JP2005025070A - Optical attenuation method for live line fiber and optical attenuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical attenuation method in which the optical power of a live line fiber can be attenuated in a restorable manner, and also to provide an optical attenuator and an operation method of a live line fiber. <P>SOLUTION: The optical attenuation method for a live line fiber attenuates the optical power of a live optical fiber in a manner restorable by a prescribed quantity. The optical attenuator for a live line fiber has an optical fiber clamping part for fixing an optical fiber, with the optical power of a live optical fiber attenuated in the similar manner. The optical fiber clamping part is equipped with an upper and a lower cover each having a corresponding curved surface. In the curved surface of either the upper or the lower cover, there is formed a groove for guiding a primary coated optical fiber, a secondary coated optical fiber tape, or an optical cable, which are alternatively clamped by the upper and the lower cover. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３０】
表１から明らかなように、＋ １９ｄＢｍ以上のハイパワー光を照射すると、樹脂が貫通してしまうことがある（例えば、＋ １９ｄＢｍで接触の場合、＋ ２２ｄＢｍで接触または１０ｍｍの距離の場合）。また、＋ １０〜＋ １６ｄＢｍに関しては、樹脂が貫通することはないが、微小範囲（φ１ｍｍ程度）で窪む（溶ける）（例えば、＋１０ｄＢｍ、＋１３ｄＢｍで接触の場合、＋１５ｄＢｍ、＋１６ｄＢｍで接触または１０ｍｍの距離の場合）。更に、通光していないファイバと同等に扱えるのは＋ ７ｄＢｍ以下のときだけであることが分かる。即ち、通光中の光ファイバの光パワーを約＋ ７ｄＢｍ以下に復元可能に減衰させると、通光していないファイバと同等に扱えるといえる。
【００３１】
クロージャ内で活線ファイバに２分岐カプラを導入する作業を例にとって、従来の作業および本発明の作業の場合を比較しながら説明する。図８は従来の作業フローを説明する図である。従来の作業フローにおいては、図８（ａ）に示すように、光ファイバは通光中である。図８（ｂ）に示すように、通光中の活線ファイバをカプラを組み入れるために切断すると、放射される光によって、クロージャ筐体、または、収納トレイが損傷する可能性がある。
更に、各ファイバ端末の境面切断処理をする際に、被覆除去具、ファイバカッタの樹脂部分の損傷の可能性がある。更に、図８（ｃ）に示すように、融着接続を行うと（入出力２箇所）、融着機の樹脂部品を損傷する可能性がある。更に、終端部も上述したと同様の可能性がある。
【００３２】
上述した部材に対する損傷を避けるためには、光パワーを減衰させてから作業する必要がある。この発明においては、上述したように、通光中の光ファイバの光パワーを所定量だけ復元可能に減衰させる。即ち、通光中の光ファイバの光パワーを減衰させることによって、ファイバ切断、被覆除去、融着接続、メカスプ接続、コネクタ着脱、コネクタ端面清掃等の作業を活線（通光中の）ファイバにおいて行うことができ、更に、復元可能に減衰しているので、作業終了後、原状に復帰することができることが重要である。
【００３３】
図１はこの発明の作業フローを説明する図である。図１（ａ）に示すように、１つの方法として、例えば、活線ファイバの切断（予定）部手前で光ファイバを小径に曲げて光パワーを減衰させてから作業を行う方法が考えられる。図１（ｂ）に示すように、上述したように光ファイバを小径に曲げて光パワーを減衰させてから、活線ファイバを切断する。この状態では、光パワーは十分に減衰されているので、放射される光によって、クロージャ筐体、または、収納トレイが損傷することはない。更に、各ファイバ端末を切断しても、被覆除去具、ファイバカッタの樹脂部分が損傷することはない。
【００３４】
更に、図１（ｃ）に示すように、融着接続を行っても（入出力２箇所）、融着機の樹脂部品を損傷することはない。更に、カプラ出力端の一方は加入者宅へ繋がり、他方の出力端は加入者があるまで解放端となっている。従来の方法によると、カプラで分配されて光パワーが低下してるとはいえ、ここから放射されてしまう光にも留意する必要がある。従って、この発明による活線ファイバの光減衰方法は、光ファイバ終端部の処理方法としても同様に効果的に利用することができる。
【００３５】
上述した本発明の活線ファイバの光減衰方法においては、光ファイバを１回曲げて、曲げによる放射損失を利用して行う場合について例示的に説明したが、光ファイバの曲げを複数回直列に配置して、曲げによる放射損失を繰り返して光ファイバの光減衰を行っても良い。即ち、カスケード式に曲げを繰り返して、少しづつ減衰して所定のパワーまで減衰する。このようにすることによって、ファイバ切断、被覆除去、融着接続、メカスプ接続、コネクタ着脱、コネクタ端面清掃等の作業を活線（通光中の）ファイバにおいて行うことができ、更に、復元可能に減衰することができる。
【００３６】
図３は、この発明の活線ファイバの光減衰器の１つの態様を示す図である。図３（ａ）は、上蓋部および下蓋部を備えたこの発明の光減衰器を説明する側面図である。図３（ｂ）は、下蓋部の上面部を説明する図である。この発明の活線ファイバの光減衰器の１つの態様は、通光中の光ファイバの光パワーを所定量だけ復元可能に減衰させた状態で光ファイバを固定する光ファイバ把持部を備えた、活線ファイバの光減衰器である。即ち、上述した光ファイバ把持部が、対応する曲面をそれぞれ有する上蓋部、および下蓋部を備えており、上蓋部および下蓋部の何れか一方の曲面に光ファイバ素線、光ファイバテープ心線、または光ケーブルを誘導する溝部が形成されており、光ファイバ素線、光ファイバテープ心線、または光ケーブルが上蓋部および下蓋部によって把持される、活線ファイバの光減衰器である。
【００３７】
図３（ａ）に示すように、この発明の活線ファイバの光減衰器は、通光中の光ファイバの光パワーを所定量だけ復元可能に減衰させた状態で光ファイバを固定する光ファイバ把持部１を備えている。光ファイバ把持部１は、上蓋部２および下蓋部３を備えている。上蓋部２および下蓋部３は、それぞれ対応する曲面４、５を有している。即ち、上蓋部２の下面４および下蓋部３の上面５は、相互に組み合わせることによって、密接に嵌合する曲面を有している。
【００３８】
更に、下蓋部３は、図３（ａ）に点線で示し、図３（ｂ）に示すように、光ファイバ素線、光ファイバテープ心線、または光ケーブルを誘導する溝部が形成されている。なお、図３に示す態様の活線ファイバの光減衰器においては、下蓋部に溝部が形成されているが、上蓋部の下面に溝部を形成しても良い。上述した、上蓋部および下蓋部の何れか一方の曲面に形成された溝部に、光ファイバ素線、光ファイバテープ心線、または光ケーブルが誘導・収容されて、上蓋部および下蓋部によって把持される。上述した光ファイバ把持部の長さを調整することによって、所望の光減衰を得ることができる。即ち、光ファイバ把持部の長さを長くすることによって、光減衰量を多くすることができ、短くすることによって、光減衰量を小さくすることができる。いずれの場合においても、復元性を考慮することが必要である。
【００３９】
図４は、この発明の活線ファイバの光減衰器の他の１つの態様を示す図である。図４（ａ）に示す態様においては、波状に組み合わせる複数個の円弧の中心角が、光の進行方向に沿って逐次大きくなっている。即ち、図の左から右に行くに従って、Ｒが小さくなっている。このような円弧の組み合わせによって、活線ファイバの光の減衰をより確実にすることができる。図４（ｂ）に示す態様においては、波状に組み合わせる複数個の円弧の中心角が光の進行方向に沿って逐次大きくなり、次いで逐次小さくなり、中心部に関して右左対象の形状を形成している。即ち、図の左から中央部にかけては、Ｒが次第に小さくなり、中央部から右に行くに従って、逆にＲが次第に大きくなり、全体として、中央に関して、左右が対称になっている。このような円弧の組み合わせによって、より効果的な光の減衰が可能になると共に、入射端、出射端の混同を防ぐことが出来る。
【００４０】
図５は、この発明の活線ファイバの光減衰器の１つの態様を説明する概略斜視図である。活線ファイバの光減衰器は、図５に示すように、相互に組み合わされて、密接に嵌合する曲面４、５を有している上蓋部２および下蓋部３を備えている。光ファイバが収納される溝部は、図３および図４を参照して説明したような形状を有している。溝部に活線ファイバが収納されて組み合わされた上蓋部２および下蓋部３は、固定部材１０によって、ファイバを把持した状態で固定される。活線ファイバの光減衰器は、使用する状況に対応して、所定形状の部材１１に搭載されていてもよい。
【００４１】
図６は、活線ファイバの光減衰器における、光ファイバの曲げ方を説明する図である。図６（ａ）は、上述したように、活線ファイバを円形に曲げた状態を説明する図である。図６（ｂ）および図６（ｃ）は、円弧を波型形状に繰り返した状態を示す図である。即ち、図６（ｂ）においては、中心角９０度で反転して波型形状に曲げた状態を示し、図６（ｃ）においては、中心角６０度で反転して波型形状に曲げた状態を示している。この発明の活線ファイバの光減衰器においては、上述したように減衰が曲げによる放射損失を利用して行われ、光ファイバ把持部が、中心角が１８０°以下の少なくとも１個の円弧からなっていてもよい。上述したファイバ把持部が、中心角が１８０°以下の複数個の円弧を波状に組み合わせたものからなっていてもよい。上述した円弧の少なくとも一つの中心角が９０°以上であってもよい。円弧の半径がＲ３〜Ｒ９であってもよい。即ち、この発明の活線ファイバの光減衰器は、図３を参照して説明した態様の他に、図６（ａ）に示す１個または複数個の円形に曲げた状態で光ファイバを保持する態様であってもよい。
【００４２】
なお、上述した光ファイバ把持部が、金属、または、白色または透明の樹脂で形成されていてもよい。その理由は、把持部材が近赤外光を吸収し易い材質（樹脂が黒色に着色されている、例えば、ＡＢＳ樹脂にカーボンブラックが配合されているＡＢＳ黒）であると、光パワーが大きい場合、ファイバからの漏れ光を吸収して発熱し、溶融してしまう可能性がある。従って、把持部材の材質は、金属等の高融点材料か、白色か透明な（近赤外光の吸収が少ない）樹脂が好ましい。
更に、この発明の活線ファイバの光減衰器の他の１つの態様は、光ファイバをファイバ把持部によって把持する際に、光ファイバに側圧をかけて、マイクロベンディングロスを発生させる、側圧付加部を更に備えていてもよい。
【００４３】
更に、この発明の活線ファイバの作業方法の１つの態様は、通光中の光ファイバの光パワーを所定量だけ復元可能に減衰させて、ファイバ切断、被覆除去、融着接続、メカスプ接続、コネクタ着脱、コネクタ端面清掃等の作業を行い、作業終了後に光パワーを復元させる、活線ファイバの作業方法である。
更に、上述したこの発明の活線ファイバの光減衰方法を用いて、ファイバ端末を処理することができる。
【００４４】
実施例
次にこの発明の活線ファイバの光減衰方法および光減衰器を実施例によって更に詳細に説明する。
現実的には、上述したような映像配信システムの場合には、光パワーは最大＋２３ｄＢｍを考えれば十分である。また、表１を参照して説明したように、光パワーが＋７ｄＢｍ以下であれば、通光していないファイバと同等に扱える安全な領域といえる。従って、安全率を考慮して、光パワーが２０ｄＢ減衰するような曲げを活線光ファイバの外部から加えることができれば、十分な効果が得られ、通光中の諸作業が可能になる。
【００４５】
汎用ＳＭＦに関して曲げ径（半径）と曲げ損失（単位長）の関係のシミュレーションを行った。その結果を図２に示す。図２において、縦軸には曲げ損失（Ｍａｃｒｏｂｅｎｄ ｌｏｓｓ （ｄＢ／ｍ））を、横軸には曲げ径（Ｂｅｎｄ ｒａｄｉｕｓ（ｍｍ））を示し、波長１５５０ｎｍのときの両者の関係を示す。更に、本結果をもとに光パワーの２０ｄＢ の減衰を実現することができる曲げ径と曲げ条長を計算した。その計算結果を表２に示す。
【００４６】
【表２】

【００４７】
クロージャ等での利用を考えると、曲げ条長が５００ｍｍ以上（Ｒ１０以上）という状態は、光ファイバを棒に巻き付けるにしても手間がかかり過ぎ現実的ではない。逆に曲げ半径Ｒが小さければ小さいほど曲げ条長は短く設計可能だが、今度はファイバ破断確率が上昇してしまう。ファイバ破断確率は、曲げ半径と負荷歪み印加時間がパラメータとなるが、融着接続作業を想定し負荷歪み印加時間を数十分とすると、曲げ半径２ｍｍ以下は現実的ではない（ファイバが破断する確率が非常に高くなる）。光パワーの減衰も、作業等の終了によって、元に戻したときに復元可能であることが重要である。従って、曲げ半径はＲ３からＲ９の間が最適であると考えられる。
【００４８】
活線ファイバを曲げる方法としては、簡単には円柱状の棒に活線ファイバを巻き付ける方法が考えられる。例えばＲ８の棒を使用した場合、周長は５０ｍｍ程度となるので、活線ファイバを棒の周りに３周以上巻けば２０ｄＢ 以上のパワーダウンが可能な計算となる。Ｒ６以下であれば１周以上巻けば良い。なお、巻き付ける棒の形状が円錐であっても良い。つまり、円錐の形状は、棒の一端がＲ９であり、もう一端がＲ３である。徐々にＲが小さくなるため、巻き付ける場所により、減衰量をコントロールすることができる。
【００４９】
他の方法としては図３を参照して説明したような光減衰器（治具）を使用することが考えられる。光減衰器は、上述したように、通光中の光ファイバの光パワーを所定量だけ復元可能に減衰させた状態で光ファイバを固定（把持）する光ファイバ把持部１を備えている。光ファイバ把持部１は、上蓋部２および下蓋部３を備えており、上蓋部２および下蓋部３は、それぞれ対応する曲面４、５を有している。即ち、上蓋部２の下面４および下蓋部３の上面５は、相互に組み合わせることによって、密接に嵌合する曲面を有している。下蓋部３は、光ファイバ素線、光ファイバテープ心線、または光ケーブルを誘導する溝部が形成されている。上述した、上蓋部および下蓋部の何れか一方の曲面に形成された溝部に、光ファイバ素線、光ファイバテープ心線、または単心、多心光ケーブルが誘導・収容されて、磁石もしくはバネ力により上蓋部および下蓋部によって把持される。上述した光ファイバ把持部の長さを調整することによって、所望の光減衰を得ることができる。即ち、光ファイバ把持部の長さを長くすることによって、光減衰量を多くすることができ、短くすることによって、光減衰量を小さくすることができる。いずれの場合においても、復元性を考慮することが必要である。
【００５０】
ここで、図２および表２に示した曲げ損失（理論値）は、曲げ方向が常に同じ場合の計算である。図３に示した通りに波状にした（曲げ方向を変えた）場合には、電界分布の揺らぎが解消されるため（直感的には直線に近づくため）、曲げ損失の実測値は理論値よりも小さくなる。具体的には以下の通りである。
【００５１】
例えば、図６（ａ）に示すように、Ｒ８で一周の輪取りを形成した場合、曲げ条長は約５０ｍｍとなる。そのときの曲げ損失（実測値）は、７．２ｄＢである。図６（ｂ）、図６（ｃ）に関してもＲ８で曲げ条長は約５０ｍｍとなる。図６（ｂ）では、中心角９０°でターンし、図６（ｃ）では、中心角６０°でターンしている。このとき、曲げ損失の理論値は６．７ｄＢであるが、実測値は、図６（ｂ）の場合で、６．６ｄＢ、図６（ｃ）の場合で、２．１ｄＢである。実験のバラツキ（光ファイバを曲げ方のバラツキ）が１ｄＢ程度あるので図６（ａ）と図６（ｂ）の間に有意差はないが、図６（ｃ）に示すように中心角６０°でターンすると、設計通りの損失が得られないことは明らかである。従って、円弧の中心角を少なくとも９０°以上にすることが望ましい。
【００５２】
【発明の効果】
この発明によると、活線ファイバの光パワーを復元可能に減衰することができる活線ファイバの光減衰方法、活線ファイバの光減衰治具、および、活線ファイバの作業方法を提供することができる。
【図面の簡単な説明】
【図１】図１は、この発明の作業フローを説明する図である。
【図２】図２は、汎用ＳＭＦに関して行った曲げ径（半径）と曲げ損失（単位長）の関係のシミュレーション結果を示すグラフである。
【図３】図３は、この発明の活線ファイバの光減衰器の１つの態様を示す図である。
【図４】図４は、この発明の活線ファイバの光減衰器の他の１つの態様を示す図である。
【図５】図５は、この発明の活線ファイバの光減衰器の１つの態様を説明する概略斜視図である。
【図６】図６は、活線ファイバの光減衰器における、光ファイバの曲げ方を説明する図である。
【図７】図７は、映像配信システムを示す概略図である。
【図８】図８は、従来の作業フローを説明する図である。
【符号の説明】
１．光減衰器（治具）
２．上蓋部
３．下蓋部
４．上蓋部の下部曲面
５．下蓋部の上部曲面
６．溝部
１０１．センタ
１０２．光源
１０３．光アンプ
１０４．光カプラ
１０５．伝送ファイバ
１０６．光カプラ
１０７．加入者
１０８．加入者
１０９．加入者[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical attenuating method and an optical attenuator, and more particularly to an optical attenuating method and an optical attenuator for a light-transmitting optical fiber for preventing damage to equipment during optical fiber installation work.
[0002]
[Prior art]
In recent years, with the increase in communication capacity and the increase in transmission distance accompanying the spread of WDM systems, the output of optical transmission lines has been increased. For example, the excitation light in an EDF amplifier or a Raman amplifier reaches several hundred mW to several W. In addition, signal light may reach several hundred mW when multiple wavelengths are combined. At this time, since the core diameter of the optical fiber is very small (in the case of SMF, about φ10 μm), the optical power density becomes very high. For this reason, when this light directly irradiates work equipment, there is a risk of equipment damage.
[0003]
Therefore, conventionally, it is not possible to work on an optical fiber that is passing light through as it is, and during optical fiber installation work (fiber cutting, sheath removal, fusion splicing, mechanical sp connection, connector attachment / detachment, connector end face cleaning, etc.) It was a common practice to work after stopping the light source. That is, the work in a state where light is transmitted through the optical fiber has not been performed.
[0004]
[Patent Literature]
JP-A-7-225319
[Problems to be solved by the invention]
However, recently, there has been an increasing demand for performing the above-described operations (fiber cutting, sheath removal, fusion splicing, mechanical splicing, connector attachment / detachment, connector end face cleaning, etc.) on live (through light) fiber. Yes. FIG. 7 is a schematic diagram showing a video distribution system. For example, in the case of a video distribution system, the light from the light source 102 is amplified by the optical amplifier 103 at the center 101, distributed by the optical coupler 104, and distributed to the subscriber 107. The remote area is transmitted by the transmission fiber 105, distributed by the optical coupler 106, and distributed to the subscribers 108 and 109. As shown in FIG. 7, since optical fibers are configured in a tree shape for subscribers and video is distributed (simultaneous distribution), once service provision is started, it is difficult to stop the service. Even when the number of subscribers increases, it is necessary to work on the above-described live fiber while passing through the optical fiber without stopping the light source.
[0006]
In the video distribution system of FIG. 7, it is a realistic value that can sufficiently occur that the optical power in the transmission fiber reaches +20 dBm. When the optical power reaches +20 dBm, the optical power density in the optical fiber (SMF) core is about 0.13 MW / cm ² , and there is a risk that various problems occur in each operation using the live fiber. For example, if the connector end face is wiped and cleaned while emitting light, the connector end face may be damaged due to the high optical power density described above.
[0007]
Actually, work such as fusion splicing of live fiber in the closure is conceivable, and there is a concern about damage to the resin parts of the fusion machine, the closure housing or the fiber storage tray in the closure.
[0008]
Accordingly, an object of the present invention is to provide a live fiber optical attenuation method, a live fiber optical attenuation jig, and a live fiber working method capable of recovering the optical power of the live fiber in a recoverable manner. There is to do.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, the optical power of the passing optical fiber is attenuated so as to be restored by a predetermined amount, that is, the passing optical fiber is bent at least once to reduce radiation loss due to bending. When the optical power is attenuated by using it, operations such as fiber cutting, stripping removal, fusion splicing, mechanical splicing, connector attachment / detachment, connector end face cleaning, etc. can be performed on a live (through light) fiber. It was found that when the bending was performed within a recoverable range, the original shape could be restored after the work was completed.
[0010]
The present invention has been made on the basis of the above-described research results, and the first aspect of the optical fiber attenuation method of the live fiber according to the present invention is capable of restoring the optical power of the passing optical fiber by a predetermined amount. This is an optical attenuation method for a live fiber, which is attenuated.
[0011]
In a second aspect of the optical fiber attenuation method of the present invention, the attenuation of the optical power is performed by bending the optical fiber at least once and making use of radiation loss due to bending. Is the method.
[0012]
The third aspect of the optical fiber optical attenuation method of the present invention is an optical fiber optical attenuation method in which the bending of the optical fiber is arranged in series a plurality of times.
[0013]
The fourth aspect of the optical fiber optical attenuation method of the present invention is an optical fiber optical attenuation method in which the bending diameter of the optical fiber is R3 to R9.
[0014]
A fifth aspect of the optical fiber attenuation method of the present invention is a hot fiber optical attenuation method in which a side pressure is applied to the optical fiber to generate a microbending loss and further increase the attenuation.
[0015]
A first aspect of the optical fiber attenuator of the present invention comprises an optical fiber gripping part for fixing the optical fiber in a state where the optical power of the optical fiber being passed through is attenuated so as to be restored by a predetermined amount. It is an optical attenuator for live fiber.
[0016]
According to a second aspect of the optical fiber attenuator of the live fiber of the present invention, the attenuation is performed using a radiation loss due to bending, and the optical fiber gripping portion has at least one arc having a central angle of 180 ° or less. This is an optical attenuator for a live fiber.
[0017]
In a third aspect of the optical fiber attenuator of the live fiber according to the present invention, the fiber gripping portion is a light of a live fiber in which a plurality of arcs having a central angle of 180 ° or less are combined in a wave shape. Attenuator.
[0018]
The 4th aspect of the optical attenuator of the live fiber of this invention is an optical attenuator of the live fiber in which at least one central angle of the said circular arc is 90 degrees or more.
[0019]
A fifth aspect of the optical fiber attenuator of the live fiber according to the present invention is an optical attenuator of the live fiber in which the diameter of the arc is R3 to R9.
[0020]
A sixth aspect of the optical fiber attenuator of the present invention is an optical fiber attenuator in which the optical fiber gripping part is made of metal, or white or transparent resin.
[0021]
According to a seventh aspect of the optical fiber attenuator of the present invention, there is further provided a side pressure adding unit that generates a microbending loss by applying a side pressure to the optical fiber when the optical fiber is held by the fiber holding unit. It is an optical attenuator for a hot-wire fiber.
[0022]
According to an eighth aspect of the optical fiber attenuator of the live fiber of the present invention, the optical fiber gripping portion includes an upper lid portion and a lower lid portion each having a corresponding curved surface, and the upper lid portion and the lower lid portion. A groove portion for guiding an optical fiber strand, an optical fiber ribbon, or an optical cable is formed in any one of the curved surfaces, and the optical fiber strand, the optical fiber ribbon, or the optical cable is connected to the upper lid portion and It is an optical attenuator of a live fiber held by the lower lid part.
[0023]
Another aspect of the optical fiber attenuator of the live fiber according to the present invention is an optical attenuator of the live fiber in which the central angles of the plurality of arcs combined in a wave shape are sequentially increased along the light traveling direction. .
[0024]
Another aspect of the optical attenuator of the live fiber according to the present invention is such that the central angle of the plurality of arcs combined in a wavy shape increases sequentially along the light traveling direction, then decreases gradually, and is symmetrical with respect to the central portion. It is an optical attenuator of a live-line fiber that forms.
[0025]
The first aspect of the working method of the live fiber according to the present invention is to attenuate the optical power of a passing optical fiber by a predetermined amount so as to be restored, so that fiber cutting, coating removal, fusion splicing, mechanical sp connection, connector This is a live fiber working method in which work such as attachment / detachment and connector end face cleaning is performed, and optical power is restored after the work is finished.
[0026]
A first aspect of the fiber terminal processing method for a live fiber according to the present invention is a fiber terminal processing method using the above-described optical attenuation method for a live fiber.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
With reference to the drawings, the optical fiber attenuating method, the optical fiber attenuator, and the active fiber working method of the present invention will be described.
One aspect of the optical fiber attenuating method of the present invention is an optical fiber attenuating method for attenuating the optical power of a passing optical fiber by a predetermined amount so as to be restored. The optical power attenuation described above may be performed by bending the optical fiber at least once and using the radiation loss due to the bending. Further, the optical fiber may be bent a plurality of times in series to perform predetermined light attenuation. Further, the above-described bending diameter of the optical fiber may be R3 to R9. In order to further increase the amount of attenuation, a microbending loss may be generated by applying a side pressure to the optical fiber.
[0028]
This will be specifically described below.
The ABS resin (black), which is sometimes used as a material for fuser parts and also as a fiber storage tray material for closures, was examined for damage to the resin by irradiating high-power light. . However, in order to confirm the harsh conditions, the experiment was conducted on the end face of the fiber end face. The results are shown in Table 1.
[0029]
[Table 1]

[0030]
As is clear from Table 1, when high-power light of +19 dBm or higher is irradiated, the resin may penetrate (for example, in the case of contact at +19 dBm, in the case of contact at +22 dBm or a distance of 10 mm). In addition, for +10 to +16 dBm, the resin does not penetrate, but is depressed (melted) in a very small range (about φ1 mm). If distance). Further, it can be seen that the fiber can be handled in the same way as a non-light-transmitting fiber only when it is +7 dBm or less. That is, it can be said that if the optical power of a passing optical fiber is attenuated so as to be restored to about +7 dBm or less, it can be handled in the same manner as a non-transmitting fiber.
[0031]
The operation of introducing the two-branch coupler into the live fiber in the closure will be described as an example, comparing the conventional work and the work of the present invention. FIG. 8 is a diagram for explaining a conventional work flow. In the conventional work flow, as shown in FIG. 8A, the optical fiber is passing light. As shown in FIG. 8B, when the live fiber that is passing light is cut to incorporate a coupler, the closure housing or the storage tray may be damaged by the emitted light.
Furthermore, there is a possibility that the coating removal tool and the resin part of the fiber cutter may be damaged when the boundary surface of each fiber terminal is cut. Furthermore, as shown in FIG. 8C, if fusion splicing is performed (two locations for input and output), there is a possibility of damaging the resin parts of the fusing machine. Further, the end portion may have the same possibility as described above.
[0032]
In order to avoid damage to the above-described member, it is necessary to work after the optical power is attenuated. In the present invention, as described above, the optical power of the optical fiber being passed through is attenuated so as to be restored by a predetermined amount. That is, by attenuating the optical power of the optical fiber that is passing light, operations such as fiber cutting, coating removal, fusion splicing, mechanical splicing, connector attachment / detachment, and connector end face cleaning are performed on live (passing light) fiber. It is important to be able to return to the original state after the end of the work since it can be done and is attenuated so that it can be restored.
[0033]
FIG. 1 is a diagram for explaining the work flow of the present invention. As shown in FIG. 1A, as one method, for example, a method is considered in which work is performed after the optical fiber is bent to a small diameter in front of the cut (planned) portion of the live fiber to attenuate the optical power. As shown in FIG. 1B, the optical fiber is bent to a small diameter as described above to attenuate the optical power, and then the live fiber is cut. In this state, since the optical power is sufficiently attenuated, the closure housing or the storage tray is not damaged by the emitted light. Furthermore, even if each fiber terminal is cut, the resin removing portion of the coating removal tool and the fiber cutter will not be damaged.
[0034]
Furthermore, as shown in FIG. 1C, even if fusion splicing is performed (two locations of input and output), the resin parts of the fusing machine are not damaged. Further, one of the coupler output terminals is connected to the subscriber's house, and the other output terminal is an open end until there is a subscriber. According to the conventional method, it is necessary to pay attention to the light emitted from the light source though it is distributed by the coupler and the optical power is reduced. Therefore, the optical fiber attenuation method according to the present invention can be effectively used as a method for treating the optical fiber terminal portion as well.
[0035]
In the above-described method for attenuating a live fiber according to the present invention, the case where the optical fiber is bent once and performed using the radiation loss due to the bending has been exemplarily described. The optical fiber may be attenuated by arranging and repeating the radiation loss due to bending. That is, the bending is repeated in a cascade manner, and gradually attenuates to a predetermined power. By doing so, operations such as fiber cutting, coating removal, fusion splicing, mechanical splicing, connector attachment / detachment, connector end face cleaning, etc. can be performed on live (through light) fiber, and further restoration is possible. Can be attenuated.
[0036]
FIG. 3 is a view showing one embodiment of the optical attenuator of the live fiber according to the present invention. FIG. 3A is a side view for explaining an optical attenuator of the present invention having an upper lid portion and a lower lid portion. FIG. 3B is a diagram illustrating the upper surface portion of the lower lid portion. One aspect of the optical fiber attenuator of the live fiber of the present invention includes an optical fiber gripping part for fixing the optical fiber in a state where the optical power of the optical fiber being passed is attenuated so as to be restored by a predetermined amount. It is an optical attenuator for a live fiber. That is, the above-described optical fiber gripping portion includes an upper lid portion and a lower lid portion each having a corresponding curved surface, and an optical fiber strand or an optical fiber tape core is provided on one curved surface of the upper lid portion or the lower lid portion. An optical attenuator for a live fiber, in which a wire or a groove for guiding an optical cable is formed, and an optical fiber strand, an optical fiber ribbon, or an optical cable is held by an upper lid portion and a lower lid portion.
[0037]
As shown in FIG. 3A, the optical fiber attenuator of the live fiber according to the present invention is an optical fiber that fixes the optical fiber in a state where the optical power of the optical fiber being transmitted is attenuated so as to be restored by a predetermined amount. A grip 1 is provided. The optical fiber gripping portion 1 includes an upper lid portion 2 and a lower lid portion 3. The upper lid portion 2 and the lower lid portion 3 have corresponding curved surfaces 4 and 5, respectively. That is, the lower surface 4 of the upper lid portion 2 and the upper surface 5 of the lower lid portion 3 have curved surfaces that are closely fitted by being combined with each other.
[0038]
Further, the lower lid portion 3 is indicated by a dotted line in FIG. 3A, and as shown in FIG. 3B, a groove portion for guiding the optical fiber strand, the optical fiber ribbon, or the optical cable is formed. . In the optical fiber attenuator of the embodiment shown in FIG. 3, the groove portion is formed in the lower lid portion, but the groove portion may be formed in the lower surface of the upper lid portion. An optical fiber strand, an optical fiber ribbon, or an optical cable is guided and accommodated in the groove formed on the curved surface of either the upper lid portion or the lower lid portion, and is gripped by the upper lid portion and the lower lid portion. Is done. A desired light attenuation can be obtained by adjusting the length of the above-described optical fiber gripping portion. That is, the optical attenuation can be increased by increasing the length of the optical fiber gripping portion, and the optical attenuation can be decreased by decreasing the length. In any case, it is necessary to consider the recoverability.
[0039]
FIG. 4 is a view showing another embodiment of the optical attenuator of the live fiber according to the present invention. In the embodiment shown in FIG. 4 (a), the central angles of a plurality of arcs combined in a wave shape are successively increased along the light traveling direction. That is, R decreases from the left to the right in the figure. By such a combination of arcs, it is possible to more reliably attenuate the light of the live fiber. In the mode shown in FIG. 4B, the central angles of a plurality of arcs combined in a wavy shape increase sequentially along the light traveling direction, then decrease gradually, forming a right-left target shape with respect to the central portion. . That is, R gradually decreases from the left to the center of the figure, and R gradually increases from the center to the right, and as a whole, the left and right are symmetrical with respect to the center. Such a combination of arcs enables more effective attenuation of light and prevents confusion between the input end and the output end.
[0040]
FIG. 5 is a schematic perspective view for explaining one embodiment of the optical attenuator of the live fiber of the present invention. As shown in FIG. 5, the optical attenuator of the hot-wire fiber includes an upper lid portion 2 and a lower lid portion 3 having curved surfaces 4 and 5 which are combined with each other and are closely fitted. The groove portion in which the optical fiber is accommodated has a shape as described with reference to FIGS. The upper lid portion 2 and the lower lid portion 3 combined with the live fiber stored in the groove portion are fixed by the fixing member 10 in a state where the fiber is gripped. The optical attenuator of the hot-wire fiber may be mounted on the member 11 having a predetermined shape in accordance with the use situation.
[0041]
FIG. 6 is a diagram for explaining how to bend an optical fiber in an optical attenuator for a live fiber. FIG. 6A is a diagram for explaining a state in which the live fiber is bent into a circle as described above. FIG. 6B and FIG. 6C are diagrams showing a state where an arc is repeated in a wave shape. That is, FIG. 6 (b) shows a state of being inverted and bent into a corrugated shape at a central angle of 90 degrees, and in FIG. 6 (c), it was inverted at a central angle of 60 degrees and bent into a corrugated shape. Indicates the state. In the optical fiber attenuator of the present invention, attenuation is performed using the radiation loss due to bending as described above, and the optical fiber gripping portion is composed of at least one arc having a central angle of 180 ° or less. It may be. The fiber gripping portion described above may be formed by combining a plurality of arcs having a central angle of 180 ° or less in a wave shape. 90 degrees or more of at least one central angle of the above-mentioned circular arc may be sufficient. The radius of the arc may be R3 to R9. That is, the optical fiber attenuator of the live fiber according to the present invention holds the optical fiber in a state of being bent into one or a plurality of circles shown in FIG. 6A in addition to the embodiment described with reference to FIG. It is also possible to use this mode.
[0042]
In addition, the optical fiber holding part mentioned above may be formed with the metal or white or transparent resin. The reason is that if the gripping member is a material that easily absorbs near-infrared light (the resin is colored black, for example, ABS black in which ABS resin is mixed with carbon black), the light power is large. The light leaking from the fiber may be absorbed to generate heat and melt. Therefore, the material of the gripping member is preferably a high melting point material such as metal or a white or transparent resin (low absorption of near infrared light).
Furthermore, another aspect of the optical fiber attenuator of the live fiber according to the present invention is a lateral pressure applying section that generates a microbending loss by applying a lateral pressure to the optical fiber when the optical fiber is gripped by the fiber gripping section. May be further provided.
[0043]
Further, according to one aspect of the working method of the live fiber of the present invention, the optical power of the passing optical fiber is attenuated so as to be restored by a predetermined amount, so that fiber cutting, coating removal, fusion splicing, mechanical sp connection, This is a live fiber working method in which work such as connector attachment / detachment and connector end face cleaning is performed, and optical power is restored after the work is completed.
Furthermore, a fiber terminal can be processed using the optical fiber optical attenuation method of the present invention described above.
[0044]
EXAMPLES Next, the optical fiber attenuating method and optical attenuator of the present invention will be described in more detail with reference to examples.
Actually, in the case of the video distribution system as described above, it is sufficient to consider the maximum optical power of +23 dBm. As described with reference to Table 1, if the optical power is +7 dBm or less, it can be said that it is a safe area that can be handled in the same manner as a fiber that does not transmit light. Accordingly, in consideration of the safety factor, if a bending that attenuates the optical power by 20 dB can be applied from the outside of the live optical fiber, a sufficient effect can be obtained, and various operations during light transmission can be performed.
[0045]
A simulation of the relationship between the bending diameter (radius) and bending loss (unit length) was performed for the general-purpose SMF. The result is shown in FIG. In FIG. 2, the vertical axis indicates bending loss (Macrobend loss (dB / m)), the horizontal axis indicates the bending diameter (Bend radius (mm)), and the relationship between the two at a wavelength of 1550 nm is shown. Furthermore, based on this result, the bending diameter and bending length capable of realizing the attenuation of 20 dB of optical power were calculated. The calculation results are shown in Table 2.
[0046]
[Table 2]

[0047]
Considering the use in a closure or the like, the state where the bending strip length is 500 mm or more (R10 or more) is not realistic even if the optical fiber is wound around the rod. Conversely, the smaller the bending radius R is, the shorter the bending strip length can be designed, but this time the fiber breaking probability increases. Bending radius and load strain application time are parameters for fiber break probability, but assuming a fusion splicing operation and a load strain application time of several tens of minutes, a bending radius of 2 mm or less is not practical (fiber breaks). The probability is very high). It is important that the attenuation of the optical power can be restored when the work is restored after the work is completed. Therefore, the bend radius is considered to be optimal between R3 and R9.
[0048]
As a method of bending the live fiber, a method of winding the live fiber around a cylindrical rod can be considered. For example, when an R8 rod is used, the circumference is about 50 mm. Therefore, if the live fiber is wound around the rod three or more times, the power can be reduced by 20 dB or more. If it is R6 or less, it may be wound more than once. In addition, the shape of the rod to wind may be a cone. In other words, the conical shape is such that one end of the rod is R9 and the other end is R3. Since R gradually becomes smaller, the amount of attenuation can be controlled depending on the winding place.
[0049]
As another method, it is conceivable to use an optical attenuator (jig) as described with reference to FIG. As described above, the optical attenuator includes the optical fiber gripping unit 1 that fixes (grasps) the optical fiber in a state where the optical power of the optical fiber being passed through is attenuated so as to be restored by a predetermined amount. The optical fiber gripping portion 1 includes an upper lid portion 2 and a lower lid portion 3, and the upper lid portion 2 and the lower lid portion 3 have corresponding curved surfaces 4 and 5, respectively. That is, the lower surface 4 of the upper lid portion 2 and the upper surface 5 of the lower lid portion 3 have curved surfaces that are closely fitted by being combined with each other. The lower lid portion 3 is formed with a groove for guiding an optical fiber, an optical fiber ribbon, or an optical cable. An optical fiber strand, an optical fiber tape core, or a single-core or multi-core optical cable is guided and accommodated in the groove formed on the curved surface of one of the upper lid and the lower lid described above, and a magnet or a spring It is gripped by the upper lid portion and the lower lid portion by force. A desired light attenuation can be obtained by adjusting the length of the above-described optical fiber gripping portion. That is, the optical attenuation can be increased by increasing the length of the optical fiber gripping portion, and the optical attenuation can be decreased by decreasing the length. In any case, it is necessary to consider the recoverability.
[0050]
Here, the bending loss (theoretical value) shown in FIG. 2 and Table 2 is a calculation when the bending direction is always the same. When the wave shape is changed as shown in FIG. 3 (the bending direction is changed), the fluctuation of the electric field distribution is eliminated (intuitively, it approaches a straight line). Becomes smaller. Specifically, it is as follows.
[0051]
For example, as shown in FIG. 6 (a), when a round wheel is formed with R8, the bending strip length is about 50 mm. The bending loss (measured value) at that time is 7.2 dB. 6 (b) and 6 (c), the bending length is about 50 mm at R8. In FIG. 6 (b), it turns at a central angle of 90 °, and in FIG. 6 (c), it turns at a central angle of 60 °. At this time, the theoretical value of the bending loss is 6.7 dB, but the actual measurement value is 6.6 dB in the case of FIG. 6B and 2.1 dB in the case of FIG. There is no significant difference between FIG. 6 (a) and FIG. 6 (b) because the variation in the experiment (the variation in how the optical fiber is bent) is about 1 dB. However, as shown in FIG. 6 (c), the central angle is 60 °. It is clear that if you turn in, you will not get the designed loss. Therefore, it is desirable that the central angle of the arc is at least 90 ° or more.
[0052]
【The invention's effect】
According to the present invention, it is possible to provide a live fiber optical attenuation method, a live fiber optical attenuation jig, and a live fiber working method capable of reversibly attenuating the optical power of the live fiber. it can.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a work flow of the present invention.
FIG. 2 is a graph showing a simulation result of a relationship between a bending diameter (radius) and a bending loss (unit length) performed for a general-purpose SMF.
FIG. 3 is a view showing one embodiment of a live fiber optical attenuator of the present invention.
FIG. 4 is a diagram showing another embodiment of the optical fiber attenuator of the live fiber according to the present invention.
FIG. 5 is a schematic perspective view illustrating one embodiment of an optical attenuator for a live fiber according to the present invention.
FIG. 6 is a diagram for explaining how to bend an optical fiber in an optical attenuator of a live fiber.
FIG. 7 is a schematic diagram showing a video distribution system.
FIG. 8 is a diagram for explaining a conventional work flow;
[Explanation of symbols]
1. Optical attenuator (jig)
2. Upper lid 3. Lower lid part 4. 4. Lower curved surface of upper lid part 5. Upper curved surface of the lower lid part Groove 101. Center 102. Light source 103. Optical amplifier 104. Optical coupler 105. Transmission fiber 106. Optical coupler 107. Subscriber 108. Subscriber 109. Subscriber

Claims (17)

An optical attenuation method for a live fiber, in which the optical power of an optical fiber during light transmission is attenuated so as to be restored by a predetermined amount. The optical fiber attenuation method according to claim 1, wherein the attenuation of the optical power is performed by bending an optical fiber at least once and using radiation loss due to bending. The optical fiber attenuation method according to claim 2, wherein the bending of the optical fiber is arranged in series a plurality of times. The optical fiber attenuation method according to claim 2 or 3, wherein the bending radius of the optical fiber is R3 to R9. 5. The optical fiber attenuation method according to claim 2, wherein a side pressure is applied to the optical fiber to generate a microbending loss and further increase an attenuation amount. 6. An optical attenuator for a live-line fiber, comprising an optical fiber gripping part for fixing the optical fiber in a state where the optical power of the optical fiber being passed through is attenuated so as to be restored by a predetermined amount. The optical attenuation of a live fiber according to claim 6, wherein the attenuation is performed using radiation loss due to bending, and the optical fiber gripping portion is formed of at least one arc having a central angle of 180 ° or less. vessel. The optical fiber attenuator for a live fiber according to claim 7, wherein the fiber gripping part is formed by combining a plurality of arcs having a central angle of 180 ° or less in a wavy shape. 9. The optical fiber attenuator of a hot-wire fiber according to claim 8, wherein the central angles of the plurality of arcs combined in a wave shape are successively increased along the light traveling direction. 9. The hot fiber according to claim 8, wherein a central angle of the plurality of arcs combined in a wavy shape sequentially increases along the light traveling direction, then decreases gradually, and forms a symmetrical shape with respect to the central portion. Optical attenuator. The optical attenuator for a live fiber according to claim 8, wherein at least one central angle of the arc is 90 ° or more. The optical attenuator for a live fiber according to any one of claims 7 to 11, wherein a radius of the arc is R3 to R9. The optical fiber attenuator according to any one of claims 6 to 12, wherein the optical fiber gripping portion is formed of a metal or a white or transparent resin. 14. The apparatus according to claim 6, further comprising a side pressure adding unit that applies a side pressure to the optical fiber to generate a microbending loss when the optical fiber is held by the fiber holding unit. Optical fiber attenuator for live fiber. The optical fiber gripping portion includes an upper lid portion and a lower lid portion each having a corresponding curved surface, and an optical fiber strand and an optical fiber tape core are provided on the curved surface of either the upper lid portion or the lower lid portion. The live wire according to claim 6, wherein a groove portion for guiding a wire or an optical cable is formed, and the optical fiber strand, the optical fiber tape core wire, or the optical cable is gripped by the upper lid portion and the lower lid portion. Fiber optical attenuator. The optical power of the passing optical fiber is attenuated so that it can be restored by a predetermined amount, and operations such as fiber cutting, coating removal, fusion splicing, mechanical sp connection, connector attachment / detachment, and connector end face cleaning are performed. A live fiber working method that restores energy. The working method of the hot-wire fiber using the method of any one of Claims 1-5.

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