体が加熱ゾーンを通過する前に加熱
を終了させる、加熱終了付近で炉の温度を下げるなどの
手法を採ることができる。図３（ｂ）は一方の非有効部
の大部分を透明ガラス化せずに不透明ガラス状態で残し
たものである。このパターンは均熱炉を使用し、一方の
非有効部を均熱範囲外として加熱し、透明ガラス化する
場合等に形成される。図３（ｃ）はゾーン加熱炉を使用
し、外付けスス体を加熱ゾーンの下方に位置させて徐々
に上昇させながら透明化を進め、透明化終了時に下端の
非有効部が不透明ガラス状態で残るようにしたものであ
る。ＶＡＤ法により作製された外付けスス体の場合、上
部のスス付け開始部分にガスの残留が生じやすい傾向が
あるので、この手法により上部非有効部を先に透明化
し、ガスの残留を防ぐことが考えられる。FIG. 3 schematically shows an example of a pattern in which an opaque glass state portion is left in an ineffective portion. In FIG. 3, 2 is a core glass rod, 4 is a transparent glass layer, and 6 is an opaque glass portion. Note that the shape of the opaque glass state portion varies depending on the heating method, the radial density distribution of the soot body, and the like, and a typical example is shown here. FIG. 3 (a) shows a state in which the vicinity of the surface of one of the non-effective portions is left in an opaque glass state without being formed into a transparent glass. This pattern uses a zone heating furnace, and when gradually inserting from the lower end of the external soot body into the heating zone and passing through the heating zone, the ineffective part at the upper end is not sufficiently transparently vitrified It is formed when leaving. Specifically, it is possible to adopt a method of terminating the heating before the entire external soot body including the ineffective portion passes through the heating zone as in the related art, or reducing the temperature of the furnace near the end of the heating. . FIG. 3B shows a case where most of the one ineffective portion is left in an opaque glass state without being formed into a transparent glass. This pattern is formed in a case where a soaking furnace is used, one of the ineffective portions is heated outside the soaking range, and the glass is turned into a transparent glass. FIG. 3 (c) shows the use of a zone heating furnace, in which the external soot body is positioned below the heating zone to gradually increase the transparency while proceeding with transparency, and at the end of the transparency, the ineffective portion at the lower end is in an opaque glass state. It is something that remains. In the case of an external soot body manufactured by the VAD method, gas tends to remain in the upper sooting start portion. Therefore, by using this method, the upper ineffective portion is first made transparent to prevent the gas from remaining. Can be considered.
【００１０】図３には非有効部の一方のみに不透明ガラ
ス状態部分を残す例を示したが、必要により両方の非有
効部に不透明ガラス状態部分を残すようにしてもよい。
なお、外付けスス体がＶＡＤ法により作製されたもので
ある場合、上方のスス付け開始部分ではススとガラスを
密着させるため、円柱状の有効部に比較してススのかさ
密度を高くしていることが多く、通常の透明化方法では
この部分が先に透明化してしまい、気泡となるガスの逃
げ道を閉止してしまう場合があるので、透明化時の剥が
れを防ぎつつ、気泡の発生を防止するためには、不透明
ガラス状態部分を残す非有効部としてスス付けを開始し
た端部の非有効部を選択するのが好ましい。また、非有
効部に不透明ガラス状態部分を残す方法は上記の例に限
定されるものではなく、外付けスス体の両端に形成され
る非有効部のいずれか一方又は両方の少なくとも一部に
不透明ガラス状態部分を残すことができるものであれば
いかなる手法を採ることもできる。FIG. 3 shows an example in which an opaque glass state portion is left in only one of the non-effective portions. However, an opaque glass state portion may be left in both of the non-effective portions if necessary.
In the case where the external soot body is manufactured by the VAD method, the soot and the glass are brought into close contact with each other at the upper soot forming start portion, so that the bulk density of the soot is higher than that of the columnar effective portion. In most cases, this part becomes transparent first, and the escape route for gas that becomes bubbles may be closed. In order to prevent this, it is preferable to select the ineffective portion at the end where sooting is started as the ineffective portion leaving the opaque glass state portion. In addition, the method of leaving the opaque glass state portion in the ineffective portion is not limited to the above example, and the opaque portion is formed in at least a part of one or both of the ineffective portions formed at both ends of the external soot body. Any method can be adopted as long as it can leave a glass state portion.
【００１１】透明ガラス化を行う際には、できるだけ分
子直径の小さいガスの雰囲気中で行い、スス体形成時に
残った大気や水分等を除去することが望ましく、ゾーン
加熱炉及び均熱炉などいずれの炉の場合であっても、Ｈ
ｅ雰囲気とするのが好ましい。また、Ｈｅは高価である
ことから、炉体内の雰囲気ガス気圧を下げて透明ガラス
化を行うのも効果的である。It is desirable to carry out the vitrification in a gas atmosphere having a molecular diameter as small as possible to remove the air, moisture, etc. remaining during the formation of the soot body. H
Preferably, the atmosphere is e. In addition, since He is expensive, it is effective to reduce the atmospheric gas pressure in the furnace to perform vitrification.
【００１２】[0012]
【実施例】以下、実施例により本発明の方法をさらに具
体的に説明する。 （実施例１、比較例１）コア用ガラスロッドの有効部分
として、ＶＡＤ法で製造したステップ状屈折率分布を持
つ光学コア部（比屈折率０．３５％、純シリカガラスに
二酸化ゲルマニウムを微量添加したもの）と、その周囲
に光学クラッド部（純シリカガラス）を持つ２層構造の
石英ガラスロッドを有効部長さ：５００ｍｍ、直径２７
ｍｍに仕上げ、その両端に非有効部用の純シリカガラス
棒を接続した。このロッドの周囲に、ＶＡＤ法によりス
ス付けを行った。スス付けのガラス微粒子生成には、Ｓ
ｉＣｌ4 を気化して酸素水素火炎内に導入する加水分解
法を用いた。その結果、有効部の直径が１６５ｍｍの外
付けスス体を得た。有効部長さはロッドの有効部長さと
同じく５００ｍｍであり、非有効部長さは上部、下部と
もに約１５０ｍｍであった。この外付けスス体をゾーン
加熱炉を使用して透明ガラス化した。図４は加熱方式及
び得られた光ファイバ母材の状態を示す模式図である。
図４の（ａ）に示すようにコア用ガラスロッド２の周囲
にガラス微粒子のスス層３が形成された外付けスス体１
を、スス付けを開始した上端部を上にしてゾーン加熱炉
にセットし、下端部から５ｍｍ／分の下降速度で１６３
０℃に調整した加熱ゾーンを通過させた。この間、加熱
ゾーンはＨｅ雰囲気に保持した。EXAMPLES The method of the present invention will be described more specifically with reference to the following examples. (Example 1, Comparative Example 1) As an effective portion of a glass rod for a core, an optical core portion having a step-like refractive index distribution manufactured by a VAD method (relative refractive index: 0.35%, pure silica glass, trace amount of germanium dioxide) And a two-layered quartz glass rod having an optical cladding part (pure silica glass) around the effective part length: 500 mm, diameter 27
mm, and a pure silica glass rod for an ineffective portion was connected to both ends. A soot was formed around the rod by the VAD method. For the generation of glass particles with soot, S
A hydrolysis method in which iCl 4 was vaporized and introduced into an oxygen-hydrogen flame was used. As a result, an external soot body having an effective portion diameter of 165 mm was obtained. The effective portion length was 500 mm, the same as the effective portion length of the rod, and the ineffective portion length was about 150 mm for both the upper and lower portions. This external soot body was transparently vitrified using a zone heating furnace. FIG. 4 is a schematic diagram showing the heating method and the state of the obtained optical fiber preform.
As shown in FIG. 4A, an external soot body 1 in which a soot layer 3 of fine glass particles is formed around a core glass rod 2.
Was set in a zone heating furnace with the upper end at which sooting was started up, and 163 at a rate of 5 mm / min from the lower end.
It was passed through a heating zone adjusted to 0 ° C. During this time, the heating zone was kept in a He atmosphere.
【００１３】図４の（ｂ）に示すように、上部非有効部
の末端から３０ｍｍの位置まで加熱ゾーンを通過させて
スス層３の全体を透明ガラス化した比較例（従来技術）
では、コア用ガラスロッド２の周囲の透明ガラス層４と
の境界付近の上端に近い部分に気泡５の残存が認められ
た。これに対し、図４の（ｃ）に示すように本発明の方
法により、図４の（ｂ）の比較例よりも４０ｍｍ上方で
加熱処理を終了させて上部非有効部の表面付近に白い多
孔質状態部分（不透明ガラス状態部分６）が残るように
した（コア用ガラスロッド界面付近は透明ガラス化）実
施例では、光ファイバ母材の有効部には気泡の残存は認
められなかった。As shown in FIG. 4B, a comparative example in which the entire soot layer 3 is made vitreous by passing through a heating zone to a position 30 mm from the end of the upper ineffective portion (prior art)
In the sample, bubbles 5 were found to remain near the upper end near the boundary with the transparent glass layer 4 around the core glass rod 2. On the other hand, as shown in FIG. 4 (c), by the method of the present invention, the heat treatment was terminated 40 mm above the comparative example of FIG. In the example in which the quality state portion (opaque glass state portion 6) was left (the vicinity of the core glass rod interface was transparently vitrified), no bubbles remained in the effective portion of the optical fiber preform.
【００１４】（実施例２、比較例２）コア用ガラスロッ
ドとしては実施例１で使用したものと同様の構造を持つ
石英ガラスロッドを使用し、これを有効部長さ：５５０
ｍｍ、直径２５ｍｍに仕上げ、その両端に非有効部用の
純シリカガラス棒を接続した。このロッドの周囲に、Ｏ
ＶＤ法によりスス付けを行った。スス付けのガラス微粒
子生成には、ＳｉＣｌ4 を気化して酸素水素火炎内に導
入する加水分解法を用い、長手方向に１０往復の堆積を
行い、有効部の直径が１２０ｍｍの外付けスス体を得
た。有効部長さはロッドの有効部長さと同じく５５０ｍ
ｍであり、非有効部長さは上部、下部ともに約１７０ｍ
ｍであった。この外付けスス体を均熱炉を使用して透明
ガラス化した。図５及び図６はこの実施例、比較例にお
ける加熱方式及び得られた光ファイバ母材の状態を示す
模式図である。先ず比較例として、図５の（ａ）に示す
ようにコア用ガラスロッド２の周囲にガラス微粒子のス
ス層３が形成された外付けスス体１を非有効部及び有効
部の全体が均熱範囲内に入るように、１５００℃に維持
したＨｅ雰囲気の均熱炉内にセットし、９０分間保持し
て透明ガラス化した。その結果得られた光ファイバ母材
には、図５の（ｂ）に示すように、コア用ガラスロッド
２の周囲の透明ガラス層４との境界付近に気泡５の残存
が認められた。これに対し、図６の（ａ）に示すように
本発明の方法により、図５の比較例よりも１１０ｍｍ上
方に外付けスス体１をセットし、上部非有効部の大半が
均熱範囲外になるようにして加熱処理し、図６の（ｂ）
に示すように上部非有効部の大部分を不透明ガラス状態
部分６として残した実施例では、光ファイバ母材の有効
部に気泡の残存は認められなかった。なお、この実施例
ではＯＶＤ法による外付けスス体の製造をＳｉＣｌ4 ＋
酸水素火炎で行った例を示したが、これをＳｉＣｌ4 ＋
メタンガス（ＣＨ4 ）とした場合でも同様の結果が得ら
れた。Example 2 and Comparative Example 2 As a glass rod for a core, a quartz glass rod having the same structure as that used in Example 1 was used, and the effective portion length was 550.
mm and a diameter of 25 mm, and a pure silica glass rod for an ineffective portion was connected to both ends thereof. O around this rod
Sooting was performed by the VD method. For the generation of soot-coated glass fine particles, a hydrolysis method of evaporating SiCl 4 and introducing it into an oxygen-hydrogen flame is performed, and deposition is performed 10 times in the longitudinal direction to form an external soot body having an effective portion diameter of 120 mm. Obtained. The effective length is 550m, the same as the effective length of the rod
m and the length of the non-effective part is about 170 m for both the upper and lower parts
m. This external soot body was vitrified transparently using a soaking furnace. FIGS. 5 and 6 are schematic diagrams showing the heating method and the state of the obtained optical fiber preform in this example and the comparative example. First, as a comparative example, as shown in FIG. 5A, an external soot body 1 in which a soot layer 3 of glass fine particles is formed around a core glass rod 2 is heated so that the non-effective portion and the entire effective portion are uniformly heated. It was set in a soaking furnace in a He atmosphere maintained at 1500 ° C. so as to fall within the range, and kept for 90 minutes to form a transparent glass. As shown in FIG. 5B, in the optical fiber preform obtained as a result, bubbles 5 were observed near the boundary between the core glass rod 2 and the transparent glass layer 4. On the other hand, as shown in FIG. 6A, by the method of the present invention, the external soot body 1 is set 110 mm above the comparative example of FIG. Heat treatment is performed as shown in FIG.
As shown in (1), in the example in which most of the upper non-effective portion was left as the opaque glass state portion 6, no air bubbles remained in the effective portion of the optical fiber preform. In this embodiment, the production of the external soot body by the OVD method is performed by using SiCl 4 +
An example in which an oxyhydrogen flame was used was shown, but this was replaced with SiCl 4 +
Similar results were obtained when using methane gas (CH 4 ).
【００１５】上記実施例１及び２で得られた光ファイバ
母材をファイバ化したところ、光ファイバのガラス径は
１２５μｍ±１μｍの範囲内で安定しており、また、こ
の光ファイバを１５５０ｎｍ帯のＯＴＤＲで分析したと
ころ伝送損失段差も極めて小さく、良好な品質の光ファ
イバが得られた。これに対し、比較例１及び２で得られ
た気泡が残存する光ファイバ母材をファイバ化したとこ
ろ、気泡に該当する部分で光ファイバのガラス径が局所
的に急変動し、１２５μｍ±１μｍの範囲を超えてしま
い、良好な製品とするためにはこれを除去する必要があ
り、歩留りの低下を招く結果となった。また、これらの
気泡を含むファイバを１５５０ｎｍ帯のＯＴＤＲで分析
したところ、気泡に該当する部分で０．１ｄＢ程度の伝
送損失段差が見られた。When the optical fiber preforms obtained in Examples 1 and 2 were converted into fibers, the glass diameter of the optical fiber was stable within a range of 125 μm ± 1 μm. Analysis by OTDR showed that the transmission loss step was very small and an optical fiber of good quality was obtained. On the other hand, when the optical fiber preform in which the bubbles obtained in Comparative Examples 1 and 2 were formed into a fiber, the glass diameter of the optical fiber locally fluctuated locally at the portion corresponding to the bubbles, and was 125 μm ± 1 μm. The range was exceeded, and it was necessary to remove this in order to obtain a good product, resulting in a decrease in yield. Further, when the fiber containing these bubbles was analyzed by OTDR in the 1550 nm band, a transmission loss step of about 0.1 dB was found in a portion corresponding to the bubbles.
【００１６】[0016]
【発明の効果】本発明の方法によれば、コア用ガラスロ
ッドの周囲にＯＶＤ法やＶＡＤ法によりスス付けを行っ
た外付けスス体を過熱透明化して光ファイバ母材を製造
する方法において、コア用ガラスロッドの周囲に生じや
すい気泡の残存を抑制することができる。According to the method of the present invention, there is provided a method for producing an optical fiber preform by overheating and transparentizing an external soot body which has been sooted around a core glass rod by an OVD method or a VAD method. It is possible to suppress the remaining of air bubbles that easily occur around the core glass rod.
【図１】外付けスス体の構造を模式的に示す説明図。FIG. 1 is an explanatory view schematically showing the structure of an external soot body.
【図２】外付けスス体を従来の方法により加熱透明化し
て光ファイバ母材とする際に残存する気泡を模式的に示
す説明図。FIG. 2 is an explanatory view schematically showing bubbles remaining when an external soot body is heated and made transparent by a conventional method to form an optical fiber preform.
【図３】本発明の方法において、非有効部に不透明ガラ
ス状態部分を残すパターンの例を模式的に示す説明図。FIG. 3 is an explanatory view schematically showing an example of a pattern that leaves an opaque glass state portion in an ineffective portion in the method of the present invention.
【図４】実施例１、比較例１における加熱方式及び得ら
れた光ファイバ母材の状態を示す模式図。FIG. 4 is a schematic diagram showing a heating method and a state of an obtained optical fiber preform in Example 1 and Comparative Example 1.
【図５】比較例２における加熱方式及び得られた光ファ
イバ母材の状態を示す模式図。FIG. 5 is a schematic diagram showing a heating method and a state of an obtained optical fiber preform in Comparative Example 2.
【図６】実施例２における加熱方式及び得られた光ファ
イバ母材の状態を示す模式図。FIG. 6 is a schematic diagram showing a heating method and a state of an obtained optical fiber preform in Example 2.
１ 外付けスス体（ガラス微粒子堆積体） ２ コア
用ガラスロッド ３ スス層（ガラス微粒子の堆積層） ４ 透明ガラ
ス層 ５ 気泡 ６ 不透明ガラス状態部分DESCRIPTION OF SYMBOLS 1 External soot body (glass particulate accumulation body) 2 Glass rod for cores 3 Soot layer (glass particulate accumulation layer) 4 Transparent glass layer 5 Bubbles 6 Opaque glass state part
───────────────────────────────────────────────────── フロントページの続き (72)発明者 相川 晴彦 神奈川県横浜市栄区田谷町１番地 住友電 気工業株式会社横浜製作所内 (72)発明者 鬼頭 毅彦 神奈川県横浜市栄区田谷町１番地 住友電 気工業株式会社横浜製作所内 Ｆターム(参考） 4G021 CA12 EA01 EA03 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruhiko Aikawa 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Takehiko Kito 1-Tagamachi, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Ki Kogyo Co., Ltd. Yokohama Works F-term (reference) 4G021 CA12 EA01 EA03
Claims (6)
よりスス付けを行い、得られた外付けスス体を熱処理し
て透明ガラス化する光ファイバ用母材の製造方法におい
て、透明ガラス化の際に、光ファイバ用母材の両端の非
有効部のいずれか一方又は両方の少なくとも一部分を不
透明ガラス状態で残すことを特徴とする光ファイバ用母
材の製造方法。1. A method for producing a preform for optical fiber, wherein a soot is formed around a core glass rod by an external method, and the obtained external soot body is heat-treated to form a transparent glass. At this time, a method of manufacturing an optical fiber preform, wherein at least a part of one or both of the ineffective portions at both ends of the optical fiber preform is left in an opaque glass state.
コア用ガラスロッドを配置し、縦方向にススを成長させ
るＶＡＤ法により行う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。2. The optical fiber mother according to claim 1, wherein the sooting by the external method is performed by a VAD method in which a glass rod for a core is arranged in a vertical direction and soot is grown in a vertical direction. The method of manufacturing the material.
して、上方に位置するスス付け開始部分を選択すること
を特徴とする請求項２に記載の光ファイバ用母材の製造
方法。3. The method for producing a preform for an optical fiber according to claim 2, wherein a sooting start portion located above is selected as an ineffective portion that leaves an opaque glass state portion.
スロッドの周囲に、層状にスス付けを行うＯＶＤ法によ
り行う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。4. The method for producing a preform for an optical fiber according to claim 1, wherein the sooting by the external method is performed by an OVD method in which a soot is layered around the core glass rod. .
熱炉を用いて行い、前記外付けスス体の加熱終了位置を
調整することにより不透明ガラス状態部分を形成させる
ことを特徴とする請求項１〜４のいずれか１項に記載の
光ファイバ用母材の製造方法。5. An opaque glass state portion is formed by performing transparent vitrification of an external soot body using a zone heating furnace and adjusting a heating end position of the external soot body. The method for producing a preform for an optical fiber according to any one of claims 1 to 4.
用いて行い、両端の非有効部のいずれか一方又は両方の
少なくとも一部分が、均熱範囲に入らないようにするこ
とにより、該非有効部に不透明ガラス状態部分を形成さ
せることを特徴とする請求項１〜４のいずれか１項に記
載の光ファイバ用母材の製造方法。6. A transparent vitrification of the external soot body is performed by using a soaking furnace, and at least a part of one or both of ineffective portions at both ends is prevented from entering a soaking range. The method for producing an optical fiber preform according to any one of claims 1 to 4, wherein an opaque glass state portion is formed in the ineffective portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28424598A JP3498590B2 (en) | 1998-10-06 | 1998-10-06 | Manufacturing method of preform for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28424598A JP3498590B2 (en) | 1998-10-06 | 1998-10-06 | Manufacturing method of preform for optical fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000109333A true JP2000109333A (en) | 2000-04-18 |
| JP3498590B2 JP3498590B2 (en) | 2004-02-16 |
Family
ID=17676050
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28424598A Expired - Lifetime JP3498590B2 (en) | 1998-10-06 | 1998-10-06 | Manufacturing method of preform for optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3498590B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010037125A (en) * | 2008-08-04 | 2010-02-18 | Fujikura Ltd | Method for producing optical fiber preform |
| US8037718B2 (en) | 2008-09-03 | 2011-10-18 | Fujikura Ltd. | Method for manufacturing optical fiber preform |
| JP2013040101A (en) * | 2012-11-12 | 2013-02-28 | Fujikura Ltd | Method for producing optical fiber preform |
-
1998
- 1998-10-06 JP JP28424598A patent/JP3498590B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010037125A (en) * | 2008-08-04 | 2010-02-18 | Fujikura Ltd | Method for producing optical fiber preform |
| US8037718B2 (en) | 2008-09-03 | 2011-10-18 | Fujikura Ltd. | Method for manufacturing optical fiber preform |
| JP2013040101A (en) * | 2012-11-12 | 2013-02-28 | Fujikura Ltd | Method for producing optical fiber preform |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3498590B2 (en) | 2004-02-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4486212A (en) | Devitrification resistant flame hydrolysis process | |
| KR830002158B1 (en) | Method for forming optical waveguide preform having continuously removable starting member | |
| Schultz | Fabrication of optical waveguides by the outside vapor deposition process | |
| JP2959877B2 (en) | Optical fiber manufacturing method | |
| JP2011230987A (en) | Method for producing glass preform | |
| EP0100174B1 (en) | Method of making glass optical fiber | |
| JP3498590B2 (en) | Manufacturing method of preform for optical fiber | |
| EP0612701B1 (en) | Vapour axial deposition process for making optical fibre preforms | |
| JP4104558B2 (en) | Manufacturing method of glass tube | |
| KR100521958B1 (en) | method and apparatus for fabricating of optical fiber preform with double torch in MCVD | |
| JPH0788231B2 (en) | Manufacturing method of optical fiber preform | |
| JPH10206669A (en) | Optical fiber and its manufacture | |
| WO2007073031A1 (en) | Method for fabricating optical fiber preform with low oh concentration using mcvd process | |
| JPH0820574B2 (en) | Dispersion shift fiber and manufacturing method thereof | |
| JPH0798671B2 (en) | Method for manufacturing preform for optical fiber | |
| JPH10206654A (en) | Optical fiber and its manufacture | |
| JP2618260B2 (en) | Method for producing intermediate for optical fiber preform | |
| JP3174682B2 (en) | Method for producing glass preform for optical fiber | |
| US7391946B2 (en) | Low attenuation optical fiber and its producing method in MCVD | |
| JP2898705B2 (en) | Manufacturing method of optical fiber preform | |
| JPH0316930A (en) | Production of optical fiber having complicate refractive index distribution | |
| JPH0327491B2 (en) | ||
| JPS62191434A (en) | Production of parent material for optical fiber | |
| JPH05124831A (en) | Production of optical fiber | |
| JPH03261631A (en) | Production of optical fiber preform |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071205 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081205 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091205 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101205 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101205 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121205 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121205 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131205 Year of fee payment: 10 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| EXPY | Cancellation because of completion of term |