JP2005062477A

JP2005062477A - Optical fiber, optical component, method for manufacturing optical fiber, and method for manufacturing optical component

Info

Publication number: JP2005062477A
Application number: JP2003292449A
Authority: JP
Inventors: Daizo Nishioka; 大造西岡; Toshifumi Hosoya; 俊史細谷; Takemi Hasegawa; 健美長谷川; Hideyori Sasaoka; 英資笹岡
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2003-08-12
Filing date: 2003-08-12
Publication date: 2005-03-10

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber which can reduce connection loss as an optical fiber which has a hole extending along the fiber axis and can reduce connection loss, an optical component, and methods for manufacturing them. SOLUTION: The optical fiber 10 is an optical fiber which has a hole H<SB>1</SB>extending along the fiber axis, and is characterized in that: a 1st area α<SB>1</SB>as a partial area which includes one end surface 10A and extends along the fiber axis is solid; in a 2nd area α<SB>2</SB>as another partial area which is adjacent to the 1st area and extends along the fiber axis, the internal diameter of the hole gradually decreases up to the border B between the 1st area and 2nd area so that the hole is closed at the border B; and a mode field diameter on the end surface at a wavelength 1.55 μm varies from a mode field diameter of a 3rd area where the internal diameter is nearly constant along the fiber axis at a wavelength of 1.55 μm. COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、ファイバ軸方向に延びる孔を有する光ファイバ、光部品、及びそれらの製造方法に関する。 The present invention relates to an optical fiber having a hole extending in the fiber axial direction, an optical component, and a manufacturing method thereof.

ファイバ軸方向に延びる孔を有する光ファイバには、ホーリーファイバやフォトニック結晶ファイバと呼ばれるものがある。以下、このようなファイバ軸方向に延びる孔を有する光ファイバを微細構造光ファイバと称す。 Some optical fibers having holes extending in the fiber axis direction are called holey fibers or photonic crystal fibers. Hereinafter, an optical fiber having such a hole extending in the fiber axial direction is referred to as a microstructured optical fiber.

微細構造光ファイバにおいては、ファイバ軸方向に延びる孔に、異物や水蒸気などが入ると微細構造光ファイバで光を伝搬させた際に光損失が増大する。孔に異物や水蒸気が入ることを防止するために、例えば、特許文献１には、微細構造光ファイバの端面部を加熱溶融して封止する技術が開示されている。
特開２００２−３２３６２５号公報。 In a microstructured optical fiber, if foreign matter, water vapor, or the like enters a hole extending in the fiber axis direction, light loss increases when light is propagated through the microstructured optical fiber. In order to prevent foreign matter and water vapor from entering the hole, for example, Patent Document 1 discloses a technique for sealing an end surface portion of a microstructured optical fiber by heating and melting.
JP 2002-323625 A.

しかしながら、少なくとも一方の端面部に封止部が設けられている微細構造光ファイバを含む２本の光ファイバを融着接続した光部品では、接続部における接続損失が増大していた。 However, in an optical component in which two optical fibers including a microstructured optical fiber in which a sealing portion is provided on at least one end surface portion is fusion-connected, the connection loss at the connection portion is increased.

本発明は上記事情に鑑みてなされたものであり、その目的はファイバ軸方向に延びる孔を有する光ファイバであって接続損失を低減することができる光ファイバ、光部品、及びそれらの製造方法を提供することである。 The present invention has been made in view of the above circumstances, and an object of the present invention is an optical fiber having a hole extending in the fiber axis direction and capable of reducing connection loss, an optical component, and a manufacturing method thereof. Is to provide.

上記課題を解決するために、本発明に係る光ファイバは、ファイバ軸方向に延びる孔を有する光ファイバであって、一方の端面を含むファイバ軸方向に沿った一部の領域である第１領域が中実であり、第１領域に隣接しておりファイバ軸方向に沿った他の一部の領域である第２領域において、第１領域及び第２領域の境界で孔が閉じるように孔の内径が境界まで次第に減少しており、端面での波長１．５５μｍにおけるモードフィールド径は、孔の内径がファイバ軸方向に沿って略一定である第３領域の波長１．５５μｍにおけるモードフィールド径から変化していることを特徴とする。 In order to solve the above problems, an optical fiber according to the present invention is an optical fiber having a hole extending in the fiber axial direction, and is a first region that is a partial region along the fiber axial direction including one end face. Is solid, and in the second region, which is adjacent to the first region and is another part of the region along the fiber axis direction, the hole is closed so that the hole is closed at the boundary between the first region and the second region. The mode field diameter at the wavelength of 1.55 μm at the end face is gradually reduced from the mode field diameter at the wavelength of 1.55 μm in the third region where the inner diameter of the hole is substantially constant along the fiber axis direction. It is characterized by changes.

この場合には、孔の内径を第１領域と第２領域との境界まで次第に変化させて、端面での波長１．５５μｍにおけるモードフィールド径（ＭＦＤ）を変化させていることから、上記光ファイバと他の光ファイバとを接続する場合に、接続部におけるＭＦＤの差を、端面におけるＭＦＤを変化させていない場合に比べて小さくすることができる。また、孔の内径を次第に変化させることで、ＭＦＤの急激な変化が抑制されている。そのため、ＭＦＤミスマッチによる接続損失を低減することが可能である。 In this case, since the inner diameter of the hole is gradually changed to the boundary between the first region and the second region, and the mode field diameter (MFD) at a wavelength of 1.55 μm at the end face is changed, the above optical fiber When connecting the optical fiber to another optical fiber, the difference in MFD at the connection portion can be made smaller than when the MFD at the end face is not changed. Moreover, the rapid change of MFD is suppressed by changing the internal diameter of a hole gradually. Therefore, it is possible to reduce connection loss due to MFD mismatch.

また、本発明に係る光ファイバにおいては、第３領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第２領域のファイバ軸方向の長さΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式１）
で表される関係を満たすことが望ましい。 In the optical fiber according to the present invention, the mode field diameter of the third region at a wavelength of 1.55 μm, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD [μm], the length ΔL [mm] in the fiber axis direction of the second region is
ΔL> 0.077 × ΔMFD−0.15 (Expression 1)
It is desirable to satisfy the relationship expressed by

この場合、微細構造光ファイバの波長１．５５μｍにおけるＭＦＤは、(式１)で表される関係を満たすΔＬの長さにわたって次第に変化する。そのため、微細構造光ファイバのＭＦＤが変化している側の端面に他の光ファイバを接続した光部品に光を伝搬させた場合、接続部近傍でのファイバ軸に直交する断面における光のパワー分布が急激に変化することが抑制される。そのため、接続損失を低減することが可能である。 In this case, the MFD at the wavelength of 1.55 μm of the microstructured optical fiber gradually changes over the length of ΔL that satisfies the relationship expressed by (Expression 1). Therefore, when light is propagated to an optical component in which another optical fiber is connected to the end face of the microstructured optical fiber on which the MFD changes, the light power distribution in a cross section perpendicular to the fiber axis in the vicinity of the connecting portion Is suppressed from changing suddenly. Therefore, connection loss can be reduced.

また、本発明に係る光ファイバは、ファイバ軸方向に延びる孔を有する光ファイバであって、一方の端面を含むファイバ軸方向に沿った一部の領域である第４領域において孔の内径が端面まで次第に変化しており、端面での波長１．５５μｍにおけるモードフィールド径は、孔の内径がファイバ軸方向に沿って略一定である第５領域での波長１．５５μｍにおけるモードフィールド径から変化していることを特徴とする。 The optical fiber according to the present invention is an optical fiber having a hole extending in the fiber axis direction, and the inner diameter of the hole is an end surface in a fourth region that is a partial region along the fiber axis direction including one end surface. The mode field diameter at a wavelength of 1.55 μm at the end face changes from the mode field diameter at a wavelength of 1.55 μm in the fifth region in which the inner diameter of the hole is substantially constant along the fiber axis direction. It is characterized by.

この場合には、孔の内径を端面まで次第に変化させて、端面での波長１．５５μｍにおけるＭＦＤを変化させていることから、上記光ファイバと他の光ファイバとを接続する場合に、接続部におけるＭＦＤの差を、端面におけるＭＦＤを変化させていない場合に比べて小さくすることができる。また、孔の内径を次第に変化させることで、ＭＦＤの急激な変化が抑制されている。そのため、ＭＦＤミスマッチによる接続損失を低減することが可能である。 In this case, since the MFD at the wavelength of 1.55 μm at the end face is changed by gradually changing the inner diameter of the hole to the end face, when connecting the optical fiber to another optical fiber, the connecting portion The difference in the MFD at can be made smaller than when the MFD at the end face is not changed. Moreover, the rapid change of MFD is suppressed by changing the internal diameter of a hole gradually. Therefore, it is possible to reduce connection loss due to MFD mismatch.

更に、本発明に係る光ファイバにおいては、第５領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ −Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第４領域のファイバ軸方向の長さをΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式２）
で表される関係を満たすことが望ましい。 Further, in the optical fiber according to the present invention, the mode field diameter at the wavelength of 1.55 μm in the fifth region, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length in the fiber axis direction of the fourth region is ΔL [mm]
ΔL> 0.077 × ΔMFD−0.15 (Expression 2)
It is desirable to satisfy the relationship expressed by

この場合、微細構造光ファイバの波長１．５５μｍにおけるＭＦＤは、（式２）で表される関係を満たすΔＬの長さにわたって次第に変化する。そのため、微細構造光ファイバのＭＦＤが変化している側の端面に他の光ファイバを接続した光部品に光を伝搬させた場合、接続部近傍でのファイバ軸に直交する断面における光のパワー分布が急激に変化することが抑制される。そのため、接続損失を低減することが可能である。 In this case, the MFD at the wavelength of 1.55 μm of the microstructured optical fiber gradually changes over the length of ΔL that satisfies the relationship expressed by (Expression 2). Therefore, when light is propagated to an optical component in which another optical fiber is connected to the end face of the microstructured optical fiber on which the MFD changes, the light power distribution in a cross section perpendicular to the fiber axis in the vicinity of the connecting portion Is suppressed from changing suddenly. Therefore, connection loss can be reduced.

また、本発明に係る光部品は、上述した光ファイバである第１の光ファイバと、第１の光ファイバの端面に融着接続されている第２の光ファイバとを有することを特徴とする。この場合には、第１の光ファイバと第２の光ファイバとが、第１の光ファイバが有する孔の内径が変化している側の端面で接続されているので、接続部でのＭＦＤミスマッチを抑制することができる。 An optical component according to the present invention includes the first optical fiber that is the above-described optical fiber, and a second optical fiber that is fusion-bonded to an end face of the first optical fiber. . In this case, since the first optical fiber and the second optical fiber are connected at the end face on the side where the inner diameter of the hole of the first optical fiber is changed, the MFD mismatch at the connection portion Can be suppressed.

また、本発明に係る光部品は、（式１）を満たす上述した光ファイバである第１の光ファイバと、（式１）を満たす上述した光ファイバである第２の光ファイバとを有し、第１の光ファイバの上記第３領域における孔の内径と第２の光ファイバの上記第３領域における孔の内径とが互いに異なっており、第１の光ファイバの上記端面と第２の光ファイバの上記端面とが融着接続されていることを特徴とする。 The optical component according to the present invention includes a first optical fiber that is the above-described optical fiber that satisfies (Expression 1), and a second optical fiber that is the above-described optical fiber that satisfies (Expression 1). The inner diameter of the hole in the third region of the first optical fiber is different from the inner diameter of the hole in the third region of the second optical fiber, and the end face of the first optical fiber and the second light The end face of the fiber is fusion-connected.

この場合、第１の光ファイバ及び第２の光ファイバ夫々が有する孔の内径は、（式１）を満たすように変化しているため、第１及び第２の光ファイバのＭＦＤは、各光ファイバの端面に向かって、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバ（以下、「標準化光ファイバ」ともいう）のＭＦＤにほぼ一致するように次第に変化している。そのため、それらの端面を突き合わせて融着接続した光部品において、接続部でのＭＦＤミスマッチを低減することが可能である。 In this case, since the inner diameters of the holes of the first optical fiber and the second optical fiber are changed so as to satisfy (Equation 1), the MFDs of the first and second optical fibers are different from each other. Toward the end face of the fiber. The optical fiber gradually changes so as to substantially match the MFD of the optical fiber standardized at 652 (hereinafter also referred to as “standardized optical fiber”). Therefore, it is possible to reduce the MFD mismatch at the connection portion in the optical component in which those end surfaces are butted and fusion-bonded.

また、本発明に係る光部品は、（式２）を満たす上述した光ファイバである第１の光ファイバと、（式２）を満たす上述した光ファイバである第２の光ファイバとを有し、第１の光ファイバの第５領域における孔の内径と第２の光ファイバの第５領域における孔の内径が互いに異なっており、第１の光ファイバの上記端面と第２の光ファイバの上記端面とが融着接続されていることを特徴とする。 An optical component according to the present invention includes a first optical fiber that is the above-described optical fiber that satisfies (Expression 2), and a second optical fiber that is the above-described optical fiber that satisfies (Expression 2). The inner diameter of the hole in the fifth region of the first optical fiber and the inner diameter of the hole in the fifth region of the second optical fiber are different from each other, and the end face of the first optical fiber and the end of the second optical fiber are different from each other. The end face is fusion-connected.

この場合にも、第１の光ファイバ及び第２の光ファイバ夫々が有する孔の内径は、（式２）を満たすように変化しているため、第１及び第２の光ファイバのＭＦＤは、各光ファイバの端面に向かって、標準化光ファイバのＭＦＤにほぼ一致するように次第に変化している。そのため、それらの端面を突き合わせて融着接続した光部品において、接続部でのＭＦＤミスマッチを低減することが可能である。 Also in this case, since the inner diameters of the holes of the first optical fiber and the second optical fiber are changed so as to satisfy (Equation 2), the MFDs of the first and second optical fibers are: It gradually changes toward the end face of each optical fiber so as to substantially match the MFD of the standardized optical fiber. Therefore, it is possible to reduce the MFD mismatch at the connection portion in the optical component in which those end faces are butted and fusion-bonded.

また、本発明に係る光ファイバの製造方法は、ファイバ軸方向に延びる孔を有する光ファイバにおいて、光ファイバの一方の端面を含むファイバ軸方向に沿った一部の領域である第１領域、及び、第１領域に隣接しておりファイバ軸方向に沿った他の一部の領域である第２領域を加熱することにより、第１領域の孔を閉じて第１領域を中実にし、第１領域及び第２領域の境界で孔を閉じるように第２領域の孔の内径を境界まで次第に減少させて、端面での波長１．５５μｍにおけるモードフィールド径を、孔の内径がファイバ軸方向に沿って略一定である第３領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 The optical fiber manufacturing method according to the present invention includes, in an optical fiber having a hole extending in the fiber axial direction, a first region that is a partial region along the fiber axial direction including one end face of the optical fiber, and By heating the second region, which is adjacent to the first region and is another partial region along the fiber axis direction, to close the hole in the first region and to make the first region solid, The inner diameter of the hole in the second region is gradually decreased to the boundary so that the hole is closed at the boundary between the region and the second region, and the mode field diameter at the wavelength of 1.55 μm at the end face is determined. The mode field diameter of the third region, which is substantially constant, is changed from the mode field diameter at 1.55 μm.

この場合には、端面での波長１．５５μｍにおけるＭＦＤを、第３領域の波長１．５５μｍにおけるＭＦＤから変化させた光ファイバをファイバ軸方向に延びる孔を有する光ファイバから容易に製造することができる。 In this case, an optical fiber in which the MFD at the wavelength of 1.55 μm at the end face is changed from the MFD at the wavelength of 1.55 μm in the third region can be easily manufactured from an optical fiber having a hole extending in the fiber axis direction. it can.

更に、本発明に係る光ファイバの製造方法においては、第３領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ −Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第３領域のファイバ軸方向の長さΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式３）
で表される関係を満たすように孔の内径を変化させることが望ましい。 Further, in the method of manufacturing an optical fiber according to the present invention, the mode field diameter of the third region at a wavelength of 1.55 μm, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD [μm], the length ΔL [mm] in the fiber axis direction of the third region is
ΔL> 0.077 × ΔMFD−0.15 (Equation 3)
It is desirable to change the inner diameter of the hole so as to satisfy the relationship expressed by:

この場合には、光ファイバの端面での波長１．５５μｍにおけるＭＦＤが標準化光ファイバの波長１．５５μｍにおけるＭＦＤと略一致するようにＭＦＤが次第に変化する光ファイバを製造することが可能である。 In this case, it is possible to manufacture an optical fiber in which the MFD gradually changes so that the MFD at the wavelength of 1.55 μm on the end face of the optical fiber substantially matches the MFD at the wavelength of 1.55 μm of the standardized optical fiber.

また、本発明に係る光ファイバの製造方法は、ファイバ軸方向に延びる孔を有する光ファイバにおいて、光ファイバの一方の端面を含むファイバ軸方向に沿った一部の領域である第４領域を加熱することにより、第４領域での孔の内径を端面まで次第に変化させて、端面での波長１．５５μｍにおけるモードフィールド径を、孔の内径がファイバ軸方向に沿って略一定である第５領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 In the optical fiber manufacturing method according to the present invention, in the optical fiber having a hole extending in the fiber axial direction, the fourth region which is a partial region along the fiber axial direction including one end face of the optical fiber is heated. Thus, the inner diameter of the hole in the fourth area is gradually changed to the end face, and the mode field diameter at the wavelength of 1.55 μm at the end face is changed to the fifth area in which the inner diameter of the hole is substantially constant along the fiber axis direction. The mode field diameter at a wavelength of 1.55 μm is changed.

更に、本発明に係る光ファイバの製造方法においては、第５領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ −Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第４領域のファイバ軸方向の長さΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式４）
で表される関係を満たすように孔の内径を変化させることが望ましい。この場合にも、光ファイバの端面での波長１．５５μｍにおけるＭＦＤが標準化光ファイバの波長１．５５μｍにおけるＭＦＤと略一致するようにＭＦＤが次第に変化する光ファイバを製造することが可能である。 Furthermore, in the optical fiber manufacturing method according to the present invention, the mode field diameter of the fifth region at a wavelength of 1.55 μm, the ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized at 652 is ΔMFD [μm], the length ΔL [mm] in the fiber axis direction of the fourth region is
ΔL> 0.077 × ΔMFD−0.15 (Expression 4)
It is desirable to change the inner diameter of the hole so as to satisfy the relationship expressed by: Also in this case, it is possible to manufacture an optical fiber in which the MFD gradually changes so that the MFD at the wavelength of 1.55 μm on the end face of the optical fiber substantially matches the MFD at the wavelength of 1.55 μm of the standardized optical fiber.

また、本発明に係る光部品の製造方法は、ファイバ軸方向に延びる孔を有する第１の光ファイバの端面と、中実の第２の光ファイバの端面とを突き合わせて加熱溶融して融着接続し、第１の光ファイバにおいて、端面を含むファイバ軸方向に沿った一部の領域である第１領域での孔を閉じて第１領域を中実にし、且つ、第１領域に隣接しておりファイバ軸方向に沿った他の一部の領域である第２領域において、第１領域及び第２領域の境界で孔が閉じるように孔の内径を境界まで次第に減少させて、第１の光ファイバの端面での波長１．５５μｍにおけるモードフィールド径を、第１の光ファイバにおける孔の内径がファイバ軸方向に沿って略一定である第３領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 In addition, the method for manufacturing an optical component according to the present invention is such that the end face of the first optical fiber having a hole extending in the fiber axial direction and the end face of the solid second optical fiber are brought into contact with each other and heated to melt. In the first optical fiber, the hole in the first region which is a partial region along the fiber axial direction including the end face is closed to make the first region solid, and adjacent to the first region. In the second region, which is another partial region along the fiber axis direction, the inner diameter of the hole is gradually decreased to the boundary so that the hole is closed at the boundary between the first region and the second region, The mode field diameter at the wavelength of 1.55 μm at the end face of the optical fiber is changed from the mode field diameter at the wavelength of 1.55 μm in the third region where the inner diameter of the hole in the first optical fiber is substantially constant along the fiber axis direction. It is characterized by letting The

この場合には、第１及び第２の光ファイバを融着接続し、第１の光ファイバの端面におけるＭＦＤを変化させることで、第１の光ファイバと第２の光ファイバとの接続部において、ＭＦＤの差が小さい光部品を製造することができる。 In this case, the first and second optical fibers are fusion-spliced, and the MFD at the end face of the first optical fiber is changed, so that the connection portion between the first optical fiber and the second optical fiber is changed. , An optical component with a small difference in MFD can be manufactured.

また、本発明に係る光部品の製造方法においては、第３領域の波長１．５５μｍに対するモードフィールド径と、ＩＴＵ −Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第２領域のファイバ軸方向の長さΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式５）
で表される関係を満たすように孔の内径を変化させることを特徴とする。 In the method of manufacturing an optical component according to the present invention, the mode field diameter for the wavelength of 1.55 μm in the third region, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD [μm], the length ΔL [mm] in the fiber axis direction of the second region is
ΔL> 0.077 × ΔMFD−0.15 (Expression 5)
The inside diameter of the hole is changed so as to satisfy the relationship represented by

この場合には、光部品を構成している第１及び第２の光ファイバの接続部において、波長１．５５μｍにおけるＭＦＤが標準化光ファイバの波長１．５５μｍのＭＦＤと略一致するように各光ファイバのＭＦＤが次第に変化している光部品を製造することが可能である。 In this case, each light is connected so that the MFD at the wavelength of 1.55 μm substantially matches the MFD of the wavelength of 1.55 μm of the standardized optical fiber at the connection portion of the first and second optical fibers constituting the optical component. It is possible to produce an optical component in which the MFD of the fiber is gradually changing.

本発明に係る光部品の製造方法は、ファイバ軸方向に延びる孔を有する第１の光ファイバの端面と、中実の第２の光ファイバの端面とを突き合わせて加熱溶融して融着接続し、第１の光ファイバにおいて、端面を含むファイバ軸方向に沿った一部の領域である第４領域での孔の内径を当該端面まで次第に変化させ、当該端面での波長１．５５μｍにおけるモードフィールド径を、孔の内径がファイバ軸方向に沿って略一定である第５領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 In the method for manufacturing an optical component according to the present invention, the end face of the first optical fiber having a hole extending in the fiber axis direction and the end face of the solid second optical fiber are brought into contact with each other and heated and melted to be fusion-bonded. In the first optical fiber, the inner diameter of the hole in the fourth region, which is a partial region along the fiber axial direction including the end surface, is gradually changed to the end surface, and the mode field at the wavelength of 1.55 μm at the end surface The diameter is changed from the mode field diameter at a wavelength of 1.55 μm in the fifth region where the inner diameter of the hole is substantially constant along the fiber axis direction.

この場合にも、第１の光ファイバと第２の光ファイバとを融着接続し、第１の光ファイバの端面におけるＭＦＤを変化させることで、第１の光ファイバと第２の光ファイバとの接続部において、ＭＦＤの差が小さい光部品を製造することができる。 Also in this case, the first optical fiber and the second optical fiber are fused and connected, and the MFD at the end face of the first optical fiber is changed, so that the first optical fiber and the second optical fiber are Thus, an optical component having a small MFD difference can be manufactured.

更に、本発明に係る光部品の製造方法においては、第５領域の波長１．５５μｍに対するモードフィールド径と、ＩＴＵ −Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ[μｍ]としたとき、第３領域のファイバ軸方向の長さΔＬ[ｍｍ]が、
ΔＬ＞０．０７７×ΔＭＦＤ−０．１５・・・（式６）
で表される関係を満たすように孔の内径を変化させることを特徴とする。 Further, in the method of manufacturing an optical component according to the present invention, the mode field diameter for the wavelength of 1.55 μm in the fifth region, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD [μm], the length ΔL [mm] in the fiber axis direction of the third region is
ΔL> 0.077 × ΔMFD−0.15 (Expression 6)
The inside diameter of the hole is changed so as to satisfy the relationship represented by

この場合にも、光部品を構成している第１及び第２の光ファイバの接続部において、波長１．５５μｍにおけるＭＦＤが標準化光ファイバの波長１．５５μｍのＭＦＤと略一致するように各光ファイバのＭＦＤが次第に変化している光部品を製造することが可能である。 Also in this case, at the connecting portion of the first and second optical fibers constituting the optical component, each light is set so that the MFD at the wavelength of 1.55 μm substantially matches the MFD of the standardized optical fiber at the wavelength of 1.55 μm. It is possible to produce an optical component in which the MFD of the fiber is gradually changing.

また、本発明に係る光部品の製造方法は、ファイバ軸方向に延びる孔を有する第１の光ファイバ及び第２の光ファイバの端面同士を突き合わせて加熱溶融して融着接続し、第１及び第２の光ファイバ夫々において、端面を含むファイバ軸方向に沿った一部の領域である第１領域の孔を閉じて第１領域を中実にし、且つ、第１領域に隣接しておりファイバ軸方向に沿った他の一部の領域である第２領域において、第１領域及び第２領域の境界で孔が閉じるように孔の内径を境界まで次第に減少させて、第１及び第２の光ファイバ夫々の端面における波長１．５５μｍにおけるモードフィールド径を、孔の内径がファイバ軸方向に沿って略一定である領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 The optical component manufacturing method according to the present invention includes a first optical fiber having a hole extending in the fiber axial direction, and end faces of the second optical fiber are brought into contact with each other, melted by heat, and fusion-bonded. In each of the second optical fibers, the first region, which is a partial region along the fiber axis direction including the end face, is closed to make the first region solid, and adjacent to the first region, the fiber In the second region, which is another partial region along the axial direction, the inner diameter of the hole is gradually decreased to the boundary so that the hole is closed at the boundary between the first region and the second region, and the first and second The mode field diameter at a wavelength of 1.55 μm at the end face of each optical fiber is changed from the mode field diameter at a wavelength of 1.55 μm in a region where the inner diameter of the hole is substantially constant along the fiber axis direction.

この場合、第１の光ファイバと第２の光ファイバとの接続部において、第１及び第２の光ファイバ夫々のＭＦＤを変化させて、各ＭＦＤをほぼ一致させることが可能であり、接続損失が低減された光部品を製造することができる。 In this case, at the connection portion between the first optical fiber and the second optical fiber, it is possible to change the MFD of each of the first and second optical fibers so that the respective MFDs are substantially matched, resulting in a connection loss. Can be produced.

また、本発明に係る光部品の製造方法においては、第１の光ファイバにおいて、第３領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ−Ｔ勧告Ｇ.６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ₁[μｍ]とし、第２の光ファイバにおいて、第３領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ₂[μｍ]としたとき、第１の光ファイバにおける第２領域のファイバ軸方向の長さΔＬ₁[ｍｍ]及び第２の光ファイバにおける第２領域のファイバ軸方向の長さΔＬ₂[ｍｍ]夫々が、
ΔＬ₁＞０．０７７×ΔＭＦＤ₁−０．１５・・・（式７ａ）
ΔＬ₂＞０．０７７×ΔＭＦＤ₂−０．１５・・・（式７ｂ）
で表される関係を満たすように第１の光ファイバ及び第２の光ファイバ夫々が有する孔の内径を変化させることが望ましい。 Further, in the method of manufacturing an optical component according to the present invention, in the first optical fiber, the mode field diameter at the wavelength of 1.55 μm in the third region and the wavelength of the optical fiber standardized by ITU-T recommendation G.652. The absolute value of the difference from the mode field diameter at 1.55 μm is ΔMFD ₁ [μm]. In the second optical fiber, the mode field diameter at a wavelength of 1.55 μm in the third region, the ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD ₂ [μm], the length ΔL ₁ of the second region in the first optical fiber in the fiber axis direction [mm] and the length ΔL ₂ [mm] in the fiber axial direction of the second region in the second optical fiber,
ΔL ₁ > 0.077 × ΔMFD ₁ −0.15 (Expression 7a)
ΔL ₂ > 0.077 × ΔMFD ₂ −0.15 (Expression 7b)
It is desirable to change the inner diameters of the holes of the first optical fiber and the second optical fiber so as to satisfy the relationship expressed by:

この場合には、光部品を構成している２本の微細構造光ファイバの接続部における波長１．５５μｍにおけるＭＦＤが、標準化光ファイバの波長１．５５μｍのＭＦＤと略一致するように、ＭＦＤが次第に変化する光部品を製造することが可能である。 In this case, the MFD is such that the MFD at the wavelength of 1.55 μm at the connecting portion of the two microstructured optical fibers constituting the optical component substantially matches the MFD at the wavelength of 1.55 μm of the standardized optical fiber. It is possible to produce gradually changing optical components.

また、本発明に係る光部品の製造方法は、ファイバ軸方向に延びる孔を有する第１の光ファイバ及び第２の光ファイバの端面同士を突き合わせて加熱溶融して融着接続し、第１及び第２の光ファイバ夫々において、端面を含むファイバ軸方向に沿った一部の領域である第４領域の孔の内径を当該端面まで次第に変化させ、当該端面における波長１．５５μｍにおけるモードフィールド径を、第１及び第２の光ファイバ夫々において孔の内径がファイバ軸方向に沿って略一定である第５領域の波長１．５５μｍにおけるモードフィールド径から変化させることを特徴とする。 The optical component manufacturing method according to the present invention includes a first optical fiber having a hole extending in the fiber axial direction, and end faces of the second optical fiber are brought into contact with each other, melted by heat, and fusion-bonded. In each of the second optical fibers, the inner diameter of the hole in the fourth region, which is a partial region along the fiber axis direction including the end surface, is gradually changed to the end surface, and the mode field diameter at the wavelength of 1.55 μm on the end surface is changed. In each of the first and second optical fibers, the inside diameter of the hole is changed from the mode field diameter at a wavelength of 1.55 μm in the fifth region where the inside diameter is substantially constant along the fiber axis direction.

また、本発明に係る光部品の製造方法においては、第１の光ファイバにおいて、第５領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ₁[μｍ]とし、第２の光ファイバにおいて、第５領域の波長１．５５μｍにおけるモードフィールド径と、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバの波長１．５５μｍにおけるモードフィールド径との差の絶対値をΔＭＦＤ₂[μｍ]としたとき、第１の光ファイバにおける第４領域のファイバ軸方向の長さΔＬ₁[ｍｍ]及び第２の光ファイバにおける第４領域のファイバ軸方向の長さをΔＬ₂[ｍｍ]夫々が、
ΔＬ₁＞０．０７７×ΔＭＦＤ₁−０．１５・・・（式８ａ）
ΔＬ₂＞０．０７７×ΔＭＦＤ₂−０．１５・・・（式８ｂ）
で表される関係を満たすように第１の光ファイバ及び第２の光ファイバ夫々が有する孔の内径を変化させることが望ましい。 In the method for manufacturing an optical component according to the present invention, in the first optical fiber, the mode field diameter at the wavelength of 1.55 μm in the fifth region, the ITU-T recommendation G. The absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized at 652 is ΔMFD ₁ [μm], and in the second optical fiber, the mode field diameter at the wavelength of 1.55 μm in the fifth region is ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD ₂ [μm], the length ΔL ₁ of the fourth region in the first optical fiber in the fiber axis direction [mm] and the length of the fourth region of the second optical fiber in the fiber axial direction are ΔL ₂ [mm],
ΔL ₁ > 0.077 × ΔMFD ₁ −0.15 (Equation 8a)
ΔL ₂ > 0.077 × ΔMFD ₂ −0.15 (Equation 8b)
It is desirable to change the inner diameters of the holes of the first optical fiber and the second optical fiber so as to satisfy the relationship expressed by:

この場合にも、第１の光ファイバと第２の光ファイバとの接続部において、第１及び第２の光ファイバ夫々のＭＦＤを変化させて、各ＭＦＤを一致させることが可能であり、接続損失が低減された光部品を製造することができる。 Also in this case, it is possible to change the MFD of each of the first optical fiber and the second optical fiber at the connection portion between the first optical fiber and the second optical fiber so that the respective MFDs coincide with each other. An optical component with reduced loss can be manufactured.

本発明によれば、接続損失を低減することができる。 According to the present invention, connection loss can be reduced.

以下、図面を参照して本発明の好適な実施形態について詳細に説明する。尚、以下の説明においては、同一の要素には同一の符号を用いることとし重複する説明は省略する。また、図面の寸法比率は、図示の比率に限られるものではない。 DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same elements, and redundant descriptions are omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

図１（ａ），（ｂ）を参照して本実施形態の光部品の構成について説明する。図１（ａ）は、本実施形態の光部品１の構成を示す説明図であり、ファイバ軸を含む平面で切断した場合の断面を模式的に表している。光部品１は、微細構造光ファイバ（第１の光ファイバ）１０と、光ファイバ（第２の光ファイバ）２０とが融着接続されたものである。図１（ｂ）は、光部品１を光ファイバ２０と微細構造光ファイバ１０とに分解した図である。図１（ａ），（ｂ）から理解されるように、光部品１は光ファイバ２０の端面２０Ａと微細構造光ファイバ１０の端面１０Ａとを突き合わせて接続されている。 The configuration of the optical component of this embodiment will be described with reference to FIGS. Fig.1 (a) is explanatory drawing which shows the structure of the optical component 1 of this embodiment, and represents typically the cross section at the time of cut | disconnecting by the plane containing a fiber axis. The optical component 1 is obtained by fusion-connecting a microstructure optical fiber (first optical fiber) 10 and an optical fiber (second optical fiber) 20. FIG. 1B is an exploded view of the optical component 1 into an optical fiber 20 and a microstructured optical fiber 10. As understood from FIGS. 1A and 1B, the optical component 1 is connected to the end face 20 A of the optical fiber 20 and the end face 10 A of the microstructured optical fiber 10.

光ファイバ２０は、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化されたシングルモード光ファイバである。光ファイバ２０は中実であり、コア領域２１と、それを取り囲むクラッド領域２２とから構成されている。コア領域２１のコア径及び屈折率夫々は、８．６μｍ及び１．４４９である。また、クラッド領域２２の屈折率は１．４４４である。光ファイバ２０のモードフィールド径（ＭＦＤ）は１０．６μｍである。なお、以下では、ＩＴＵ−Ｔ勧告Ｇ．６５２で標準化された光ファイバ（すなわち、光ファイバ２０）を標準化光ファイバとも称す。 The optical fiber 20 is an ITU-T recommendation G.264. This is a single mode optical fiber standardized at 652. The optical fiber 20 is solid and includes a core region 21 and a cladding region 22 surrounding the core region 21. The core diameter and refractive index of the core region 21 are 8.6 μm and 1.449, respectively. The refractive index of the cladding region 22 is 1.444. The mode field diameter (MFD) of the optical fiber 20 is 10.6 μm. In the following, ITU-T Recommendation G. The optical fiber standardized at 652 (that is, the optical fiber 20) is also referred to as a standardized optical fiber.

微細構造光ファイバ１０は、コア領域１１と、コア領域１１を取り囲むクラッド領域１２とから構成されている。コア領域１１のコア径は、光ファイバ２０のコア領域２１のコア径と同じであり８．６μｍである。また、コア領域１１の屈折率は、光ファイバ２０のコア領域２１の屈折率と同じ１．４４９である。クラッド領域１２には、ファイバ軸方向に延びる孔Ｈ₁がファイバ軸に直交する断面において複数形成されている。複数の孔Ｈ₁の内径は全て同じである。図１（ａ），（ｂ）では、簡単のために２つの孔Ｈ₁を示している。クラッド領域１２の屈折率は、１．４４４である。 The microstructured optical fiber 10 includes a core region 11 and a cladding region 12 surrounding the core region 11. The core diameter of the core region 11 is the same as the core diameter of the core region 21 of the optical fiber 20 and is 8.6 μm. The refractive index of the core region 11 is 1.449, which is the same as the refractive index of the core region 21 of the optical fiber 20. A plurality of holes H ₁ extending in the fiber axis direction are formed in the cladding region 12 in a cross section perpendicular to the fiber axis. The inner diameters of the plurality of holes H ₁ are all the same. In FIGS. 1A and 1B, two holes H ₁ are shown for simplicity. The refractive index of the cladding region 12 is 1.444.

また、微細構造光ファイバ１０は、端面１０Ａを含むファイバ軸方向に沿った一部の領域である第１領域α₁、その第１領域α₁に隣接しておりファイバ軸方向に沿った他の一部の領域である第２領域α₂、及び第２領域α₂に隣接しており孔Ｈ₁の内径がファイバ軸方向にほぼ一定である第３領域α₃を含んで構成されている。なお、第３領域α₃における孔Ｈ₁の内径はＤ₁[ｍｍ]である。 The microstructured optical fiber 10 includes a first region α ₁ , which is a partial region along the fiber axis direction including the end face 10A, and another region along the fiber axis direction that is adjacent to the first region α ₁ . the second region alpha _2, and the second area alpha ₂ the inner diameter of the adjacent and hole H ₁ in is configured to include a third region alpha ₃ is substantially constant in the axial direction of the fiber, which is part of the region. The inner diameter of the hole H ₁ in the third region α ₃ is D ₁ [mm].

図１（ａ）を参照すると、第１領域α₁に孔Ｈ₁は形成されておらず、第１領域α₁は中実となっている。第１領域α₁のコア領域１１の屈折率及びクラッド領域１２の屈折率並びにコア径夫々は、光ファイバ２０のコア領域２１の屈折率及びクラッド領域２２の屈折率並びにコア径と一致しており、第１領域α₁は標準化光ファイバと同じ構成となっている。なお、第１領域α₁のファイバ軸方向の長さはＬ[ｍｍ]である。 Referring to FIG. 1 (a), holes H ₁ in a first region alpha ₁ is not formed, the first area alpha ₁ has a solid. The refractive index of the core region 11, the refractive index of the cladding region 12, and the core diameter of the first region α ₁ are the same as the refractive index of the core region 21 of the optical fiber 20, the refractive index of the cladding region 22, and the core diameter. The first region α ₁ has the same configuration as the standardized optical fiber. The length of the first region α _{1 in} the fiber axis direction is L [mm].

第２領域α₂において、孔Ｈ₁の内径は、第１領域α₁と第２領域α₂との境界Ｂまで次第に小さくなっており、境界Ｂの位置で孔Ｈ₁は閉じている。なお、微細構造光ファイバ１０における孔Ｈ₁の内径がファイバ軸方向にほぼ一定である第３領域α₃での孔Ｈ₁の内径はＤ₁である。また、第２領域α₂のファイバ軸方向の長さΔＬ₁[ｍｍ]は、
ΔＬ₁＞０．０７７×ΔＭＦＤ₁−０．１５・・・（式９）
で表される関係を満たすことが好適である。ここで、ΔＭＦＤ₁は、第３領域α₃（接続部Ａ₁からＬ₁＋ΔＬ₁より離れた領域）の波長１．５５μｍにおけるＭＦＤと、光ファイバ２０の波長１．５５μｍにおけるＭＦＤとの差の絶対値である。ΔＬ₁が（式９）で表される関係を満たす場合、接続部Ａ₁において微細構造光ファイバ１０及び光ファイバ２０の波長１．５５μｍにおけるＭＦＤがほぼ一致するように、微細構造光ファイバ１０の波長１．５５μｍにおけるＭＦＤは境界Ｂまで次第に変化している。これにより、光部品１に光を伝搬させたときに接続部Ａ₁でのＭＦＤミスマッチが低減され、接続損失が０．２ｄＢより小さくなる。 In the second region α ₂ , the inner diameter of the hole H ₁ gradually decreases to the boundary B between the first region α ₁ and the second region α _2, and the hole H ₁ is closed at the position of the boundary B. Incidentally, the inner diameter of the hole H ₁ of the third region alpha ₃ the inner diameter of the hole H ₁ of the micro-structured optical fiber 10 is approximately constant in the fiber axis direction is D _1. The length ΔL ₁ [mm] in the fiber axis direction of the second region α ₂ is
ΔL ₁ > 0.077 × ΔMFD ₁ −0.15 (Equation 9)
It is preferable to satisfy the relationship represented by: Here, ΔMFD ₁ is the difference between the MFD at the wavelength 1.55 μm in the third region α ₃ (the region away from the connection portion A ₁ from L ₁ + ΔL ₁ ) and the MFD at the wavelength 1.55 μm of the optical fiber 20. Absolute value. When ΔL ₁ satisfies the relationship expressed by (Equation 9), the MFD of the microstructured optical fiber 10 is substantially matched so that the MFDs at the wavelength 1.55 μm of the microstructured optical fiber 10 and the optical fiber 20 substantially match at the connection portion A ₁ . The MFD at the wavelength of 1.55 μm gradually changes to the boundary B. Thus, MFD mismatch at the junction A ₁ is reduced when the optical component 1 was propagated through the optical connection loss becomes smaller than 0.2 dB.

次に、光部品１の製造方法について説明する。図２（ａ）〜図２（ｃ）は、光部品１を製造する工程の一例を示す工程図である。先ず、図２（ａ）に示すように、孔Ｈ₁の内径が長手方向に沿ってほぼ一定である微細構造光ファイバ１０₀及び光ファイバ２０を用意する。続いて、図２（ｂ）に示すように微細構造光ファイバ１０₀の一方の端面１０Ａと、光ファイバ２０の端面２０Ａとを軸合わせして突き合わせる。 Next, a method for manufacturing the optical component 1 will be described. FIG. 2A to FIG. 2C are process diagrams showing an example of a process for manufacturing the optical component 1. First, as shown in FIG. 2 (a), the inner diameter of the hole H ₁ is prepared microstructured optical fiber 10 ₀ and the optical fiber 20 is substantially constant along the longitudinal direction. Then, matched and combined axial and one end face 10A of the micro-structured optical fiber 10 ₀ As shown in FIG. 2 (b), the end face 20A of the optical fiber 20.

次に、図２（ｃ）に示すように、対向する一対の電極を含んで構成される融着器（加熱手段）３０で融着接続する。この際、融着器３０を制御して、接続部Ａ₁を含みファイバ軸方向に沿った一部の領域である第１領域α₁、言い換えれば、ファイバ軸方向に沿った領域のうち接続部Ａ₁からＬ₁離れた位置までの領域における孔Ｈ₁を潰して第１領域α₁を中実にし、孔Ｈ₁が接続部Ａ₁からＬ₁離れた位置で閉じるように接続部Ａ₁に向かって孔Ｈ₁の内径を次第に減少させて第２領域α₂を形成する。言い換えれば、第２領域α₂において、孔Ｈ₁が第１領域α₁及び第２領域α₂の境界Ｂで閉じるように孔Ｈ₁の内径を境界Ｂまで次第に減少させる。孔Ｈ₁を上記のように変化させて、接続部Ａ₁での波長１．５５μｍにおけるＭＦＤを、第３領域α₃の波長１．５５μｍにおけるＭＦＤから変化させて光ファイバ２０の波長１．５５μｍにおけるＭＦＤとほぼ一致させる。 Next, as shown in FIG. 2 (c), fusion-splicing is performed by a fuser (heating means) 30 including a pair of opposed electrodes. At this time, the fuser 30 is controlled so that the first region α ₁ which is a partial region including the connection portion A ₁ along the fiber axis direction, in other words, the connection portion of the region along the fiber axis direction. the first area alpha ₁ in the solid smashed hole H ₁ in the region from a ₁ to L ₁ away, connecting portion a ₁ to close at a position hole H ₁ is L ₁ away from the connecting portion a ₁ The second region α ₂ is formed by gradually decreasing the inner diameter of the hole H ₁ . In other words, in the second region alpha _2, holes H ₁ gradually decreases the inner diameter of the hole H ₁ to close the first region alpha ₁ and the second region alpha ₂ of the boundary B to the boundary B. The hole H ₁ is changed as described above, and the MFD at the wavelength 1.55 μm at the connection portion A ₁ is changed from the MFD at the wavelength 1.55 μm of the third region α ₃ to change the wavelength of the optical fiber 20 to 1.55 μm. This is almost the same as the MFD in FIG.

以上の工程により、孔Ｈ₁の内径が長手方向に沿ってほぼ一定である微細構造光ファイバ１０₀は、光ファイバ２０と融着接続され、端面１０Ａでの波長１．５５μｍにおけるＭＦＤが光ファイバ２０の波長１．５５μｍにおけるＭＦＤにほぼ等しい微細構造光ファイバ１０となり、図１の光部品１が製造される。なお、第２領域α₂のファイバ軸方向の長さΔＬ₁が、（式９）を満たすように孔Ｈ₁の内径を変化させることは、接続損失をより小さくする観点から好適である。 Through the above steps, the microstructure optical fiber 10 ₀ is substantially constant inner diameter along the longitudinal direction of the hole H ₁ is the optical fiber 20 and fusion splice, MFD optical fiber at a wavelength 1.55μm at the end face 10A The optical fiber 10 having a microstructure substantially equal to the MFD at 20 wavelength 1.55 μm is obtained, and the optical component 1 shown in FIG. 1 is manufactured. It is preferable to change the inner diameter of the hole H ₁ so that the length ΔL ₁ in the fiber axis direction of the second region α ₂ satisfies (Equation 9) from the viewpoint of further reducing the connection loss.

次に、上記光部品１に光を伝搬させた場合のΔＬ₁と接続損失との関係について説明する。図３は、接続損失を算出するための計算に用いた図１の微細構造光ファイバ１０のファイバ軸に直交する断面の構造を示す模式図である。複数の孔Ｈ₁は、ファイバ軸に直交する断面においてコア領域１１を取り囲むように六角形状に分布している。図３に示す断面構造をした微細構造光ファイバ１０において、孔Ｈ₁の内径がＤ₁となっている第３領域α₃での波長１．５５μｍにおけるＭＦＤは７．５１μｍである。また、図４は、接続損失を算出するための計算に用いた図１の光ファイバ２０のファイバ軸に直交する断面の構造を示す模式図である。なお、微細構造光ファイバ１０及び光ファイバ２０のコア領域１１，２１及びクラッド領域１２，２２の屈折率は上述したとおりである。 Next, the relationship between ΔL ₁ and connection loss when light is propagated to the optical component 1 will be described. FIG. 3 is a schematic diagram showing a cross-sectional structure perpendicular to the fiber axis of the microstructured optical fiber 10 of FIG. 1 used for calculation for calculating the connection loss. The plurality of holes H ₁ are distributed in a hexagonal shape so as to surround the core region 11 in a cross section orthogonal to the fiber axis. In the microstructure optical fiber 10 having the cross-sectional structure shown in FIG. 3, the MFD at a wavelength of 1.55 μm in the third region α ₃ where the inner diameter of the hole H ₁ is D ₁ is 7.51 μm. FIG. 4 is a schematic diagram showing a cross-sectional structure orthogonal to the fiber axis of the optical fiber 20 of FIG. 1 used for calculation for calculating the connection loss. The refractive indexes of the core regions 11 and 21 and the cladding regions 12 and 22 of the microstructured optical fiber 10 and the optical fiber 20 are as described above.

図５は、ΔＬ₁と接続損失との関係を示すグラフである。横軸はΔＬ₁[ｍｍ]を示し、縦軸は接続損失[ｄＢ]を示している。ΔＬ₁が小さい場合には接続損失が大きく、ΔＬ₁が大きくなるにつれて接続損失が小さくなってきていることが理解できる。これは、ΔＬ₁が大きくなるにつれてＭＦＤが変化する領域が長くなり、ＭＦＤが徐々に変化するからである。 FIG. 5 is a graph showing the relationship between ΔL ₁ and connection loss. The horizontal axis represents ΔL ₁ [mm], and the vertical axis represents the connection loss [dB]. It can be understood that when ΔL ₁ is small, the connection loss is large, and as ΔL ₁ increases, the connection loss decreases. This is because as ΔL ₁ increases, the region where the MFD changes becomes longer and the MFD changes gradually.

上述した微細構造光ファイバ１０と光ファイバ２０とのＭＦＤの差の絶対値であるΔＭＦＤ₁は３．１μｍである。このとき、０．０９ｍｍより長いΔＬ₁は（式９）を満たす。図５より、ΔＬ₁が０．０９ｍｍより大きい場合には、接続損失が約０．２ｄＢよりも小さく低接続損失になっていることが分かる。更に、ΔＬ₁が０．１２ｍｍより大きい場合、接続損失は約０．１６ｄＢよりも小さく、ΔＬ₁が０．１７ｍｍよりも大きくなれば、接続損失は約０．１ｄＢよりも小さくなる。 ΔMFD _1, which is the absolute value of the difference in MFD between the microstructured optical fiber 10 and the optical fiber 20 described above, is 3.1 μm. At this time, ΔL ₁ longer than 0.09 mm satisfies (Equation 9). FIG. 5 shows that when ΔL ₁ is larger than 0.09 mm, the connection loss is smaller than about 0.2 dB and the connection loss is low. Furthermore, if [Delta] L ₁ is greater than 0.12 mm, the connection loss is less than about 0.16 dB, if [Delta] L ₁ is becomes larger than 0.17 mm, the connection loss is less than about 0.1 dB.

以上より、上記構成の光部品１では、微細構造光ファイバ１０の波長１．５５μｍにおけるＭＦＤは、微細構造光ファイバ１０と光ファイバ２０との接続部Ａ₁を構成する端面１０Ａにおいて、光ファイバ２０のＭＦＤとほぼ一致するように変化していることから、光部品１に光を伝搬させたときに接続部Ａ₁での接続損失を低減することができる。 As described above, in the optical component 1 having the above-described configuration, the MFD at the wavelength of 1.55 μm of the microstructured optical fiber 10 is the optical fiber 20 at the end face 10 A constituting the connection portion A ₁ between the microstructured optical fiber 10 and the optical fiber 20. Therefore, when the light is propagated to the optical component ₁ , the connection loss at the connection portion A ₁ can be reduced.

以上、本発明の好適な実施形態について説明したが、上記実施形態は種々変形が可能である。例えば、上記実施形態では、光部品１における接続部Ａ₁において孔Ｈ₁は閉じているとしたが、ΔＬ₁が（式９）を満たしていれば、図６のように孔Ｈ₁が接続部Ａ₁まで延びていても良い。図６は、孔Ｈ₁が接続部Ａ₁（微細構造光ファイバ１０の端面）にまで孔Ｈ₁が延びている光部品２の構成を説明するための説明図である。なお、光部品２において、端面１０Ａを含むファイバ軸方向に沿った領域であって孔Ｈ₁の内径が変化している部分である第４領域α₄が上記第２領域α₂に相当する。また、ファイバ軸方向に沿って孔Ｈ₁の内径がほぼ一定である第５領域α₅が上記第３領域α₃に相当する。 Although the preferred embodiments of the present invention have been described above, the above embodiments can be variously modified. For example, in the above embodiment, the hole H ₁ is closed at the connection portion A ₁ in the optical component 1. However, if ΔL ₁ satisfies (Equation 9), the hole H ₁ is connected as shown in FIG. part may extend up to A _1. Figure 6 is an explanatory diagram for explaining a configuration of an optical component 2 hole H ₁ is the hole H ₁ extends up to the connecting portion A ₁ (end surface of the microstructured optical fiber 10). In the optical component 2, the fourth region alpha ₄ corresponds to ₂ the second region alpha is the fiber axis direction in a region at a inner diameter of the hole H ₁ along including the end face 10A is a part that changes. Further, the fifth region α ₅ in which the inner diameter of the hole H ₁ is substantially constant along the fiber axis direction corresponds to the third region α ₃ .

なお、光部品２は、例えば、次のように製造すれば良い。先ず、上記光部品１を製造する場合と同様に微細構造光ファイバ１０₀及び光ファイバ２０の端面同士を突き合わせて加熱溶融して融着接続する。そして、端面１０Ａを含むファイバ軸方向に沿った一部の領域（第４領域α₄）の孔Ｈ₁の内径を端面１０Ａに向かって次第に変化させ、端面１０Ａでの波長１．５５μｍにおけるＭＦＤが光ファイバ２０のＭＦＤに一致するように端面１０Ａの上記ＭＦＤを第５領域α₅の波長１．５５μｍにおけるＭＦＤから変化させる。第４領域α₄のファイバ軸方向に沿った方向の長さΔＬ₁が（式９）を満たすように孔Ｈ₁の内径を変化させることが好適であるのは光部品１の場合と同様である。 In addition, what is necessary is just to manufacture the optical component 2 as follows, for example. First, fusion splicing by heating and melting by abutting the end faces of the case as well as micro-structured optical fiber 10 ₀ and the optical fiber 20 for manufacturing the optical component 1. Then, the inner diameter of the hole H ₁ of a partial region (fourth region α ₄ ) along the fiber axis direction including the end surface 10A is gradually changed toward the end surface 10A, and the MFD at a wavelength of 1.55 μm at the end surface 10A is obtained. The MFD of the end face 10A is changed from the MFD at the wavelength 1.55 μm of the fifth region α ₅ so as to coincide with the MFD of the optical fiber 20. As in the case of the optical component 1, it is preferable to change the inner diameter of the hole H ₁ so that the length ΔL ₁ in the direction along the fiber axis direction of the fourth region α ₄ satisfies (Equation 9). is there.

更に、上記光部品１は、孔Ｈ₁の内径Ｄ₁がファイバ軸方向にほぼ一定の微細構造光ファイバ１０₀を先ず用意し、微細構造光ファイバ１０₀と光ファイバ２０とを融着接続し、孔Ｈ₁の内径Ｄ₁を部分的に変化させて製造しているが、次のように製造しても良い。 Further, the optical component 1 is first prepared substantially constant micro-structured optical fiber 10 ₀ inside diameter D ₁ of the hole H ₁ is the fiber axis direction, and fusion splicing the microstructured optical fiber 10 ₀ and the optical fiber 20 While the inner diameter D ₁ of the hole H ₁ is manufactured partially changed, it may be prepared as follows.

先ず、孔Ｈ₁の内径が変化していない微細構造光ファイバ１０₀、言い換えれば、孔Ｈ₁の内径がファイバ軸方向にほぼ一定である微細構造光ファイバ１０₀を用意する。そして、その端面１０Ａ近傍をバーナなどの加熱手段により加熱して、第１領域α₁の孔Ｈ₁を閉じて第１領域α₁を中実にし、端面１０Ａからファイバ軸方向にＬ₁離れた位置で孔Ｈ₁が閉じるように孔Ｈ₁の内径を端面１０Ａに向かって次第に変化させる。これにより、端面１０Ａでの波長１．５５μｍにおけるＭＦＤを、第３領域α₃における波長１．５５μｍにおけるＭＦＤから変化させた微細構造光ファイバ１０が製造される。 First, a microstructured optical fiber 10 ₀ in which the inner diameter of the hole H ₁ has not changed, in other words, a microstructured optical fiber 10 _{0 in} which the inner diameter of the hole H ₁ is substantially constant in the fiber axis direction is prepared. Then, the end surface 10A near heated by a heating means such as a burner, a first area alpha ₁ in the solid closing the hole H ₁ of the first area alpha _1, and the fiber axis direction from the end face 10A L ₁ apart The inner diameter of the hole H ₁ is gradually changed toward the end face 10A so that the hole H ₁ is closed at the position. Thus, the MFD at a wavelength of 1.55μm at the end face 10A, the third micro-structured optical fiber 10 is changed from MFD at a wavelength of 1.55μm in the area alpha ₃ is manufactured.

続いて、微細構造光ファイバ１０の端面１０Ａと光ファイバ２０の端面２０Ａとを突き合わせて融着接続して光部品１を製造する。孔Ｈ₁を変化させる場合には、第２領域α₂のファイバ軸方向の長さΔＬ₁が（式９）を満たすことが好適であるのは上述したとおりである。 Subsequently, the end face 10 A of the microstructured optical fiber 10 and the end face 20 A of the optical fiber 20 are abutted and fusion spliced to manufacture the optical component 1. As described above, when the hole H ₁ is changed, it is preferable that the length ΔL ₁ in the fiber axis direction of the second region α ₂ satisfies (Equation 9).

また、図１の光部品１は微細構造光ファイバ１０と光ファイバ２０とを接続して構成されているが、光ファイバ２０の波長１．５５μｍにおけるＭＦＤとほぼ一致するように、端面での波長１．５５μｍにおけるＭＦＤが変換された微細構造光ファイバ同士が融着接続されたものとしても良い。 Further, the optical component 1 in FIG. 1 is configured by connecting the microstructured optical fiber 10 and the optical fiber 20, and the wavelength at the end face is substantially equal to the MFD at the wavelength 1.55 μm of the optical fiber 20. It is good also as what the fine structure optical fiber in which MFD in 1.55 micrometer was converted was fusion-spliced.

図７は、微細構造光ファイバ１０に第２の光ファイバとして微細構造光ファイバ４０を融着接続した場合の光部品３の構成を示す説明図である。２本の微細構造光ファイバ１０，４０において、孔Ｈ₁，Ｈ₂の内径がファイバ軸方向にほぼ一定である第３領域α₃の内径Ｄ₁，Ｄ₂は互いに異なっている。また、孔Ｈ₁，Ｈ₂の内径夫々は、接続部Ａ₂に向かって次第に減少しており、接続部Ａ₂から距離Ｌ₁，Ｌ₂の位置、言い換えれば、各微細構造光ファイバ１０，４０における第１領域α₁と第２領域α₂との境界Ｂで夫々閉じている。すなわち、孔Ｈ₁，Ｈ₂の内径夫々は、各微細構造光ファイバ１０，４０における第１領域α₁と第２領域α₂との境界Ｂで夫々閉じるように境界Ｂまで次第に減少している。上記のように孔Ｈ₁，Ｈ₂の内径が変化することで、各微細構造光ファイバ１０，４０において、接続部Ａ₂となるべき各端面での波長１．５５μｍにおけるＭＦＤが、各微細構造光ファイバ１０，４０の第３領域α₃の波長１．５５μｍにおけるＭＦＤから変化している。 FIG. 7 is an explanatory diagram showing the configuration of the optical component 3 when the microstructured optical fiber 40 is fused and connected to the microstructured optical fiber 10 as the second optical fiber. In the two microstructured optical fibers 10 and 40, the inner diameters D ₁ and D ₂ of the third region α _{3 in which} the inner diameters of the holes H ₁ and H ₂ are substantially constant in the fiber axis direction are different from each other. Further, the inner diameters of the holes H ₁ and H ₂ are gradually decreased toward the connection portion A ₂ , and the positions of the distances L ₁ and L ₂ from the connection portion A ₂ , in other words, the microstructured optical fibers 10, 40 is closed at the boundary B between the first region α ₁ and the second region α ₂ . That is, the inner diameters of the holes H ₁ and H ₂ are gradually decreased to the boundary B so as to be closed at the boundary B between the first region α ₁ and the second region α ₂ in each of the microstructured optical fibers 10 and 40, respectively. . As described above, by changing the inner diameters of the holes H ₁ and H ₂ , the MFD at the wavelength of 1.55 μm at each end face to be the connection portion A ₂ in each microstructure optical fiber 10 and 40 becomes each microstructure. The third region α ₃ of the optical fibers 10 and 40 changes from the MFD at the wavelength of 1.55 μm.

また、孔Ｈ₁の内径が変化している第２領域α₂のファイバ軸方向の長さΔＬ₁は（式９）で表される関係を満たし、微細構造光ファイバ４０において孔Ｈ₂の内径が変化している領域である第２領域α₂のファイバ軸方向の長さΔＬ₂[ｍｍ]は、
ΔＬ₂＞０．０７７×ΔＭＦＤ₂−０．１５・・・（式１０）
で表される関係を満たしていることが好適である。ここで、ΔＭＦＤ₂は、微細構造光ファイバ４０における孔Ｈ₂の内径がファイバ軸方向にほぼ一定である第３領域α₃のＭＦＤと、標準化光ファイバである光ファイバ２０の波長１．５５μｍにおけるＭＦＤとの差の絶対値である。 Further, the length ΔL ₁ in the fiber axis direction of the second region α ₂ in which the inner diameter of the hole H ₁ is changed satisfies the relationship expressed by (Equation 9), and the inner diameter of the hole H ₂ in the microstructured optical fiber 40 is satisfied. The length ΔL ₂ [mm] in the fiber axis direction of the second region α ₂ , which is a region where
ΔL ₂ > 0.077 × ΔMFD ₂ −0.15 (Equation 10)
It is preferable that the relationship represented by Here, ΔMFD ₂ is the MFD in the third region α ₃ in which the inner diameter of the hole H ₂ in the microstructured optical fiber 40 is substantially constant in the fiber axis direction, and the wavelength of the standardized optical fiber 20 at 1.55 μm. Absolute value of difference from MFD.

光部品３では、各微細構造光ファイバ１０，４０の端面におけるＭＦＤが標準化光ファイバの波長１．５５μｍにおけるＭＦＤとほぼ一致するように形成されていることから、第３領域α₃での波長１．５５μｍにおけるＭＦＤが各微細構造光ファイバ１０，４０で互いに異なっていても、接続部Ａ₂におけるＭＦＤの差を小さくすることができる。そのため、接続損失を小さくすることが可能である。 In the optical component 3, the MFD at the end face of each microstructured optical fiber 10, 40 is formed so as to substantially coincide with the MFD at the wavelength of 1.55 μm of the standardized optical fiber, so that the wavelength 1 in the third region α ₃ Even if the MFD at .55 μm is different between the microstructured optical fibers 10 and 40, the difference in MFD at the connection portion A ₂ can be reduced. Therefore, connection loss can be reduced.

なお、光部品４は、微細構造光ファイバ１０，４０となるべき２本の微細構造光ファイバの端面同士を突き合わせて融着接続し、それら２本の微細構造光ファイバの孔夫々を、光部品１の製造において微細構造光ファイバ１０を形成する場合と同様の方法で変形させて製造すれば良い。 Note that the optical component 4 has two micro-structure optical fibers that should become the micro-structure optical fibers 10 and 40, but the end surfaces of the two micro-structure optical fibers are brought into contact with each other, and the holes of the two micro-structure optical fibers are connected to the optical component. 1 may be produced by being deformed by the same method as that for forming the microstructured optical fiber 10.

なお、図７では、接続部Ａ₂で孔Ｈ₁及び孔Ｈ₂は共に閉じているが、必ずしも閉じている必要はなく、接続部Ａ₂となるべき各微細構造光ファイバ１０，４０の端面において、波長１．５５μｍにおけるＭＦＤがほぼ一致するようになっていれば良い。図８に、孔Ｈ₁，Ｈ₂が閉じていない場合の光部品４の構成の一例を示す。なお、光部品４の各微細構造光ファイバ１０，４０において、接続部Ａ₂を構成すべき各端面を含むファイバ軸方向に沿った領域であって孔Ｈ₁の内径が変化している領域である第４領域α₄は上記第２領域α₂に相当する。また、ファイバ軸方向に沿って孔Ｈ₁の内径がほぼ一定である第５領域α₅は上記第３領域α₃に相当する。 In FIG. 7, the holes H ₁ and hole H ₂ at the junction A ₂ are both closed, but not necessarily need to be closed, the end face of the microstructure to be a connection portion A ₂ optical fibers 10 and 40 In this case, it is only necessary that the MFDs at the wavelength of 1.55 μm substantially coincide with each other. FIG. 8 shows an example of the configuration of the optical component 4 when the holes H ₁ and H ₂ are not closed. In each of the microstructured optical fibers 10 and 40 of the optical component 4, a region along the fiber axial direction including each end surface that should form the connection portion A ₂ and the inner diameter of the hole H ₁ is changing. A certain fourth area α ₄ corresponds to the second area α ₂ . The fifth region α ₅ in which the inner diameter of the hole H ₁ is substantially constant along the fiber axis direction corresponds to the third region α ₃ .

更にまた、上記実施形態では、光部品１は一方が微細構造光ファイバである２つの光ファイバから構成されているとしているが必ずしも２つに限らない。例えば、図９に示す光部品５のように３つの微細構造光ファイバ１０，５０，６０を融着接続したものでも良い。微細構造光ファイバ５０，６０は、夫々が有する孔Ｈ₃，Ｈ₄の内径Ｄ₃，Ｄ₄が異なる点、及び、微細構造光ファイバ５０は両端面近傍で孔Ｈ₃の内径が変化している点で微細構造光ファイバ１０と相違する。この場合には、各微細構造光ファイバ１０，５０，６０における第１領域α₁と第２領域α₂との境界Ｂまで孔Ｈ₁，Ｈ₃，Ｈ₄の内径が次第に小さくなっており、各接続部Ａ₃，Ａ₄での波長１．５５μｍにおけるＭＦＤが、各微細構造光ファイバ１０，５０，６０の第３領域α₃での波長１．５５μｍにおけるＭＦＤから変化させられている。 Furthermore, in the above-described embodiment, the optical component 1 is composed of two optical fibers, one of which is a microstructured optical fiber, but the number is not necessarily limited to two. For example, the optical fiber 5 shown in FIG. 9 may be one in which three microstructured optical fibers 10, 50, 60 are fusion-connected. Microstructured optical fiber 50 and 60, holes H ₃ having the respective, H ₄ of the inner diameter D _3, D ₄ are different, and, microstructured optical fiber 50 after changing the inner diameter of the hole H ₃ at both end faces near It is different from the microstructured optical fiber 10 in that it is. In this case, the inner diameters of the holes H ₁ , H ₃ , H ₄ are gradually reduced to the boundary B between the first region α ₁ and the second region α ₂ in each microstructured optical fiber 10, 50, 60, The MFD at a wavelength of 1.55 μm at each connection A ₃ , A ₄ is changed from the MFD at a wavelength of 1.55 μm in the third region α ₃ of each microstructured optical fiber 10, 50, 60.

なお、微細構造光ファイバ１０のΔＬ₁が（式９）を満たし、微細構造光ファイバ５０，６０における第２領域α₂のファイバ軸方向に沿った長さΔＬ₃[ｍｍ],ΔＬ₄[ｍｍ]夫々が
ΔＬ₃＞０．０７７×ΔＭＦＤ₃−０．１５・・・（式１１）
ΔＬ₄＞０．０７７×ΔＭＦＤ₄−０．１５・・・（式１２）
で表される関係を満たすことが接続損失をより低減する観点から好適である。（式１１）及び（式１２）におけるΔＭＦＤ₃及びΔＭＦＤ₄は、微細構造光ファイバ５０，６０の孔Ｈ₃，Ｈ₄の内径が夫々Ｄ₃，Ｄ₄である領域での波長１．５５μｍにおけるＭＦＤと標準化光ファイバ（光ファイバ２０）の波長１．５５μｍにおけるＭＦＤとの差の絶対値である。 Note that ΔL _{1 of} the microstructured optical fiber 10 satisfies (Equation 9), and the lengths ΔL ₃ [mm] and ΔL ₄ [mm] of the second region α ₂ in the microstructured optical fibers 50 and 60 along the fiber axis direction. ] respectively is _{_{ΔL 3> 0.077 × ΔMFD 3 -0.15}} ··· ( equation 11)
ΔL ₄ > 0.077 × ΔMFD ₄ −0.15 (Equation 12)
It is preferable to satisfy the relationship represented by the above from the viewpoint of further reducing the connection loss. ΔMFD ₃ and ΔMFD ₄ in (Expression 11) and (Expression 12) are obtained at a wavelength of 1.55 μm in a region where the inner diameters of the holes H ₃ and H ₄ of the microstructured optical fibers 50 and 60 are D ₃ and D ₄ , respectively. It is the absolute value of the difference between the MFD and the MFD at the wavelength of 1.55 μm of the standardized optical fiber (optical fiber 20).

微細構造光ファイバ１０，５０における接続部Ａ₃となるべき各端面、及び、微細構造光ファイバ５０，６０における接続部Ａ₄となるべき各端面での波長１．５５μｍにおけるＭＦＤは、標準化光ファイバの波長１．５５μｍにおけるＭＦＤとほぼ一致するように各微細構造光ファイバ１０，５０，６０の第１領域α₁と第２領域α₂との境界Ｂまで次第に変化している。そのため、光部品５に光を伝搬させても接続損失が低減される。 The MFD at a wavelength of 1.55 μm at each end face to be the connection portion A ₃ in the microstructure optical fibers 10 and 50 and each end face to be the connection portion A ₄ in the microstructure optical fibers 50 and 60 is a standardized optical fiber. Gradually changes to the boundary B between the first region α ₁ and the second region α ₂ of each of the microstructured optical fibers 10, 50, 60 so as to substantially match the MFD at a wavelength of 1.55 μm. Therefore, even if light is propagated to the optical component 5, the connection loss is reduced.

なお、上述したように中央の微細構造光ファイバ５０では、接続部Ａ₃及び接続部Ａ₄に向かって孔Ｈ₃の内径が小さくなっている、言い換えれば、微細構造光ファイバ５０の両端面に向かって孔Ｈ₃の内径が小さくなっている。光部品１では、一方の端面に向かって孔Ｈ₁の内径が次第に変化している場合を示しているが、このように両端に向かって孔の内径を変化させていても良い。また、３つの微細構造光ファイバ１０，５０，６０における孔Ｈ₁，Ｈ₃，Ｈ₄の内径Ｄ₁，Ｄ₃，Ｄ₄が全て等しい場合でもファイバ軸に直交する断面での孔Ｈ₁，Ｈ₃，Ｈ₄の分布形状が異なれば、接続部を構成する端面に向かってＭＦＤを変化させることは有効である。 In the center of the microstructured optical fiber 50 as described above, the inner diameter of the hole H ₃ toward the connecting portion A ₃ and the connecting portion A ₄ is small, in other words, on both end faces of the microstructured optical fiber 50 The inner diameter of the hole H ₃ is becoming smaller. In the optical component 1, but toward one of the end faces the inner diameter of the hole H ₁ shows a case in which gradually changes, thus may alter the inner diameter of the hole toward both ends. Further, even if the inner diameters D ₁ , D ₃ , D ₄ of the holes H ₁ , H ₃ , H _{4 in} the _three microstructured optical fibers 10, 50, 60 are all equal, the holes H ₁ , If the distribution shapes of H ₃ and H ₄ are different, it is effective to change the MFD toward the end face constituting the connecting portion.

また、図９では各微細構造光ファイバ１０，５０，６０の第１領域α₁と第２領域α₂との境界Ｂで孔Ｈ₁，Ｈ₃，Ｈ₄は夫々閉じているが、図１０に示す光部品６のように、接続部Ａ₃，Ａ₄まで孔Ｈ₁，Ｈ₃，Ｈ₄が延びていても良い。更に、上述したような複数の微細構造光ファイバを融着接続した光部品では、微細構造光ファイバが異なれば孔の内径も異なるとしているが、その場合に限らない。光部品を構成すべき微細構造光ファイバ間において、ファイバ軸方向に延びる孔の内径が一定である領域での上記ＭＦＤが異なっている微細構造光ファイバ同士を接続する場合にも上述した方法により微細構造光ファイバを接続する光部品の製造方法は有効である。更に、上記実施形態では、クラッド領域１２に孔を設けているとしているが必ずしもクラッド領域に限らなくても良い。 In FIG. 9, the holes H ₁ , H ₃ , and H ₄ are closed at the boundary B between the first region α ₁ and the second region α _{2 of} each microstructured optical fiber 10, 50, 60. Holes H ₁ , H ₃ , H ₄ may extend to the connecting portions A ₃ , A ₄ as in the optical component 6 shown in FIG. Furthermore, in an optical component in which a plurality of microstructure optical fibers as described above are fusion-connected, the inner diameter of the hole is different if the microstructure optical fiber is different, but this is not a limitation. In the case where the microstructured optical fibers having different MFDs in the region where the inner diameter of the hole extending in the fiber axial direction is constant between the microstructured optical fibers that constitute the optical component are also connected by the above-described method. An optical component manufacturing method for connecting structured optical fibers is effective. Further, in the above-described embodiment, the holes are provided in the cladding region 12, but the holes are not necessarily limited to the cladding region.

図１（ａ），（ｂ）は、本発明に係る光部品の一実施形態の構成を概略的に説明するための説明図である。FIGS. 1A and 1B are explanatory views for schematically explaining the configuration of an embodiment of an optical component according to the present invention. 図２（ａ）〜（ｃ）は、図１（ａ）の光部品を製造する工程の工程図である。2A to 2C are process diagrams of a process for manufacturing the optical component of FIG. 図１（ａ）の光部品における微細構造光ファイバのファイバ軸に直交する模式断面図である。It is a schematic cross section orthogonal to the fiber axis of the microstructure optical fiber in the optical component of Fig.1 (a). 図１（ａ）の光部品における光ファイバのファイバ軸に直交する模式断面図である。It is a schematic cross section orthogonal to the fiber axis of the optical fiber in the optical component of Fig.1 (a). ΔＬ₁と接続損失との関係を示すグラフである。Is a graph showing the relationship between [Delta] L ₁ and connection loss. 図１（ａ）の光部品の一変形形態の構成を概略的に示す説明図である。It is explanatory drawing which shows schematically the structure of the deformation | transformation form of the optical component of Fig.1 (a). ２本の微細構造光ファイバから構成される光部品の一例を示す説明図である。It is explanatory drawing which shows an example of the optical component comprised from two microstructured optical fibers. 図７の光部品の一変形形態の構成を概略的に示す説明図である。FIG. 8 is an explanatory diagram schematically showing a configuration of a variation of the optical component in FIG. 7. ３本の微細構造光ファイバから構成される光部品の一例の構成を概略的に示す説明図である。It is explanatory drawing which shows roughly the structure of an example of the optical component comprised from three microstructured optical fibers. 図９の光部品の一変形形態の構成を概略的に示す説明図である。FIG. 10 is an explanatory diagram schematically showing a configuration of a variation of the optical component in FIG. 9.

Explanation of symbols

１〜６…光部品、１０…微細構造光ファイバ（第１の光ファイバ）、１１…コア領域、１２…クラッド領域、２０…光ファイバ（第２の光ファイバ）、２１…コア領域、２２…クラッド領域、３０…融着器，４０…微細構造光ファイバ（第２の光ファイバ）、５０，６０…微細構造光ファイバ、Ａ₁，Ａ₂，Ａ₃，Ａ₄…接続部、Ｂ…境界、Ｈ₁，Ｈ₂，Ｈ₃，Ｈ₄…孔、α₁…第１領域、α₂…第２領域、α₃…第３領域、α₄…第４領域、α₅…第５領域。

DESCRIPTION OF SYMBOLS 1-6 ... Optical component, 10 ... Fine structure optical fiber (1st optical fiber), 11 ... Core area | region, 12 ... Cladding area | region, 20 ... Optical fiber (2nd optical fiber), 21 ... Core area | region, 22 ... Cladding region, 30 ... fuser, 40 ... fine structure optical fiber (second optical fiber), 50, 60 ... fine structure optical fiber, A ₁ , A ₂ , A ₃ , A ₄ ... connection part, B ... boundary , H ₁ , H ₂ , H ₃ , H ₄ ... Hole, α ₁ ... first region, α ₂ ... second region, α ₃ ... third region, α ₄ ... fourth region, α ₅ ... fifth region.

Claims

An optical fiber having a hole extending in the fiber axial direction,
The first region, which is a partial region along the fiber axis direction including one end face, is solid, and is adjacent to the first region and the other partial region along the fiber axis direction. In a certain second region, the inner diameter of the hole gradually decreases to the boundary so that the hole is closed at the boundary between the first region and the second region,
The mode field diameter at a wavelength of 1.55 μm on the end face is changed from the mode field diameter at a wavelength of 1.55 μm in the third region where the inner diameter of the hole is substantially constant along the fiber axis direction. And optical fiber.

The mode field diameter of the third region at a wavelength of 1.55 μm, ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the second region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Expression 1)
The optical fiber according to claim 1, wherein the relationship represented by:

An optical fiber having a hole extending in the fiber axial direction,
The inner diameter of the hole gradually changes to the end surface in a fourth region which is a partial region along the fiber axis direction including one end surface;
The mode field diameter at a wavelength of 1.55 μm on the end face is changed from the mode field diameter at a wavelength of 1.55 μm in the fifth region where the inner diameter of the hole is substantially constant along the fiber axis direction. Characteristic optical fiber.

The mode field diameter of the fifth region at a wavelength of 1.55 μm, ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the fourth region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Expression 2)
The optical fiber according to claim 3, wherein the relationship represented by:

A first optical fiber that is the optical fiber according to any one of claims 1 to 4,
An optical component comprising: a second optical fiber fused and connected to the end face of the first optical fiber.

A first optical fiber which is the optical fiber according to claim 2;
A second optical fiber that is the optical fiber according to claim 2,
The inner diameter of the hole in the third region of the first optical fiber is different from the inner diameter of the hole in the third region of the second optical fiber;
An optical component, wherein the end face of the first optical fiber and the end face of the second optical fiber are fusion-connected.

A first optical fiber which is the optical fiber according to claim 4;
A second optical fiber which is the optical fiber according to claim 4,
The inner diameter of the hole in the fifth region of the first optical fiber is different from the inner diameter of the hole in the fifth region of the second optical fiber;
An optical component, wherein the end face of the first optical fiber and the end face of the second optical fiber are fusion-connected.

In an optical fiber having a hole extending in the fiber axis direction, a first region that is a partial region along the fiber axis direction including one end face of the optical fiber, and adjacent to the first region, By heating the second region, which is another partial region along the fiber axis direction, the hole in the first region is closed to make the first region solid, and the first region and the second region The inner diameter of the hole in the second region is gradually reduced to the boundary so as to close the hole at the boundary of the region, and the mode field diameter at the wavelength of 1.55 μm at the end surface is set so that the inner diameter of the hole is the fiber axis. A method of manufacturing an optical fiber, wherein the mode field diameter is changed from a mode field diameter at a wavelength of 1.55 μm, which is substantially constant along the direction.

The mode field diameter of the third region at a wavelength of 1.55 μm, ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the third region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Equation 3)
The method for manufacturing an optical fiber according to claim 8, wherein the inner diameter of the hole is changed so as to satisfy the relationship represented by:

In the optical fiber having a hole extending in the fiber axis direction, the hole in the fourth area is heated by heating a fourth area which is a partial area along the fiber axis direction including one end face of the optical fiber. The mode field diameter at a wavelength of 1.55 μm at the end face is gradually changed to the end face, and the mode field diameter at the end face is substantially constant along the fiber axis direction at a wavelength of 1.55 μm. A method for manufacturing an optical fiber, wherein the mode field diameter is changed.

The mode field diameter of the fifth region at a wavelength of 1.55 μm, ITU-T Recommendation G. When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the fourth region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Expression 4)
The method of manufacturing an optical fiber according to claim 10, wherein the inner diameter of the hole is changed so as to satisfy the relationship represented by:

The end face of the first optical fiber having a hole extending in the fiber axis direction and the end face of the solid second optical fiber are brought into contact with each other by heat melting and fusion-bonded. Closing the hole in the first region, which is a partial region along the fiber axis direction, and making the first region solid, and adjacent to the first region and extending in the fiber axis direction In the second region that is another partial region along the first region, the inner diameter of the hole is gradually decreased to the boundary so that the hole is closed at the boundary between the first region and the second region, A mode field diameter at a wavelength of 1.55 μm at the end face of the optical fiber is a mode at a wavelength of 1.55 μm in a third region in which the inner diameter of the hole in the first optical fiber is substantially constant along the fiber axis direction. field A method for manufacturing an optical component, characterized in that the diameter is changed from the diameter.

A mode field diameter for the wavelength of 1.55 μm in the third region; When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the second region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Expression 5)
The method of manufacturing an optical component according to claim 12, wherein an inner diameter of the hole is changed so as to satisfy a relationship represented by:

The end face of the first optical fiber having a hole extending in the fiber axis direction and the end face of the solid second optical fiber are brought into contact with each other by heat melting and fusion-bonded. The inner diameter of the hole in the fourth region that is a partial region along the fiber axis direction is gradually changed to the end surface, and the mode field diameter at the wavelength of 1.55 μm at the end surface is changed to the inner diameter of the hole. Is changed from the mode field diameter at a wavelength of 1.55 μm in the fifth region, which is substantially constant along the fiber axis direction.

A mode field diameter for the wavelength of 1.55 μm in the fifth region; When the absolute value of the difference from the mode field diameter at the wavelength of 1.55 μm of the optical fiber standardized by 652 is ΔMFD [μm], the length ΔL [mm] of the third region in the fiber axis direction is:
ΔL> 0.077 × ΔMFD−0.15 (Expression 6)
The method for manufacturing an optical component according to claim 14, wherein an inner diameter of the hole is changed so as to satisfy a relationship represented by:

The end faces of the first optical fiber and the second optical fiber having holes extending in the fiber axis direction are brought into contact with each other, heated and melted, and fusion-spliced;
In each of the first and second optical fibers, the first region is closed by closing the hole of the first region, which is a partial region along the fiber axis direction including the end surface, and In the second region, which is adjacent to the first region and is another part of the region along the fiber axis direction, the hole is closed so that the hole is closed at the boundary between the first region and the second region. By gradually reducing the inner diameter to the boundary, the mode field diameter at a wavelength of 1.55 μm at the end face of each of the first and second optical fibers is substantially constant along the fiber axis direction. A method of manufacturing an optical component, wherein the mode field diameter in a third region is changed from a mode field diameter at a wavelength of 1.55 μm.

In the first optical fiber, the mode field diameter of the third region at a wavelength of 1.55 μm, ITU-T Recommendation G. The absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD ₁ [μm],
In the second optical fiber, the mode field diameter of the third region at a wavelength of 1.55 μm, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter at a wavelength of 1.55 μm of the optical fiber standardized at 652 is ΔMFD ₂ [μm],
The length ΔL ₁ [mm] of the second region of the first optical fiber in the fiber axis direction and the length ΔL ₂ [mm] of the second region of the second optical fiber in the fiber axis direction are respectively determined. ,
ΔL ₁ > 0.077 × ΔMFD ₁ −0.15 (Expression 7a)
ΔL ₂ > 0.077 × ΔMFD ₂ −0.15 (Expression 7b)
The method for manufacturing an optical component according to claim 16, wherein an inner diameter of the hole of each of the first optical fiber and the second optical fiber is changed so as to satisfy the relationship represented by:

The end faces of the first optical fiber and the second optical fiber having holes extending in the fiber axis direction are brought into contact with each other, heated and melted, and fusion-spliced;
In each of the first and second optical fibers, the inner diameter of the hole in the fourth region which is a partial region along the fiber axis direction including the end surface is gradually changed to the end surface, and the wavelength at the end surface is changed. The mode field diameter at 1.55 μm is determined from the mode field diameter at a wavelength of 1.55 μm in the fifth region where the inner diameter of the hole is substantially constant along the fiber axis direction in each of the first and second optical fibers. A method of manufacturing an optical component, wherein the optical component is changed.

In the first optical fiber, the mode field diameter of the fifth region at a wavelength of 1.55 μm, ITU-T recommendation G. The absolute value of the difference from the mode field diameter of the optical fiber standardized at 652 at a wavelength of 1.55 μm is ΔMFD ₁ [μm],
In the second optical fiber, the mode field diameter of the fifth region at a wavelength of 1.55 μm, the ITU-T recommendation G. When the absolute value of the difference from the mode field diameter at a wavelength of 1.55 μm of the optical fiber standardized at 652 is ΔMFD ₂ [μm],
The length ΔL ₁ [mm] of the fourth region of the first optical fiber in the fiber axis direction and the length of the fourth region of the second optical fiber in the fiber axis direction are ΔL ₂ [mm]. Each of them
ΔL ₁ > 0.077 × ΔMFD ₁ −0.15 (Equation 8a)
ΔL ₂ > 0.077 × ΔMFD ₂ −0.15 (Equation 8b)
The method for manufacturing an optical component according to claim 18, wherein an inner diameter of the hole of each of the first optical fiber and the second optical fiber is changed so as to satisfy the relationship expressed by: