JPS59232927A - Manufacture of preform for optical fluoride fiber - Google Patents

Manufacture of preform for optical fluoride fiber

Info

Publication number
JPS59232927A
JPS59232927A JP10401983A JP10401983A JPS59232927A JP S59232927 A JPS59232927 A JP S59232927A JP 10401983 A JP10401983 A JP 10401983A JP 10401983 A JP10401983 A JP 10401983A JP S59232927 A JPS59232927 A JP S59232927A
Authority
JP
Japan
Prior art keywords
mold
core
preform
casting mold
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
Application number
JP10401983A
Other languages
Japanese (ja)
Inventor
Yasutake Oishi
泰丈 大石
Nariyuki Mitachi
成幸 三田地
Shiro Takahashi
志郎 高橋
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.)
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone Corp
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 Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP10401983A priority Critical patent/JPS59232927A/en
Publication of JPS59232927A publication Critical patent/JPS59232927A/en
Pending legal-status Critical Current

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
    • C03B37/01265—Manufacture of preforms for drawing fibres or filaments starting entirely or partially from molten glass, e.g. by dipping a preform in a melt
    • C03B37/01268—Manufacture of preforms for drawing fibres or filaments starting entirely or partially from molten glass, e.g. by dipping a preform in a melt by casting
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/80—Non-oxide glasses or glass-type compositions
    • C03B2201/82—Fluoride glasses, e.g. ZBLAN glass

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Abstract

PURPOSE:To manufacture the titled long-sized preform having a core part with high roundness by charging molten fluoride glass for a clad into the space between the body of a cylindrical casting mold and an internal casting mold which is concentric with the body, charging molten fluoride glass for a core into the internal casting mold, drawing out the internal casting mold, and carrying out vitrification. CONSTITUTION:The tip of an internal casting mold 21 is fixed around a projection 22 provided on the bottom of a cylindrical casting mold so that the mold 21 is concentrically placed in the body 20 of the cylindrical casting mold. Molten fluoride glass 24 for a clad in a crucible 23 is charged into the space between the body 20 and the mold 21, and molten fluoride glass 26 for a core in a crucible 25 is charged into the hollow 27 of the mold 21. The mold 21 is then drawn out, and vitrification, annealing and cooling to room temp. are carried out. A long-sized preform for an optical fluoride fiber having a core part with high roundness is obtd. The preform has a high ratio of core/clad diameter.

Description

【発明の詳細な説明】 本発明は長尺にして真円度の高いコア部を有するフッ化
物光フアイバ用プリフォームに関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preform for a fluoride optical fiber having a long core portion with high roundness.

第１図＋ａ）、（ｂ）、ｆｏｌは、従来のフッ化物光フ
アイバ用プリフォームを製造する方法を示す工程図であ
り、前記第１図中、１は円筒形黄銅性鋳型、２はクラッ
ド用フッ化物ガラス融液、３はクラッドガラス管、４は
コア用フッ化物ガラス融液、５はルツボである。Figures 1+a), (b), and fol are process diagrams showing a conventional method for manufacturing a preform for fluoride optical fiber. In Figure 1, 1 is a cylindrical brass mold, 2 is a cladding 3 is a clad glass tube, 4 is a fluoride glass melt for a core, and 5 is a crucible.

この第１図より明らかなように、従来のフッ化物光フア
イバ用プリフォームの製造方法は、まず円筒形黄銅型の
鋳型１にルツボ５よりクラッド用フッ化物ガラス融液２
をキャスティングし、融液２全体がガラス化する前に、
鋳型１との界面に近い外周部寄り粘度が低く、流動層の
高い中心部を流し出し、クラッドガラス管３を鋳型１の
内壁に沿って形成させる。その後、クラッドガラス管３
の中心部に形成された空隙に、コア用フッ化物ガラス融
液４をキャスティングして製造していた。As is clear from FIG. 1, in the conventional manufacturing method for a fluoride optical fiber preform, first, a fluoride glass melt for cladding is poured into a cylindrical brass mold 1 from a crucible 5.
and before the entire melt 2 is vitrified,
The clad glass tube 3 is formed along the inner wall of the mold 1 by pouring out the central part of the fluidized bed where the viscosity is low near the interface with the mold 1 and is high. After that, clad glass tube 3
The core was produced by casting a fluoride glass melt 4 into a gap formed in the center of the core.

しかしながら、上述の方法においてはコア径のゆらぎの
大きさが１％以下の、均一な長尺プリフォームを製造す
ることは困難であり、加えてフッ化物光ファイバの最低
損失波長域である２〜４μｍ帯において単一モード導波
路となる３０μｍ以下の細径なコアを有するプリフォー
ムをえることは困難であった。However, with the above method, it is difficult to manufacture a uniform long preform with a core diameter fluctuation of 1% or less. It has been difficult to obtain a preform having a thin core of 30 μm or less that becomes a single mode waveguide in the 4 μm band.

本発明は上述の点に鑑み成されたものであり、コア部の
真円度が高く、コア・クラツド径比の大きな長尺フッ化
物光フアイバ用プリフォームをえることを目的とする。The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a preform for a long fluoride optical fiber having a high roundness of the core portion and a large core-to-cladding diameter ratio.

したがって、本発明によるフン化物光フアイバ用プリフ
ォームの製造方法は、円筒形鋳型本体にコア部形成用の
中空部を有する内部鋳型を同心的に挿入し、前記内部鋳
型と円筒形鋳型本体で構成される空隙にクラッド用フッ
化物ガラス融液を、内部鋳型の中空部にコア用フッ化物
ガラス融液をそれぞれキャスティングし、次いで前記内
部鋳型を引抜き、ガラス化することを特徴とするもので
ある。Therefore, the method for manufacturing a preform for a fluoride optical fiber according to the present invention includes concentrically inserting an internal mold having a hollow part for forming a core into a cylindrical mold body, and comprising the internal mold and the cylindrical mold body. The method is characterized in that a fluoride glass melt for the cladding is cast into the gap formed by the mold, and a fluoride glass melt for the core is cast into the hollow part of the inner mold, and then the inner mold is pulled out and vitrified.

本発明によるフッ化物光フアイバ用プリフォームの製造
方法によれば、コア部の真円度が高く、かつコア・クラ
ツド比の大きな長尺フッ化物光フアイバ用プリフォーム
を容易に製造できるという利点がある。The method for manufacturing a fluoride optical fiber preform according to the present invention has the advantage that a long fluoride optical fiber preform with a high roundness of the core portion and a large core-to-cladding ratio can be easily manufactured. be.

本発明を更に詳しく説明する。The present invention will be explained in more detail.

本発明による光フアイバ用プリフォームの製造方法によ
れば、まず円筒形鋳型本体を容易する。According to the method for manufacturing an optical fiber preform according to the present invention, first, a cylindrical mold body is prepared.

この鋳型本体は、従来この種のフッ化物光フアイバ用プ
リフォームを製造するために用いられるものであればい
かなるものでもよく、前述の黄銅磨であってもよく、ま
た石英ガラス製、炭素製などであってもよい。This mold body may be made of any material conventionally used to manufacture preforms for fluoride optical fibers of this kind, and may be made of polished brass as described above, or may be made of quartz glass, carbon, etc. It may be.

この円筒形鋳型本体に同心的に挿入されるコア形成用鋳
型の材質は、基本的に限定されるものではない。たとえ
ば、上述の黄銅、石英ガラス、炭素などにより製造する
ことができる。The material of the core forming mold that is inserted concentrically into the cylindrical mold body is basically not limited. For example, it can be manufactured from the above-mentioned brass, quartz glass, carbon, or the like.

本発明によれば、この内部鋳型を前記円筒形鋳型本体に
同心的に挿入する。According to the invention, this internal mold is inserted concentrically into the cylindrical mold body.

この内部鋳型の挿入によって形成される内部鋳型外壁と
鋳型本体内壁で構成される空隙に、クラッド用ガラス融
液を、内部鋳型の中空部にコア用ガラス融液をそれぞれ
キャスティングし、次いで内部鋳型を鋳型本体中より引
き抜く。このとき、クラッド用ガラス融液をコア用ガラ
ス融液よりも粘性が高くなるように調整することが望ま
しい。The glass melt for the cladding is cast into the gap formed by the inner mold outer wall and the inner wall of the mold body formed by inserting the inner mold, and the glass melt for the core is cast into the hollow part of the inner mold, and then the inner mold is inserted. Pull it out from inside the mold body. At this time, it is desirable to adjust the viscosity of the glass melt for the cladding to be higher than that of the glass melt for the core.

コア用ガラス融液がクラッド用が融液中に拡散するのを
防止するためである。This is to prevent the core glass melt from diffusing into the clad glass melt.

このように内部鋳型を引き抜くことにより、クラッド用
ガラス融液の中心部にコア用ガラス融液が挿通されたこ
とになる。したがって、これらをガラス化すれば、フッ
化物光フアイバ用プリフォームを製造できるのである。By pulling out the internal mold in this way, the core glass melt is inserted into the center of the cladding glass melt. Therefore, if these are vitrified, a preform for a fluoride optical fiber can be manufactured.

本発明において用いられるガラス融液は基本的に限定さ
れるものではなく、従来この種のフッ化物光フアイバ用
プリフォームを製造するために用いられるクラッド用ガ
ラス融液、コアガラス融液が有効に用いることができる
。たとえば、ＺｒＦ　４ＢａＦｐ　　　ＧｄＦ３ＡＩＦ
ａ系ガラス、ＺｒＦ４−ＴｈＦａ　　　ＢａＦ２系ガラ
ス、ＢｅＦ　４系ガラス、ＺｎＣ１２系ガラス、ＴｈＦ
　４系ガラス、ＨｆＦ４系ガラス、へ１Ｆ４系ガラスな
どであることができる。The glass melt used in the present invention is basically not limited, and cladding glass melt and core glass melt conventionally used to manufacture this type of fluoride optical fiber preform can be effectively used. Can be used. For example, ZrF 4BaFp GdF3AIF
a-based glass, ZrF4-ThFa BaF2-based glass, BeF 4-based glass, ZnC12-based glass, ThF
The glass may be 4-based glass, HfF4-based glass, HfF4-based glass, or the like.

次ぎに本発明の実施例について説明する。Next, examples of the present invention will be described.

実施例 第２図に示すような円筒形鋳型本体２０の底部に内部鋳
型２１を支持するための突起２２を設けるとともに、こ
の突起２２に内部鋳型２１の先端部を嵌合し、内部鋳型
２１を鋳型本体２０と同心的に挿入する。次いで、ルツ
ボ２３中のクラッド用ガラス融液２４を鋳型本体２０と
内部鋳型２１で構成される空隙に導入し、一方ルツボ２
５中のコア用ガラス融液２６を内部鋳型２１の中空部２
７に装入した。Embodiment As shown in FIG. 2, a protrusion 22 for supporting the internal mold 21 is provided at the bottom of the cylindrical mold body 20, and the tip of the internal mold 21 is fitted into this protrusion 22, so that the internal mold 21 is Insert concentrically with the mold body 20. Next, the cladding glass melt 24 in the crucible 23 is introduced into the gap formed by the mold body 20 and the internal mold 21, while the crucible 2
The core glass melt 26 in 5 is poured into the hollow part 2 of the internal mold 21.
7 was charged.

前記クラッド用ガラス融液２４として、ＺｒＦａ　　（
５９，４４ｍｏ１％）　−Ｂａｎ２（３１，１３ｍｏ１
％）　−ＧｄＦｓ（３，７７ｍｏ１％）　−ＡＩＦａ　
　（５，６６ｍｏ１　％）を用い、コア用ガラス融液と
してＺｒＦ４（６０，５７ｍｏｌ　％）ＢａＦＱ（３１
，７３ｍｏ１％）−ＧｄＦ３（３，８５ｍｏ１％）−八
ＩＦａ　　（３，８５ｍｏ１％）を用いた。As the glass melt 24 for cladding, ZrFa (
59,44mo1%) -Ban2(31,13mo1
%) -GdFs (3,77mo1%) -AIFa
ZrF4 (60,57 mol %) and BaFQ (31 mol %) were used as core glass melt.
, 73 mo1%)-GdF3 (3,85 mo1%)-8 IFa (3,85 mo1%) was used.

次ぎに、内部鋳型２１を引抜き、コア用ガラス融液２６
がクラッド用ガラス融液２４の中心に残留するようにし
、ガラス化した。２８０℃で２４時間アニールしたのち
、室温まで徐冷し、クラツド径２０鶴φ、コア径３ｍｍ
φ、長さ１００　ｍのフッ化物光フアイバ用プリフォー
ム３０をえた。Next, the internal mold 21 is pulled out, and the core glass melt 26 is removed.
remained in the center of the cladding glass melt 24, and vitrification was performed. After annealing at 280°C for 24 hours, it was slowly cooled to room temperature, and the clad diameter was 20 mm and the core diameter was 3 mm.
A preform 30 for a fluoride optical fiber having a diameter of φ and a length of 100 m was obtained.

このように製造されたプリフォームを、第３図に示すよ
うに弗素樹脂チューブ３１に挿入したのち、電気炉台３
２に載置された小型電気炉３３を上昇させて加熱しなが
ら、引っ張って光ファイバ３４とし巻き取りホビン３５
により巻き取った。After inserting the preform manufactured in this way into the fluororesin tube 31 as shown in FIG.
While raising the small electric furnace 33 placed on the holder 2 and heating it, the optical fiber 34 is pulled and wound into the hobbin 35.
It was wound up.

このようにして製造された光ファイバは、クラツド径１
０７　μｍ、コア径１６　μ和、コアークラッド間の比
屈折率差０．２％、カットオフ波長が２゜０μｍのステ
ップインデックス型フフ化物単一モード″（長さ　１０
０ｍ）光ファイバであった。The optical fiber manufactured in this way has a cladding diameter of 1
07 μm, core diameter 16 μm, relative refractive index difference between core and cladding 0.2%, cutoff wavelength 2°0 μm, step index type fluoride single mode'' (length 10
0m) was an optical fiber.

この光ファイバのコア径のゆらぎは１％以下であり、伝
送損失は、２．５　ｐｍ帯で、２０ｄＢ／ｋｍであった
。The core diameter fluctuation of this optical fiber was 1% or less, and the transmission loss was 20 dB/km in the 2.5 pm band.

また、石英ガラス、炭素製の鋳型本体、内部鋳型を用い
て、前記と同様な方法によって、２〜４μｍ帯で単一モ
ード導波路となる光フアイバ用プリフォームを製造する
ことができた。Further, by using a mold body made of quartz glass or carbon, and an internal mold, an optical fiber preform that becomes a single mode waveguide in the 2 to 4 μm band could be manufactured by the same method as described above.

以上説明したように、本発明によるフン化物光フアイバ
用プリフォームの製造方法によれば、真円度が高く、勝
つ細径なコアを有するフッ化物光フアイバ用プリフォー
ムを容易に製造でき、石英系光ファイバより低損失とな
ることが期待される２〜４μｍ帯で単一モード導波路と
なる光ファイバが製造できるので、超低損失大容量光伝
達方式が可能になる□とい−う利点がある。As explained above, according to the method for manufacturing a fluoride optical fiber preform according to the present invention, it is possible to easily manufacture a fluoride optical fiber preform having a highly rounded core and a small diameter core. Since it is possible to manufacture optical fibers that serve as single mode waveguides in the 2-4 μm band, which is expected to have lower loss than conventional optical fibers, it has the advantage of enabling ultra-low loss, high-capacity optical transmission systems. be.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来のフッ化物光フアイバ用プリフォームの製
造方法を示した工程図、第２図は本発明のフン化物光フ
アイバ用プリフォームの製造方法　、を示した工程図、
第３図は前記方法で製造されたプリフォームより光ファ
イバを製造する場合の工程図である。 ２０・・・鋳型本体、２１・・・内部鋳型、２４・・・
クラッド用ガラス融液、２６・・・コア用ガラス融液、
２７・・・中空部。 出願人代理人　　　　　雨　宮　正　季節　１ （ａ）　　　　　　　　　　（ｂ） （Ｃ） 第２図 （ｏ）　　　　　　　　　　（ｂ）FIG. 1 is a process diagram showing a conventional method for manufacturing a preform for a fluoride optical fiber, and FIG. 2 is a process diagram showing a method for manufacturing a preform for a fluoride optical fiber according to the present invention.
FIG. 3 is a process diagram for manufacturing an optical fiber from the preform manufactured by the method described above. 20... Mold body, 21... Internal mold, 24...
Glass melt for cladding, 26... Glass melt for core,
27...Hollow part. Applicant's agent Tadashi Amemiya Season 1 (a) (b) (C) Figure 2 (o) (b)

Claims (1)

【特許請求の範囲】[Claims] （１１円筒形鋳型本体にコア部形成用の中空部を有する
内部鋳型を同心的に挿入し、前記内部鋳型と円筒形鋳型
本体で構成される空隙にクラッド用フッ化物ガラス融液
を、また内部鋳型の中空部にコア用フッ化物ガラス融液
をそれぞれキャスティングし、次いで前記内部鋳型を引
抜き、ガラス化することを特徴とするフッ化物光フアイ
バ用プリフォームの製造方法。(11) An internal mold having a hollow part for forming a core part is concentrically inserted into the cylindrical mold body, and a fluoride glass melt for cladding is poured into the gap formed by the internal mold and the cylindrical mold body. 1. A method for producing a preform for a fluoride optical fiber, which comprises casting a core fluoride glass melt into a hollow part of a mold, and then pulling out the inner mold and vitrifying it.
JP10401983A 1983-06-10 1983-06-10 Manufacture of preform for optical fluoride fiber Pending JPS59232927A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP10401983A JPS59232927A (en) 1983-06-10 1983-06-10 Manufacture of preform for optical fluoride fiber

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10401983A JPS59232927A (en) 1983-06-10 1983-06-10 Manufacture of preform for optical fluoride fiber

Publications (1)

Publication Number Publication Date
JPS59232927A true JPS59232927A (en) 1984-12-27

Family

ID=14369544

Family Applications (1)

Application Number Title Priority Date Filing Date
JP10401983A Pending JPS59232927A (en) 1983-06-10 1983-06-10 Manufacture of preform for optical fluoride fiber

Country Status (1)

Country Link
JP (1) JPS59232927A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63123826A (en) * 1986-11-11 1988-05-27 Sumitomo Electric Ind Ltd Production of preform for fluoride glass
EP0711734A1 (en) * 1994-11-14 1996-05-15 AT&T Corp. Core insertion method and apparatus for making optical fiber preforms and optical fibers fabricated therefrom

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5571637A (en) * 1978-11-22 1980-05-29 Hitachi Ltd Forming method for glass fine powder for optical fiber

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5571637A (en) * 1978-11-22 1980-05-29 Hitachi Ltd Forming method for glass fine powder for optical fiber

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63123826A (en) * 1986-11-11 1988-05-27 Sumitomo Electric Ind Ltd Production of preform for fluoride glass
JPH0583495B2 (en) * 1986-11-11 1993-11-26 Sumitomo Electric Industries
EP0711734A1 (en) * 1994-11-14 1996-05-15 AT&T Corp. Core insertion method and apparatus for making optical fiber preforms and optical fibers fabricated therefrom

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