JPS59456B2 - Manufacturing method of optical glass fiber - Google Patents

Description

【発明の詳細な説明】 本発明は光ガラスファイバを寸法精度良く、連続的に製
造する方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing optical glass fibers with high dimensional accuracy.

光ガラスファイバは光通信に用いられる伝送媒体として
有望視されている。Optical glass fiber is seen as a promising transmission medium for optical communications.

光ガラスファイバは光が集中して伝搬する芯ガラスと、
これより屈折率の低いガラス被覆層からなり、現在、伝
送ラインとして使用されるうえで、解決しなければなら
ない重要な問題は、伝送ラインとして使用できる程度の
構造上の寸法精度をもち、比較的安価に光ガラスファイ
バを製造する技術を確立することである。１９７０年項
に光伝送媒体として光ガラスファイバがクローズアップ
された時は、光ガラスファイバの光損失の低減化が最大
の問題点であつた。Optical glass fiber consists of a core glass in which light is concentrated and propagated,
The important problem that must be solved for glass coating layers that have a lower refractive index than this and is currently used as transmission lines is to have a relatively The goal is to establish a technology to manufacture optical glass fibers at low cost. When optical glass fibers came into focus as optical transmission media in 1970, the greatest problem was reducing optical loss in optical glass fibers.

しかし光損失の低減化は、たとえば特開昭４８−７３５
２３号光学的繊維の製造方法、特開昭５０１２０３５２
号光学繊維の製法等で示されている石英管内に芯ガラス
を堆積させ、中実にしこれを適当な方法で線引きして光
ガラスファイバを得ることにより、ほぼ解決した。し力
走これらの方法は、石英管の寸法精度、中実工程で、通
信用媒体として使用し得る構造上の寸法精度が得られな
い欠点がある。また、これらの製造方法は１本ずつ製造
するので、均質な構造のラインを大量に必要とする通信
用媒体の製法としては適していないうえ、１本ずつ製造
するので、コスト高にもなる欠点がある。一方、寸法精
度の高いガラスファイバの製造方法として、ロッドイン
チューブ法が知られている。However, reduction of optical loss has been achieved, for example, in Japanese Patent Application Laid-open No. 48-735.
No. 23 Method for manufacturing optical fiber, JP-A-50120352
This problem was almost solved by depositing core glass in a quartz tube, making it solid, and drawing it using an appropriate method to obtain an optical glass fiber, as shown in the method for manufacturing optical fibers. These methods have the drawback that the dimensional accuracy of the quartz tube cannot be obtained in the solid process, and the structural dimensional accuracy that can be used as a communication medium cannot be obtained. In addition, since these manufacturing methods produce one piece at a time, they are not suitable for manufacturing communication media, which requires a large number of lines with a homogeneous structure, and they also have the disadvantage of increasing costs because each piece is manufactured one at a time. There is. On the other hand, the rod-in-tube method is known as a method for manufacturing glass fibers with high dimensional accuracy.

第１図にその概略を示すが、芯ガラス１を外被管２に挿
着し、適当な加熱装置３で加熱して線引きする方法であ
る。従来のこの方法では芯ガラスの接する外被管の内周
面平滑精度が悪く、コアとクラッド界面に気泡または異
物が混入し、これが光散乱源となり、低損失光ファイバ
を得ることはできなかつた。As shown schematically in FIG. 1, this is a method in which a core glass 1 is inserted into a jacket tube 2, heated with a suitable heating device 3, and drawn. In this conventional method, the inner circumferential surface of the jacket tube in contact with the core glass had poor smoothness, and air bubbles or foreign matter got mixed in at the interface between the core and cladding, which became a source of light scattering, making it impossible to obtain a low-loss optical fiber. .

本発明はこれらの欠点を除去するため、研磨加工技術に
より光ガラスファイバの寸法精度を向上させた新規な光
ガラヌフアイバの製造方法を提供し、この製造方法によ
り光伝送媒体として使用し得る低損失の光ガラスファイ
バを安価に提供しようとするものである。本発明に使用
する光損失の小さい石英ロツドは、たとえば特願昭５０
−８２６７９号（高純度透明石英ガラス体の製造方法）
等により得られるが、本発明は低損失ガラスロツドに表
面平滑さ０．０１關以下の光学研磨をほどこせば、十分
光散乱損失の小さいフアイバに線引きできることを発見
したことにより考案された。In order to eliminate these drawbacks, the present invention provides a new method for manufacturing an optical glass fiber in which the dimensional accuracy of the optical glass fiber is improved by polishing technology, and by this manufacturing method, a low-loss fiber that can be used as an optical transmission medium is provided. The aim is to provide optical glass fibers at low cost. The quartz rod with low optical loss used in the present invention is, for example,
No.-82679 (method for manufacturing high-purity transparent quartz glass body)
However, the present invention was devised based on the discovery that a fiber with sufficiently low light scattering loss can be drawn by optically polishing a low-loss glass rod to a surface smoothness of 0.01 degree or less.

光吸収損失の十分小さい高純度石英ガラスロツドから一
般の機械加工技術により芯ガラスを作り、外被管は十分
内周面研磨のできる位短く切断し、光散乱損失が十分小
さくなる程度（０．０１μｍ以下）に内周面研磨された
外被管を作る。The core glass is made from a high-purity quartz glass rod with sufficiently low light absorption loss using general machining techniques, and the outer tube is cut short enough to allow polishing of the inner peripheral surface, and cut to a length (0.01 μm) that minimizes light scattering loss. (below) to make an outer jacket tube with a polished inner surface.

この外被管に芯ガラスを挿着し、適当な方法で加熱して
線引きし、光ガラスフアイバを得る。芯ガラスを心棒に
し、これに対し十分内周面研磨された数個の外被管用ガ
ラスを軸方向に重ねて、加熱して線引するので、光損失
が十分小さく、フアイバ購造および寸法の十分制御され
た光フアイバが得られる。A core glass is inserted into this envelope tube, heated and drawn by an appropriate method, and an optical glass fiber is obtained. The core glass is used as the mandrel, and several pieces of glass for the jacket tube with sufficiently polished inner surfaces are layered in the axial direction and drawn by heating, so the optical loss is sufficiently small and it is easy to purchase and size the fiber. A well-controlled optical fiber is obtained.

長尺のフアイバを得るためには芯ガラスも軸方向に複数
本積み重ね、その外側に多数の外被管用ガラスを重ねて
いけばよい。In order to obtain a long fiber, a plurality of core glasses may be stacked in the axial direction, and a large number of jacket tube glasses may be stacked on the outside thereof.

以下図面を用いて詳細に説明する。This will be explained in detail below using the drawings.

実施例 １ 市販の低損失石英ガラスロツドを第２図に示すような長
さ１５０ｍｍ１直径５ｍｍ１真直度１／１００ｍｍ１真
円度５μｍの芯石英ガラスの外周面４および端面５を０
．０１μｍ以下の表面円滑さに研磨し、これに第３図に
示すような外径８ｍｍ１内径５ｍ１１長さ３０ｍ７１１
の低損失石英製円筒外被管（内周面６および端面７，７
′を０．０１μｍ以下に、外周面８を０．１μｍ以下の
平滑さに研磨したもの）をかぶせ、第４図に示すように
外被管１０を軸方向に複数個積み重ね、さらに心ガラス
９′を芯ガラス９の上に積み重ねて、１８０００Ｃ〜２
２０『Ｃに加熱できる加熱装置１１により加熱して線引
きした。Example 1 A commercially available low-loss quartz glass rod was prepared with a core of quartz glass having a length of 150 mm, a diameter of 5 mm, a straightness of 1/100 mm, and a roundness of 5 μm as shown in FIG.
．． The surface was polished to a smoothness of 0.01 μm or less, and then the outer diameter was 8 mm, the inner diameter was 5 m, and the length was 30 m, as shown in Figure 3.
low-loss quartz cylindrical jacket tube (inner peripheral surface 6 and end surfaces 7, 7
' is polished to a smoothness of 0.01 μm or less and the outer peripheral surface 8 is polished to a smoothness of 0.1 μm or less), and as shown in FIG. ' stacked on top of the core glass 9 and heated to 18000C~2
The wire was drawn by heating with a heating device 11 capable of heating to 20°C.

これにより外径１２５μｍ１芯の径８０μｍ１離心率０
．１％の購造精度を持つ光損失３ｄＢ／Ｋｍ（測定波長
０．８５μｍ）の低損失多モード光フアイバを得た。As a result, the outer diameter is 125 μm, the diameter of 1 core is 80 μm, and the eccentricity is 0.
．． A low-loss multimode optical fiber with an optical loss of 3 dB/Km (measurement wavelength 0.85 μm) and a purchasing accuracy of 1% was obtained.

この光損失のうち２ｄＢ／Ｋｍは芯石英ガラヌの吸収損
失、１ｄＢ／Ｋｍは購造等による散乱損失であつた。実
施例 ２ 実施例１と同じ工程で出発材を準備し、線引き時に一気
にフアイバとせず、１８００〜２２００℃の温度で外径
５ｍｍ１こなるまで引き延ばした。Of this optical loss, 2 dB/Km was an absorption loss of the core quartz galanus, and 1 dB/Km was a scattering loss due to purchasing and the like. Example 2 A starting material was prepared in the same process as in Example 1, and instead of being drawn into a fiber all at once, it was drawn to an outer diameter of 5 mm at a temperature of 1800 to 2200°C.

この形成体を十分研磨された外径２０１ｔｍ１内径５ｍ
１１の石英ガラス管に入れ再び直径１０ｍ１１ｔになる
まで引き延ばした。これを一般市販品の外径１２詣、内
径１０ｍ１の石英管に挿着し、加熱炉で加熱して線引き
し、外径１２０μｍ１コア径５μｍ）真円度１％以内、
離心率０．１％の構造で、光損失は実施例１と同程度の
十分低損失な単一モードフアイバを得た。なおこの実施
例では、外被管を１層かぶせるごとに加熱して線引きし
たが、外被管を一度に２層以上つみ重ねて加熱して線引
きしてもよい。This formed body is sufficiently polished with an outer diameter of 201 tm and an inner diameter of 5 m.
It was placed in a No. 11 quartz glass tube and stretched again to a diameter of 10 m and 11 tons. This was inserted into a commercially available quartz tube with an outer diameter of 12 mm and an inner diameter of 10 m1, heated in a heating furnace and drawn into a wire (outer diameter 120 μm, core diameter 5 μm), circularity within 1%
A single mode fiber having a structure with an eccentricity of 0.1% and a sufficiently low optical loss comparable to that of Example 1 was obtained. In this embodiment, the jacketed tube was heated and drawn each time it was covered with one layer, but the jacketed tube may be stacked in two or more layers at a time and then heated and drawn.

以上説明したように、本発明の光ガラスフアイバの製造
方法は十分内周面研磨のできる長さの外被管用円筒ガラ
スを作製し、これを心ガラスに対して積み重ねた後、線
引きすることにあり、伝送線路として十分使用に耐える
ような形伏、寸法精度をもち、低損失な光フアイバを長
尺にわたり作製することができる。外被管用円筒ガラス
および芯ガラスのつなぎ面は、重ね合わせておくのみで
も、順次融着されて連続の光フアイバとなる。As explained above, the optical glass fiber manufacturing method of the present invention involves producing a cylindrical glass for an outer jacket tube with a length that allows for sufficient polishing of the inner peripheral surface, stacking this on a core glass, and then drawing it. This makes it possible to produce long length optical fibers with low loss and shape and dimensional accuracy that are sufficient to withstand use as transmission lines. Even if the connecting surfaces of the cylindrical glass for the jacket tube and the core glass are simply overlapped, they will be sequentially fused to form a continuous optical fiber.

それぞれのつなぎ面に高純度ガラスの微粉末を小量入れ
ておき、この部分を加熱してあらかじめ融着、一体化し
ておけば、線引き時の取り扱いは、さらに容易となる。
また実施例は石英ガラスについて示してあるが、多成分
を有する低融点ガラスについても、本発明が使用できる
ことはもち論である。なおこれらの実施例の中で屈折率
についてふれていないが、芯ガラスの屈折率を外被管の
屈折率より適当な値大きくとることは、当業者にとつて
常識である。If a small amount of fine powder of high-purity glass is placed on each joining surface and these parts are heated to fuse and integrate in advance, handling during wire drawing will become easier.
Moreover, although the embodiments are shown using quartz glass, it goes without saying that the present invention can also be used for low-melting glass having multiple components. Although the refractive index is not mentioned in these embodiments, it is common knowledge for those skilled in the art to set the refractive index of the core glass to be an appropriate value larger than the refractive index of the jacket tube.

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

第１図は従来のロツドインチユーブ法の概略図、第２図
および第３図は本発明の製造方法に用いる購成物の概略
図、第４図は本発明の一実施例の概略図である。 １・・・・・・芯ガラス、２・・・・・・外被管、３・
・・−・・加熱装置、４・・・・・・芯ガラスの外周面
、５・・・・・・芯ガラスの端面、６・・・・・・外被
管の内周面、７，７″・・・・・・外被管の端面、８・
・・・・・外被管の外周面、９，９′・・・・・・芯ガ
ラス、１０・・・・・・外被管、 １１・・・・・・加熱装置。Fig. 1 is a schematic diagram of the conventional rod incubation method, Figs. 2 and 3 are schematic diagrams of products used in the manufacturing method of the present invention, and Fig. 4 is a schematic diagram of an embodiment of the present invention. It is. 1... Core glass, 2... Outer tube, 3.
... Heating device, 4 ... Outer peripheral surface of core glass, 5 ... End surface of core glass, 6 ... Inner peripheral surface of jacket tube, 7. 7″...End face of jacket tube, 8.
...Outer circumferential surface of jacket tube, 9,9'...core glass, 10... jacket tube, 11...heating device.

Claims (1)

【特許請求の範囲】 １ 外周面および端面を研磨した１本または軸方向に重
ねた複数本の心ガラスに対して、内周面、外周面および
端面を研磨した複数片の外被管用ガラスを軸方向に積層
し、これを加熱して線引きすることを特徴とする光ガラ
スファイバの製造方法。 ２ １本または軸方向に重ねた複数本の芯ガラスに対し
て、内周面外周面および端面を研磨した外被管用円筒ガ
ラスを２層もしくは２層以上軸方向につみ重ねて加熱し
て線引きするか、または前記外被管用円筒ガラスを１層
かぶせるごとに加熱して線引きすることを特徴とする特
許請求の範囲第１項記載の光ガラスファイバの製造方法
。[Scope of Claims] 1. A plurality of pieces of glass for an envelope tube whose inner circumferential surface, outer circumferential surface, and end surfaces have been polished for one core glass or a plurality of core glasses stacked in the axial direction whose outer circumferential surfaces and end surfaces have been polished. A method for producing an optical glass fiber, which is characterized by laminating the fibers in the axial direction, heating the fibers, and drawing the fibers. 2. Two or more layers of cylindrical glass for jacket tubes with polished inner circumferential surfaces, outer circumferential surfaces, and end surfaces are piled up in the axial direction for one core glass or a plurality of core glass stacked in the axial direction, and then heated and drawn. 2. The method of manufacturing an optical glass fiber according to claim 1, wherein the cylindrical glass fiber for the jacket tube is heated and drawn each time it is covered with one layer.