JP3952136B2

JP3952136B2 - Reinforcing member for optical fiber fusion part

Info

Publication number: JP3952136B2
Application number: JP2001314231A
Authority: JP
Inventors: 弘昭森上; 博之金木
Original assignee: Nippon Electric Glass Co Ltd
Current assignee: Nippon Electric Glass Co Ltd
Priority date: 2001-03-12
Filing date: 2001-10-11
Publication date: 2007-08-01
Anticipated expiration: 2021-10-11
Also published as: JP2002341171A

Description

【０００１】
【発明の属する技術分野】
本発明は、光ファイバの融着部を補強するために用いられる補強部材に関する。
【０００２】
【従来の技術】
光ファイバを接続する方法の一つに、それぞれの光ファイバの先端同士を突き合わせた状態で加熱して融着する方法がある。また、光ファイバカプラの一種に、複数本の光ファイバを並列させて加熱し融着した後、延伸して細径とする融着型カプラと称されるものがある。このような光ファイバの融着部を、折損等から保護するために接着剤を介して補強部材で固定し補強する等の処置がなされ、光ファイバの接続部や光ファイバカプラの信頼性向上が図られている。
【０００３】
光ファイバの融着部の固定に用いられる補強部材は、図４に示すように、光ファイバ１の融着部２を上下から挟む一対の板状又は棒状の部材からなるものがあるが、このような補強部材３、４を用いて光ファイバ１の融着部２を固定するには、予め一方の補強部材４の上面に、加熱により軟化して冷却により短時間で硬化する熱可塑性の接着剤５を塗布または貼り付けて固着しておき、その上に、融着部２が補強部材４の略中央に位置するように光ファイバ１を載置し、さらにその上に、同様に接着剤５を塗布または貼り付けて固着したもう一方の補強部材３を重ねて上下の補強部材３、４を加熱して接着し、融着部２を固定することにより補強する方法が採用されている。
【０００４】
上記の光ファイバ１の融着部２を固定するのに用いられる補強部材３、４としては、石英系の光ファイバ１の融着部２を固定する部位において、環境温度の変化により部材の熱膨張差に起因する応力が光ファイバ１に生じず、変形等を起こさせることがない材料が好適とされ、このような条件を満たす材料として低熱膨張の石英ガラスや結晶化ガラス等が知られている。
【０００５】
また、補強部材３、４には、丸棒又は管を半割りにした棒状のものや、板状のものなど、種々の形状のものが存在する。
【０００６】
従来、上記の丸棒を半割りにした棒状の補強部材３は、例えば、図５示すような工程を経て作製されている。まず、ガラス生地をダウンドロー法又はアップドロー法により丸棒状に成形し、図５（Ａ）に示すような丸棒状のガラスを熱処理炉７に導入し、温度制御しながら熱処理してガラス内部に微結晶を析出させて結晶化ガラスの丸棒Ｍを得る。この結晶化ガラスの丸棒Ｍをダイヤモンド回転砥石で半径方向に向かって所定の形状まで研削して図５（Ｂ）に示すような略半月形の横断面を有する棒状の結晶化ガラスＭ’を得、この棒状の結晶化ガラスを、図５（Ｃ）に示すように所定の長さに切断して、一方の面が平坦面で、他方の面が略半月形の凸面をした補強部材３を作製している。
【０００７】
また、平板状の補強部材４は、結晶化ガラスの板状体を所定の厚さに研削・研磨した後、切断することにより作製されている。
【０００８】
【発明が解決しようとする課題】
上記、補強部材３、４の材料である結晶化ガラスは、析出した結晶の硬度が高いために切断や切削等の加工が容易でなく、しかも、このような機械加工を行う際に、抗折応力が集中する部位となる光ファイバ１の融着部２を固定する部位である補強部材３の表面３ａに潜傷等の微細クラックが入り、機械的強度が低下する原因になっている。
【０００９】
この対策として、従来、結晶化ガラスからなる補強部材３、４は、結晶化ガラスからなる材料に切断や研削等の機械加工を施して所定の寸法形状に仕上げた後に、機械的強度を向上させるためにイオン交換による処理が行われている。
【００１０】
このようなイオン交換処理は、ガラスを加熱した溶融塩中に浸漬させ、ガラス中の元素の半径が小さいＮａ等のアルカリイオンと溶融塩の元素の半径が大きいＫ等のアルカリイオンとを置換することにより、ガラスの表面層に圧縮応力を形成させて強度を増大させるガラスの強化法であり、風冷強化等の他のガラス強化法に比べて、高い強度が得られる、形状、肉厚等の制限を受けない、変形が起こらないため高い寸法精度が得られる等の長所を備えている。
【００１１】
しかしながら、イオン交換処理には長時間を要するためコスト高になるという問題があった。
【００１２】
また、光ファイバ１の融着部２の補強部材３は、従来、丸棒状ガラスの成形、結晶化、研削、切断等、その完成までには多くの工程を経る必要があり、しかも、最終的に完成品として利用されるのは材料である丸棒状のガラスの２０％余に過ぎず、大部分が加工によるガラス屑となるため材料の利用率は極めて低かった。
【００１３】
本発明は、上記問題に鑑みてなされたものであり、低熱膨張の結晶化ガラスの利点を維持しつつ、融着された光ファイバ接続部や光ファイバカプラの信頼性を向上させるに足りる高い機械的強度を有し、かつ安価に製造することができる光ファイバ融着部の補強部材を提供することを目的とする。
【００１４】
【課題を解決するための手段】
上記の課題を解決するために、本発明の光ファイバ融着部の補強部材は、β−石英固溶体結晶又はβ−スポジュメン結晶を主結晶として析出した低熱膨張の結晶化ガラスからなり、光ファイバに略平行となる冷間加工が施された加工面を有する略板状又は棒状の光ファイバ融着部の補強部材において、加熱処理により前記加工面に、β−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層が形成されて該表面が覆われていることを特徴とする。
【００１５】
本発明の光ファイバ融着部の補強部材において、光ファイバに略平行となる冷間加工が施された加工面を有するとは、ガラス材料や結晶化ガラス材料に切削、研削、研磨等の冷間加工を施すことにより、光ファイバに略平行となる表面が加工面になっていることであり、溶融ガラスや軟化状態のガラスから直接最終形状に成形された後に結晶化処理された先記の丸棒等の補強部材は含まないことを意味するものである。また、融着部を有する光ファイバと略平行となる表面にあるβ−石英固溶体結晶（β−ＳｉＯ₂ｓｏｌｉｄｓｏｌｕｔｉｏｎ）又はβ−スポジュメン固溶体結晶（β−Ｌｉ₂Ｏ・Ａｌ₂Ｏ₃・４ＳｉＯ₂ｓｏｌｉｄｓｏｌｕｔｉｏｎ）を主結晶として析出した表面層は、加熱処理されることにより析出した時のままのものであり、研削加工により表面層が除去されて内部から露出したβ−石英固溶体結晶又はβ−スポジュメン結晶とは構成上異なるものである。
【００１６】
本発明の光ファイバ融着部の補強部材に使用する低熱膨張の結晶化ガラスとしては、光ファイバ融着接続部の補強には、β−石英固溶体結晶を主結晶として透明である日本電気硝子株式会社製のネオセラムＮ−０等が適しており、また、温度変化の影響に対してより厳しい要求がなされる光ファイバカプラ等の補強には、膨張係数が光ファイバを構成する石英ガラスの熱膨張係数に適合させることが可能であるので、β−スポジュメン結晶を主結晶として白色を呈する日本電気硝子株式会社製ネオセラムＮ−１１等が適している。
【００１７】
また、本発明の光ファイバ融着部の補強部材は、長手方向中央部の表面が、β-石英固溶体結晶析出時の表面層又はβ-スポジュメン結晶析出時の表面層により被覆されていることが好ましい。
【００１８】
光ファイバ融着部の補強部材の抗折強度に係わる長手方向中央部の表面とは、光ファイバ融着部の補強部材に曲げモーメント荷重が負荷された場合に抗折応力が集中する部位の表面を意味しており、細長い形状のものでは長手方向中央部が抗折応力の集中する部位となる。補強部材のこのような部位の表面をβ−石英固溶体結晶析出時の表面層又はβ−スポジュメン結晶析出時の表面層が被覆していることが、負荷の方向性に関係なく抗折強度に代表される機械的強度を維持する上で重要である。
【００１９】
また、本発明の光ファイバ融着部の補強部材は、融着部を有する光ファイバと略平行となる補強部材の端部及びその付近の表面を除く全表面が、β−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層により被覆されていることを特徴とする。
【００２０】
融着部を有する光ファイバと略平行となるほぼ全表面がβ−石英固溶体結晶析出時の表面層又はβ−スポジュメン結晶析出時の表面層が被覆されているとは、β−石英固溶体結晶析出時の表面層又はβ−スポジュメン結晶析出時の表面層により光ファイバ融着部の補強部材の全表面が被覆されている場合や、全表面が被覆されている低熱膨張の結晶化ガラスからなる長尺材料を切断加工した際に、抗折強度に殆ど係わらない端部及びその付近の表面だけがβ−石英固溶体結晶析出時の表面層又はβ−スポジュメン結晶析出時の表面層で被覆されていない場合を意味している。
【００２１】
【作用】
本発明の光ファイバ融着部の補強部材は、β−石英固溶体結晶又はβ−スポジュメン結晶を主結晶として析出した低熱膨張の結晶化ガラスからなるので、補強部材で固定された光ファイバ融着部に著しい熱応力を発生させることがなく、光ファイバに略平行となる冷間加工が施された加工面に、加熱処理によりβ−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層が形成されて該表面が覆われているので、加傷や潜傷等を起因とする微細クラックが成長せず、高い機械的強度を有する。
【００２２】
また、本発明の光ファイバ融着部の補強部材は、長手方向中央部の表面が、β-石英固溶体結晶又はβ-スポジュメン結晶析出時の表面層により被覆されていると、負荷の方向性に関係なく補強部材の高い抗折強度を維持することができる。
【００２３】
また、本発明の光ファイバ融着部の補強部材は、融着部を有する光ファイバと略平行となる補強部材の端部及びその付近の表面を除く全表面が、β−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層により被覆されているので、全表面が被覆されている低熱膨張の結晶化ガラスからなる長尺材料から高い機械的強度を有する光ファイバ融着部の補強部材を効率的に作製することが可能となる。
【００２４】
【発明の実施の形態】
以下に、本発明の光ファイバ融着部の補強部材を、実施例に基づいて詳細に説明する。
【００２５】
図１は本発明に係る光ファイバ融着部の補強部材の斜視図、図２は本発明に係る光ファイバ融着部の補強部材の製造工程を示す説明図、先記した図３は光ファイバの融着部を補強部材で固定するときの分解斜視図である。各図において、１１は光ファイバを、１２は融着部を、１３、１４は補強部材を、１５は接着剤をそれぞれ示している。
【００２６】
光ファイバ１としては、単芯、複数芯のものがあるが、いずれでもよい。光ファイバ１の融着部２としては、光ファイバ１の先端同士を突き合わせて加熱し融着接続されたもの、あるいは光ファイバカプラのように、複数本の光ファイバ１を並列させて加熱し融着した後、延伸して細径として形成されるもの等がある。
【００２７】
補強部材１３、１４は、図１に示すように、所定の寸法形状を有して、少なくとも光ファイバ１１の融着部１２との対向面を含む略平行面１３ａ、１３ｂ、１４ａ、１４ｂに熱処理によって、β−石英固溶体結晶析出時の表面層が形成されて表面が覆われている。例えば、日本電気硝子株式会社製ネオセラムＮ−０又はβ−スポジュメン結晶析出時の表面層を保有する、例えば、日本電気硝子株式会社製ネオセラムＮ−１１等の低熱膨張の結晶化ガラスからなる。補強部材１３、１４の熱膨張係数としては、光ファイバ１１を構成する石英ガラスの熱膨張係数４×１０^-7／Ｋと略同等のものが好適である。
【００２８】
また、透明性を有するネオセラムＮ−０等の結晶化ガラスを使用して光ファイバ１１の融着部１２と略平行な表面１３ａ、１３ｂ、１４ａ、１４ｂにβ−石英固溶体結晶析出時の表面層を保有する補強部材１３、１４を作製すれば、補強作業中及び補強後に光ファイバ１１の融着部１２の状態を外部から観察することができ、さらに、略半月形の横断面を有する補強部材１３であれば、レンズ作用により光ファイバ１１の融着部１２の状態が拡大されてよりよく観察することができる。
【００２９】
先記した図３に示す接着剤５としては、加熱により軟化溶融し、冷却により短時間で硬化する熱可塑性の接着剤が適しており、透明なものがより好ましい。
【００３０】
本発明の実施例として、熱膨張係数が−６×１０^-7／Ｋと、光ファイバを構成する石英ガラスの熱膨張係数である４×１０^-7／Ｋと略同等で小さく、弧の長さ８．７ｍｍ、弦の長さ７．７ｍｍ、高さ１．８ｍｍの略半月形の横断面を有して長さ４０ｍｍの寸法を有する補強部材１３の試料を５０本準備した。
【００３１】
比較例１として、研削により弧の長さ８．７ｍｍ、弦の長さ７．７ｍｍ、高さ１．８ｍｍの略半月形の横断面を有し、長さ４０ｍｍの寸法を有する補強部材の試料を５０本準備した。
【００３２】
比較例２として、研削により研削により弧の長さ８．７ｍｍ、弦の長さ７．７ｍｍ、高さ１．８ｍｍの略半月形の横断面を有し、長さ４０ｍｍの寸法を有する棒状体を作製した後、イオン交換処理により強化した補強部材の試料を５０本準備した。
【００３３】
実施例及び比較例１、２の抗折強度を評価するために、各試料の３点曲げ強度試験を行った。測定条件は、島津製作所製オートグラフ試験器（型番ＡＧＳ−５００Ｄ）を使用し、使用ポンチの先端Ｒが６ｍｍ、スパン＝３０ｍｍ、クロスヘッドスピード＝０．５ｍｍ／分の条件で破壊荷重の測定を行った。その結果を表１に示す。
【００３４】
【表１】

【００３５】
実施例の補強部材３は、３．３〜７．５ｋｇｆ、平均５．８ｋｇｆの高い破壊荷重となる抗折強度を有するものであり、実際に使用されているイオン交換処理により強化されている比較例２と遜色なく、実用に耐え得るものとなっている。
【００３６】
これに対して、比較例１の補強部材は、破壊荷重が２．８〜８．０ｋｇｆ、平均５．０ｋｇｆと、補強部材としては信頼性に劣るレベルの抗折強度であった。
【００３７】
また、略半月形の横断面を有するβ−石英固溶体結晶が析出した結晶化ガラスからなる補強部材３は、上記の特性に加えて可視光線の透過率が８５％以上で、高い透明性を有するもので、補強作業中及び補強後に光ファイバ１１の融着部１２の状態を外部から観察することができ、レンズ作用により光ファイバ１１の融着部１２の状態が拡大されてよりよく観察することができるので、容易に補強作業ミスの有無を確認することができた。
【００３８】
次に、本発明に係る光ファイバ融着部の補強部材の製造方法を説明する。
【００３９】
本発明の光ファイバ融着部の透明な補強部材１３は、図２に示すような工程を経て製造される
まず、質量％でＳｉＯ₂ ６７％、Ａｌ₂Ｏ₃ ２３％、Ｌｉ₂Ｏ４％、ＴｉＯ₂ ２％、ＺｒＯ₂ ３％、Ｐ₂Ｏ₃ １％の組成からなるガラス原料を溶融して得られるガラス生地を、表面に断面が略半月形の凹部を複数列形成したロ−ラと、表面が無地の平坦面であるローラとが一定の間隔を空けて上下に対向配置され、それぞれのローラが回転するロール成形装置（図示省略）に供給し、回転する両ローラの隙間を通過させると、ガラス生地の片面にローラに形成された断面が略半月形の凹部が転写され、図２（Ａ）に示すような片面に横断面が略半月形の凸部を複数列有する長さ９０ｍｍの型板ガラスＧを得る。
【００４０】
次いで、この型板ガラスＧを４０ｍｍの長さに切断し、片面に形成された略半月形の横断面の弦に沿ってダイヤカッターホイール、ワイヤーソー等で切り離すことにより、図２（Ｂ）に示すように、弧の長さ８．７ｍｍ、弦の長さ７．７ｍｍ、高さ１．８ｍｍの略半月形の横断面を有する長さ４０ｍｍの棒状のガラスを分離することによりガラス部材Ｇ’を作製する。
【００４１】
最後に、このガラス部材Ｇ’を図２（Ｃ）に示す熱処理炉１０に導入し、８５０〜９５０℃の高温雰囲気中で温度制御しながら１時間保持すると、ガラス部材Ｇ’に数ｎｍの表面層を保有するβ−石英固溶体結晶が析出してガラス部材Ｇ’が結晶化して、所望の補強部材１３が完成する。
【００４２】
なお、片面に横断面が略半月形の凸部を複数列有する型板ガラスＧを得るには、上記の方法に限らず、表面に半径５．０ｍｍの円の一部を切欠いてできる弧の長さ８．７ｍｍ、弦の長さ７．７ｍｍ、高さ１．８ｍｍの断面が略半月形の凹部を複数列形成した雄型と、表面が無地の平坦面である雌型とからなるプレス成形装置（図示省略）を用いて、雌型の表面に載置したガラス生地に雄型を押付け、雄型に形成された断面が略半月形の凹部を転写する方法によっても可能である。
【００４３】
上記の補強部材１３を１５００個製造するのに要する時間は１時間であり、従来の製造方法に比べて３分の１と大幅に短縮された。
【００４４】
なお、本発明の光ファイバ融着部の補強部材にイオン交換処理を施し、結晶化ガラスの表面層に圧縮応力を形成させて強度を増大させると、機械的強度が一層高くなり、さらに信頼性の高い補強部材が得られる。
【００４５】
【発明の効果】
以上説明したように、本発明の光ファイバ融着部の補強部材は、β−石英固溶体結晶又はβ−スポジュメン結晶を主結晶として析出した低熱膨張の結晶化ガラスからなるので、周囲の温度変化に対しても変形を来さず、補強部材で固定された光ファイバ融着部に著しい熱応力を発生させることがなく、かつ、融着部を有する光ファイバに略平行となる冷間加工が施された加工面に、加熱処理によりβ−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層が形成され表面が被覆されているので、光ファイバ融着部を固定する部位に加傷や潜傷等に起因する微細クラックが成長せず、光ファイバ融着部の補強部材に求められる十分な機械的強度を有し、光ファイバ融着部の信頼性を向上させることができる。
【００４６】
また、本発明の光ファイバ融着部の補強部材は、長手方向中央部の表面がβ-石英固溶体結晶又はβ-スポジュメン結晶析出時の表面層により被覆されていると、負荷の方向性に関係なく補強部材の高い抗折強度を維持することができる。
【００４７】
さらに、本発明の光ファイバ融着部の補強部材は、融着部を有する光ファイバと略平行となる補強部材の端部及びその付近の表面を除く全表面が、β−石英固溶体結晶又はβ−スポジュメン結晶析出時の表面層により被覆されているので、全表面が結晶析出時の表面層で被覆されている低熱膨張の結晶化ガラスからなる長尺材料から高い機械的強度を有する光ファイバ融着部の補強部材を効率的に作製することが可能となる実用上極めて優れた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の光ファイバ融着部の補強部材を示す説明図であって、（Ａ）は、略半月形の横断面を有する補強部材の斜視図を、（Ｂ）は板状の補強部材の斜視図。
【図２】本発明の光ファイバ融着部の補強部材を作製する工程を示す説明図であって、（Ａ）は片面に横断面が略半月形の凸部を複数列有する形成された型板ガラス、（Ｂ）は横断面が略半月形の棒状ガラスと、残部の板状ガラスとに分離する説明図、（Ｃ）は切断されて所要の寸法形状を有するガラス部材を熱処理炉で結晶化する説明図。
【図３】光ファイバ融着部を本発明の補強部材で固定・保護するときの分解斜視図。
【図４】光ファイバ融着部を従来の補強部材で固定・保護するときの分解斜視図。
【図５】従来の光ファイバ融着部補強部材の製造方法を示す説明図であって、（Ａ）は丸棒状ガラスを熱処理炉で結晶化する説明図、（Ｂ）は半径方向に向かって研削し略半月形の横断面を有する棒状の結晶化ガラスに加工する説明図、（Ｃ）は従来の製造方法で得られる補強部材の説明図。
【符号の説明】
１、１１光ファイバ
２、１２融着部
３、４、１３、１４補強部材
５、１５接着剤
７、１０熱処理炉
１３ａ、１３ｂ、１４ａ、１４ｂ表面
Ｇ型板ガラス
Ｇ’ ガラス部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforcing member used for reinforcing a fused portion of an optical fiber.
[0002]
[Prior art]
One method of connecting optical fibers is a method of heating and fusing each optical fiber in a state where the ends of the optical fibers are in contact with each other. Further, as one type of optical fiber coupler, there is one called a fusion type coupler in which a plurality of optical fibers are juxtaposed, heated and fused, and then drawn to have a small diameter. In order to protect the fused portion of the optical fiber from breakage or the like, measures such as fixing and reinforcing with a reinforcing member via an adhesive are made, and the reliability of the optical fiber connection portion and the optical fiber coupler is improved. It is illustrated.
[0003]
As shown in FIG. 4, the reinforcing member used for fixing the fused portion of the optical fiber includes a pair of plate-like or rod-like members that sandwich the fused portion 2 of the optical fiber 1 from above and below. In order to fix the fused portion 2 of the optical fiber 1 using the reinforcing members 3 and 4 as described above, a thermoplastic adhesive that is softened by heating and hardened in a short time by cooling to the upper surface of one reinforcing member 4 in advance. The optical fiber 1 is placed on the adhesive member 5 so that the fused portion 2 is positioned at the approximate center of the reinforcing member 4, and the adhesive agent is similarly applied thereon. A method is adopted in which the other reinforcing member 3 fixed by applying or affixing 5 is overlapped, the upper and lower reinforcing members 3 and 4 are heated and bonded, and the fused portion 2 is fixed.
[0004]
As the reinforcing members 3 and 4 used for fixing the fused portion 2 of the optical fiber 1 described above, the heat of the member is changed due to a change in the environmental temperature at the portion where the fused portion 2 of the quartz optical fiber 1 is fixed. A material that does not cause stress due to the expansion difference in the optical fiber 1 and does not cause deformation or the like is suitable, and low thermal expansion quartz glass, crystallized glass, and the like are known as materials satisfying such conditions. Yes.
[0005]
In addition, the reinforcing members 3 and 4 have various shapes such as a round bar or a rod-shaped rod having a half-pipe or a plate-shaped member.
[0006]
Conventionally, the rod-shaped reinforcing member 3 obtained by dividing the above-described round bar into halves has been manufactured through a process as shown in FIG. 5, for example. First, the glass dough is formed into a round bar shape by the downdraw method or the updraw method, and the round bar-shaped glass as shown in FIG. 5 (A) is introduced into the heat treatment furnace 7 and heat-treated while controlling the temperature inside the glass. Microcrystals are deposited to obtain a round bar M of crystallized glass. This crystallized glass round bar M is ground to a predetermined shape in the radial direction with a diamond rotary grindstone, and a rod-shaped crystallized glass M ′ having a substantially half-moon-shaped cross section as shown in FIG. 5B is obtained. This rod-shaped crystallized glass is cut into a predetermined length as shown in FIG. 5 (C), and the reinforcing member 3 has one surface which is a flat surface and the other surface is a substantially half-moon-shaped convex surface. Is making.
[0007]
The flat reinforcing member 4 is produced by grinding and polishing a crystallized glass plate to a predetermined thickness and then cutting.
[0008]
[Problems to be solved by the invention]
The crystallized glass that is the material of the reinforcing members 3 and 4 is difficult to process such as cutting and cutting because of the high hardness of the precipitated crystals. Fine cracks such as latent scratches enter the surface 3a of the reinforcing member 3 which is a part for fixing the fused portion 2 of the optical fiber 1 which is a part where the stress is concentrated, which causes a decrease in mechanical strength.
[0009]
As countermeasures, conventionally, the reinforcing members 3 and 4 made of crystallized glass improve the mechanical strength after finishing the material made of crystallized glass by machining such as cutting and grinding to a predetermined size and shape. Therefore, processing by ion exchange is performed.
[0010]
In such an ion exchange treatment, glass is immersed in a heated molten salt, and alkali ions such as Na having a small element radius in the glass and alkali ions such as K having a large radius of the molten salt element are replaced. This is a glass strengthening method that increases the strength by forming a compressive stress on the surface layer of the glass. Compared with other glass strengthening methods such as air-cooling strengthening, the shape, thickness, etc. There are advantages such as not being limited by the above, and high dimensional accuracy can be obtained because no deformation occurs.
[0011]
However, since the ion exchange process requires a long time, there is a problem that the cost is increased.
[0012]
In addition, the reinforcing member 3 of the fused portion 2 of the optical fiber 1 conventionally needs to go through many processes until its completion, such as molding, crystallization, grinding, cutting, etc. of a round bar glass. However, only 20% of the round bar-shaped glass used as a material is used as a finished product, and most of the glass becomes glass scraps due to processing, and the utilization rate of the material was extremely low.
[0013]
The present invention has been made in view of the above-mentioned problems, and is a high machine that is sufficient to improve the reliability of a fused optical fiber connection part and an optical fiber coupler while maintaining the advantages of low thermal expansion crystallized glass. It is an object of the present invention to provide a reinforcing member for an optical fiber fusion part that has high strength and can be manufactured at low cost.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the reinforcing member of the fused portion of the optical fiber according to the present invention is made of low thermal expansion crystallized glass in which β-quartz solid solution crystal or β-spodumene crystal is precipitated as a main crystal, and is applied to the optical fiber. in a substantially plate-like or rod-like reinforcing member of the optical fiber fusion part of having a generally machined surface cold working is performed as a parallel to the working surface by heat treatment, beta-quartz solid solution crystal or beta-spodumene crystals formed surface layer during deposition is characterized that you have covered the surface.
[0015]
In the reinforcing member of the optical fiber fusion part of the present invention, having a processed surface that is cold-worked substantially parallel to the optical fiber means that the glass material or the crystallized glass material is cooled by cutting, grinding, polishing, or the like. The surface that is substantially parallel to the optical fiber is a processed surface by performing the inter-process, and the crystallization treatment is performed after the glass is directly molded into a final shape from molten glass or softened glass. This means that a reinforcing member such as a round bar is not included. Further, in the optical fiber and are substantially parallel surface with the fused part β- quartz solid solution crystals (β-SiO ₂ solid solution) or β- spodumene solid solution crystals _{(β-Li 2 O · Al} 2 O 3 · 4SiO _The surface layer deposited with ₂ solid solution as the main crystal is the same as when it was deposited by heat treatment, and the β-quartz solid solution crystal or β exposed from the inside after the surface layer was removed by grinding -It is structurally different from spodumene crystals.
[0016]
As a low thermal expansion crystallized glass used for a reinforcing member of an optical fiber fusion part according to the present invention, for the reinforcement of an optical fiber fusion splicing part, Nippon Electric Glass Co., Ltd. is transparent with a β-quartz solid solution crystal as a main crystal. Company-made neo-serum N-0 is suitable, and for the reinforcement of optical fiber couplers and the like that are more severely affected by the temperature change, the thermal expansion of quartz glass that constitutes the optical fiber is used for the reinforcement of optical fiber couplers. Since it is possible to adapt the coefficient, Neoceram N-11 manufactured by Nippon Electric Glass Co., Ltd., which exhibits a white color with a β-spodumene crystal as the main crystal, is suitable.
[0017]
The reinforcing member of the optical fiber fusion part of the present invention, the surface of the long-side direction central portion is covered by β- quartz solid solution crystal precipitation at the surface layer or β- spodumene surface layer during crystallization Is preferred .
[0018]
The surface of the central portion in the longitudinal direction related to the bending strength of the reinforcing member of the optical fiber fused portion is the surface of the portion where the bending stress is concentrated when a bending moment load is applied to the reinforcing member of the optical fiber fused portion. In the case of an elongated shape, the central portion in the longitudinal direction is a portion where bending stress is concentrated. The surface of such a portion of the reinforcing member is covered with the surface layer at the time of β-quartz solid solution crystal precipitation or the surface layer at the time of β-spodumene crystal precipitation, which is representative of the bending strength regardless of the direction of the load. It is important in maintaining the mechanical strength.
[0019]
The reinforcing member of the optical fiber fusion part of the present invention, the entire surface except the end portion and the surface of the vicinity of the optical fiber and are substantially parallel reinforcing member having a fusing unit, beta-quartz solid solution crystal or It is characterized by being covered with a surface layer at the time of β-spodumene crystal precipitation.
[0020]
Β-quartz solid solution crystal precipitation means that almost the entire surface substantially parallel to the optical fiber having the fused portion is coated with a surface layer at the time of β-quartz solid solution crystal precipitation or a surface layer at the time of β-spodumene crystal precipitation. When the entire surface of the reinforcing member of the fused portion of the optical fiber is covered with the surface layer at the time of precipitation or the β-spodumene crystal precipitation, or the length of the low thermal expansion crystallized glass covered with the entire surface When cutting the scale material, only the end portion and the surface in the vicinity thereof that are hardly involved in the bending strength are not covered with the surface layer at the time of β-quartz solid solution crystal precipitation or the surface layer at the time of β-spodumene crystal precipitation. Means the case.
[0021]
[Action]
The reinforcing member of the optical fiber fusion part of the present invention is made of low thermal expansion crystallized glass precipitated with β-quartz solid solution crystal or β-spodumene crystal as the main crystal, so the optical fiber fusion part fixed with the reinforcing member without causing significant thermal stress, approximately a machining surface which cold working is applied consisting parallel to the optical fiber, the heat treatment β- quartz solid solution crystal or a surface layer at the time of β- spodumene crystals precipitated form has been Runode covered the surface, does not grow fine cracks originating from scratching or latent scratches, it has high mechanical strength.
[0022]
The reinforcing member of the optical fiber fusion part of the present invention, the surface of the long-side direction center portion, beta-quartz solid solution crystal or are covered with a surface layer at the time of beta-spodumene crystallization, the direction of the load The high bending strength of the reinforcing member can be maintained regardless of the nature.
[0023]
The reinforcing member of the optical fiber fusion part of the present invention, the entire surface except the end portion and the surface of the vicinity of the optical fiber and are substantially parallel reinforcing member having a fusing unit, beta-quartz solid solution crystal or Since it is covered with a surface layer at the time of β-spodumene crystal precipitation, a reinforcing member for an optical fiber fusion part having high mechanical strength is formed from a long material made of crystallized glass with low thermal expansion, which is coated on the entire surface. It becomes possible to produce efficiently.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Below, the reinforcement member of the optical fiber fusion | melting part of this invention is demonstrated in detail based on an Example.
[0025]
FIG. 1 is a perspective view of a reinforcing member for an optical fiber fusion portion according to the present invention, FIG. 2 is an explanatory view showing a manufacturing process of the reinforcing member for an optical fiber fusion portion according to the present invention, and FIG. It is a disassembled perspective view when fixing the melt | fusion part of this with a reinforcement member. In each figure, 11 is an optical fiber, 12 is a fused part, 13 and 14 are reinforcing members, and 15 is an adhesive.
[0026]
The optical fiber 1 includes a single core and a plurality of cores. As the fusion part 2 of the optical fiber 1, the ends of the optical fibers 1 are abutted and heated and fusion-bonded, or a plurality of optical fibers 1 are heated in parallel, such as an optical fiber coupler. Some of them are stretched to form a narrow diameter after being worn.
[0027]
As shown in FIG. 1, the reinforcing

members

13 and 14 have a predetermined size and shape, and heat treatment is performed on substantially

parallel surfaces

13 a, 13 b, 14 a, and 14 b including at least a surface facing the fused portion 12 of the optical fiber 11. Thus, a surface layer at the time of β-quartz solid solution crystal precipitation is formed and the surface is covered. For example, it consists of low thermal expansion crystallized glass such as Neoceram N-11 manufactured by Nippon Electric Glass Co., Ltd., which has a surface layer at the time of precipitation of Neoceram N-0 or β-spodumene crystal manufactured by Nippon Electric Glass Co., Ltd. As the thermal expansion coefficient of the reinforcing

members

13 and 14, a coefficient approximately equivalent to the thermal expansion coefficient of 4 × 10 ⁻⁷ / K of the quartz glass constituting the optical fiber 11 is suitable.
[0028]
Further, a surface layer at the time of β-quartz solid solution crystal deposition on the

surfaces

13a, 13b, 14a, and 14b substantially parallel to the fused portion 12 of the optical fiber 11 using crystallized glass such as neo-serum N-0 having transparency. If the reinforcing

members

13 and 14 having the above are manufactured, the state of the fused portion 12 of the optical fiber 11 can be observed from the outside during and after the reinforcing operation, and the reinforcing member has a substantially semicircular cross section. If it is 13, the state of the fusion | melting part 12 of the optical fiber 11 will be expanded according to a lens effect | action, and it can observe better.
[0029]
As the adhesive 5 shown in FIG. 3, a thermoplastic adhesive that softens and melts by heating and hardens in a short time by cooling is suitable, and a transparent one is more preferable.
[0030]
As an example of the present invention, the thermal expansion coefficient is −6 × 10 ⁻⁷ / K, which is substantially the same as the thermal expansion coefficient of quartz glass constituting the optical fiber, 4 × 10 ⁻⁷ / K, and is small. Fifty samples of the reinforcing member 13 having a substantially half-moon-shaped cross section with a length of 8.7 mm, a string length of 7.7 mm, and a height of 1.8 mm and a length of 40 mm were prepared.
[0031]
As Comparative Example 1, a sample of a reinforcing member having an approximately half-moon-shaped cross section having an arc length of 8.7 mm, a chord length of 7.7 mm, and a height of 1.8 mm by grinding and having a length of 40 mm 50 were prepared.
[0032]
As Comparative Example 2, a rod-shaped body having a substantially half-moon-shaped cross section with an arc length of 8.7 mm, a chord length of 7.7 mm, and a height of 1.8 mm by grinding and having a length of 40 mm. 50 samples of reinforcing members strengthened by ion exchange treatment were prepared.
[0033]
In order to evaluate the bending strength of Examples and Comparative Examples 1 and 2, a three-point bending strength test of each sample was performed. The measurement conditions were an autograph tester manufactured by Shimadzu (model number AGS-500D), and the fracture load was measured under the conditions that the tip R of the punch used was 6 mm, the span was 30 mm, and the crosshead speed was 0.5 mm / min. went. The results are shown in Table 1.
[0034]
[Table 1]

[0035]
The reinforcing member 3 of the example has a bending strength that is a high breaking load of 3.3 to 7.5 kgf and an average of 5.8 kgf, and is a comparison that is strengthened by the ion exchange treatment that is actually used. It is comparable to Example 2 and can withstand practical use.
[0036]
On the other hand, the reinforcing member of Comparative Example 1 had a fracture load of 2.8 to 8.0 kgf and an average of 5.0 kgf, and had a bending strength that was inferior in reliability as a reinforcing member.
[0037]
Further, the reinforcing member 3 made of crystallized glass on which β-quartz solid solution crystals having a substantially semicircular cross section are deposited has a high transparency with a visible light transmittance of 85% or more in addition to the above characteristics. Thus, the state of the fused portion 12 of the optical fiber 11 can be observed from the outside during and after the reinforcement work, and the state of the fused portion 12 of the optical fiber 11 is enlarged by the lens action and better observed. As a result, it was possible to easily confirm whether there was a mistake in reinforcement work.
[0038]
Next, the manufacturing method of the reinforcement member of the optical fiber fusion part which concerns on this invention is demonstrated.
[0039]
The transparent reinforcing member 13 of the optical fiber fusion part of the present invention is manufactured through a process as shown in FIG. 2. First, SiO ₂ 67%, Al ₂ O ₃ 23%, Li ₂ O 4% by mass%. Roller in which a glass fabric obtained by melting a glass raw material composed of 2% TiO ₂ , 3% ZrO _{2 and} 1% P ₂ O ₃ is formed with a plurality of recesses having a substantially semicircular cross section on the surface. And a roller that is a flat surface with a plain surface are arranged opposite to each other at regular intervals, and are supplied to a roll forming device (not shown) in which each roller rotates, and passes through a gap between both rotating rollers. Then, a concave portion having a substantially half-moon shaped cross section formed on the roller is transferred to one side of the glass fabric, and a length having a plurality of rows of convex portions having a substantially half-moon shaped cross section on one side as shown in FIG. A 90 mm template glass G is obtained.
[0040]
Next, this template glass G is cut into a length of 40 mm, and cut with a diamond cutter wheel, a wire saw or the like along a string of a substantially half-moon-shaped cross section formed on one side, and shown in FIG. As described above, the glass member G ′ is obtained by separating the rod-shaped glass having a length of arc of 8.7 mm, a chord length of 7.7 mm and a height of 1.8 mm and having a substantially half-moon-shaped cross section. Make it.
[0041]
Finally, when this glass member G ′ is introduced into the heat treatment furnace 10 shown in FIG. 2 (C) and kept in a high temperature atmosphere of 850 to 950 ° C. for 1 hour, the glass member G ′ has a surface of several nm. The β-quartz solid solution crystal having the layer is precipitated and the glass member G ′ is crystallized to complete the desired reinforcing member 13.
[0042]
In addition, in order to obtain the template glass G having a plurality of rows of convex portions having a substantially semicircular cross section on one side, the length of an arc formed by cutting out a part of a circle having a radius of 5.0 mm is not limited to the above method. Press molding consisting of a male mold in which a plurality of recesses whose cross section is approximately half-moon shaped with a length of 8.7 mm, a chord length of 7.7 mm, and a height of 1.8 mm are formed, and a female mold whose surface is a plain flat surface It is also possible to use a device (not shown) by pressing a male mold against a glass fabric placed on the surface of a female mold and transferring a concave portion having a substantially half-moon shaped cross section formed on the male mold.
[0043]
The time required to manufacture 1500 of the reinforcing members 13 is 1 hour, which is significantly reduced to 1/3 compared to the conventional manufacturing method.
[0044]
In addition, if the reinforcing member of the optical fiber fusion part of the present invention is subjected to ion exchange treatment to form a compressive stress on the surface layer of the crystallized glass to increase the strength, the mechanical strength is further increased and the reliability is further improved. A high reinforcing member can be obtained.
[0045]
【The invention's effect】
As described above, the reinforcing member for the fused portion of the optical fiber according to the present invention is made of low thermal expansion crystallized glass in which β-quartz solid solution crystal or β-spodumene crystal is precipitated as the main crystal. However, no deformation is caused, no significant thermal stress is generated in the optical fiber fusion part fixed by the reinforcing member, and cold working is performed so as to be substantially parallel to the optical fiber having the fusion part. the working surface that is, since the heat treatment β- quartz solid solution crystal or a surface is the surface layer at the time of β- spodumene crystallization is formed is covered, Kakizu or latent in a portion for fixing the optical fiber fusion part Fine cracks due to scratches and the like do not grow, have sufficient mechanical strength required for the reinforcing member of the optical fiber fusion part, and can improve the reliability of the optical fiber fusion part.
[0046]
The reinforcing member of the optical fiber fusion part of the present invention, the surface of the long-side direction central portion β- quartz solid solution crystal or are covered with a surface layer at the time of β- spodumene crystallization, the direction of the load The high bending strength of the reinforcing member can be maintained regardless of the above.
[0047]
Further, the reinforcing member of the optical fiber fusion part of the present invention, the entire surface except the end portion and the surface of the vicinity of the optical fiber and are substantially parallel reinforcing member having a fusing unit, beta-quartz solid solution crystal or Optical fiber having high mechanical strength from a long material made of crystallized glass with low thermal expansion whose entire surface is coated with the surface layer at the time of crystal precipitation because it is coated with the surface layer at the time of β-spodumene crystal precipitation This provides a practically excellent effect that makes it possible to efficiently produce a reinforcing member for the fused portion.
[Brief description of the drawings]
1A and 1B are explanatory views showing a reinforcing member of an optical fiber fusion part according to the present invention, in which FIG. 1A is a perspective view of a reinforcing member having a substantially half-moon-shaped cross section, and FIG. The perspective view of a reinforcement member.
FIG. 2 is an explanatory view showing a process for producing a reinforcing member for an optical fiber fusion part according to the present invention, in which (A) is a mold formed with a plurality of rows of convex portions having a substantially semicircular cross section on one side. Sheet glass, (B) is an explanatory diagram that separates into a substantially half-moon-shaped rod-shaped glass and the remaining sheet-shaped glass, and (C) is a glass member that is cut and crystallized in a heat treatment furnace. FIG.
FIG. 3 is an exploded perspective view when an optical fiber fusion part is fixed and protected by the reinforcing member of the present invention.
FIG. 4 is an exploded perspective view when an optical fiber fusion part is fixed and protected by a conventional reinforcing member.
FIGS. 5A and 5B are explanatory views showing a conventional method for manufacturing an optical fiber fused portion reinforcing member, wherein FIG. 5A is an explanatory view of crystallizing a round bar glass in a heat treatment furnace, and FIG. The explanatory view which grinds and processes into the rod-shaped crystallized glass which has the cross section of a substantially half moon shape, (C) is the explanatory view of the reinforcement member obtained by the conventional manufacturing method.
[Explanation of symbols]
DESCRIPTION OF

SYMBOLS

1, 11

Optical fiber

2, 12

Fusion part

3, 4, 13, 14

Reinforcement member

5, 15

Adhesive

7, 10

Heat treatment furnace

13a, 13b, 14a, 14b Surface G Type | mold plate glass G 'Glass member

Claims

Substantially plate-like or rod-like light, which is made of low thermal expansion crystallized glass precipitated with β-quartz solid solution crystal or β-spodumene crystal as the main crystal, and has a processed surface that is cold-worked substantially parallel to the optical fiber An optical fiber characterized in that, in the reinforcing member of the fiber fusion part, a surface layer is formed on the processed surface by heat treatment, and a surface layer is formed at the time of precipitation of β-quartz solid solution crystal or β-spodumene crystal. Reinforcing member for fusion part.