JP2004191947A - Holey fiber drawing method - Google Patents

Holey fiber drawing method Download PDF

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JP2004191947A
JP2004191947A JP2003388062A JP2003388062A JP2004191947A JP 2004191947 A JP2004191947 A JP 2004191947A JP 2003388062 A JP2003388062 A JP 2003388062A JP 2003388062 A JP2003388062 A JP 2003388062A JP 2004191947 A JP2004191947 A JP 2004191947A
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hole
glass
base material
differential pressure
pressure
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Tetsuya Otsusaka
哲也 乙坂
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Shin Etsu Chemical Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C03B37/02781—Hollow fibres, e.g. holey fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/10—Internal structure or shape details
    • C03B2203/14—Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/42—Photonic crystal fibres, e.g. fibres using the photonic bandgap PBG effect, microstructured or holey optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/08—Sub-atmospheric pressure applied, e.g. vacuum

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

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holey fiber drawing method by which a hole diameter can easily be adjusted and the forms and diameters of the holes are stabilized in the longitudinal direction. <P>SOLUTION: The method is provided of drawing an optical fiber through which a plurality of holes are formed over the whole length of the fiber in the axial direction. When heating, softening and drawing a glass base material 1 provided with a plurality of hollow holes 2 in the axial direction, a pressure difference between the pressure inside the hollow holes of the glass base material 1 and the atmospheric pressure is controlled. When controlling the pressure difference between the pressure inside the hollow holes of the glass base material and the atmospheric pressure, it is preferable to control the pressure difference by connecting a glass tube 3 having an inner diameter larger than the circumscribed circle diameter of the hollow hole part to the opening end of the glass base material provided with the plurality of hollow holes 2 in the axial direction, and providing the glass tube 3 with a pressure difference regulating means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

本発明は、全長にわたって複数の孔があいた光ファイバ（以下、単に空孔ファイバと称する）の孔形状及び孔径が、長手方向に安定した空孔ファイバの線引き方法に関する。   The present invention relates to a method for drawing a holey fiber in which the hole shape and hole diameter of an optical fiber having a plurality of holes over its entire length (hereinafter simply referred to as a holey fiber) are stable in the longitudinal direction.

通常広く使用されている光ファイバは、石英ガラス等の中心部にコアと称される屈折率の高い領域を持つ、中実の構造を有している。これに対し、フォトニック結晶ファイバやホーリーファイバといった、長手方向に孔の設けられた光ファイバが最近注目されている。フォトニック結晶ファイバは、規則正しく配列した孔をファイバ中に設けることにより、フォトニックバンドギャップを形成し、これに欠陥を付与することで光を導波するものである。   An optical fiber that is generally widely used has a solid structure having a high refractive index region called a core in a central portion of quartz glass or the like. On the other hand, optical fibers having holes in the longitudinal direction, such as photonic crystal fibers and holey fibers, have recently attracted attention. The photonic crystal fiber forms a photonic band gap by providing regularly arranged holes in the fiber, and guides light by providing a defect in the band.

また、ホーリーファイバは、クラッド中に孔を設け、クラッドの実効屈折率を低下させてコアとの間に屈折率差を与えるものであり、その導波原理には、従来の光ファイバと同様に全反射が用いられている（特許文献１参照）。また、従来の光ファイバのコア周辺に孔を開けた、空孔付加型ファイバも提案されている。
これらのファイバが有する孔は、その形状、大きさ及び配列等がその伝送特性に大きな影響を与える。 The holey fiber has a hole in the cladding, reduces the effective refractive index of the cladding, and gives a difference in refractive index between the core and the core. Total reflection is used (see Patent Document 1). Also, a hole-added fiber in which a hole is formed around the core of a conventional optical fiber has been proposed.
The shape, size, arrangement, and the like of the holes of these fibers greatly affect their transmission characteristics.

米国特許第5,802,236号US Patent 5,802,236

このようなファイバの製造には、一般的にガラス細管を束ねたものを線引きするという手法が採られているが、この方法では、ガラス細管同士の間隙が埋まる際に、孔が変形するという問題があった。ガラス細管同士の間隙を残さずに埋めるためには、特許文献１に記載されているように、キャピラリの上端を封止して、キャピラリ内部の圧を保持するという方法があるが、この方法は、線引きが進行するにつれてキャピラリ内部の圧と孔径が変化するため、長手方向への孔形状の安定性及び制御性が悪い。   In the production of such a fiber, a method of drawing a bundle of glass tubules is generally employed, but this method has a problem that the holes are deformed when the gap between the glass tubules is filled. was there. In order to fill the gap without leaving a gap between the glass capillaries, as described in Patent Literature 1, there is a method of sealing the upper end of the capillary and holding the pressure inside the capillary. Since the pressure and the hole diameter inside the capillary change as the drawing progresses, the stability and controllability of the hole shape in the longitudinal direction are poor.

また、ガラス細管同士の間隙を孔として残す場合、この孔を潰さないためには、できるだけガラスの粘度を小さく保ちながら線引きする必要があるため、通常の光ファイバの線引きに比べ、高張力で低温かつ低速で線引きを行っており、生産性が悪く、また、破断する確立が高いという問題があった。   In addition, when leaving a gap between glass thin tubes as a hole, it is necessary to draw while keeping the viscosity of the glass as low as possible in order to avoid crushing this hole. In addition, there is a problem that the drawing is performed at a low speed, the productivity is low, and the probability of breaking is high.

本発明は、上記事情に鑑み、容易に孔径を調節することができ、長手方向に孔形状及び孔径の安定した空孔ファイバの線引き方法を提供することを目的としている。   The present invention has been made in view of the above circumstances, and has as its object to provide a method of drawing a holey fiber in which the hole diameter can be easily adjusted and the hole shape and the hole diameter are stable in the longitudinal direction.

本発明の空孔ファイバの線引き方法は、軸方向に、全長にわたって複数の孔があいた光ファイバの製造方法であって、軸方向に複数の空孔が設けられたガラス母材を加熱し軟化させて線引きする際、該ガラス母材の空孔内部と大気圧との差圧を制御することを特徴としている。   The method for drawing a holey fiber of the present invention is a method of manufacturing an optical fiber having a plurality of holes in the axial direction, the entire length thereof being heated and softened by heating a glass preform provided with a plurality of holes in the axial direction. When drawing, the pressure difference between the inside of the pores of the glass base material and the atmospheric pressure is controlled.

ガラス母材の空孔内部と大気圧との差圧は、軸方向に複数の空孔が設けられたガラス母材の開放端に、空孔部分の外接円の径よりも大きな内径を有するガラス管を接続し、該ガラス管に差圧調整手段を設けることにより、制御することができる。
また、接続したガラス管の内部を仕切り、仕切られた各室にそれぞれ差圧調整手段を設け、線引き中、各室毎に該室に通じるガラス母材の空孔内部と大気圧との差圧を制御するようにしてもよい。 The pressure difference between the inside of the pores of the glass base material and the atmospheric pressure is such that the glass having a larger inner diameter than the diameter of the circumcircle of the hole portion at the open end of the glass base material having a plurality of holes formed in the axial direction. It can be controlled by connecting a tube and providing a differential pressure adjusting means on the glass tube.
Further, the inside of the connected glass tube is partitioned, and a differential pressure adjusting means is provided in each of the partitioned chambers. During the drawing, the differential pressure between the inside of the pores of the glass base material communicating with the chamber and the atmospheric pressure is provided for each chamber. May be controlled.

差圧調整手段は、空孔内部の圧力測定手段、加圧ガス供給装置及びガス排出ポートからなる構成、あるいは、空孔内部の圧力測定手段、シリンダ及びピストンからなる構成としてもよく、さらには、安全弁で構成してもよい。
光ファイバの孔径は、差圧調整手段の設定圧力を変化させることによって、あるいは加熱炉の温度を変化させることによって、もしくは線引き速度を変化させることによっても、調節することができる。線引き速度で孔径を調節する場合は、50m/min以上とするのが好ましい。なお、空孔の内圧、温度及び線引き速度のなかから適宜組み合わせて、あるいはこれらを同時に制御して孔径を調節するようにしてもよい。 The differential pressure adjusting means may be configured to include a pressure measuring means inside the hole, a pressurized gas supply device and a gas discharge port, or may be configured to include a pressure measuring means inside the hole, a cylinder and a piston. You may comprise with a safety valve.
The hole diameter of the optical fiber can be adjusted by changing the set pressure of the differential pressure adjusting means, or by changing the temperature of the heating furnace, or by changing the drawing speed. In the case where the pore size is adjusted by the drawing speed, it is preferable to be 50 m / min or more. The hole diameter may be adjusted by appropriately combining the internal pressure, temperature, and drawing speed of the holes, or by simultaneously controlling these.

また、差圧調整手段の設定圧力を変化させるには、先に線引きされた光ファイバの断面形状、分散特性、伝送損失、光パワー分布のうち、少なくとも１つを測定し、この測定結果にもとづき設定圧力を変化させるのが好ましい。
ガラス母材に接続したガラス管の内圧と大気圧との差圧Ｐ[Pa]は、ガラス母材の最も大きい空孔の半径をＲ[m]、ガラス母材の表面張力をＴ[N/m]としたときに、Ｐ≦Ｔ/Ｒとされる。
ガラス母材は、実質的に純粋な石英ガラスからなり、ドーパントを含んでいてもよい。また、多成分系ガラスからなるものであっても良い。このようにして、本発明の空孔ファイバが製造される。 To change the set pressure of the differential pressure adjusting means, at least one of the cross-sectional shape, dispersion characteristics, transmission loss, and optical power distribution of the previously drawn optical fiber is measured, and based on the measurement result, It is preferable to change the set pressure.
The differential pressure P [Pa] between the internal pressure of the glass tube connected to the glass preform and the atmospheric pressure is represented by R [m], the radius of the largest hole in the glass preform, and T [N / m], P ≦ T / R.
The glass preform is made of substantially pure quartz glass and may contain a dopant. Further, it may be made of multi-component glass. Thus, the holey fiber of the present invention is manufactured.

本発明の線引き方法によれば、容易に光ファイバの孔径を調節することができ、長手方向に孔形状及び孔径の安定した空孔ファイバが得られる。   ADVANTAGE OF THE INVENTION According to the drawing method of this invention, the hole diameter of an optical fiber can be adjusted easily, and the hole fiber whose hole shape and hole diameter were stable in the longitudinal direction can be obtained.

本発明の空孔ファイバの製造方法について、図に基づいて詳細に説明するが、本発明はこれらの形態に限定されず、様々な態様が可能である。
図１は、本発明の空孔ファイバの製造方法を示す概略説明図であり、図１（ａ）は、ガラス母材を線引き装置にセットした状態を示し、図１（ｂ）は、空孔ファイバの線引き状態を示している。 The method for manufacturing a holey fiber of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and various embodiments are possible.
FIG. 1 is a schematic explanatory view showing a method for producing a holey fiber according to the present invention. FIG. 1A shows a state in which a glass preform is set in a drawing apparatus, and FIG. The drawing state of the fiber is shown.

ガラス母材１の開放端には、複数の空孔２が設けられている空孔部分の外径よりも大きな内径を有するガラス管３が接続され、ガラス管３の上部には差圧調整手段４が取り付けられている。このガラス管３は、昇降装置５で保持されている。ガラス母材１の下端には引き落とし部６が形成され、これを加熱炉７で加熱すると、粘度が低下し、引き落とし部６が自重で落下し、線引きが開始される。
ガラス母材１の下方には、コーティング装置８及び引き取り装置９が配設されている。 A glass tube 3 having an inner diameter larger than an outer diameter of a hole portion provided with a plurality of holes 2 is connected to an open end of the glass base material 1. 4 are attached. The glass tube 3 is held by a lifting device 5. At the lower end of the glass base material 1, a draw-down portion 6 is formed, and when this is heated in the heating furnace 7, the viscosity decreases, and the draw-down portion 6 falls by its own weight, and drawing starts.
Below the glass preform 1, a coating device 8 and a take-up device 9 are provided.

ガラス管３の内部及び空孔２内の内圧と、大気圧との差圧Ｐは、線引き中、差圧調整手段４により自在に変化させることができる。さらに、ガラス管３は、二重管を使用する等の方法によってその内部をさらに分室し、各分室に差圧調整手段４を設けるようにしてもよい。
線引きは、空孔ファイバ10の外径を測定しながら昇降装置５の下降速度と引き取り装置９の引き取り速度を調節することで、空孔ファイバ10の外径を一定に保つことができる。なお、空孔ファイバ10は、コーティング装置８を通る間にコーティングが施される。 The differential pressure P between the internal pressure inside the glass tube 3 and the inside of the hole 2 and the atmospheric pressure can be freely changed by the differential pressure adjusting means 4 during drawing. Further, the inside of the glass tube 3 may be further divided by a method such as using a double tube, and the differential pressure adjusting means 4 may be provided in each of the divided rooms.
In the drawing, the outer diameter of the hole fiber 10 can be kept constant by adjusting the lowering speed of the lifting device 5 and the drawing speed of the pickup device 9 while measuring the outer diameter of the hole fiber 10. The holey fiber 10 is coated while passing through the coating device 8.

空孔ファイバに形成される孔の径は、線引き時の空孔の内圧、表面張力及び粘度によって決まるため、温度と線引き速度を一定に保ちつつ、ガラス母材の空孔の内圧を調整することで、空孔ファイバの孔径を制御することができる。また、粘度は温度によって決まるため、空孔の内圧を一定にした状態で線引き温度を調整することで、孔径を制御することもできる。その他、線引き速度を変化させても、加熱領域での滞在時間が変化するため、孔径を制御することができる。もちろん、空孔の内圧、温度及び線引き速度のなかから適宜組み合わせて、あるいはこれら全てを同時に制御してもよい。   Since the diameter of the hole formed in the hole fiber is determined by the internal pressure, surface tension and viscosity of the hole at the time of drawing, it is necessary to adjust the internal pressure of the hole of the glass base material while keeping the temperature and drawing speed constant. Thus, the hole diameter of the holey fiber can be controlled. Further, since the viscosity is determined by the temperature, the pore diameter can be controlled by adjusting the drawing temperature while keeping the internal pressure of the pores constant. In addition, even if the drawing speed is changed, the residence time in the heating region changes, so that the hole diameter can be controlled. Of course, the internal pressure, the temperature, and the drawing speed of the holes may be appropriately combined, or all of them may be simultaneously controlled.

また、差圧調整手段は、特には限定されないが、０〜数千Paの範囲内で制御できるものが好ましく、例えば、空孔内部の圧力測定手段とガス排出ポート及び加圧ガス供給装置からなるもの、あるいは、空孔内部の圧力測定手段とシリンダ及びピストンからなるもの等が挙げられる。
なお、圧力を一定に制御するだけが目的であれば、線引きが進むにつれて、大きな容積を持つガラス管内のガスが暖められて圧力が増加する傾向にあるため、単に安全弁を用いるだけでもよい。 Further, the differential pressure adjusting means is not particularly limited, but preferably can be controlled within a range of 0 to several thousand Pa, and includes, for example, a pressure measuring means inside a hole, a gas discharge port, and a pressurized gas supply device. Or a device comprising a cylinder and a piston, a pressure measuring means inside the hole, and the like.
If the purpose is only to control the pressure to be constant, the gas in the glass tube having a large volume tends to be warmed and the pressure tends to increase as the drawing progresses. Therefore, a simple safety valve may be used.

また、制御する空孔の内圧が高すぎる場合、内圧が表面張力に勝ってしまい、ガラス母材の加熱部分が膨れてはじける。このため、内圧を高くし過ぎないことが重要であり、その制御範囲は、大気圧と内圧の差をＰ[Pa]、ガラス母材の最も大きい空孔の半径をＲ[m]、表面張力をＴ[N/m]としたときに、Ｐ≦Ｔ/Ｒとすることで、ガラス母材を膨らませることなく線引きすることができる。例えば、石英ガラスの場合は、表面張力Ｔが約0.3
N/mであるので、空孔の半径が0.3 mmの場合、Ｐを1,000 Pa未満に設定する。なお、ガラス母材は、ゲルマニウム、フッ素、リン等のドーパントを含む実質的に純粋な石英ガラスからなっている。ガラス母材には、その他に多成分系ガラスが挙げられ、製造された空孔ファイバを様々な用途に供することができる。 If the internal pressure of the pore to be controlled is too high, the internal pressure exceeds the surface tension, and the heated portion of the glass base material swells and pops. For this reason, it is important not to raise the internal pressure too much, and the control range is P [Pa], the difference between the atmospheric pressure and the internal pressure, R [m] the radius of the largest hole in the glass base material, surface tension. Is set to T [N / m], by setting P ≦ T / R, it is possible to draw without expanding the glass base material. For example, in the case of quartz glass, the surface tension T is about 0.3
Since N / m, when the radius of the hole is 0.3 mm, P is set to less than 1,000 Pa. The glass base material is made of substantially pure quartz glass containing a dopant such as germanium, fluorine, and phosphorus. Other examples of the glass base material include a multi-component glass, and the manufactured holey fiber can be used for various applications.

図２に示したように、外径30 mmφ、長さ400 mmで、石英ガラスロッド10の長手方向に、三角格子状に直径1.4 mmφの孔11を２mmピッチで60個開けて、空孔ファイバ用ガラス母材を作製した。
このガラス母材に、この空孔部分の外接円12の径よりも大きな内径を有する石英ガラス管（外径30 mmφ、内径20 mmφ）を接続し、さらに、この石英ガラス管に圧力測定手段とガス排出ポート及び加圧ガス供給装置からなる差圧調整装置を取り付けた。 As shown in FIG. 2, 60 holes 11 having an outer diameter of 30 mmφ and a length of 400 mm and having a diameter of 1.4 mmφ in a triangular lattice in a longitudinal direction of the quartz glass rod 10 are opened at a pitch of 2 mm, and 60 holes are formed. A glass base material was prepared.
A quartz glass tube (outer diameter 30 mmφ, inner diameter 20 mmφ) having an inner diameter larger than the diameter of the circumcircle 12 of the hole is connected to the glass base material. A differential pressure regulator consisting of a gas discharge port and a pressurized gas supply was attached.

なおこれには、図３（ａ）のように、流量調節弁13,14を手動で差圧計16が設定値を示すように調節してもよく、あるいは図３（ｂ）のように、自動流量調節弁（又はマスフローコントローラ）17を差圧計19の検出圧力が設定値となるようにコントローラ20を介して、差圧を自動調整するようにしてもよい。なお、符号15，18は閉止弁である。   This may be achieved by manually adjusting the flow rate control valves 13 and 14 so that the differential pressure gauge 16 indicates a set value as shown in FIG. 3A, or by automatically adjusting the flow rate as shown in FIG. The differential pressure may be automatically adjusted via the controller 20 so that the detected pressure of the differential pressure gauge 19 becomes a set value at the flow rate control valve (or mass flow controller) 17. Reference numerals 15 and 18 are closing valves.

ガラス母材の空孔に通じている石英ガラス管内の圧と大気圧との差圧を430 Paに設定し、ヒーター温度2,030℃、線引き速度100 m/minで、直径125μmφの光ファイバに線引きしたところ、光ファイバ中に形成された孔はいずれも直径5.6μmφで、長手方向でも安定していた。このときの石英ガラスロッドの表面張力Ｔは0.3
N/mで、Ｔ/Ｒ＝0.3［N/ｍ］/0.0007［ｍ］≒430［Pa］であり、穴径/外径はプリフォームで0.047、光ファイバで0.045であり、ほぼプリフォームの径比が維持された。 The pressure difference between the pressure in the quartz glass tube communicating with the hole in the glass preform and the atmospheric pressure was set to 430 Pa, and the wire was drawn into an optical fiber with a diameter of 125 μmφ at a heater temperature of 2,030 ° C and a drawing speed of 100 m / min. However, each of the holes formed in the optical fiber had a diameter of 5.6 μmφ and was stable in the longitudinal direction. The surface tension T of the quartz glass rod at this time is 0.3
In N / m, T / R = 0.3 [N / m] /0.0007 [m] ≒ 430 [Pa], and the hole diameter / outer diameter is 0.047 for the preform and 0.045 for the optical fiber. The diameter ratio was maintained.

実施例１と同じガラス母材と石英ガラス管を使用し、この石英ガラス管に圧力測定手段とシリンダ及びピストンからなる差圧調整装置を接続し、差圧を300 Paに設定した。差圧の調整は、図４（ａ）に示すように、シリンダ21のピストン22を、差圧計23が設定値を示すように手動で調節してもよく、あるいは図４（ｂ）のように、差圧計26の検出圧力が設定値となるようにコントローラ27を介して、シリンダ24に接続されたモータ25を制御することにより、差圧を自動調整するようにしてもよい。
ヒーター温度2,030℃、線引き速度100 m/minで、直径125μmφの光ファイバに線引きしたところ、光ファイバ中に形成された孔はいずれも直径2.9μmφで、長手方向でも安定していた。P＝300，Ｔ/Ｒ＝430でＰ≦Ｔ/Ｒとなっている。 The same glass base material and quartz glass tube as in Example 1 were used, and a pressure measuring means and a differential pressure adjusting device comprising a cylinder and a piston were connected to the quartz glass tube, and the differential pressure was set to 300 Pa. As shown in FIG. 4A, the differential pressure may be adjusted by manually adjusting the piston 22 of the cylinder 21 so that the differential pressure gauge 23 indicates a set value, or as shown in FIG. Alternatively, the differential pressure may be automatically adjusted by controlling the motor 25 connected to the cylinder 24 via the controller 27 so that the detected pressure of the differential pressure gauge 26 becomes a set value.
When drawn into an optical fiber having a diameter of 125 μmφ at a heater temperature of 2,030 ° C. and a drawing speed of 100 m / min, all the holes formed in the optical fiber had a diameter of 2.9 μmφ and were stable in the longitudinal direction. P ≦ T / R when P = 300 and T / R = 430.

実施例１と同じガラス母材と石英ガラス管を使用し、この石英ガラス管に差圧調整装置として200 Paで動作する安全弁を設けた。この安全弁には、例えば、図５に示す構成のものが挙げられる。なお、符号28は加圧ばね、符号29は弁であり、符号30はシール材である。
ヒーター温度2,030℃、線引き速度100 m/minで、直径125μmφの光ファイバに線引きしたところ、光ファイバ中に形成された孔はいずれも直径1.1μmφで、長手方向でも安定していた。P＝200，Ｔ/Ｒ＝430でＰ≦Ｔ/Ｒとなっている。 The same glass base material and quartz glass tube as in Example 1 were used, and a safety valve operating at 200 Pa was provided as a differential pressure adjusting device on the quartz glass tube. This safety valve has, for example, the configuration shown in FIG. Reference numeral 28 denotes a pressure spring, reference numeral 29 denotes a valve, and reference numeral 30 denotes a seal material.
When drawn into an optical fiber having a diameter of 125 μmφ at a heater temperature of 2,030 ° C. and a drawing speed of 100 m / min, all the holes formed in the optical fiber had a diameter of 1.1 μmφ and were stable in the longitudinal direction. P ≦ T / R when P = 200 and T / R = 430.

実施例１と同じガラス母材と石英ガラス管を使用し、差圧を300 Paに設定して、ヒーター温度2,130℃、線引き速度100 m/minとした以外は、実施例１と同じ条件で、直径125μmφの光ファイバに線引きしたところ、光ファイバ中に形成された孔はいずれも直径2.4μmφで、長手方向でも安定していた。P＝300，Ｔ/Ｒ＝430でＰ≦Ｔ/Ｒとなっている。   The same conditions as in Example 1 were used, except that the same glass preform and quartz glass tube as in Example 1 were used, the differential pressure was set to 300 Pa, the heater temperature was 2,130 ° C., and the drawing speed was 100 m / min. When drawn into an optical fiber having a diameter of 125 μmφ, all the holes formed in the optical fiber had a diameter of 2.4 μmφ and were stable in the longitudinal direction. P ≦ T / R when P = 300 and T / R = 430.

実施例１と同じガラス母材と石英ガラス管を使用し、差圧を300 Paに設定して、ヒーター温度2, 030℃、線引き速度150 m/minとした以外は、実施例１と同じ条件で、直径125μmφの光ファイバに線引きしたところ、光ファイバ中に形成された孔はいずれも直径3.2μmφで、長手方向でも安定していた。P＝300，Ｔ/Ｒ＝430でＰ≦Ｔ/Ｒとなっている。   The same conditions as in Example 1 except that the same glass preform and quartz glass tube as in Example 1 were used, the differential pressure was set to 300 Pa, the heater temperature was 2,030 ° C., and the drawing speed was 150 m / min. Then, when drawn into an optical fiber having a diameter of 125 μmφ, all the holes formed in the optical fiber had a diameter of 3.2 μmφ and were stable in the longitudinal direction. P ≦ T / R when P = 300 and T / R = 430.

実施例１と同じガラス母材と石英ガラス管を使用し、ヒーター温度を2, 030℃に設定して、直径125μmφの光ファイバに線引きした。線引き中、先に線引きされた光ファイバの断面形状を測定し、穴径が5.6μmであることを確認した。また、圧力を400Paに下げたところ、5.0μmになった。この測定結果にもとづき、所望の断面形状、穴径4.8μmが得られるように、差圧調整手段の設定圧力を392 Paに変化させたところ、穴径4.8μmの空孔ファイバが得られた。
上記実施例１〜6の結果を、以下の比較例１〜３の結果と併せて表１にまとめて示した。
［比較例１］ Using the same glass base material and quartz glass tube as in Example 1, the heater temperature was set to 2,030 ° C., and an optical fiber having a diameter of 125 μmφ was drawn. During the drawing, the cross-sectional shape of the previously drawn optical fiber was measured, and it was confirmed that the hole diameter was 5.6 μm. When the pressure was reduced to 400 Pa, it became 5.0 μm. Based on this measurement result, when the set pressure of the differential pressure adjusting means was changed to 392 Pa so as to obtain a desired cross-sectional shape and a hole diameter of 4.8 μm, a hole fiber having a hole diameter of 4.8 μm was obtained.
The results of Examples 1 to 6 are summarized in Table 1 together with the results of Comparative Examples 1 to 3 below.
[Comparative Example 1]

実施例１と同じガラス母材と石英ガラス管を使用し、差圧調整機構を設けずに、差圧０ Paでヒーター温度2,030℃、線引き速度100 m/minで直径125μmφの光ファイバに線引きしたところ、光ファイバ中に孔が残存しなかった。
［比較例２］ Using the same glass base material and quartz glass tube as in Example 1, without providing a differential pressure adjusting mechanism, an optical fiber having a diameter of 125 μmφ was drawn at a heater temperature of 2,030 ° C at a differential pressure of 0 Pa and a drawing speed of 100 m / min. However, no holes remained in the optical fiber.
[Comparative Example 2]

実施例１と同じガラス母材と石英ガラス管を使用し、差圧を500 Paに設定して、ヒーター温度2, 030℃、線引き速度150 m/minで直径125μmφの光ファイバに線引きしようとしたが、ガラス母材が加熱炉内で膨らみ、光ファイバに線引きすることができなかった。このときのＴ/Ｒ〜430であり、Ｐ＞Ｔ/Ｒとなっていた。
［比較例３］ An attempt was made to draw an optical fiber having a diameter of 125 μmφ at a heater temperature of 2,030 ° C. and a drawing speed of 150 m / min by using the same glass base material and quartz glass tube as in Example 1 and setting the differential pressure to 500 Pa. However, the glass preform swelled in the heating furnace and could not be drawn into the optical fiber. At this time, T / R〜430, and P> T / R.
[Comparative Example 3]

実施例１と同じガラス母材を使用し、この上端を封止し、引き落とし部の先端を切って、空孔内の空気が外へ逃げるようにし、ヒーター温度2, 030℃、線引き速度100
m/minで直径125μmφの光ファイバに線引きしたところ、光ファイバの孔径が長手方向で、5.9〜7.2μmφの範囲で変動していた。 The same glass base material as in Example 1 was used, the upper end was sealed, the tip of the drawn-down portion was cut so that the air in the holes escaped outside, the heater temperature was 2,030 ° C, and the drawing speed was 100.
When drawn at a rate of m / min into an optical fiber having a diameter of 125 μmφ, the hole diameter of the optical fiber fluctuated in the longitudinal direction in the range of 5.9 to 7.2 μmφ.

Figure 2004191947
Figure 2004191947

本発明によれば、長手方向に孔径及び孔形状が安定し、伝送特性に優れた空孔ファイバ、例えば、フォトニック結晶ファイバやホーリーファイバが得られる。   ADVANTAGE OF THE INVENTION According to this invention, the hole diameter and hole shape are stabilized in the longitudinal direction, and the hole fiber excellent in transmission characteristics, for example, a photonic crystal fiber or an holey fiber, is obtained.

本発明の空孔ファイバの製造方法を説明する図であり、図１（ａ）は、ガラス母材を線引き装置にセットした状態を示し、図１（ｂ）は、空孔ファイバの線引き状態を示す概略説明図である。It is a figure explaining the manufacturing method of the hole fiber of the present invention, and Drawing 1 (a) shows the state where the glass base material was set to the drawing device, and Drawing 1 (b) shows the drawing state of the hole fiber. FIG. 本発明の空孔ファイバを示す概略断面図である。FIG. 1 is a schematic cross-sectional view showing a holey fiber of the present invention. （ａ），（ｂ）は、実施例１で使用した差圧調整装置を備えた線引き装置を示す概略図である。(A), (b) is the schematic which shows the drawing apparatus provided with the differential pressure adjustment apparatus used in Example 1. FIG. （ａ），（ｂ）は、実施例２で使用した差圧調整装置を備えた線引き装置を示す概略図である。(A), (b) is the schematic which shows the drawing apparatus provided with the differential pressure adjustment apparatus used in Example 2. FIG. 実施例３で使用した差圧調整装置を備えた線引き装置を示す概略図である。FIG. 13 is a schematic diagram illustrating a drawing device including a differential pressure adjusting device used in Embodiment 3.

符号の説明Explanation of reference numerals

１．…ガラス母材、
２．…空孔、
３．…ガラス管、
４．…差圧調整手段、
５．…昇降装置、
６．…引き落とし部、
７．…加熱炉、
８．…コーティング装置、
９．…引き取り装置、
１０．…石英ガラスロッド、
１１．…孔、
１２．…空孔部分の外接円、
１３．…流量調節弁、
１４．…流量調節弁、
１５，１８．…閉止弁、
１６，１９，２３，２６．…差圧計、
１７．…自動流量調節弁（又はマスフローコントローラ）、
２０，２７．…コントローラ、
２１，２４．…シリンダ、
２２．…ピストン、
２５．…モータ、
２８．…加圧ばね、
２９．…弁、
３０．…シール材。 1. ... glass base material,
2. …Vacancy,
3. ... glass tube,
4. … Differential pressure adjusting means,
5. …lift device,
6. … Withdrawal department,
7. …heating furnace,
8. … Coating equipment,
9. … Pick-up device,
10. … Quartz glass rod,
11. ... holes,
12. … Circumcircle of the hole,
13. … Flow control valve,
14． … Flow control valve,
15, 18. … Close valve,
16, 19, 23, 26. … Differential pressure gauge,
17. ... automatic flow control valve (or mass flow controller),
20, 27. …controller,
21, 24. …Cylinder,
22. …piston,
25. …motor,
28. … Pressure spring,
29. …valve,
30. ... Seal material.

Claims (17)

軸方向に、全長にわたって複数の孔があいた光ファイバの製造方法であって、軸方向に複数の空孔が設けられたガラス母材を加熱し軟化させて線引きする際、該ガラス母材の空孔内部と大気圧との差圧を制御することを特徴とする空孔ファイバの線引き方法。 A method of manufacturing an optical fiber having a plurality of holes in the axial direction over its entire length, wherein the glass base material provided with a plurality of holes in the axial direction is heated, softened, and drawn. A method for drawing a holey fiber, comprising controlling a pressure difference between the inside of the hole and the atmospheric pressure. ガラス母材の空孔内部と大気圧との差圧を制御するに際し、軸方向に複数の空孔が設けられたガラス母材の開放端に、空孔部分の外接円の径よりも大きな内径を有するガラス管を接続し、該ガラス管に差圧調整手段を設けて制御する請求項１に記載の空孔ファイバの線引き方法。 When controlling the pressure difference between the inside of the pores of the glass base material and the atmospheric pressure, the open end of the glass base material provided with a plurality of holes in the axial direction has an inner diameter larger than the diameter of the circumscribed circle of the hole portion. 2. The method of drawing a holey fiber according to claim 1, wherein a glass tube having the following is connected, and the glass tube is controlled by providing a differential pressure adjusting means. ガラス管の内部を仕切り、仕切られた各室にそれぞれ差圧調整手段を設け、線引き中、各室毎に該室に通じるガラス母材の空孔内部と大気圧との差圧を制御する請求項１又は２に記載の空孔ファイバの線引き方法。 Claims for partitioning the inside of a glass tube, providing differential pressure adjusting means for each of the partitioned chambers, and controlling the differential pressure between the inside of the pores of the glass base material communicating with the chamber and the atmospheric pressure for each chamber during drawing. Item 3. The method for drawing a holey fiber according to Item 1 or 2. 差圧調整手段が、空孔内部の圧力測定手段、加圧ガス供給装置及びガス排出ポートからなる請求項１乃至３のいずれかに記載の空孔ファイバの線引き方法。 The method for drawing a hole fiber according to any one of claims 1 to 3, wherein the differential pressure adjusting means comprises a pressure measuring means inside the hole, a pressurized gas supply device, and a gas discharge port. 差圧調整手段が、空孔内部の圧力測定手段、シリンダ及びピストンからなる請求項１乃至３のいずれかに記載の空孔ファイバの線引き方法。 The method for drawing a hole fiber according to any one of claims 1 to 3, wherein the differential pressure adjusting means comprises a pressure measuring means inside the hole, a cylinder and a piston. 差圧調整手段が、安全弁である請求項１乃至３のいずれかに記載の空孔ファイバの線引き方法。 4. The method according to claim 1, wherein the differential pressure adjusting means is a safety valve. 差圧調整手段の設定圧力を変化させることにより、光ファイバの孔径を調節する請求項１乃至６のいずれかに記載の空孔ファイバの線引き方法。 7. The method according to claim 1, wherein the hole diameter of the optical fiber is adjusted by changing a set pressure of the differential pressure adjusting means. 先に線引きされた光ファイバの断面形状、分散特性、伝送損失、光パワー分布のうち、少なくとも１つを測定し、この測定結果にもとづき差圧調整手段の設定圧力を変化させる請求項７に記載の空孔ファイバの線引き方法。 8. The method according to claim 7, wherein at least one of a cross-sectional shape, a dispersion characteristic, a transmission loss, and an optical power distribution of the previously drawn optical fiber is measured, and the set pressure of the differential pressure adjusting means is changed based on the measurement result. Hole fiber drawing method. ガラス母材に接続したガラス管の内圧と大気圧との差圧Ｐ[Pa]が、ガラス母材の最も大きい空孔の半径をＲ[m]、ガラス母材の表面張力をＴ[N/m]としたときに、Ｐ≦Ｔ/Ｒとする請求項１乃至７のいずれかに記載の空孔ファイバの線引き方法。 The differential pressure P [Pa] between the internal pressure of the glass tube connected to the glass preform and the atmospheric pressure is represented by R [m], the radius of the largest hole in the glass preform, and T [N / The method of drawing a holey fiber according to any one of claims 1 to 7, wherein, when m], P ≦ T / R. 加熱炉の温度を変化させることにより、光ファイバの孔径を調節する請求項１乃至９のいずれかに記載の空孔ファイバの線引き方法。 The method according to any one of claims 1 to 9, wherein the diameter of the optical fiber is adjusted by changing the temperature of the heating furnace. 線引き速度を変化させることにより、光ファイバの孔径を調節する請求項１乃至９のいずれかに記載の空孔ファイバの線引き方法。 The method for drawing a holey fiber according to any one of claims 1 to 9, wherein the hole diameter of the optical fiber is adjusted by changing the drawing speed. 線引き速度が、50m/min以上である請求項１１に記載の空孔ファイバの線引き方法。 The method according to claim 11, wherein the drawing speed is 50 m / min or more. 空孔の内圧、温度及び線引き速度のなかから適宜組み合わせて、又はこれらを同時に制御して、光ファイバの孔径を調節する請求項１乃至１２のいずれかに記載の空孔ファイバの線引き方法。 The method of drawing a hole fiber according to any one of claims 1 to 12, wherein the hole diameter of the optical fiber is adjusted by appropriately combining the internal pressure of the hole, the temperature, and the drawing speed, or controlling these at the same time. ガラス母材が、実質的に純粋な石英ガラスからなる請求項１乃至１３のいずれかに記載の空孔ファイバの線引き方法。 14. The method for drawing a holey fiber according to claim 1, wherein the glass preform is made of substantially pure quartz glass. ガラス母材が、ドーパントを含む石英ガラスからなる請求項１乃至１３のいずれかに記載の空孔ファイバの線引き方法。 14. The method for drawing a holey fiber according to claim 1, wherein the glass base material is made of silica glass containing a dopant. ガラス母材が、多成分系ガラスからなる請求項１乃至１３のいずれかに記載の空孔ファイバの線引き方法。 14. The method for drawing a holey fiber according to claim 1, wherein the glass base material is made of a multi-component glass. 請求項１乃至１６のいずれかに記載の空孔ファイバの線引き方法を用いて製造してなる空孔ファイバ。

A holey fiber manufactured using the method for drawing a holey fiber according to any one of claims 1 to 16.

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