JPH0369526A - Production of glass base material for optical fiber - Google Patents
Production of glass base material for optical fiberInfo
- Publication number
- JPH0369526A JPH0369526A JP20276489A JP20276489A JPH0369526A JP H0369526 A JPH0369526 A JP H0369526A JP 20276489 A JP20276489 A JP 20276489A JP 20276489 A JP20276489 A JP 20276489A JP H0369526 A JPH0369526 A JP H0369526A
- Authority
- JP
- Japan
- Prior art keywords
- heat treatment
- fluorine
- glass
- gas
- optical fiber
- 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
Links
- 239000011521 glass Substances 0.000 title claims abstract description 62
- 239000013307 optical fiber Substances 0.000 title claims abstract description 15
- 239000000463 material Substances 0.000 title claims abstract description 8
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 238000010438 heat treatment Methods 0.000 claims abstract description 47
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 44
- 239000011737 fluorine Substances 0.000 claims abstract description 44
- 238000000034 method Methods 0.000 claims abstract description 18
- 230000018044 dehydration Effects 0.000 claims abstract description 5
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 5
- 238000010574 gas phase reaction Methods 0.000 claims abstract description 4
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 4
- 239000002245 particle Substances 0.000 claims description 40
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 21
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 9
- 229910052681 coesite Inorganic materials 0.000 abstract description 3
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 3
- 239000010453 quartz Substances 0.000 abstract description 3
- 229910052682 stishovite Inorganic materials 0.000 abstract description 3
- 229910052905 tridymite Inorganic materials 0.000 abstract description 3
- 239000000377 silicon dioxide Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 42
- 238000009826 distribution Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000011148 porous material Substances 0.000 description 5
- 229910052814 silicon oxide Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 238000005253 cladding Methods 0.000 description 3
- 101100453511 Danio rerio kazna gene Proteins 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- -1 C7!2 Substances 0.000 description 1
- 241000406668 Loxodonta cyclotis Species 0.000 description 1
- 238000011276 addition treatment Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000012024 dehydrating agents Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004334 fluoridation Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000000275 quality assurance Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 238000004017 vitrification Methods 0.000 description 1
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
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、光ファイバ用ガラス母材の製造方法に関する
ものであり、詳しくはコアが純石英ガラス（Ｓｉ ０２
）からなり、クラッドがフッ素添加石英ガラス（Ｆ
５ｉ０２と記載する場合もある）からなる光ファイバ用
ガラス母材の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a glass base material for optical fibers, and more specifically, the present invention relates to a method for manufacturing a glass base material for optical fibers.
), and the cladding is fluorine-doped quartz glass (F
5i02)).
コアが純石英ガラスからなり、クラッドがフッ素添加石
英ガラスからなる、いわゆる純石英コア光ファイバは伝
送損失が低く、長距離通信用線路として注目されている
。 この純石英コア光ファイバに使用されるフッ素添
加石英ガラスは、通常、例えば特開昭６２−２７５０３
５号公報あるいは特開昭６０−９０８４２号公報に示さ
れるように、焼結炉内でフッ素添加を行なう。A so-called pure silica core optical fiber, in which the core is made of pure silica glass and the cladding is made of fluorine-doped silica glass, has low transmission loss and is attracting attention as a line for long-distance communication. The fluorine-doped silica glass used for this pure silica core optical fiber is generally disclosed in Japanese Patent Application Laid-Open No. 62-27503, for example.
Fluorine addition is carried out in a sintering furnace as shown in Japanese Patent Application Laid-Open No. 60-90842.
すなわち、ＶＡＤ法や外（＝１け法などの気相反応によ
り合成されたＳｔ Ｏｚガラス粒子体を加熱炉内で脱水
処理し、その後、フッ素系ガス含有雰囲気下で、好まし
くは１０００℃から１２００℃の熱処理を行なうことに
より、フッ素添加し、その後、フッ素系ガス含有雰囲気
あるいは不活性ガス雰囲気において、加熱により透明ガ
ラス化して、フッ −
素添加石英ガラスを得る。That is, StOz glass particles synthesized by a gas phase reaction such as the VAD method or the external method are dehydrated in a heating furnace, and then heated preferably from 1000°C to 1200°C in an atmosphere containing a fluorine gas. Fluorine is added by performing heat treatment at .degree. C., and then transparent glass is obtained by heating in a fluorine-based gas-containing atmosphere or an inert gas atmosphere.
従来、フッ素系ガス含有雰囲気下での高温熱処理による
フッ素添加方法では、５ｉＣｈガラス粒子体の半径方向
及び長平方向に、フッ素添加量が変動するという問題が
あった。Conventionally, the method of adding fluorine by high-temperature heat treatment in an atmosphere containing a fluorine-based gas has had a problem in that the amount of fluorine added varies in the radial direction and longitudinal direction of the 5iCh glass particles.
特に、半径方向のフッ素添加においては、」−記Ｓｉ
Ｏｘガラス粒子体の中心部へのフッ素添加が少なく、そ
の結果、中心で屈折率が高く、外周に向かって次第に屈
折率が低下するような、第６図に示す屈折率分布が形成
されやすいという問題があった。In particular, in the case of radial fluoridation, Si
There is little fluorine added to the center of the Ox glass particles, and as a result, the refractive index distribution shown in Figure 6 is likely to be formed, where the refractive index is high at the center and gradually decreases toward the outer periphery. There was a problem.
不均一にフッ素添加されたガラス母相の場合、光ファイ
バとしたときの伝送特性が安定せず、製造上、品質保障
上大きな問題となる。In the case of a glass matrix that is unevenly fluorinated, the transmission characteristics when used as an optical fiber are unstable, which poses a major problem in terms of manufacturing and quality assurance.
従来、この種の問題に対して、フッ素系ガスの含浸が不
十分であるとの立場から、フッ素系ガスの濃度を」二げ
たり、炉温を調整するなどの改善が行われてきたが、い
ずれの方法によるも、未だ十分な効果が得られていない
。純石英コア光ファイバの特性を安定させるためには、
フッ素を均一に添加する熱処理技術のさらなる開発が不
可欠である。Conventionally, in response to this type of problem, improvements such as lowering the concentration of fluorine gas or adjusting the furnace temperature have been made from the standpoint that the impregnation of fluorine gas is insufficient. However, no sufficient effect has yet been obtained with either method. In order to stabilize the characteristics of pure silica core optical fiber,
Further development of heat treatment technology to uniformly add fluorine is essential.
本発明は、このような現状に鑑みてなされたもので、純
石英コア、フッ素添加クラッドの構造の光ファイバ用母
材において、フッ素を均一に添加できる光ファイバ用ガ
ラス母材の製造方法を提供することを目的としている。The present invention has been made in view of the current situation, and provides a method for manufacturing an optical fiber glass base material that can uniformly add fluorine to an optical fiber base material having a structure of a pure quartz core and a fluorine-doped cladding. It is intended to.
上記問題点を解決するための本発明の構成は、気相反応
により合成したＳｉ ０２ガラス拉子体を加熱炉内で脱
水のための第１の熱処理及びフッ素添加のための第２の
熱処理を行い、その後透明ガラス化して光ファイバ用ガ
ラス母材を製造する方法において、上記第２の熱処理時
の雰囲気ガスを熱処理用ヒータよりも上流において予め
加熱しておくことを特徴とするものである。The configuration of the present invention for solving the above problems is to perform a first heat treatment for dehydration and a second heat treatment for fluorine addition in a heating furnace on a Si02 glass sample body synthesized by a gas phase reaction. The method of manufacturing a glass preform for an optical fiber by performing transparent vitrification thereafter is characterized in that the atmospheric gas during the second heat treatment is preheated upstream of the heat treatment heater.
上記本発明において、第２の熱処理の雰囲気ガスを予め
加熱しておく温度が、」二記熱処理塩度と等しい又はそ
れよりも２００℃低い温度範囲内に設定されていること
が特に好ましい。In the present invention, it is particularly preferable that the temperature at which the atmospheric gas for the second heat treatment is preheated is set within a temperature range that is equal to or 200° C. lower than the salinity of the second heat treatment.
本発明者らは、フッ素添加条件、あるいはＳｉ Ｏ２ガ
ラス粒子体の性状について、詳細に調べた結果、５ｉＯ
ｐガラス粒子体中心部にフッ素が添加されにくい原因は
、特に、フッ素原料ガスの温度及び５ｉ０２ガラス粒子
体の温度が上がりにくいことにより、Ｓｉ Ｏｘガラス
粒粒子体中郡部温度が上がり難いことにあることを見出
した。The present inventors investigated in detail the fluorine addition conditions or the properties of SiO2 glass particles, and found that 5iO
The reason why it is difficult to add fluorine to the center of the P glass particles is that the temperature of the central part of the SiOx glass particles is difficult to rise because the temperature of the fluorine raw material gas and the temperature of the 5i02 glass particles are difficult to rise. I discovered that.
Ｓｔ ０２ガラス粒子体は、０． Ｉ〜Ｑ、 ５ ／Ｉ
ＴＩ＋の微細なガラス粒子が集合して形成されているも
のであり、空孔がかなりの割合で存在している。例えば
、カザ密度（空孔も含めた体積に帯する密度を表ず：ｇ
／ｃｍ ）が、０．３ ｇ／ｃａｒのものでは、ガラス
粒子と空孔の占める体積比は、およそ１：６．４となっ
ている。このため、Ｓｉ Ｏｘガラス粒子体の熱伝導率
は、空孔を満たすガスの熱伝導率で代表される。The St 02 glass particle body is 0. I~Q, 5/I
It is formed by an aggregation of fine TI+ glass particles, and contains a considerable proportion of pores. For example, Kaza density (expressing the density banded in the volume including vacancies: g
/cm 2 ) is 0.3 g/car, the volume ratio occupied by glass particles and pores is approximately 1:6.4. Therefore, the thermal conductivity of the SiOx glass particles is represented by the thermal conductivity of the gas filling the pores.
ところがガスの熱伝導率は一般に固体より小さく、例え
ばガスとしては熱伝導率の良い陽でも、例えばガラスの
それに比ると、１ケタ小さな値でしかない。このことか
ら炉芯管に入れて炉芯管外部から加熱する場合、その外
周部にくらべＳｉｎｇガラス粒子体の内部は、加熱され
にくいことが推察される。すなわち、第５図に示すよう
な温度分布となりやすくなる。このため、Ｓｉｎｇガラ
ス粒子体中に浸透したフッ素系ガスが分解してＦがガラ
スに添加される反応が進行せず、フッ素添加は中心部で
十分に進行しないものと考えられる。However, the thermal conductivity of gases is generally lower than that of solids; for example, even if a gas has good thermal conductivity, its value is only an order of magnitude smaller than that of glass, for example. From this, it can be inferred that when the Sing glass particles are placed in a furnace core tube and heated from the outside of the furnace core tube, the inside of the Sing glass particle body is less likely to be heated than the outer peripheral portion thereof. In other words, a temperature distribution as shown in FIG. 5 is likely to occur. For this reason, it is thought that the reaction in which the fluorine-based gas that has permeated into the Sing glass particles is decomposed and F is added to the glass does not proceed, and fluorine addition does not proceed sufficiently in the center.
そこで、まず、ガラス粒子体中心部の温度を」二げるべ
く、炉温を上昇させてみた。しかし、フッ素含有雰囲気
下で炉温を上げると、比較的に温度が上がるガラス粒子
体外周部では、フッ素添加がより速く進行するため、フ
ッ素が添加されたことによるガラス粘度の低下により、
透明化が進行してしまう。ガラス粒子体の外周が透明化
するに伴い、フッ素系ガスは、この透明ガラス部で遮ら
れ、内部に浸透しなくなる。このため、内部のフッ素添
加が十分に進行せず、問題解決にはならなかった。Therefore, we first tried increasing the furnace temperature in order to lower the temperature at the center of the glass particles. However, when the furnace temperature is raised in a fluorine-containing atmosphere, fluorine addition progresses more rapidly at the outer periphery of the glass particle body, where the temperature rises comparatively.
Transparency progresses. As the outer periphery of the glass particle body becomes transparent, the fluorine-based gas is blocked by the transparent glass portion and no longer permeates into the inside. For this reason, internal fluorine addition did not progress sufficiently, and the problem was not solved.
また、外周が透明化しない温度で止めたとじても、炉芯
管にガラス粒子体を入れ炉芯管外部の加熱ヒータで加熱
する方法では、やはり中心と外周の温度差は存在する以
上、フッ素添加量に差がついてしまう。すなわち、 フ
ッ素添加を均一に行なうためには、フッ素系ガス存在下
でガラス粒子体内部の温度が比較的均一になっているこ
とが必要である。Furthermore, even if the temperature is stopped at a temperature at which the outer periphery does not become transparent, in the method of placing glass particles in the furnace core tube and heating it with a heater outside the furnace core tube, there is still a temperature difference between the center and the outer periphery, so fluorine There will be a difference in the amount added. That is, in order to uniformly add fluorine, it is necessary that the temperature inside the glass particles be relatively uniform in the presence of a fluorine-based gas.
ここで本発明者等は、Ｓｔ Ｏｘガラス粒子体のような
、空孔の占める割合の多い多孔質体の場合の温度を決定
する要因としては、雰囲気ガスにより伝達する熱量が支
配的と考え、フッ素系ガスを含有する雰囲気ガスの温度
について考察と実験を繰り返し、本発明の予め加熱し雰
囲気ガスを熱処理用ヒータ上流に導入する方法が、多孔
質体であるＳｉ Ｏｘガラス粒子体の内部まで十分均一
に加熱できる手段であることを見出したのである。Here, the present inventors believe that the amount of heat transferred by the atmospheric gas is the dominant factor that determines the temperature in the case of a porous body with a large proportion of pores, such as St Ox glass particles, After repeated consideration and experiments regarding the temperature of the atmospheric gas containing fluorine-based gas, we found that the method of the present invention, in which the atmospheric gas is preheated and introduced upstream of the heat treatment heater, was able to reach the inside of the SiOx glass particles, which is a porous body, sufficiently. They discovered that it is a means of heating evenly.
本発明の構成を第１図に示す。雰囲気ガスのコントロー
ルのため、密閉容器（炉芯管）■内に、ガラス粒子体２
を挿入し、電気ヒータ３にて熱処理を行なう。このとき
、炉芯管ｌ内には、雰囲気ガス田及びフッ素原料ガスが
導入されるが、これらのガスは、少なくとも１種又はす
べてが炉芯管１、に導入する前の加熱器４により高温に
加熱される。加熱されたガスは、炉芯管ｌ内に設置され
たガラス粒子体２を通過し、炉芯管１」二部より排気さ
れる。このときガスはガラス粒子体２の空孔を通って、
ガラス粒子体２の内部を加熱する。このためにガラス粒
子体を均一に加熱することができる。したがって、ガラ
ス粒子体内にフッ素を均一に添加することが容易となる
。The configuration of the present invention is shown in FIG. In order to control the atmospheric gas, glass particles 2 are placed in a closed container (furnace core tube).
is inserted, and heat treatment is performed using the electric heater 3. At this time, an atmospheric gas field and a fluorine raw material gas are introduced into the furnace core tube 1, but at least one or all of these gases are heated to a high temperature by the heater 4 before being introduced into the furnace core tube 1. is heated to. The heated gas passes through the glass particle body 2 installed in the furnace core tube 1, and is exhausted from the second part of the furnace core tube 1''. At this time, the gas passes through the pores of the glass particle body 2,
The inside of the glass particle body 2 is heated. For this reason, the glass particles can be heated uniformly. Therefore, it becomes easy to uniformly add fluorine into the glass particles.
ガラス粒子体２内の均一加熱のためには、フッ素添加の
ための第２の熱処理時のヒータ設定値に対して、０℃〜
２００℃低い温度範囲内にガス温度を調整することが望
ましい。具体的にはフッ素添加のための第２の熱処理温
度を１）００℃〜１３５０℃程度に設定し、ガス温度を
これより０℃〜２００℃低温度の範囲内に調整する等で
ある。In order to uniformly heat the inside of the glass particle body 2, the heater setting value during the second heat treatment for fluorine addition must be set at 0°C to
It is desirable to adjust the gas temperature to within a 200°C lower temperature range. Specifically, the second heat treatment temperature for fluorine addition is set at 1) approximately 00°C to 1350°C, and the gas temperature is adjusted within a range of 0°C to 200°C lower than this.
なお、ガス全体の温度が高い方が有利なので、フッ素系
ガス及び不活性ガス等のフッ素系ガス以外のガスの両方
が加熱されているほうが有利であるので、本発明の実施
例では両方を加熱する方法を示した。In addition, since it is advantageous that the temperature of the entire gas is high, it is advantageous that both the fluorine-based gas and the gas other than the fluorine-based gas such as an inert gas are heated, so in the embodiment of the present invention, both are heated. I showed you how to do it.
また、本発明において第２の熱処理の雰囲気ガス加熱は
、第２図のように、炉芯管ｌの下部に電気ヒータ５を設
置して、加熱用ヒータ（熱処理用ヒータ）３よりは上流
の炉芯管内部で予熱を行うことでも、同様の効果を期待
できる。In addition, in the present invention, atmospheric gas heating in the second heat treatment is performed by installing an electric heater 5 at the lower part of the furnace core tube l, as shown in FIG. A similar effect can be expected by performing preheating inside the furnace core tube.
本発明に係る第２の熱処理に用いるフッ素添加のための
雰囲気ガスとしては、例えばＩし、Ｎ７等の不活性ガス
及びフッ素系ガス例えばＳｉ Ｆ４、Ｓ Ｆ ａ等を用
いることができる。As the atmospheric gas for adding fluorine used in the second heat treatment according to the present invention, for example, an inert gas such as I, N7, etc., and a fluorine-based gas such as Si F4, S Fa, etc. can be used.
本発明に係る第１の熱処理に用いる脱水のための雰囲気
ガスとしては、例えばＣ７！２、ＣＣｌ４等の脱水剤ガ
スと、例えば１ら、Ｎ３等の不活性ガスからなるガスを
挙げることができる。Examples of the atmospheric gas for dehydration used in the first heat treatment according to the present invention include a gas consisting of a dehydrating agent gas such as C7!2, CCl4, and an inert gas such as 1, N3, etc. .
また、この時のＳｉ Ｃｈ粒子体のカザ密度はＯ１）〜
０、５ ｇｌｃｘｄｌ度が好ましい。In addition, the Kaza density of the Si Ch particles at this time is O1) ~
0.5 glcxdl degrees is preferred.
さらにまた、フッ素添加はＳｉ Ｏｘ粒子体内にその他
のドーパント、例えばＧｅ Ｏｔ 、 Ｂｚ Ｏｓ、Ｐ
２Ｏ３などが含まれているのでも、同様の効果を得るこ
とができる。Furthermore, fluorine doping can introduce other dopants within the SiOx particles, such as GeOt, BzOs, P
A similar effect can be obtained even if 2O3 or the like is included.
比較例１
ＶＡＤ法により合成した、外径１４０ｍｍ、長さ５００
ｍｍのＳｉ Ｏｘガラス粒子体を、第１図に示すリン
グ状電気ヒータ３を持つ加熱炉にて、熱処理を行った。Comparative Example 1 Synthesized by VAD method, outer diameter 140 mm, length 500 mm
A SiOx glass particle body of mm was heat-treated in a heating furnace equipped with a ring-shaped electric heater 3 shown in FIG.
雰囲気ガス加熱用ヒータ４は使用せず、雰囲気ガスは室
温に保たれた状態で、炉芯管１内に導入された。この状
態で、Ｓｉ ０２ガラス粒子体をリング状ヒータ３中に
トラバースすることにより熱処理を行った。熱処理は、
表１に示ず３ステツプに分けて行い、それぞれ第１ステ
ップ：５ｉＯｔガラス粒子体の脱水、不純物除去処理、
第２ステップ：フッ素添加処理、第３ステップ；透明化
処理である。The atmosphere gas heating heater 4 was not used, and the atmosphere gas was introduced into the furnace core tube 1 while being kept at room temperature. In this state, the Si 02 glass particles were traversed into the ring-shaped heater 3 to perform heat treatment. Heat treatment is
The process is divided into three steps (not shown in Table 1), and the first step is: dehydration of 5iOt glass particles, impurity removal treatment,
2nd step: fluorine addition treatment; 3rd step: transparentization treatment.
透明化した後、得られたガラス中の屈折率分布を測定し
たところ、第４図に示すように、中心と外周で０．０８
％の屈折率差を生じてしまっていた。After making the glass transparent, the refractive index distribution in the obtained glass was measured, and as shown in Figure 4, it was 0.08 at the center and outer periphery.
% difference in refractive index.
０
実施例１
比較例と同様の５ｉ（ｈガラス粒子体を用い、表１に示
ず３ステツプ熱処理を行った。雰囲気ガスは、第２ステ
ツプにおいて、第１図に示す雰囲気ガス加熱ヒータ４に
より１２００℃に加熱して、炉芯管内に導入した。この
結果、得られた本発明によるガラスでは、第３図に示す
ように、はぼ均一な屈折率分布を得ることができた。中
心と外周の屈折率差は、約０．００５％と小さく、非常
に均一性の良いものであった。0 Example 1 Using the same 5i (h) glass particles as in the comparative example, a three-step heat treatment not shown in Table 1 was performed.Atmosphere gas was heated in the second step by the atmosphere gas heating heater 4 shown in FIG. It was heated to 1200°C and introduced into the furnace core tube.As a result, the obtained glass according to the present invention was able to obtain a fairly uniform refractive index distribution as shown in Fig. 3. The refractive index difference around the outer periphery was as small as about 0.005%, and the uniformity was very good.
以」二の比較例、実施例では、ゾーン炉を用いてＳｉ
Ｏｘガラス粒子体を炉中トラバースさせて加熱する方法
を例示して説明したが、本発明の方法は均熱炉を用いる
場合でも勿論有効であり、この場合トラバースして加熱
する方法、炉中の定位置に設置して加熱する方法のどち
らでもよい。In the following Comparative Examples and Examples, Si
Although the method of heating the Ox glass particles by traversing them in the furnace has been described as an example, the method of the present invention is of course effective even when using a soaking furnace. Either method of installing it in a fixed position and heating it may be used.
以」二説明したように、本発明では雰囲気ガスを予め加
熱して炉芯管内に導入することにより、ｓｌｏ、ガラス
粒子体の中心部の温度を上げることができるため、均一
なフッ素添加量を持つ透明ガラス体を得ることができる
。フッ素添加量の均一なガラス体は、純石英コアファイ
バの中間製品として好適に用いられ、特性の安定した純
石英コアファイバを得ることができる。As explained below, in the present invention, by preheating the atmospheric gas and introducing it into the furnace core tube, it is possible to raise the temperature of the slo, the center of the glass particles, so that a uniform amount of fluorine can be added. A transparent glass body can be obtained. A glass body with a uniform amount of fluorine added can be suitably used as an intermediate product for pure silica core fiber, and it is possible to obtain a pure quartz core fiber with stable characteristics.
本発明は、ガラス出発ロットの外周に気相法によりＳｉ
Ｏｘガラス粒子体をイ」着堆積させた複合体について
も、同様の効果を期待することができる。In the present invention, Si is applied to the outer periphery of a glass starting lot by a vapor phase method.
A similar effect can be expected from a composite in which Ox glass particles are deposited.
第１図は本発明の実施態様を説明する概略図、第２図は
本発明の別の実施態様を説明する概略図、第３図は本発
明の実施例１で製造したガラス体中の屈折率分布を示す
図、第４図は比較例１で製造したガラス体中の屈折率分
布を示す図、第５図は従来法においてＳｉ Ｏｔ粒子体
内部にできる温度分布を示す図、第６図はフッ素添加が
均一にできなかった場合き代表的な屈折率分布を示す図
である。
図中、１は炉芯管、２はＳｉ Ｃｈ粒子体、３は加熱炉
ヒータ、４及び５は雰囲気ガス加熱用ヒータを示す。
象
四口FIG. 1 is a schematic diagram explaining an embodiment of the present invention, FIG. 2 is a schematic diagram explaining another embodiment of the present invention, and FIG. 3 is a refraction diagram in a glass body manufactured in Example 1 of the present invention. Figure 4 is a diagram showing the refractive index distribution in the glass body produced in Comparative Example 1. Figure 5 is a diagram showing the temperature distribution created inside the SiOt particle body in the conventional method. Figure 6 is a diagram showing a typical refractive index distribution when fluorine addition cannot be uniformly performed. In the figure, 1 is a furnace core tube, 2 is a Si Ch particle body, 3 is a heating furnace heater, and 4 and 5 are heaters for heating atmospheric gas. elephant four mouths
Claims (2)
を加熱炉内で脱水のための第１の熱処理及びフッ素添加
のための第２の熱処理を行い、その後透明ガラス化して
光ファイバ用ガラス母材を製造する方法において、上記
第２の熱処理時の雰囲気ガスを熱処理用ヒータよりも上
流において予め加熱しておくことを特徴とする光ファイ
バ用ガラス母材の製造方法。(1) SiO_2 glass particles synthesized by gas phase reaction are subjected to a first heat treatment for dehydration and a second heat treatment for fluorine addition in a heating furnace, and then made into transparent glass to form a glass base material for optical fibers. A method for manufacturing a glass preform for an optical fiber, characterized in that the atmospheric gas during the second heat treatment is preheated upstream of the heat treatment heater.
おく温度が、上記の第２の熱処理温度と等しい又はそれ
よりも２００℃低い温度範囲内に設定されていることを
特徴とする請求項（１）に記載の光ファイバ用ガラス母
材の製造方法。(2) The temperature at which the atmospheric gas is preheated during the second heat treatment is set within a temperature range that is equal to or 200°C lower than the second heat treatment temperature. The method for manufacturing a glass preform for optical fiber according to claim (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20276489A JPH0369526A (en) | 1989-08-07 | 1989-08-07 | Production of glass base material for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20276489A JPH0369526A (en) | 1989-08-07 | 1989-08-07 | Production of glass base material for optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0369526A true JPH0369526A (en) | 1991-03-25 |
Family
ID=16462782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20276489A Pending JPH0369526A (en) | 1989-08-07 | 1989-08-07 | Production of glass base material for optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0369526A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20030049018A (en) * | 2001-12-13 | 2003-06-25 | 엘지전선 주식회사 | Chemical Preheating Method for Increasing Usable Length of Preform and Apparatus therefor |
| US11713272B2 (en) | 2019-03-05 | 2023-08-01 | Corning Incorporated | System and methods for processing an optical fiber preform |
-
1989
- 1989-08-07 JP JP20276489A patent/JPH0369526A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20030049018A (en) * | 2001-12-13 | 2003-06-25 | 엘지전선 주식회사 | Chemical Preheating Method for Increasing Usable Length of Preform and Apparatus therefor |
| US11713272B2 (en) | 2019-03-05 | 2023-08-01 | Corning Incorporated | System and methods for processing an optical fiber preform |
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