JPH0451497B2 - - Google Patents
Info
- Publication number
- JPH0451497B2 JPH0451497B2 JP59135255A JP13525584A JPH0451497B2 JP H0451497 B2 JPH0451497 B2 JP H0451497B2 JP 59135255 A JP59135255 A JP 59135255A JP 13525584 A JP13525584 A JP 13525584A JP H0451497 B2 JPH0451497 B2 JP H0451497B2
- Authority
- JP
- Japan
- Prior art keywords
- glass
- composite
- gas
- fluorine
- fine particle
- 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.)
- Expired - Lifetime
Links
- 239000011521 glass Substances 0.000 claims description 78
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 48
- 239000007789 gas Substances 0.000 claims description 35
- 239000010419 fine particle Substances 0.000 claims description 31
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 25
- 239000002131 composite material Substances 0.000 claims description 23
- 239000002245 particle Substances 0.000 claims description 18
- 229910052731 fluorine Inorganic materials 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 16
- 239000013307 optical fiber Substances 0.000 claims description 16
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 14
- 239000011737 fluorine Substances 0.000 claims description 14
- 238000000151 deposition Methods 0.000 claims description 13
- 239000000567 combustion gas Substances 0.000 claims description 12
- 150000002222 fluorine compounds Chemical class 0.000 claims description 12
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 10
- 229910003902 SiCl 4 Inorganic materials 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- RPAJSBKBKSSMLJ-DFWYDOINSA-N (2s)-2-aminopentanedioic acid;hydrochloride Chemical class Cl.OC(=O)[C@@H](N)CCC(O)=O RPAJSBKBKSSMLJ-DFWYDOINSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 238000000034 method Methods 0.000 description 21
- 235000012239 silicon dioxide Nutrition 0.000 description 13
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 12
- 238000005253 cladding Methods 0.000 description 11
- 230000008021 deposition Effects 0.000 description 8
- 239000000835 fiber Substances 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 6
- 239000010453 quartz Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 238000011109 contamination Methods 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 125000001153 fluoro group Chemical group F* 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000012024 dehydrating agents Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004017 vitrification Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 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]
- C03B37/01413—Reactant delivery systems
- C03B37/0142—Reactant deposition burners
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/36—Fuel or oxidant details, e.g. flow rate, flow rate ratio, fuel additives
- C03B2207/38—Fuel combinations or non-standard fuels, e.g. H2+CH4, ethane
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は低損失な単一モード光フアイバー用ガ
ラス母材の新規な製造方法に関するる。特に本発
明は、第１図に実線で示す構造を持つ、コアが純
石英ガラスであり、クラツドが弗素を添加した石
英ガラスからなる単一モード光フアイバー用ガラ
ス母材の製法に関する。なお本発明にいう単一モ
ード光フアイバ用ガラス母材は、第１図のクラツ
ド層の外側にさらに石英ジヤケツト層（第１図に
破線で示す）を持つものも含む。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel method for manufacturing a glass base material for a single mode optical fiber with low loss. In particular, the present invention relates to a method for producing a glass preform for a single mode optical fiber having the structure shown by the solid line in FIG. 1, in which the core is made of pure silica glass and the cladding is made of fluorine-doped quartz glass. The glass base material for a single mode optical fiber according to the present invention also includes a glass base material having a quartz jacket layer (indicated by a broken line in FIG. 1) on the outside of the cladding layer shown in FIG.
（従来の技術）
第１図に示すような構造をもつ単一モード型光
フアイバー作製方法に関しては、すでに種々の方
法が提案されている。(Prior Art) Various methods have already been proposed for producing a single mode optical fiber having a structure as shown in FIG.
その一例として、特公昭53−12603号公報に記
載されるように、「第１の円柱状のガラス物体の
外側に、第１の屈折率より低い屈折率を有する粒
状ガラス物質を附着および被覆し、更に加熱延伸
する」方法がある。 As an example, as described in Japanese Patent Publication No. 53-12603, "a granular glass substance having a refractive index lower than the first refractive index is attached and coated on the outside of the first cylindrical glass object. There is a method of further heating and stretching.
上記公報記載の方法に従つて、第１図に示す構
造をもつ光フアイバーを作製するには、まず純粋
石英ガラス棒を用意し、SiCl4と弗素化合物を火
炎中に投入して火炎加水分解反応により合成した
弗素含有シリカ微粒子を該石英ガラス棒の外側に
堆積した後、加熱焼結して透明ガラス化する。 In order to produce an optical fiber having the structure shown in Figure 1 according to the method described in the above publication, first a pure silica glass rod is prepared, SiCl 4 and a fluorine compound are put into a flame, and a flame hydrolysis reaction takes place. After depositing the fluorine-containing fine silica particles synthesized by the method on the outside of the quartz glass rod, the rod is heated and sintered to form transparent glass.
しかし上記の方法には実際的な生産手としては
大きな難点がある。すなわち弗素をシリカ微粒子
形成プロセスに導入すると、シリカ微粒子の核成
長が抑制され、実質的なガラス微粒子堆積体の成
長速度が低下することである。 However, the above method has major drawbacks for practical production. That is, when fluorine is introduced into the silica fine particle formation process, the nucleus growth of the silica fine particles is suppressed, and the substantial growth rate of the glass fine particle deposit is reduced.
第５図はこの事実を示す実験データのグラフで
あつて、第５図の横軸にはガラス原料ガス中の弗
素原子濃度（％）を、又縦軸にはガラス微粒子堆
積体の成長速度（ｇ／分）がとつてある。このグ
ラフからも明らかなように、ガラス原料ガス中の
弗素原子濃度が増すほど、ガラス微粒子堆積体の
成長速度は低下することがわかる。したがつて上
記方法では石英ガラス中に含有させる弗素量は実
質的には限界があると言える。 FIG. 5 is a graph of experimental data showing this fact. The horizontal axis of FIG. 5 shows the fluorine atom concentration (%) in the frit gas, and the vertical axis shows the growth rate ( g/min). As is clear from this graph, it can be seen that as the fluorine atom concentration in the frit gas increases, the growth rate of the glass fine particle deposit decreases. Therefore, in the above method, it can be said that there is a practical limit to the amount of fluorine that can be contained in the quartz glass.
一方、た在単一モード型フアイバーが実用的に
使用される波長帯は、石英ガラスの透過率が最も
高くなる1.0μｍ〜1.7μｍの長波長領域である。該
波長域において、低損失フアイバーとするには、
OH基に由来する吸収をできるだけ低減する必要
がある。ここで上記のように火炎加水分解反応に
よりクラツド層として弗素を含んだガラス微粒子
をコアとなる透明、ガラス母材の外側に堆積する
前に、該コア用透明ガラス母材を所定の径に延伸
する工程があるが、該工程では延伸の熱源として
酸水素炎を使用することが多い。ところが酸水素
炎の高温水蒸気がガラス表面に浸透し、OH基と
してガラス中に残留し該長波長帯での吸収損失要
因となつてしまう。 On the other hand, the wavelength band in which a single mode fiber is practically used is a long wavelength region of 1.0 μm to 1.7 μm, where the transmittance of quartz glass is highest. In order to obtain a low loss fiber in this wavelength range,
It is necessary to reduce absorption derived from OH groups as much as possible. As described above, before depositing fluorine-containing glass particles as a cladding layer on the outside of the transparent glass base material as a core, the transparent glass base material for the core is stretched to a predetermined diameter. However, in this process, an oxyhydrogen flame is often used as a heat source for stretching. However, high-temperature water vapor from the oxyhydrogen flame penetrates the glass surface and remains in the glass as OH groups, causing absorption loss in the long wavelength band.
さらに、単一モードフアイバーの伝送損失特性
を良好なものとするためには、合成されたクラツ
ドの径とコアの径の比率を大きくとることがあげ
られる。これは、単一モードフアイバーにおいて
は、伝送される基底モードのパワーの拡りが大き
く、外側の石英パイプの影響を受けて、伝送損失
が劣化するためで、これを防ぐにはクラツド径が
コア径の６〜７倍以上であることが必要である
と、実験的に知られている。特に第１図に示すよ
うな本発明の目的とするフアイバー構造において
は、基底モードが厳密には漏洩モードとしてしか
伝搬しえないため、合成クラツド径を大きくとる
ことは必須となる。 Furthermore, in order to improve the transmission loss characteristics of the single mode fiber, it is possible to increase the ratio between the diameter of the composite cladding and the diameter of the core. This is because in a single mode fiber, the power of the transmitted fundamental mode spreads widely, and the transmission loss deteriorates due to the influence of the outer quartz pipe.To prevent this, the cladding diameter should be set at the core. It is experimentally known that the diameter needs to be 6 to 7 times or more. Particularly in the fiber structure as shown in FIG. 1, which is the object of the present invention, since the fundamental mode can strictly be propagated only as a leaky mode, it is essential to have a large composite cladding diameter.
以上に述べた従来法における諸問題点、すなわ
ち、弗素化合物ガス導入によるガラス微粒子成
長速度低下の問題、延伸熱減としての酸水素炎
に由来する、OH基による吸収損失増大の問題、
さらには合成クラツドの径をコア径の６倍以上
にする問題を解決する手段として、本発明者らは
すでに特願昭58−194104号明細書において１つの
新しい光フアイバ製造方法を提案している。上記
明細書に記載の方法は、基本的には、「表面加工
を施した棒状の高純石英ガラスの外側に純石英ガ
ラス微粒子を堆積させ、次いで少なくとも弗素化
合物ガスを含む雰囲気において加熱処理すること
により光フアイバ用コアクラツド母材とする」も
のであつて、従来法における上記の問題点〜
を解決する有力な方法ではあるが、得られたフア
イバの特性として多少の残留OH基による伝送損
失増加を生じる場合があるという問題があつた。
本発明者はこの残留OH基の原因は調べた結果以
下の知見を得た。即ち、棒状の出発石英ガラスの
外側に火炎加水分解反応を用いて純石英ガラス微
粒子を堆積させる過程において、火炎の燃料ガス
としてH2ガスを用いると火炎中に含まれる未反
応のH2分子が出発石英ガラス棒の表面から内部
へ拡散浸透し、石英ガラス中でSi−OH結合を形
成しこれが後工程での加熱処理段階で完全に排除
することができず残留することが判明した。 The various problems with the conventional method described above, namely, the problem of a decrease in the growth rate of glass particles due to the introduction of fluorine compound gas, the problem of an increase in absorption loss due to OH groups due to the oxyhydrogen flame as a drawing heat loss,
Furthermore, as a means to solve the problem of increasing the diameter of the synthetic cladding to more than 6 times the core diameter, the present inventors have already proposed a new optical fiber manufacturing method in Japanese Patent Application No. 1941-1988. . The method described in the above specification basically involves depositing pure silica glass fine particles on the outside of a surface-treated rod-shaped high-purity quartz glass, and then heat-treating it in an atmosphere containing at least a fluorine compound gas. This method is used as a core clad base material for optical fibers, and the above problems in the conventional method
Although this is an effective method for solving the problem, there is a problem in that the resulting fiber may have some residual OH groups, which may cause an increase in transmission loss.
The present inventor investigated the cause of this residual OH group and obtained the following knowledge. That is, in the process of depositing pure silica glass particles on the outside of a rod-shaped starting quartz glass using a flame hydrolysis reaction, when H 2 gas is used as a fuel gas for the flame, unreacted H 2 molecules contained in the flame are It was found that Si--OH bonds were diffused into the interior of the starting quartz glass rod from the surface thereof, forming Si--OH bonds in the quartz glass, which could not be completely eliminated in the subsequent heat treatment step and remained.
ここで、純石英ガラス堆積工程でH2ガスを用
いることの理由としては、H2ガスの燃焼反応に
より生成する物質がH2Oのみであることから、
ガラス微粒子堆積層中に含まれるOH基或いは
H2O以外の不純物濃度を極めて低くすることが
容易であることによる。その他の燃料ガスについ
ては、資源的に豊富で安価な為入手しやすい、
CH4ガスなどの炭化水素系ガスが利用される場合
があるが、炭化水素系ガスでは、燃焼反応に伴
い、炭素がガラス微粒子堆積体中に析出し易い。
特に生産性の向上を目指してガラス原料を多量に
火炎中に供給しガラス微粒子堆積速度を向上させ
ようとする際には多量の燃焼ガスも供給する必要
があり、炭素の析出防止がより困難になる。 Here, the reason for using H 2 gas in the pure silica glass deposition process is that the only substance produced by the combustion reaction of H 2 gas is H 2 O.
OH groups or
This is because it is easy to reduce the concentration of impurities other than H 2 O to an extremely low level. Other fuel gases are easy to obtain as they are abundant and inexpensive.
Hydrocarbon-based gases such as CH 4 gas are sometimes used, but carbon tends to precipitate into the glass particle deposits as a result of combustion reactions with hydrocarbon-based gases.
In particular, when trying to increase the rate of glass particle deposition by supplying a large amount of glass raw material into the flame with the aim of improving productivity, it is necessary to also supply a large amount of combustion gas, making it more difficult to prevent carbon precipitation. Become.
また燃焼ガスとして、Ｈ原子を含まないCOガ
スを用いることも考えられる。しかしながらCO
ガスを用いる場合、ガラス原料であるSiCl4のガ
ラス化反応は
SiCl4＋O2→SiO2＋2Cl2
なる酸化反応であり、H2または炭化水素ガスを
用いた場合の火炎加水分解反応に比べ反応効率が
悪く、生産性向上を目指したガラス微粒子の堆積
速度向上に対しては不利である。 It is also conceivable to use CO gas, which does not contain H atoms, as the combustion gas. However, CO
When gas is used, the vitrification reaction of SiCl 4 , which is a glass raw material, is an oxidation reaction of SiCl 4 + O 2 → SiO 2 + 2Cl 2 , and the reaction efficiency is lower than the flame hydrolysis reaction when H 2 or hydrocarbon gas is used. This is disadvantageous for improving the deposition rate of glass particles aimed at improving productivity.
一方、燃焼ガスとして炭化水素ガスを用いる利
点としては、火炎中にH2分子が存在する確率が、
H2ガスを燃焼ガスとして用いる場合に比べ格段
に低くなることが期待でき、出発石英ガラス内部
へのH2散によるOH基汚染を低減できる可能性が
ある。 On the other hand, the advantage of using hydrocarbon gas as the combustion gas is that the probability that H2 molecules exist in the flame is
This can be expected to be much lower than when H 2 gas is used as the combustion gas, and there is a possibility that OH group contamination due to H 2 dispersion inside the starting quartz glass can be reduced.
また燃焼ガスとしてCOガスを用いる利点とし
ては、火炎中にH2分子或はH2O分子が存在する
ことがないため、出発石英ガラス棒のOH基汚染
が全くなくなることが期待できることである。 Furthermore, an advantage of using CO gas as the combustion gas is that since no H 2 molecules or H 2 O molecules are present in the flame, it can be expected that the starting quartz glass rod will be completely free from OH group contamination.
本発明は以上の問題点を解決し、生産性を低下
させずかつ出発石英ガラス棒のOH汚染を低減
し、低損失な単一モード光フアイバ用母材を提供
することを目的としている。
The present invention aims to solve the above-mentioned problems, reduce OH contamination of a starting quartz glass rod without reducing productivity, and provide a low-loss single-mode optical fiber base material.
すなわち本発明は、(A)メタンを燃焼ガスとする
火炎中にSiCl4を導入し、純SiO2ガラス微粒子を
発生させ、該SiO2ガラス微粒子を高純度石英ガ
ラス棒の外側に堆積させたのち、該高純度石英ガ
ラス棒と該SiO2ガラス微粒子堆積体の複合体を
少なくとも弗素化合物ガスを含む雰囲気中で加熱
処理することにより、該高純度石英ガラス棒とこ
れを取り囲む弗素を含有した石英ガラス層との複
合体を形成したのち、(B)該ガラス複合体を所定の
径に延伸し、該ガラス複合体の外側に酸・水素火
炎により純SiO2ガラス微粒子堆積体を形成し、
該ガラス複合体と該純SiO2ガラス微粒子堆積体
とのさらなる複合体を少なくとも弗素を含む雰囲
気中で加熱処理することからなり、工程(B)は必要
に応じて２回以上繰り返すことを特徴とする光フ
アイバ用母材の製造方法を提供する。
That is, in the present invention, (A) SiCl 4 is introduced into a flame with methane as the combustion gas to generate pure SiO 2 glass particles, and the SiO 2 glass particles are deposited on the outside of a high-purity quartz glass rod. , by heat-treating the composite of the high-purity quartz glass rod and the SiO 2 glass fine particle deposit in an atmosphere containing at least a fluorine compound gas, the high-purity quartz glass rod and the fluorine-containing quartz glass surrounding it are produced. After forming a composite with the layer, (B) stretching the glass composite to a predetermined diameter, forming a pure SiO 2 glass fine particle deposit on the outside of the glass composite with an acid/hydrogen flame,
The further composite of the glass composite and the pure SiO 2 glass fine particle deposit is heat-treated in an atmosphere containing at least fluorine, and step (B) is repeated two or more times as necessary. Provided is a method for manufacturing an optical fiber base material.
本発明の基本的な構成は、メタンガスと酸素か
らなる火炎中にSiCl4を導入して純SiO2ガラス微
粒子を発生させ、該純SiO2ガラス微粒子を棒状
の高純度石英ガラスの外側に堆積させたのち、該
高純度ガラス棒と純SiO2ガラス微粒子堆積層の
複合体を、少なくも弗素化合物ガスを含む雰囲気
中にて加熱処理することにより、該純SiO2ガラ
ス微粒子堆積層中に弗素を含有せしめるとともに
透明ガラス化し、高純度石英ガラス部とこれを取
り囲む弗素を含有した石英ガラス部からなる複合
ガラス体を形成したのち、さらに該複合ガラス体
を所定の径に延伸加工し、次いで該複合ガラス体
の外側に酸水素火炎により、純SiO2ガラス微粒
子を堆積させ再び該複合ガラス体と純SiO2ガラ
ス微粒子層の複合体を少なくとも弗素化合物ガス
を含む雰囲気中にて加熱処理することからなる。 The basic structure of the present invention is to introduce SiCl 4 into a flame consisting of methane gas and oxygen to generate pure SiO 2 glass particles, and deposit the pure SiO 2 glass particles on the outside of a rod-shaped high-purity quartz glass. Thereafter, the composite of the high-purity glass rod and the pure SiO 2 glass fine particle deposited layer is heat-treated in an atmosphere containing at least a fluorine compound gas to inject fluorine into the pure SiO 2 glass fine particle deposited layer. After forming a composite glass body consisting of a high-purity quartz glass part and a fluorine-containing quartz glass part surrounding it, the composite glass body is further stretched to a predetermined diameter. Pure SiO 2 glass particles are deposited on the outside of the glass body using an oxyhydrogen flame, and the composite of the composite glass body and pure SiO 2 glass particle layer is again heat-treated in an atmosphere containing at least a fluorine compound gas. .
本発明の特徴は、）弗素を含有したクラツド
層の厚みを十分に厚くとるために、透明ガラス棒
上への純SiO2ガラス微粒子堆積層の形成及び該
純SiO2ガラス微粒子堆積層への弗素添加の為の
加熱処理を２回以上くり返して行うこと、）
OH吸収損失に与える影響の大きい、１回目のガ
ラス微粒子堆積層の形成に、出発石英ガラス棒へ
のOH汚染の少ないメタンガス、を燃焼ガスとし
て用いること、）OH吸収損失に与える影響の
小ない２回目以降のガラス微粒子堆積層の形成を
生産性向上に有利な水素ガスを燃焼ガスとして用
いること、である。 The features of the present invention are as follows:) In order to obtain a sufficiently thick cladding layer containing fluorine, a pure SiO 2 glass fine particle deposit layer is formed on a transparent glass rod, and fluorine is added to the pure SiO 2 glass fine particle deposit layer. (The heating treatment for addition is repeated two or more times.)
(2) Using methane gas, which has little OH contamination on the starting quartz glass rod, as the combustion gas for the formation of the first glass fine particle deposition layer, which has a large effect on OH absorption loss. Hydrogen gas is used as the combustion gas, which is advantageous for improving productivity in forming the glass fine particle deposit layer from the second time onward.
以下本発明を具体的に説明する。 The present invention will be specifically explained below.
光フアイバのコア部に相当する高純度石英ガラ
ス棒は、ガラス原料をSiCl4のみとした通常の
VAD法等を用いて作製でき、該高純度石英ガラ
ス棒に含まれる残留OH基量をppbレベルに下げ
ることができる。この高純度石英ガラス棒を棒表
面からのOH基の浸入のない方法にて所定外径に
延伸加工する。この加工法としてはプラズマ火
炎、或いは電気抵抗炉等の水蒸気を発生させない
熱源により高純度石英ガラス棒を加熱し延伸する
方法がある。得られた高純度ガラス棒と純SiO2
ガラス微粒子複合体を弗素素化合物ガス雰囲気中
で加熱処理する際には、1000〜1650℃の温度域に
て弗素化合物としてSF6，CF4，C2F6等のフロン
系ガスとヘリウム等の不活性ガスの混合ガス雰囲
気中に該複合体を置くことにより、十分な量の弗
素がガラス微粒子堆積層中に実質的に均一に添加
せしめることができる。 The high-purity quartz glass rod, which corresponds to the core of an optical fiber, is made of ordinary glass using only SiCl 4 as the glass raw material.
It can be produced using a VAD method or the like, and the amount of residual OH groups contained in the high-purity quartz glass rod can be reduced to ppb level. This high-purity quartz glass rod is stretched to a predetermined outer diameter using a method that does not allow OH groups to penetrate from the rod surface. This processing method includes a method in which a high purity quartz glass rod is heated and stretched using a heat source that does not generate water vapor, such as a plasma flame or an electric resistance furnace. Obtained high purity glass rod and pure SiO2
When heat-treating a glass particle composite in a fluorine compound gas atmosphere, fluorine compounds such as SF 6 , CF 4 , C 2 F 6 and other fluorocarbon gases such as helium are used in the temperature range of 1000 to 1650°C. By placing the composite in an atmosphere of a mixed gas of an inert gas, a sufficient amount of fluorine can be added substantially uniformly into the glass fine particle deposited layer.
この際、弗素合物ガスは脱水剤としての役割も
果たすので十分な量のフツ素化合物ガスを雰囲気
ガス中に供給しておくことによりガラス微粒子堆
積中の水分或いはOH基は十分除去できると考え
られるが、ガラス微粒子堆積層の収縮が進まない
時点までCl2等の他の脱水剤を雰囲気ガス中に流
しておくことにより脱水をより完壁なものにする
ことも可能である。 At this time, the fluorine compound gas also plays the role of a dehydrating agent, so it is thought that by supplying a sufficient amount of the fluorine compound gas into the atmospheric gas, the moisture or OH groups in the deposited glass particles can be sufficiently removed. However, it is also possible to make the dehydration more complete by flowing another dehydrating agent such as Cl 2 into the atmospheric gas until the shrinkage of the glass fine particle deposited layer does not proceed.
実施例 １
VAD法により外径40mmφ、長さ200mmの十分に
脱水された純SiO2ガラス母材を作製した。該母
材を4MHz、30kWの高周波プラズマ炎を用いて
延伸加工し外径12mmφの石英ガラス棒とした。次
に第２図に示す装置を用いて、上記純石英ガラス
棒１の外周部に純SiO2ガラス微粒子堆積層２を
形成した。３はガラス微粒子合成用バーナーであ
り、該バーナー３に燃焼ガスとしてCH4を３／
分、助燃ガスとしてO210／分をガラス原料と
してSiCl4300c.c.／分を送り込み、SiO2微粒子をを
火炎中で形成し、ガラス棒１上に堆積させていつ
た。この時ガラス棒１を回転・引上装置４により
接続棒５を介して回転させつつ、徐々に上方に引
き上げていくことにより、純石英棒１上に軸方向
に、ガラス微粒子堆積層２を形成していつた。こ
の時のガラス微粒子堆積速度は0.5ｇ／分であつ
た。
Example 1 A sufficiently dehydrated pure SiO 2 glass base material having an outer diameter of 40 mmφ and a length of 200 mm was prepared by the VAD method. The base material was stretched using a high frequency plasma flame of 4 MHz and 30 kW to obtain a quartz glass rod with an outer diameter of 12 mmφ. Next, using the apparatus shown in FIG. 2, a pure SiO 2 glass fine particle deposition layer 2 was formed on the outer periphery of the pure silica glass rod 1. 3 is a burner for glass particle synthesis, and CH 4 is supplied to the burner 3 as combustion gas.
SiO 2 fine particles were formed in the flame and deposited on the glass rod 1 by feeding O 2 10/min as a combustion auxiliary gas and SiCl 4 300 c.c./min as a glass raw material. At this time, the glass rod 1 is rotated by the rotating/pulling device 4 via the connecting rod 5 and gradually pulled upward, thereby forming a glass fine particle deposit layer 2 on the pure quartz rod 1 in the axial direction. I was doing it. The glass fine particle deposition rate at this time was 0.5 g/min.
得られたガラス微粒子堆積層２と石英ガラス棒
１との複合体の外径は75mmφであつた。該複合体
をSF6とHeとの容量比が２：50の雰囲気中で加
熱処理しつつ、透明ガラス化した。透明ガラス化
後の母材径は30mmφであつた。 The outer diameter of the resulting composite of the glass fine particle deposit layer 2 and the quartz glass rod 1 was 75 mmφ. The composite was heat-treated in an atmosphere with a volume ratio of SF 6 to He of 2:50, and was turned into transparent glass. The diameter of the base material after transparent vitrification was 30 mmφ.
さらに、得られた母材を再度プラズマ火炎によ
り11mmφに延伸し、該延伸母材上に第２図に示し
た装置により今度はH2ガスを燃焼ガスとして用
いて、純SiO2ガラス微粒子層を形成した。この
ときの流量条件は、H224／分、O216／分、
SiCl4450c.c.／分であつた。該純SiO2ガラス微粒子
層の外径は120mmφであつた。また、該純SiO2ガ
ラス微粒子堆積速度は1.5ｇ／分であつた。 Furthermore, the obtained base material was again stretched to 11 mmφ by plasma flame, and a layer of pure SiO 2 glass particles was formed on the stretched base material using the apparatus shown in FIG. 2 using H 2 gas as a combustion gas. Formed. The flow conditions at this time were H 2 24/min, O 2 16/min,
SiCl 4 was 450 c.c./min. The outer diameter of the pure SiO 2 glass fine particle layer was 120 mmφ. Further, the pure SiO 2 glass fine particle deposition rate was 1.5 g/min.
得られた母材の外径は44mmφであつた。該母材
を延伸し市販の天然石英パイプで被覆したのち、
外径125mmφの光フアイバとした。該光フアイバ
の屈折率分布を第３図に示す。第３図において
１′は出発棒の純粋石英ガラスの部分、２′はCH4
を用いて合成されたガラス微粒子堆積層弗素化合
物ガスを含む雰囲気中で加熱処理した部分、２′
はH2を用いて合成されたガラス微粒子堆積層を
弗素化合物ガスを含む雰囲気中で加熱処理した部
分、６は天然石英管の部分に各々対応する。クラ
ツド・コア間の比屈折率差は0.32％、クラツド
径／コア径比は10.0であつた。このフアイバは単
長５Km、カツトオフ波長1.15μｍ、波長1.3μｍで
の伝送損失は0.5dB／Km以下と良好であり、波長
1.39μｍでのOH吸収損失増加量も５dB/Kmと実用
上問題のないものであつた。 The outer diameter of the obtained base material was 44 mmφ. After stretching the base material and covering it with a commercially available natural quartz pipe,
An optical fiber with an outer diameter of 125 mmφ was used. The refractive index distribution of the optical fiber is shown in FIG. In Figure 3, 1' is the pure silica glass part of the starting rod, and 2' is the CH 4
Part 2' of the glass fine particle deposited layer synthesized using
6 corresponds to a portion where a glass fine particle deposited layer synthesized using H 2 was heat-treated in an atmosphere containing a fluorine compound gas, and 6 corresponds to a portion of a natural quartz tube. The relative refractive index difference between the cladding and the core was 0.32%, and the cladding diameter/core diameter ratio was 10.0. This fiber has a single length of 5 km, a cutoff wavelength of 1.15 μm, and a transmission loss of less than 0.5 dB/Km at a wavelength of 1.3 μm.
The increase in OH absorption loss at 1.39 μm was also 5 dB/Km, which was not a problem for practical use.
本発明の方法は、酸水素炎に由来するOH基の
もたらす吸収損失増大を第１回目の純ガラス微粒
子堆積にはメタンガスを燃焼ガスに用いることに
より低減し、かつ第２回目以降の純ガラス微粒子
堆積には酸水素炎を用いて生産性を向上し、さら
にフツ素を含有するクラツドの径がコアの径の６
倍以上の伝送特性のすぐれた単一モードフアイバ
を安定製造できる非常に有効、かつ経済的な方法
である。
The method of the present invention reduces the increase in absorption loss caused by OH groups derived from oxyhydrogen flame by using methane gas as the combustion gas for the first deposition of pure glass fine particles, and An oxyhydrogen flame is used for deposition to improve productivity, and the diameter of the fluorine-containing cladding is 66% smaller than the core diameter.
This is a very effective and economical method that can stably produce single mode fibers with transmission characteristics that are more than twice as good.
第１図は本発明の目的とする単一モード型光フ
アイバーの屈折率分布を示す図。第２図は本発明
の実施態様例においてガラス微粒子堆積体を作製
する工程の説明図。第３図は本発明の実施例にお
いて得られた光フアイバの屈折率分布。第４図は
第３図の光フアイバの伝送損失スペクトルであ
る。第５図は従来方法による場合の、ガラス原料
ガス中の弗素原子濃度（％）とガラス微粒子堆積
体成長速度（ｇ／分）の関係を示すグラフ。
FIG. 1 is a diagram showing the refractive index distribution of a single mode optical fiber, which is the object of the present invention. FIG. 2 is an explanatory diagram of the process of producing a glass fine particle deposit body in an embodiment of the present invention. FIG. 3 shows the refractive index distribution of an optical fiber obtained in an example of the present invention. FIG. 4 is a transmission loss spectrum of the optical fiber of FIG. FIG. 5 is a graph showing the relationship between the fluorine atom concentration (%) in the glass raw material gas and the growth rate (g/min) of glass fine particle deposits in the conventional method.
Claims (1)
SiCl4を導入し、純SiO2ガラス微粒子を発生させ、
該SiO2ガラス微粒子を高純度石英ガラス棒の外
側に堆積させたのち、該高純度石英ガラス棒と該
SiO2ガラス微粒子堆積体の複合体を少なくとも
弗素化合物ガスを含む雰囲気中で加熱処理するこ
とにより、該高純度石英ガラス棒とこれを取り囲
む弗素を含有した石英ガラス層との複合体を形成
したのち、(B)該ガラス複合体を所定の径に延伸
し、該ガラス複合体の外側に酸・水素火炎により
純SiO2ガラス微粒子堆積体を形成し、該ガラス
複合体と該純SiO2ガラス微粒子堆積体とのさら
なる複合体を少なくとも弗素を含む雰囲気中で加
熱処理することからなり、工程(B)は必要に応じて
２回以上繰り返すことを特徴とする光フアイバ用
母材の製造方法。1 (A) In a flame with methane gas as the combustion gas
Introducing SiCl 4 to generate pure SiO 2 glass particles,
After depositing the SiO 2 glass particles on the outside of the high-purity quartz glass rod, the high-purity quartz glass rod and the
After forming a composite of the high-purity quartz glass rod and a fluorine-containing quartz glass layer surrounding it by heat-treating the composite of SiO 2 glass fine particle deposits in an atmosphere containing at least fluorine compound gas. , (B) Stretch the glass composite to a predetermined diameter, form a pure SiO 2 glass fine particle deposit on the outside of the glass composite with an acid/hydrogen flame, and separate the glass composite and the pure SiO 2 glass fine particles. 1. A method for producing an optical fiber base material, which comprises heat-treating a further composite with the deposit in an atmosphere containing at least fluorine, and step (B) is repeated two or more times as necessary.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13525584A JPS6117432A (en) | 1984-07-02 | 1984-07-02 | Manufacture of optical fiber preform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13525584A JPS6117432A (en) | 1984-07-02 | 1984-07-02 | Manufacture of optical fiber preform |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6117432A JPS6117432A (en) | 1986-01-25 |
| JPH0451497B2 true JPH0451497B2 (en) | 1992-08-19 |
Family
ID=15147431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13525584A Granted JPS6117432A (en) | 1984-07-02 | 1984-07-02 | Manufacture of optical fiber preform |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6117432A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63242941A (en) * | 1987-03-30 | 1988-10-07 | Sumitomo Electric Ind Ltd | Production of preform for optical fiber |
| KR100288739B1 (en) * | 1997-01-20 | 2001-05-02 | 윤종용 | Optical preform manufacturing method |
| US6947650B1 (en) * | 2004-05-06 | 2005-09-20 | Luna Energy Llc | Long wavelength, pure silica core single mode fiber and method of forming the same |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5978943A (en) * | 1982-10-22 | 1984-05-08 | Sumitomo Electric Ind Ltd | Manufacture of glass containing fluorine |
-
1984
- 1984-07-02 JP JP13525584A patent/JPS6117432A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5978943A (en) * | 1982-10-22 | 1984-05-08 | Sumitomo Electric Ind Ltd | Manufacture of glass containing fluorine |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6117432A (en) | 1986-01-25 |
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