JPH0881233A - Production of preform material for optical fiber - Google Patents

Production of preform material for optical fiber

Info

Publication number
JPH0881233A
JPH0881233A JP21879894A JP21879894A JPH0881233A JP H0881233 A JPH0881233 A JP H0881233A JP 21879894 A JP21879894 A JP 21879894A JP 21879894 A JP21879894 A JP 21879894A JP H0881233 A JPH0881233 A JP H0881233A
Authority
JP
Japan
Prior art keywords
optical fiber
transparent
preform
base material
temperature
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.)
Pending
Application number
JP21879894A
Other languages
Japanese (ja)
Inventor
Tsutomu Yabuki
勉 矢吹
Yoshihiro Narita
芳大 成田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Cable Ltd
Original Assignee
Hitachi Cable Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Cable Ltd filed Critical Hitachi Cable Ltd
Priority to JP21879894A priority Critical patent/JPH0881233A/en
Publication of JPH0881233A publication Critical patent/JPH0881233A/en
Pending legal-status Critical Current

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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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Thermal Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Abstract

PURPOSE: To obtain a preform material for optical fiber capable of suppressing bubble development in the optical fiber made by its drawing. CONSTITUTION: In the production process for this preform material by sintering and transparently vitrifying a porous preform material produced by accumulating glass fine particles in an He gas atmosphere, the sintered transparent preform material is heated in an atmosphere other than He to such a temperature as to be enough to diffuse the He in the preform material.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、ガラス微粒子を堆積さ
せて焼結した光ファイバ母材中の気泡の原因になるガス
量の低減を図った光ファイバ母材の製造方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical fiber preform in which glass particles are deposited and sintered to reduce the amount of gas that causes bubbles in the optical fiber preform.

【０００２】[0002]

【従来の技術】光ファイバ母材の製造方法の一つとして
ＶＡＤ法がある。ＶＡＤ法は、回転するターゲットの先
端にガラス微粒子を堆積させて多孔質母材を製造するも
のである。また、回転するターゲット棒の外周にガラス
微粒子を堆積させる方法を外付ＶＡＤ法という。これら
ＶＡＤ法により製造された多孔質母材は、Ｈｅ，Ｃｌ2
ガス雰囲気下の石英炉芯管内に導かれて、そこで例えば
約1600℃に加熱され、脱水、焼結されて透明な光ファイ
バ母材となる。Ｈｅは、母材に気泡が入ることを抑制す
るために炉芯管内に供給されると共に、Ｃｌ2 ガス中に
多孔質母材をさらすことによりＣｌ2 ガスとＯＨ基とを
反応させ、母材の脱水処理を図る。透明ガラス化した母
材はその後酸水素炎やカーボン抵抗体などからなる電気
炉で例えば約2000℃に加熱され、これにより所定の径に
延伸されて線引され、光ファイバとなる。2. Description of the Related Art The VAD method is one of the methods for manufacturing an optical fiber preform. The VAD method is a method of producing a porous base material by depositing glass particles on the tip of a rotating target. Further, a method of depositing glass particles on the outer circumference of a rotating target rod is called an external VAD method. The porous base materials produced by these VAD methods are He, Cl 2
It is introduced into a quartz furnace core tube under a gas atmosphere, where it is heated to, for example, about 1600 ° C., dehydrated and sintered to form a transparent optical fiber preform. He is supplied to the furnace core tube in order to prevent the air bubbles from entering the base material is reacted with Cl 2 gas and OH groups by exposing the porous base material 2 gas Cl, preform Try to dehydrate. The transparent vitrified preform is then heated to, for example, about 2000 ° C. in an electric furnace composed of an oxyhydrogen flame, a carbon resistor, etc., and thereby drawn to a predetermined diameter and drawn to form an optical fiber.

【０００３】[0003]

【発明が解決しようとする課題】ところで、前述の光フ
ァイバ母材の製造方法で光ファイバ母材を製造する場
合、Ｈｅ，Ｃｌ2 ガス雰囲気下で透明ガラス化したまま
であると透明ガラス母材中に過剰のＨｅが含まれていた
り、ターゲットとの界面の気泡中にＨｅが含まれていた
りしている。そのため、このような透明ガラス母材から
得た光ファイバ母材を線引すると、過剰なＨｅや気泡中
のＨｅが加熱により膨張しファイバ中に大きな気泡を発
生させ光ファイバの機械的特性、伝送特性を著しく低下
させる。By the way, in the case of producing an optical fiber preform by the above-mentioned method for producing an optical fiber preform, it is necessary that the vitrified glass preform remains in the vitrified He / Cl 2 gas atmosphere. Excess He is contained therein, or He is contained in bubbles in the interface with the target. Therefore, when an optical fiber preform obtained from such a transparent glass preform is drawn, excessive He and He in bubbles expand due to heating and generate large bubbles in the fiber, causing mechanical characteristics and transmission of the optical fiber. Remarkably deteriorates the characteristics.

【０００４】本発明の目的は、前記した従来技術の課題
を解消し、光ファイバとした際に気泡の発生を抑制する
光ファイバ母材を製造できる光ファイバ母材の製造方法
を提供することにある。An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing an optical fiber preform capable of producing an optical fiber preform which suppresses the generation of bubbles when formed into an optical fiber. is there.

【０００５】[0005]

【課題を解決するための手段】前記目的を達成するため
に、本発明の光ファイバ母材の製造方法は、ガラス微粒
子を堆積させて得た多孔質母材をＨｅ含有雰囲気下で焼
結し透明ガラス化する光ファイバ母材の製造方法におい
て、前記焼結した透明母材を、Ｈｅ以外の雰囲気下で母
材中のＨｅが拡散する温度に加熱するものである。In order to achieve the above object, a method for producing an optical fiber preform according to the present invention comprises a step of sintering a porous preform obtained by depositing glass fine particles in a He-containing atmosphere. In the method for producing an optical fiber preform that becomes transparent glass, the sintered transparent preform is heated to a temperature at which He in the preform diffuses in an atmosphere other than He.

【０００６】また、ガラス微粒子を堆積させて得た多孔
質母材をＨｅ含有雰囲気下で焼結し透明ガラス化する光
ファイバ母材の製造方法において、前記焼結した透明母
材を、窒素ガス雰囲気下で透明ガラス化した温度と同じ
温度に加熱するものである。In addition, in the method for producing an optical fiber preform in which a porous preform obtained by depositing glass fine particles is sintered in a He-containing atmosphere to form a transparent glass, the sintered transparent preform is replaced with nitrogen gas. It is heated to the same temperature as the temperature at which the glass is transparentized in the atmosphere.

【０００７】[0007]

【作用】多孔質母材を透明ガラス化しただけではこの透
明母材中にＨｅが含まれ、ファイバとした際に気泡を発
生させる要因となるが、ガラス化した透明母材をさらに
母材中のＨｅが拡散する温度に加熱処理することで、母
材中のＨｅは拡散して脱ガスするので、これを線引きし
てもファイバ中に大きな気泡が発生することが抑制され
る。The function of He is contained in the transparent base material when the porous base material is made into transparent vitreous, which is a factor to generate bubbles in the fiber. However, the vitrified transparent base material is further contained in the base material. Since the He in the base material is diffused and degassed by the heat treatment at a temperature at which the He diffuses, the generation of large bubbles in the fiber is suppressed even if the He is drawn.

【０００８】また、ガラス化後の熱処理を窒素ガス雰囲
気下で透明ガラス化した温度と同じ温度で行うことで、
母材の変形及び生産性の面で問題なく透明母材中のＨｅ
の拡散を図れる。即ち、熱処理温度が高すぎると母材が
軟化し、逆に低すぎると加熱時間が長くなり生産性の面
で問題がある。Further, by performing the heat treatment after vitrification at the same temperature as the temperature at which transparent vitrification was performed in a nitrogen gas atmosphere,
He in the transparent base material has no problem in terms of deformation and productivity of the base material
Can be diffused. That is, if the heat treatment temperature is too high, the base material is softened, while if it is too low, the heating time becomes long and there is a problem in productivity.

【０００９】[0009]

【実施例】以下、本発明の実施例を詳述する。EXAMPLES Examples of the present invention will be described in detail below.

【００１０】まず、ＶＡＤ法により多孔質母材を形成す
る。石英ガラス製のチャンバ内でターゲットであるコア
ガラスロッドを回転させながら上方に移動させる間に、
コアガラスロッドに対し、ＳｉＣｌ4 およびＨ2 ，
Ｏ2 ，Ａｒガスなどのガラス原材料を多重管バーナーか
ら吹き出し、酸水素火炎中の加水分解により生成するガ
ラス微粒子（ＳｉＯ2 微粉末）をコアガラスロッドの外
周に一定の外径、長さになるように堆積させ、多孔質母
材を形成する。First, a porous base material is formed by the VAD method. While moving the core glass rod, which is the target, in the quartz glass chamber while rotating,
For core glass rods, SiCl 4 and H 2 ,
Glass raw materials such as O 2 and Ar gas are blown out from a multi-tube burner, and fine glass particles (SiO 2 fine powder) generated by hydrolysis in an oxyhydrogen flame are formed on the outer circumference of the core glass rod to have a constant outer diameter and length. To form a porous matrix.

【００１１】次に、多孔質母材を炉芯管構造の電気炉
（例えば抵抗加熱炉）内で透明ガラス化する。この際、
石英炉芯管の外側に配設されたカーボンヒータで炉心管
内に徐々に挿入される母材を加熱すると共に、炉芯管内
にＨｅとＣｌ2 ガスを供給する。これにより、母材中の
ＯＨ基がＣｌ2 ガスと反応して脱水されると共に多孔質
母材は加熱されてガラス化し、透明母材となる。Next, the porous preform is made into transparent glass in an electric furnace having a furnace core tube structure (for example, a resistance heating furnace). On this occasion,
A carbon heater arranged outside the quartz furnace core tube heats the base material gradually inserted into the furnace core tube, and He and Cl 2 gas are supplied into the furnace core tube. As a result, the OH group in the base material reacts with Cl 2 gas to be dehydrated, and the porous base material is heated to vitrify to become a transparent base material.

【００１２】そして、この透明母材をさらに熱処理す
る。この熱処理は、多孔質母材を透明ガラス化する装置
と同一構造の炉芯管を用いることができ、一つの炉芯管
でガスの供給を切り換えて透明ガラス化と熱処理を行っ
てもよく、また、二つの炉芯管を直列に配置して透明ガ
ラス化と熱処理をそれぞれの炉芯管で行うようにしても
よい。一つの炉芯管を用いる場合には、透明ガラス化を
行った後、石英炉芯管内に流していたＨｅとＣｌ2 ガス
の供給を止め代りにＮ2 ガスを供給し、このＮ2 ガスが
流れる管内で透明母材を加熱する。この際、カーボンヒ
ータで母材を加熱する温度は透明ガラス化した時の温度
と同じにすることが好ましい。このように、Ｈｅ以外の
ガス雰囲気中で透明母材を加熱して熱処理を行うことに
より、透明母材に含まれていたＨｅが分散して母材から
除去（脱ガス）される。即ち、多孔質母材を透明ガラス
化しただけではこの透明母材中にＨｅが含まれ、ファイ
バとした際に気泡を発生させる要因となるが、ガラス化
した透明母材をさらに母材中のＨｅが拡散する温度に加
熱処理（熱処理）することで、そのＨｅは拡散して母材
から脱ガスするので、これを線引きしてもファイバ中に
大きな気泡が発生することがない。Then, the transparent base material is further heat-treated. This heat treatment can use a furnace core tube having the same structure as the device for making the porous base material into a transparent vitrification, and the gas supply may be switched in one furnace core tube to perform the transparent vitrification and the heat treatment, Alternatively, two furnace core tubes may be arranged in series so that transparent vitrification and heat treatment are performed in each furnace core tube. When using one of the furnace core tube after the transparent vitrification, and the N 2 gas is supplied instead stopping the supply of He and Cl 2 gas was flowed into the quartz furnace core tube, the N 2 gas The transparent matrix is heated in a flowing tube. At this time, it is preferable that the temperature at which the base material is heated by the carbon heater is the same as the temperature at which the vitrification is performed. As described above, by heating the transparent base material in a gas atmosphere other than He to perform heat treatment, He contained in the transparent base material is dispersed and removed (degassed) from the base material. That is, only by vitrifying the porous base material into transparent glass, He is contained in the transparent base material, which becomes a factor to generate bubbles when forming a fiber. By performing heat treatment (heat treatment) at a temperature at which He diffuses, the He diffuses and is degassed from the base material. Therefore, even if the He is drawn, large bubbles are not generated in the fiber.

【００１３】具体的には、まず、コア部と一部クラッド
部からなる外径φ15mm、長さ1300mmの透明ガラスロッド
外周に外付ＶＡＤ法によりＳｉＯ2 微粉末を堆積させ、
外径φ 100mmの多孔質母材を形成した。Specifically, first, SiO 2 fine powder is deposited by an external VAD method on the outer circumference of a transparent glass rod having an outer diameter of φ15 mm and a length of 1300 mm consisting of a core portion and a partial clad portion,
A porous base material having an outer diameter of 100 mm was formed.

【００１４】次に、この母材を、Ｈｅガス流量５リットル／
min 、Ｃｌ2 ガス流量400cc/min の雰囲気下の石英炉芯
管内に入れて、上から下方向へ4mm/min の速度で移動さ
せると共に、カーボンヒータの表面温度を1600℃にして
加熱し、母材下端から透明ガラス化した。Next, this base material was filled with He gas at a flow rate of 5 liters /
min., put it in a quartz furnace core tube in an atmosphere with a Cl 2 gas flow rate of 400 cc / min, move it from top to bottom at a speed of 4 mm / min, and heat the carbon heater to a surface temperature of 1600 ° C to heat it. Transparent vitrification was performed from the lower end of the material.

【００１５】全長透明ガラス化後、この透明母材を石英
炉芯管から取り出すことなくガラス化時に流していたＨ
ｅとＣｌ2 ガスの代りにＮ2 ガスを10リットル／min 流すと
共に、透明ガラス化した時の温度と同じ温度すなわちカ
ーボンヒータ表面温度1600℃の状態にして、透明母材を
4mm/min の移動速度で引き上げながら加熱して、光ファ
イバ母材を製造した。After the full length transparent vitrification, the transparent base material was flown during vitrification without taking out from the quartz furnace core tube.
Instead of e and Cl 2 gas, N 2 gas was made to flow at 10 liters / min, and the same temperature as the temperature of vitrification, that is, the carbon heater surface temperature was 1600 ° C, and the transparent base material was
An optical fiber preform was manufactured by heating while pulling up at a moving speed of 4 mm / min.

【００１６】このようにして製造した光ファイバ母材と
ガラス化後熱処理を行わない光ファイバ母材（従来の母
材）との外径φ40mm、長さ 900mm当たり（光ファイバ長
85kmに相当）の気泡発生率を調べた。その結果、熱処理
を行った本発明に係る母材から得た光ファイバでは気泡
の発生は全く見られず０ヶ／85kmであり、しかも機械的
光学的特性が向上すると同時に歩留りも向上した。これ
に対して、従来の母材からの光ファイバの気泡発生率は
５ヶ／85kmであった。[0016] The optical fiber preform thus produced and the optical fiber preform which is not heat-treated after vitrification (conventional preform) have an outer diameter of 40 mm and a length of 900 mm (optical fiber length
The bubble generation rate of 85 km) was investigated. As a result, in the optical fiber obtained from the heat-treated preform according to the present invention, no bubbles were observed and the number was 0/85 km, and the mechanical and optical characteristics were improved and the yield was also improved. On the other hand, the bubble generation rate of the optical fiber from the conventional base material was 5/85 km.

【００１７】従って、Ｈｅガスを含む雰囲気下で透明ガ
ラス化後、さらにこの透明母材をＨｅガス以外の例えば
Ｎ2 ガス雰囲気下で透明ガラス化と同じ温度で加熱処理
することにより、線引きして光ファイバとしても気泡が
発生することがない光ファイバ母材を製造することがで
きる。Therefore, after transparent vitrification in an atmosphere containing He gas, the transparent base material is further heat-treated at the same temperature as the transparent vitrification in an atmosphere other than He gas, for example, N 2 gas to draw a wire. It is possible to manufacture an optical fiber preform that does not generate bubbles even as an optical fiber.

【００１８】また、熱処理を透明ガラス化温度と同じ温
度で行うため、過剰なＨｅや界面の空隙に残っているＨ
ｅが低濃度部すなわちガラスロッド外部へ拡散しやすく
短時間で処理ができる。すなわち、ＨｅやＨ2 のガスは
石英ガラス中を他のガスよりも容易に拡散しやすいこと
に起因しており、さらに温度を上げて高温にすればする
ほど、ＨｅやＨ2 のガスが石英ガラス中を拡散しやすく
なりガラス中のＨｅやＨ2 のガスは抜けやすい。しか
し、熱処理温度を透明ガラス化温度よりも高くしすぎる
と透明ガラス化した母材は軟化し、自重により変形し長
手方向に外径変動を生じる虞がある。また熱処理温度を
透明ガラス化温度よりも低くしすぎると、ガラス中のガ
スは拡散しにくいため、加熱時間が長くなり生産性の面
で問題がある。よって、熱処理を透明ガラス化温度とほ
ぼ同じ温度で行うことで、母材の変形もなく歩留り及び
生産性が向上した光ファイバ母材を製造することがで
き、工業的価値が大である。Further, since the heat treatment is performed at the same temperature as the transparent vitrification temperature, excess He and H remaining in the voids at the interface are used.
e easily diffuses to the low concentration portion, that is, outside the glass rod, and can be treated in a short time. That is, the He or H 2 gas is more easily diffused in the quartz glass than the other gases, and the higher the temperature and the higher the temperature, the more the He or H 2 gas becomes quartz. It easily diffuses in the glass, and He and H 2 gas in the glass easily escapes. However, if the heat treatment temperature is set higher than the transparent vitrification temperature, the transparent vitrified base material is softened and may be deformed by its own weight to cause an outer diameter variation in the longitudinal direction. Further, if the heat treatment temperature is too lower than the transparent vitrification temperature, the gas in the glass is less likely to diffuse, so that the heating time becomes longer and there is a problem in productivity. Therefore, by carrying out the heat treatment at a temperature almost equal to the transparent vitrification temperature, it is possible to manufacture an optical fiber preform with improved yield and productivity without deformation of the preform, which is of great industrial value.

【００１９】[0019]

【発明の効果】以上要するに本発明によれば、ガラス中
に気泡のない光ファイバを得ることが可能な光ファイバ
母材を製造できる。In summary, according to the present invention, it is possible to manufacture an optical fiber preform capable of obtaining an optical fiber having no bubbles in glass.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 ガラス微粒子を堆積させて得た多孔質母
材をＨｅ含有雰囲気下で焼結し透明ガラス化する光ファ
イバ母材の製造方法において、前記焼結した透明母材
を、Ｈｅ以外の雰囲気下で母材中のＨｅが拡散する温度
に加熱することを特徴とする光ファイバ母材の製造方
法。1. A method for producing an optical fiber preform in which a porous preform obtained by depositing glass fine particles is sintered in a He-containing atmosphere to form a transparent glass, wherein the sintered transparent preform is other than He. The method for producing an optical fiber preform, which comprises heating to a temperature at which He in the preform diffuses in the atmosphere described in 1. 【請求項２】 ガラス微粒子を堆積させて得た多孔質母
材をＨｅ含有雰囲気下で焼結し透明ガラス化する光ファ
イバ母材の製造方法において、前記焼結した透明母材
を、窒素ガス雰囲気下で透明ガラス化した温度と同じ温
度に加熱することを特徴とする光ファイバ母材の製造方
法。2. A method for producing an optical fiber preform in which a porous preform obtained by depositing glass fine particles is sintered in a He-containing atmosphere to form a transparent vitrification, wherein the sintered transparent preform is nitrogen gas. A method for producing an optical fiber preform characterized by heating to the same temperature as the temperature of transparent vitrification in an atmosphere.
JP21879894A 1994-09-13 1994-09-13 Production of preform material for optical fiber Pending JPH0881233A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21879894A JPH0881233A (en) 1994-09-13 1994-09-13 Production of preform material for optical fiber

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21879894A JPH0881233A (en) 1994-09-13 1994-09-13 Production of preform material for optical fiber

Publications (1)

Publication Number Publication Date
JPH0881233A true JPH0881233A (en) 1996-03-26

Family

ID=16725536

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21879894A Pending JPH0881233A (en) 1994-09-13 1994-09-13 Production of preform material for optical fiber

Country Status (1)

Country Link
JP (1) JPH0881233A (en)

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