JPH05116976A - Production of base material for optical fiber - Google Patents
Production of base material for optical fiberInfo
- Publication number
- JPH05116976A JPH05116976A JP30532791A JP30532791A JPH05116976A JP H05116976 A JPH05116976 A JP H05116976A JP 30532791 A JP30532791 A JP 30532791A JP 30532791 A JP30532791 A JP 30532791A JP H05116976 A JPH05116976 A JP H05116976A
- Authority
- JP
- Japan
- Prior art keywords
- inert gas
- base material
- optical fiber
- concentration
- core
- 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
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
Landscapes
- 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
Description
【０００１】[0001]
【産業上の利用分野】本発明は光通信等に使用される低
伝送損失特性の光ファイバを得るための光ファイバ母材
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 manufacturing an optical fiber preform for obtaining an optical fiber having a low transmission loss characteristic used for optical communication and the like.
【０００２】[0002]
【従来の技術】光ファイバ母材を製造するには既知の如
く脱水工程、透明ガラス化工程等を経て行われる。この
場合、脱水工程で十分に脱水された多孔質母材を使用し
ても、透明ガラス化時に不活性ガスと共に透明ガラス化
用炉内にＣｌ2 を導入しないと、不活性ガス中に含まれ
る水分量以下には残留ＯＨ基を低減させることはできな
い。そこで従来より、低伝送損失特性の光ファイバ母材
を得るには不活性ガスにＣｌ2 を添加して導入してい
た。2. Description of the Related Art An optical fiber preform is manufactured by a known dehydration process, a transparent vitrification process, and the like. In this case, even if the porous base material sufficiently dehydrated in the dehydration step is used, if Cl 2 is not introduced into the transparent vitrification furnace together with the inert gas during the transparent vitrification, it is contained in the inert gas. Residual OH groups cannot be reduced below the water content. Therefore, conventionally, in order to obtain an optical fiber preform having a low transmission loss characteristic, Cl 2 is added to an inert gas for introduction.
【０００３】[0003]
【発明が解決しようとする課題】前記のように多孔質母
材の透明ガラス化時にＣｌ2 を添加すると、同母材中に
Ｃｌ2 が残留して同母材の構造欠陥が増加することが知
られている。この構造欠陥は、線引き工程で誘起される
欠陥と同じく、石英系ファイバの主成分であるＳｉＯ2
のＳｉがＨ原子と結合してＳｉ−Ｈとなり、図３に示す
ように波長：λ＝１．５２μｍにおいて吸収ピ−ク（水
素ロス）発生の原因となるものである。しかし他方にお
いては透明ガラス化工程で導入されるＣｌ2 は、脱水工
程後も多孔質母材中に残留する微量の不純物（ＯＨ基
等）を除去する効果があり、光ファイバの伝送損失特性
を向上させる面もある。As described above, when Cl 2 is added during the transparent vitrification of the porous base material, Cl 2 remains in the base material and the structural defects of the base material increase. Are known. This structural defect is the same as the defect induced in the drawing process, that is, SiO 2 which is the main component of the silica fiber.
Si is bonded to H atoms to form Si—H, which causes absorption peak (hydrogen loss) at a wavelength of λ = 1.52 μm as shown in FIG. On the other hand, on the other hand, Cl 2 introduced in the transparent vitrification step has an effect of removing a trace amount of impurities (OH group, etc.) remaining in the porous base material even after the dehydration step. There are aspects to improve.
【０００４】そこで本発明は、構造欠陥の発生を抑え、
しかも脱水効果を生じさせるＣｌ2の量を規定して伝送
損失特性の優れた光ファイバ母材の製造方法を提供する
ことである。Therefore, the present invention suppresses the occurrence of structural defects,
Moreover, it is an object of the present invention to provide a method for producing an optical fiber preform having excellent transmission loss characteristics by defining the amount of Cl 2 that causes a dehydration effect.
【０００５】[0005]
【課題を解決するための手段】本発明者は、多孔質母材
の透明ガラス化工程における不活性ガス（Ｈｅガス）中
のＣｌ2 の流量を種々変えて実験をしたところ、図２に
示すようにＨｅガスに含まれる水の濃度の１０倍以上の
濃度のＣｌ2 ガスを添加すると、この条件のもとで作製
される光ファイバのλ＝１．３μｍ及びλ＝１．３９μ
ｍの低損失化が顕著となることがわかった。これはス−
ト密度０．５ｇ／ｃｍ3 以下にあるＶＡＤス−ト（ＶＡ
Ｄ法で製造した多孔質母材をいう）ではコア中心部への
Ｃｌ2 拡散が燒結速度に比べ速くなるためである。 た
だし、各々のファイバを室温１ａｔｍ、１００％Ｈ2 雰
囲気に８時間保持し損失スペクトルを測定すると、Ｈｅ
の量に対してＣｌ2 の量が１．０％を越えると図３に示
すようにλ＝１．５２μｍの水素ロス増が発生した。Means for Solving the Problems The present inventor has made various experiments by changing the flow rate of Cl 2 in an inert gas (He gas) in the transparent vitrification step of the porous base material, and it is shown in FIG. As described above, when Cl 2 gas having a concentration 10 times or more the concentration of water contained in He gas is added, λ = 1.3 μm and λ = 1.39 μm of the optical fiber manufactured under these conditions.
It was found that the loss of m was significantly reduced. This is
VAD soot with a density of 0.5 g / cm 3 or less (VA
This is because Cl 2 diffuses into the center of the core faster than the sintering rate in the porous base material produced by the method D). However, when each fiber was kept in a 100% H 2 atmosphere at room temperature of 1 atm for 8 hours and the loss spectrum was measured,
When the amount of Cl 2 exceeds 1.0% with respect to the amount of hydrogen, an increase in hydrogen loss of λ = 1.52 μm occurs as shown in FIG.
【０００６】本発明の光ファイバ母材の製造方法は、コ
アまたはコアを含む多孔質母材を脱水後、透明ガラス化
する光ファイバ母材の製造方法において、この透明ガラ
ス化時にＨｅ等の不活性ガスと共に、同不活性ガス中に
含まれる水の濃度の１０倍以上の濃度で且つ同不活性ガ
スの量の１．０％以下の量のＣｌ2ガスを導入するもの
である。The method for producing an optical fiber preform according to the present invention is a method for producing an optical fiber preform in which a core or a porous preform containing the core is dehydrated and then vitrified into a transparent glass. Along with the active gas, Cl 2 gas having a concentration 10 times or more the concentration of water contained in the inert gas and 1.0% or less of the amount of the inert gas is introduced.
【０００７】[0007]
【作用】本発明の光ファイバ母材の製造方法では、多孔
質母材の透明ガラス化工程で使用するＨｅ等の不活性ガ
スに含有される水（Ｈ2 Ｏ）の濃度の１０倍以上の濃度
のＣｌ2 を導入するようにした。この不活性ガス中のＣ
ｌ2 濃度の増加は、Ｈｅ置換速度より下記化学反応式に
おける右方向への化学反応の方が速くなり、ファイバ母
材に残留するＯＨ基をさらに低減することとなり、結果
として、このＯＨ基による吸収に起因する伝送損失を低
減させることができる。 Ｈ2 Ｏ ＋ Ｃｌ2 ←→ ２ＨＣｌ ＋ １／２・Ｏ2 In the method for producing an optical fiber preform of the present invention, the concentration of water (H 2 O) contained in the inert gas such as He used in the transparent vitrification step of the porous preform is 10 times or more. A concentration of Cl 2 was introduced. C in this inert gas
The increase in the l 2 concentration makes the chemical reaction to the right in the following chemical reaction formula faster than the He substitution rate, further reducing the OH groups remaining in the fiber preform, and as a result, the OH groups The transmission loss due to absorption can be reduced. H 2 O + Cl 2 ← → 2HCl + 1/2 · O 2
【０００８】さらに、本発明では前記不活性ガスに添加
するＣｌ2 の量を不活性ガスの量の１．０％以下にした
ため、Ｃｌ2 添加による透明ガラス化後の欠陥が無視で
きるほど少なく抑えることができ、線引き後のファイバ
にＨ原子が拡散しても波長：λ＝１．５２μｍでの水素
ロスの増加を防ぐことができる。Further, in the present invention, the amount of Cl 2 added to the inert gas is set to 1.0% or less of the amount of the inert gas, so that the defects after the transparent vitrification due to the addition of Cl 2 are suppressed to a negligible amount. Even if H atoms are diffused in the drawn fiber, it is possible to prevent an increase in hydrogen loss at a wavelength of λ = 1.52 μm.
【０００９】[0009]
【実施例】本発明の光ファイバ母材の製造方法の一実施
例を示す図１において、１は石英ガラス等によりなる多
孔質母材、２は透明ガラス化用炉の炉心管、３は同母材
１を支持する支持棒、４は加熱炉のヒータである。脱水
工程では、多孔質母材１が燒結しない温度に保たれた炉
心管２内に、不活性ガス（例えばＨｅガス）及びＣｌ2
ガスを導入し、その雰囲気中に同多孔質母材１を引き下
げて挿入する。温度分布は長手方向に勾配を有してお
り、多孔質母材１の全長が最高温度部を通過後、それを
脱水工程の開始位置まで高速で引き戻し、今度は炉心管
２内をヒータ４により加熱して燒結温度まで上昇させ、
再び多孔質母材１を引き下げ、光ファイバ母材を透明ガ
ラス化する。1 shows an embodiment of a method for producing an optical fiber preform of the present invention, 1 is a porous preform made of quartz glass or the like, 2 is a transparent vitrification furnace core tube, and 3 is the same. Support rods 4 for supporting the base material 1 are heaters of a heating furnace. In the dehydration step, an inert gas (for example, He gas) and Cl 2 are introduced into the core tube 2 kept at a temperature at which the porous base material 1 is not sintered.
A gas is introduced, and the porous base material 1 is pulled down and inserted into the atmosphere. The temperature distribution has a gradient in the longitudinal direction, and after the entire length of the porous base material 1 has passed the highest temperature part, it is pulled back at high speed to the start position of the dehydration process, and this time the inside of the core tube 2 is heated by the heater 4. Heat it up to the sintering temperature,
The porous preform 1 is pulled down again to turn the optical fiber preform into transparent glass.
【００１０】以上の作業を下記表１に示す条件下で行な
い、この条件で製造した光ファイバ母材を線引きして得
られた光ファイバの伝送損失を測定したところ、λ＝
１．３μｍで０．３３５ｄＢ／ｋｍ、λ＝１．３９μｍ
のピ−ク０．０５ｄＢ／ｋｍが得られた。また同光ファ
イバを室温１ａｔｍ、１００％Ｈ2 雰囲気に８時間保持
し、再び損失スペクトルを測定したところλ＝１．５２
μｍで図３に仮想線で示すようになり同波長での水素ロ
ス増は認められなかった。The above operation was performed under the conditions shown in Table 1 below, and the transmission loss of the optical fiber obtained by drawing the optical fiber preform manufactured under these conditions was measured.
0.335 dB / km at 1.3 μm, λ = 1.39 μm
Peak of 0.05 dB / km was obtained. Also, the optical fiber was kept in a 100% H 2 atmosphere at room temperature of 1 atm for 8 hours, and the loss spectrum was measured again, where λ = 1.52.
As shown in phantom line in FIG. 3 at μm, no increase in hydrogen loss was observed at the same wavelength.
【００１１】 ちなみに、この実施例で使用した不活性ガス（Ｈｅ）中
の水の濃度は２．５ｐｐｍであり、例えば添加するＣｌ
2 の量が０．０５（ｌ／Ｍ）＝５０（ｃｃ／Ｍ）、即ち
Ｃｌ2 の濃度が５０００ｐｐｍの場合、不活性ガスに含
有されるＣｌ2の濃度は水の濃度の２０００倍となる。[0011] By the way, the concentration of water in the inert gas (He) used in this example is 2.5 ppm.
When the amount of 2 is 0.05 (l / M) = 50 (cc / M), that is, the concentration of Cl 2 is 5000 ppm, the concentration of Cl 2 contained in the inert gas is 2000 times the concentration of water. ..
【００１２】[0012]
【比較例】表１の条件下で、Ｃｌ2 無添加にして、多孔
質母材を透明ガラス化し、この母材から得られた光ファ
イバの伝送損失を測定したところλ＝１．３μｍで０．
３４８ｄＢ／ｋｍ、λ＝１．３９μｍのピ−ク０．２０
ｄＢ／ｋｍであった。[Comparative Example] Under the conditions shown in Table 1, the porous preform was made into a transparent glass without adding Cl 2 and the transmission loss of the optical fiber obtained from this preform was measured and found to be 0 at λ = 1.3 μm. ．
Peak 0.20 with 348 dB / km and λ = 1.39 μm
It was dB / km.
【００１３】[0013]
【発明の効果】このように本発明の光ファイバ母材の製
造方法によれば、構造欠陥（水素ロス増）の発生を抑え
た低損失光ファイバの製造が可能となる。As described above, according to the method for producing an optical fiber preform of the present invention, it is possible to produce a low loss optical fiber in which the occurrence of structural defects (hydrogen loss increase) is suppressed.
【図１】本発明の光ファイバ母材の製造方法の一実施例
を示す概略図。FIG. 1 is a schematic view showing an embodiment of a method for manufacturing an optical fiber preform according to the present invention.
【図２】不活性ガス中のＣｌ2 濃度と伝送損失との関係
を示す説明図。FIG. 2 is an explanatory diagram showing the relationship between Cl 2 concentration in an inert gas and transmission loss.
【図３】不活性ガスの量に対して１．０％以上の量のＣ
ｌ2 ガスを添加した場合のファイバの水素処理後のロス
スペクトルの説明図。FIG. 3 shows an amount of C of 1.0% or more based on the amount of inert gas.
illustration of the loss spectrum after hydrogen treatment of the fiber in the case of adding l 2 gas.
１ 多孔質母材 ２ 炉心管 ３ 支持棒 ４ ヒータ 1 Porous base material 2 Core tube 3 Support rod 4 Heater
Claims (1)
後、透明ガラス化する光ファイバ母材の製造方法におい
て、この透明ガラス化時にＨｅ等の不活性ガスと共に、
同不活性ガス中に含まれる水の濃度の１０倍以上の濃度
で且つ同不活性ガスの量の１．０％以下の量のＣｌ2 ガ
スを導入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 core or a porous preform containing the core is dehydrated and then vitrified into a transparent vitrified glass, together with an inert gas such as He during the vitrification.
A Cl 2 gas having a concentration of 10 times or more the concentration of water contained in the inert gas and 1.0% or less of the amount of the inert gas is introduced. Production method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30532791A JPH05116976A (en) | 1991-10-24 | 1991-10-24 | Production of base material for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30532791A JPH05116976A (en) | 1991-10-24 | 1991-10-24 | Production of base material for optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05116976A true JPH05116976A (en) | 1993-05-14 |
Family
ID=17943780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30532791A Pending JPH05116976A (en) | 1991-10-24 | 1991-10-24 | Production of base material for optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05116976A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002102725A1 (en) * | 2001-06-13 | 2002-12-27 | Sumitomo Electric Industries, Ltd. | Glass base material and method of manufacturing glass base material |
-
1991
- 1991-10-24 JP JP30532791A patent/JPH05116976A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002102725A1 (en) * | 2001-06-13 | 2002-12-27 | Sumitomo Electric Industries, Ltd. | Glass base material and method of manufacturing glass base material |
| EP1405830A1 (en) * | 2001-06-13 | 2004-04-07 | Sumitomo Electric Industries, Ltd. | Glass base material and method of manufacturing glass base material |
| EP1405830A4 (en) * | 2001-06-13 | 2011-06-08 | Sumitomo Electric Industries | Glass base material and method of manufacturing glass base material |
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