JPS60246233A - Manufacture of glass preform for optical fiber - Google Patents
Manufacture of glass preform for optical fiberInfo
- Publication number
- JPS60246233A JPS60246233A JP59100639A JP10063984A JPS60246233A JP S60246233 A JPS60246233 A JP S60246233A JP 59100639 A JP59100639 A JP 59100639A JP 10063984 A JP10063984 A JP 10063984A JP S60246233 A JPS60246233 A JP S60246233A
- Authority
- JP
- Japan
- Prior art keywords
- base material
- gas
- core
- fluorine
- atmosphere containing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01413—Reactant delivery systems
- C03B37/0142—Reactant deposition burners
-
- 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
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C13/00—Fibre or filament compositions
- C03C13/04—Fibre optics, e.g. core and clad fibre compositions
- C03C13/045—Silica-containing oxide glass compositions
- C03C13/047—Silica-containing oxide glass compositions containing deuterium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/22—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with deuterium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/28—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with phosphorus
-
- 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
- C03B2203/22—Radial profile of refractive index, composition or softening point
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/04—Multi-nested ports
- C03B2207/06—Concentric circular ports
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/20—Specific substances in specified ports, e.g. all gas flows specified
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/50—Multiple burner arrangements
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/08—Doped silica-based glasses containing boron or halide
- C03C2201/12—Doped silica-based glasses containing boron or halide containing fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
- C03C2201/22—Doped silica-based glasses containing non-metals other than boron or halide containing deuterium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
- C03C2201/23—Doped silica-based glasses containing non-metals other than boron or halide containing hydroxyl groups
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
- C03C2201/28—Doped silica-based glasses containing non-metals other than boron or halide containing phosphorus
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2203/00—Production processes
- C03C2203/40—Gas-phase processes
- C03C2203/42—Gas-phase processes using silicon halides as starting materials
- C03C2203/44—Gas-phase processes using silicon halides as starting materials chlorine containing
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2203/00—Production processes
- C03C2203/50—After-treatment
- C03C2203/52—Heat-treatment
- C03C2203/54—Heat-treatment in a dopant containing atmosphere
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geochemistry & Mineralogy (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Optics & Photonics (AREA)
- Thermal Sciences (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
- Glass Compositions (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、光フアイバ用ガラス母材の製造方法に関する
ものであり、更に詳細に述べるならば、光フアイバ用の
ガラス微粒子堆積体即ち多孔質母材(以下ではスート母
材という)を作製し、高温炉で焼結し透明ガラス化する
方法に於て、コア相当部に少量のP、0.と重水をドー
プすることにより、クラッド相当部に選択的にフッ素を
容易に添加できて、コア・クラッド間の屈折率差を添加
フッ素量から調整することのできる光フアイバ用ガラス
母材の製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a glass base material for optical fibers, and more specifically, the present invention relates to a method for manufacturing a glass base material for optical fibers. In this method, a small amount of P, 0.5%, or A method for producing a glass base material for an optical fiber, in which fluorine can be easily added selectively to the portion corresponding to the cladding by doping it with heavy water and the refractive index difference between the core and the cladding can be adjusted from the amount of added fluorine. It is related to.
従来の技術
光ファイバは、通常、第1図に示すように、コア部と呼
ばれる光の通る中心部1とクラッド部と呼ばれる周辺部
2から成っている。コア部1の屈折率n1は、光を伝送
する都合上、第1図の屈折率分布に示すように、クラッ
ド部2の屈折率n、より高くしである。BACKGROUND OF THE INVENTION As shown in FIG. 1, a conventional optical fiber usually consists of a central portion 1 called a core portion through which light passes, and a peripheral portion 2 called a cladding portion. The refractive index n1 of the core portion 1 is higher than the refractive index n of the cladding portion 2, as shown in the refractive index distribution in FIG. 1, for the convenience of transmitting light.
そして、コアとクラッドの比屈折率差△n1Δn: (
n、−nl )/n。Then, the relative refractive index difference △n1Δn between the core and the cladding: (
n, -nl)/n.
を高くすることにより、クラッド面で全反射する受光角
を大きくすることができ、光ガラスファイバを曲げた場
合のパワーロスが小さくなる郷の利点かめる。Δnを高
くする方法としては、火炎加水分解法によるスート母料
製造に於いて、スート母材のコア相当部にGoo、、A
4,0. 、Tie。By increasing the angle, the receiving angle for total reflection on the cladding surface can be increased, which has the advantage of reducing power loss when bending the optical glass fiber. As a method to increase Δn, in the production of soot base material by flame hydrolysis method, Goo, A, etc.
4,0. , Tie.
等の金属酸化物ドーパントを添加してコア部1の屈折率
n1 を大きくする方法と、あるいは、スート母材のク
ラッド相当部にフッ素系ガスを添加し、クラッド部の屈
折率n8を下げる方法が考えられる。これ等の方法はV
AD法、 ovp。There is a method of increasing the refractive index n1 of the core portion 1 by adding a metal oxide dopant such as, or a method of lowering the refractive index n8 of the cladding portion by adding a fluorine-based gas to a portion of the soot base material corresponding to the cladding. Conceivable. These methods are V
AD method, ovp.
法として、それぞれ特公昭57−40096号、米国特
許第3.757.292号明細書に記載されている。The methods are described in Japanese Patent Publication No. 57-40096 and US Pat. No. 3,757,292, respectively.
ところが、前者のドーパント添加によるコア部1の屈折
率nlを大きくする方法の場合、上記ドーパントの増加
に伴い、次の問題点が生じる。However, in the case of the former method of increasing the refractive index nl of the core portion 1 by adding a dopant, the following problem occurs as the amount of the dopant increases.
(1) ドーパント量を増やすと、ドーパント添加に伴
う光散乱(レイリー散乱)が生じ、かつ、この散乱の大
きさは、ドーパント量に比例する。この散乱は伝送損失
を増加せしめ、光伝送上好ましくガい。(1) When the amount of dopant is increased, light scattering (Rayleigh scattering) occurs due to the addition of dopant, and the magnitude of this scattering is proportional to the amount of dopant. This scattering increases transmission loss, which is undesirable for optical transmission.
(2) ドーパントを多量に添加すると、ガラス母材中
に、気泡や単結晶を生じさせ易い。(2) Adding a large amount of dopants tends to cause bubbles and single crystals in the glass base material.
例えば、Ge0.を用いた場合、Ge02 ガスに由来
する気泡を生じさせることがある。For example, Ge0. When using Ge02 gas, bubbles may be generated due to Ge02 gas.
At、O,を用いた場合ではAt、O,結晶のクラスタ
ーを生じさせ易い。かかる気泡や結晶相の存在は光伝送
上の損失原因(すなわち散乱損失)となり、好ましくな
い。加えて、光ファイバの断線の原因となる。また、T
ie。When At, O, is used, clusters of At, O, and crystals are likely to occur. The presence of such bubbles and crystal phases causes loss in optical transmission (ie, scattering loss), which is undesirable. In addition, it may cause the optical fiber to break. Also, T
ie.
を用いた場合にはT1″+ に由来する着色を生じるこ
とがある。When using T1″+, coloring may occur due to T1″+.
(3) ドーパントが多量に入ることでガラス内に構造
的な欠陥が生じ、該欠陥に由来する紫外線吸収や、欠陥
とH,ガスの結合によるOH基吸収の発生等が起こり、
ファイバの光学特性が悪くなる。これはドーパントにお
いては、A Z3 + 、 T 1$ 十、 Gem+
など4価より低価バレンスの方が比較的安定なことに起
因すると考えられている。(3) Structural defects occur in the glass due to the presence of a large amount of dopant, which causes ultraviolet absorption due to the defects and OH group absorption due to the bonding of the defects with H and gas.
The optical properties of the fiber deteriorate. In the dopant, this is A Z3 + , T 1$ 10, Gem+
This is thought to be due to the fact that low-value valences are relatively more stable than tetravalent valences.
これに対して後者のクラッド相当部にフッ素系ガスを添
加して屈折率n8を下げる方法は、上記の不都合を解消
する上で非常に有効である。この方法は、コア部を純シ
リカ、あるいは純シリカにG so、等のドーパントを
添加して高屈折率とし、クラッド部のみを少なくとも一
時期、フッ素系ガスを含む雰囲気で高温加熱することに
よつ−Cクラッド部にフッ素を添加し、クラッド部の屈
折率を下げ、最終的に透明ガラス母材を得る方法である
。On the other hand, the latter method of lowering the refractive index n8 by adding fluorine-based gas to the portion corresponding to the cladding is very effective in solving the above-mentioned disadvantages. This method involves making the core part pure silica or adding a dopant such as Gso to pure silica to give it a high refractive index, and heating only the cladding part at a high temperature for at least a period of time in an atmosphere containing fluorine gas. -C This is a method of adding fluorine to the cladding part to lower the refractive index of the cladding part, and finally obtaining a transparent glass base material.
しかしながら、この方法に於いても、以下のような問題
が生じていた。す々わち、フッ素系ガス雰囲気内におい
て単純に高温加熱したのでは、スート母材のコア部にま
で均一にフッ素が添加され、その結果としてΔnを高く
することができない。そこで従来、脱水−焼結工程にお
いて、クラッド部にのみフッ素を添加する方法が提案さ
れ実用化されている(例えば特開昭 55−67533
号公報等)。そこでは、フッ素系ガスを投入する時点の
炉内の温度が、クラッド部のみにフッ素を添加するため
の重要な条件になっている。However, even in this method, the following problems have occurred. That is, simply heating at a high temperature in a fluorine-based gas atmosphere will uniformly add fluorine to the core portion of the soot base material, and as a result, Δn cannot be increased. Therefore, a method of adding fluorine only to the cladding part in the dehydration-sintering process has been proposed and put into practical use (for example, Japanese Patent Application Laid-Open No. 55-67533
Publications, etc.). In this case, the temperature inside the furnace at the time when the fluorine-based gas is introduced is an important condition for adding fluorine only to the cladding portion.
元来フッ素は非常に反応性に富んでいるためクラッド部
にのみフッ素を添加するだめの高温炉内の温度制御、フ
ッ素系ガス濃度及び処理時間の制御が非常にむずかしい
。Since fluorine is originally highly reactive, it is extremely difficult to control the temperature in a high-temperature furnace, the concentration of fluorine-based gas, and the treatment time, even if fluorine is added only to the cladding.
このため、従来のドーパント分布及びカサ密度分布をも
ったスート母材に対してクラッド相当部にのみフッ素添
加を行うには±50℃程度の厳密な温度制御が必要であ
り、この方法により所期のΔnの値の光ガラスファイバ
をつくることが極めて困難であった。Therefore, in order to add fluorine only to the portion corresponding to the cladding of a soot base material with a conventional dopant distribution and bulk density distribution, strict temperature control of approximately ±50°C is required. It was extremely difficult to produce an optical glass fiber with a Δn value of .
一方、従来法においては、コアイノ(中の不純物、特に
残留水分の除去に関する問題がある。コア部の伝送損失
特性を低くするためには、ファイバ中の残留水分着(O
H基量)を極力抑え、OH基に由来する吸収をなくす必
要がある。このため、スート母材を塩素を含む高温雰囲
気中にて処理することにより、OH基を除去する方法が
提案された(特公昭57−40096号、特公昭58−
15503号公報)。上記公報記載の方法によれば、ガ
ラス中のOH基量を〜50 ppb程度とすることが可
能であって、コアイノ(の伝送損失特性に及ぼすOH基
の影響をなくすることができる。On the other hand, in the conventional method, there is a problem with the removal of impurities in the fiber, especially residual water.
It is necessary to suppress the amount of H groups as much as possible and eliminate absorption derived from OH groups. For this reason, a method was proposed in which the OH groups were removed by treating the soot base material in a high-temperature atmosphere containing chlorine (Japanese Patent Publication No. 57-40096, Japanese Patent Publication No. 58-40096,
15503). According to the method described in the above-mentioned publication, it is possible to reduce the amount of OH groups in the glass to about 50 ppb, and it is possible to eliminate the influence of the OH groups on the transmission loss characteristics of Core Ino.
しかしながら、上記公報記載の方法により塩素含有高温
雰囲気にて低OH基化した〇em、等のドーパントを含
むファイバでは、以下に説明するような、低OH基化に
起因する新たな問題が生じた。However, in fibers containing dopants such as 〇em, which have been made to have low OH groups in a chlorine-containing high-temperature atmosphere by the method described in the above publication, new problems have arisen due to the low OH groups, as explained below. .
その第1は、γ線や中性子線等の放射線によりファイバ
に紫外域の吸収が発生し易くなることである。例えば放
射線照射前に波長185μm における伝送損失が2.
5 /’knであったファイバーが、放射線照射後には
100 dBAllにも損失増大し、塩素含有高温雰囲
気により低OH基化しカい場合に比して10〜50倍も
吸収が増加した。The first is that absorption in the ultraviolet region is likely to occur in the fiber due to radiation such as gamma rays and neutron rays. For example, before radiation irradiation, the transmission loss at a wavelength of 185 μm is 2.
5/'kn, after irradiation, the loss increased to 100 dBAll, and the absorption increased by 10 to 50 times compared to the case where the OH group was reduced by a high temperature atmosphere containing chlorine.
第2には、塩素含有高温雰囲気により低OH基化したコ
ア部にGeO2を含有するファイバを密閉された雰囲気
もしくはケーブル構造中に放置するとき、1〜10年の
期間中に再びOH基吸収が起きてしまうことである。著
しい場合には、ファイバ伝送に耐えられない程の伝送損
失増加をもたらした。Second, when a fiber containing GeO2 in its core, which has been reduced in OH groups due to a chlorine-containing high-temperature atmosphere, is left in a sealed atmosphere or in a cable structure, OH group absorption occurs again within a period of 1 to 10 years. It's something that happens. In severe cases, the transmission loss increased to an extent that fiber transmission could no longer be tolerated.
これらの現象は、ファイバーを構成する又はファイバー
を囲む材料中の水素が拡散移動してコア部に達し、コア
部に存在する既述の欠陥と結合してOH基を生成するた
めもたらされると考えられている。These phenomena are thought to be caused by hydrogen in the material that makes up or surrounds the fiber diffusing and moving, reaching the core, and combining with the aforementioned defects present in the core to generate OH groups. It is being
以上詳述した現象は、従来方法により得られるファイバ
では未だ欠陥が多く、長期的信頼性に劣ることを意味す
ることは明らかである。It is clear that the phenomenon described in detail above means that fibers obtained by conventional methods still have many defects and are inferior in long-term reliability.
(発明が解決しようとする問題点)
本発明の目的は、上述の従来方法によるファイバーの問
題点を解消して、コア相当部のガラスの構造的欠陥を極
力少なくシ、シかも低損失、高品質かつ長期信頼性を有
する光フアイバー用母材の製法を提供するところにある
。(Problems to be Solved by the Invention) It is an object of the present invention to solve the problems of the fiber according to the conventional method described above, to minimize the structural defects of the glass in the core-corresponding part, to achieve low loss, high fiber The purpose of the present invention is to provide a method for producing a base material for optical fiber that has high quality and long-term reliability.
(問題点を解決する手段)
本発明者らは鋭意研究の結果、上述の問題点を解決する
手段として、スート母材のコア相当部に若干のP、 O
,を添加して、コアとクラッド部の加熱時の収縮のし易
さを調整することで、クラッド部のみにフッ素を添加せ
しめて、コア・クラッド間の屈折率差を犬とし、併せて
、少なくともコア部のOH基は01)基に置換された構
造となるように処理することを考えつき、本発明に到達
した。(Means for solving the problem) As a result of intensive research, the present inventors found that as a means to solve the above-mentioned problem, some P and O were added to the core-corresponding part of the soot base material.
By adding , to adjust the ease of contraction of the core and cladding part when heated, fluorine is added only to the cladding part, and the refractive index difference between the core and cladding is reduced, and at the same time, The present invention was achieved based on the idea of processing the material so that at least the OH group in the core portion is substituted with a 01) group.
すなわち本発明は、コア相当部がp、o、を含有する石
英からなり、クラッド相当部が純石英である光フアイバ
用石英系多孔質母材を焼結して透明ガラス母材を製造す
る方法において、該多孔質母材を重水素系ガスを含むガ
ス雰囲気にて加熱処理した後、フッ素系ガスを含むガス
雰囲気にて加熱処理し、それによりコア相当部にはOD
基を少なくとも1〜20ppm添加し、クラッド部にの
みフッ素を添加することを特徴とする光フアイバ用ガラ
ス母材の製造方法を提供する。That is, the present invention provides a method for manufacturing a transparent glass base material by sintering a quartz-based porous base material for an optical fiber, in which the core portion is made of quartz containing p, o, and the cladding portion is pure quartz. In this step, the porous base material is heat-treated in a gas atmosphere containing deuterium-based gas, and then heat-treated in a gas atmosphere containing fluorine-based gas, whereby the portion corresponding to the core has OD.
Provided is a method for producing a glass preform for an optical fiber, characterized in that at least 1 to 20 ppm of groups are added and fluorine is added only to the cladding portion.
スート母材製造時にコア部にP、0. を添加すると、
かかるスート母材を高温加熱処理する場合、P、0.添
加部分の収縮は P2O,無添加の部分と比べて早くな
るため、コア部はクラッド部に比べ早く収縮する(すな
わちガラス化する時間が短くなる)。従って、コア・ク
ラッド間の屈折率差△nを大きくするために、クラッド
にのみフッ素を添加するには、スート母材作成時にコア
相当部にP、 O,をドープしておき、高温加熱処理に
よりコア部を早く収縮させ、その後の高温加熱処理途中
のある時期に、雰囲気内にフッ素ガスを投入しても、ス
ート母材の早く焼結したコア相当部の最外周部がフッ素
のコア内部浸透を抑える働きをするため、フッ素はコア
内部に添加されずにクラッド相当部にのみ選択的に添加
されることとなり、このことはすでに知られている。When manufacturing the soot base material, P, 0. When you add
When such a soot base material is subjected to high temperature heat treatment, P, 0. Since the added portion shrinks faster than the P2O-unadded portion, the core portion shrinks faster than the cladding portion (that is, the time for vitrification becomes shorter). Therefore, in order to add fluorine only to the cladding in order to increase the refractive index difference △n between the core and the cladding, the core-corresponding portion should be doped with P, O, and then subjected to high-temperature heat treatment when creating the soot base material. Even if fluorine gas is introduced into the atmosphere at some point during the subsequent high-temperature heat treatment, the outermost periphery of the early sintered core portion of the soot base material will shrink inside the fluorine core. In order to suppress penetration, fluorine is not added inside the core, but is selectively added only to the portion corresponding to the cladding, and this is already known.
このよりなP!Os添加の効果について、本発明者らが
実験により得た知見に基き説明する。第10図はガラス
母材中のP、O,量(motX)と透明ガラス化温度の
関係について本発明者らが得た実験データである。この
図より、P、 OI を添加した石英系多孔質母材の収
縮は純石英に比べ低い温度で起り、早く透明ガラス化す
る。P□Os が多い程より低温となることが判る。こ
のことから、コア部のみを早く収縮させたい時は少なく
ともP、 O,がα025motX以上必要で、これに
よりクラッド部より50℃低い温度で収縮し、透明ガラ
ス化する。しかし、あまシにP、0.の量が多いと、収
縮が早く、母材中に気泡が残り易く、本発明者等の実験
範囲では(L 5 rnol X以上は好ましくなかっ
た。This more P! The effect of adding Os will be explained based on the findings obtained through experiments by the present inventors. FIG. 10 shows experimental data obtained by the present inventors regarding the relationship between the amount of P, O, (motX) in the glass base material and the transparent vitrification temperature. From this figure, the contraction of the silica-based porous base material doped with P and OI occurs at a lower temperature than that of pure quartz, and it becomes transparent vitrified quickly. It can be seen that the more P□Os there is, the lower the temperature becomes. From this, when it is desired to shrink only the core portion quickly, at least P and O are required to be at least α025motX, thereby shrinking at a temperature 50° C. lower than that of the cladding portion and making it transparent vitrified. However, P, 0. If the amount is large, the shrinkage is rapid and bubbles are likely to remain in the base material, and in the range of experiments conducted by the present inventors, (L 5 rnol X or more) was not preferable.
なお、コア部のみを収縮させるP、0.量は重量%で言
えば101〜5重量%の範囲が好″ましい。Note that P, which causes only the core portion to contract, is 0. The amount is preferably in the range of 101 to 5% by weight.
しかしこのようにP、 O,が添加された箇所は欠陥を
生成し易いうえに、また欠陥も多く存在する。このため
に耐放射線特性やOH基の再吸収が起こってしまう。こ
の事実もすでに知られている。However, in places where P and O are added in this way, defects are likely to occur, and there are also many defects. This causes radiation resistance and reabsorption of OH groups. This fact is already known.
ガラス中にP、0.が多いと、欠陥に由来する紫外部吸
収が大きくなり、この欠陥に由来する吸収はOH基を添
加すると減少することを本発明者らは実験により確認し
た。これは欠陥とOHが結合するためである。P in glass, 0. The present inventors have confirmed through experiments that when there are many OH groups, the ultraviolet absorption resulting from the defects increases, and when OH groups are added, the absorption resulting from the defects decreases. This is because the defect and OH are combined.
OOH
欠陥 十H,O−→欠陥解消
欠陥を少なくするためには少なくとも 1PPm以上の
OH基が存在する方が好ましいことか、本発明に到る過
程で判明した。事実、ファイバ化して伝送損失を調べた
ところ、α65μm近傍での欠陥に由来する吸収は殆ん
どなくなった。これはOH基が欠陥を解消していること
を示している。OOH Defect 10H,O-→Defect EliminationIt was found in the course of developing the present invention that in order to reduce the number of defects, it is preferable for at least 1 PPm or more of OH groups to exist. In fact, when it was fabricated into a fiber and the transmission loss was investigated, absorption due to defects in the vicinity of α65 μm almost disappeared. This indicates that the OH group eliminates defects.
しかしながら、OH基量が多いと、OH基に由来する波
長095μm、1.24μm 、 1.39μmに大き
な吸収があり、光フアイバ通信に用いられる波長1.5
0μm における伝送損失値を大きくする。このため許
容されるOH量は0.3ppmが限度とされている。し
たがってOHiを増やすと、欠陥を解消できるものの、
逆に1.30μmでの伝送損失を大きくする。However, when the amount of OH groups is large, there is a large absorption at wavelengths of 095 μm, 1.24 μm, and 1.39 μm derived from OH groups, and the wavelengths of 1.5 μm used for optical fiber communication are
Increase the transmission loss value at 0 μm. For this reason, the permissible amount of OH is limited to 0.3 ppm. Therefore, although increasing OHi can eliminate defects,
Conversely, the transmission loss at 1.30 μm is increased.
また一方、Plol を添加したガラスでは、さらに1
.55μm 近傍にP −OHに由来する吸収が存在す
ることが知られている。これも1.55μm帯での光伝
送に対して悪影響を及ぼす。On the other hand, in the glass doped with Plol, an additional 1
.. It is known that absorption derived from P-OH exists near 55 μm. This also has an adverse effect on optical transmission in the 1.55 μm band.
生成のし易さを、OD基で置換して解消することを見出
した。この理由は次のごとくである。表1はOHおよび
ODの振動吸収波長と各振動吸収波長での1000 p
pmの吸収強度(dB/kII)を示す。OH基のα9
4,1.24゜1.39μmでの吸収に対応するOD基
の吸収は、表1に示すとおり夫々、1.2B、1.68
゜1.88μmでの吸収であるが、一般にOH基の吸収
に対応するOD基の吸収の強度は、OH基の約0.57
倍であることが知られている。It has been found that the ease of production can be overcome by substitution with an OD group. The reason for this is as follows. Table 1 shows the vibrational absorption wavelengths of OH and OD and 1000p at each vibrational absorption wavelength.
It shows the absorption intensity (dB/kII) of pm. α9 of OH group
The absorptions of the OD group corresponding to the absorptions at 4, 1.24° and 1.39μm are 1.2B and 1.68B, respectively, as shown in Table 1.
Although the absorption is at 1.88 μm, the intensity of the absorption of OD group, which generally corresponds to the absorption of OH group, is about 0.57 μm of OH group.
It is known that twice as much.
例えば1.50 μmでOH基1 ppm添加量に対す
る吸収増はα6 dB/ki+であるが、OD基1 p
pmでは[1L01dB/kmとなる。このためOH基
αS ppmでの1.30μmでの吸収増と同じになる
OD基童はおよそ20 ppmである。従ってOD基の
量は1〜20ppmが好ましい範囲である。For example, at 1.50 μm, the absorption increase for 1 ppm of OH group is α6 dB/ki+, but for 1 p of OD group, the increase in absorption is α6 dB/ki+.
At pm, it becomes [1L01dB/km. Therefore, the OD base value that is the same as the absorption increase at 1.30 μm at OH group αS ppm is approximately 20 ppm. Therefore, the preferable range of the amount of OD groups is 1 to 20 ppm.
7/
表1゜
−ナ3Bを用いて、燃焼ガスとして酸素を供給口4から
、水素を供給口5から供給して、多心管バーナの最も外
側の環状ボートとその内側ボートより噴出させる。同時
に原料ガスとしての5iCt4 をArガス等の不活性
ガスをキャリアガスに用いて、供給ロアから供給して多
心管バーナの中心ボートから送り込み反応させる。また
、原料ガスがバーナの先端より数關離れだ空間で反応す
る様に遮蔽用としてArガスを供給口6より供給して、
中央ボートの次の環状ボートより噴出させる。このよう
な状態で、ガラス微粒子体のロッド即ちスート母材を得
るように、回転する出発母材8の先端から軸方向にガラ
ス微粒子を堆積させる。7/ Table 1 Using the burner 3B, oxygen is supplied from the supply port 4 and hydrogen is supplied from the supply port 5 as combustion gases, and they are ejected from the outermost annular boat of the multicore tube burner and its inner boat. At the same time, 5iCt4 as a raw material gas is supplied from the supply lower using an inert gas such as Ar gas as a carrier gas, and is fed from the center boat of the multi-core tube burner to cause a reaction. In addition, Ar gas is supplied from the supply port 6 for shielding so that the raw material gas reacts in a space several steps away from the tip of the burner.
It will be ejected from the circular boat next to the central boat. In this state, glass particles are deposited in the axial direction from the tip of the rotating starting base material 8 so as to obtain a rod of glass fine particles, that is, a soot base material.
次いで、第3図に示すように、コア相当部9のドーパン
トPtOs量もしくはカサ密度を局所的に高くするため
に、上バーナ5Aの供給口4から8t/分の割合で酸素
を、供給口6から21/分の割合でArを夫々供給し、
供給口5から水素を6t〜8t/分、供給ロアから5i
cz、を10〜50ccZ分の範囲で供給する。上バー
ナ3Aは、ドーパント濃度あるいはカサ密度を局所的(
11Aと11Bの間)K高くする働きと共に、クラッド
相当部10を合成する働きも兼ねている。カサ密度を局
所的に高くするには水素の流量を上げ、コア相当部の表
面温度を高くするとよい。Next, as shown in FIG. 3, in order to locally increase the amount of dopant PtOs or bulk density in the core-corresponding portion 9, oxygen is supplied from the supply port 4 of the upper burner 5A at a rate of 8 t/min to the supply port 6. Ar is supplied at a rate of 21/min from
6t~8t/min of hydrogen from supply port 5, 5i from supply lower
cz, is supplied in the range of 10 to 50 ccZ. The upper burner 3A adjusts the dopant concentration or bulk density locally (
11A and 11B), it serves not only to increase K but also to synthesize the cladding equivalent portion 10. In order to locally increase the bulk density, it is recommended to increase the flow rate of hydrogen and increase the surface temperature of the portion corresponding to the core.
一方、下バーナ−5Bは、コア部を合成する働きを持ち
、供給ロアからPool、を20 cc7%及び、5i
oz、を200cc/分の割合で同時に供給し、O,/
H,火炎点中で燃焼させればよい。またGeO2を添加
する場合には同時にGeCl4を供給すればよい。なお
、上記の条件は一例であって、本発明を限定するもので
はない。On the other hand, the lower burner 5B has the function of synthesizing the core part, and supplies Pool from the supply lower with 20 cc7% and 5i
oz, is simultaneously supplied at a rate of 200cc/min, O,/
H. It can be burned at the flame point. Moreover, when GeO2 is added, GeCl4 may be supplied at the same time. Note that the above conditions are just an example and do not limit the present invention.
以上の如くして、コア相当部のp、 o I濃度又はカ
サ密度がクラッド部より高いスート母材が製造できる。In the manner described above, a soot base material in which the p, o I concentration or bulk density of the core-corresponding portion is higher than that of the cladding portion can be manufactured.
次に上記スート母材を純石英から成る炉心管やアルミナ
製の炉心管などの耐熱性のある炉心管に挿入して高温加
熱することで重水ドープ脱水及び焼結する。Next, the soot base material is inserted into a heat-resistant core tube such as a pure quartz core tube or an alumina core tube and heated to a high temperature to perform heavy water dope dehydration and sintering.
この際、まず該スート世態を重水ドープすることに主眼
をおいて、例えば600℃〜1100℃の温度範囲でH
θガス5t/分、重水ガスα51/分程度供給される雰
囲気内で処理することが好ましい0重水の使用はOD置
換が目的であり、Dl +1JDl rcD4 *等の
重水素系ガスを用いることができる。まだ重水の純度は
995X以上であることが好ましい。なぜなら重水の不
純物は主にH,Oであるため、OH基の残存を招くから
である。重水化温度が600℃以下ではスート母材内の
HjO,OH基を除去することはできず、かつ重水素化
にも時間がかかり不利となる。また重水雰囲気下で11
00℃以上加熱にするとジャケット部のスート母材も収
縮が起こり始め、第二段階でフッ素系ガスを投入しても
、スート母材のカサ密度が全体にわたって高くなってし
まうために、フッ素をスート母材ジャケット部に添加す
るのが困難となる。At this time, the main focus is first on doping the soot with heavy water, for example, in a temperature range of 600°C to 1100°C.
It is preferable to process in an atmosphere where θ gas is supplied at about 5 t/min and heavy water gas at about 51/min. The purpose of using heavy water is OD replacement, and deuterium gas such as Dl + 1 JDl rcD4 * can be used. . It is still preferable that the purity of the heavy water is 995X or higher. This is because impurities in heavy water are mainly H and O, which causes OH groups to remain. If the deuteration temperature is below 600° C., the HjO and OH groups in the soot base material cannot be removed, and deuteration also takes time, which is disadvantageous. In addition, 11
When heated above 00°C, the soot base material in the jacket part begins to shrink, and even if fluorine-based gas is introduced in the second stage, the bulk density of the soot base material increases throughout, so fluorine is not added to the soot base material. It is difficult to add it to the base material jacket.
上記第一段階の加熱処理に引続いて、フッ素の添加を主
眼とした第二段階の加熱処理を行う。この場合の温度は
火炎加水分解反応で得られたスート母材内コア部のp、
osの添加物の分布とカサ密度分布に依存するが、概
ね1150℃土150℃の範囲が好ましい。即ち、スー
ト母材を上記構成にすることにより、1000℃前後で
コア相当部の少なくとも最外周部11Bが焼結し、その
後、1600℃以上でスートf、d4J全体が焼結完了
するまでの加熱処理中に雰囲気をフッ素系ガスとして、
フッ素をクラッド相当部10のみに添加することができ
る。Following the first-stage heat treatment, a second-stage heat treatment is performed that focuses on the addition of fluorine. In this case, the temperature is p of the core inside the soot base material obtained by the flame hydrolysis reaction,
Although it depends on the distribution of os additives and bulk density distribution, a range of approximately 1150°C and 150°C is preferable. That is, by configuring the soot base material as described above, at least the outermost peripheral portion 11B of the core-corresponding portion is sintered at around 1000°C, and then heated at 1600°C or higher until the entire soot f and d4J are sintered. During processing, the atmosphere is fluorine-based gas,
Fluorine can be added only to the cladding portion 10.
換伺するならば、スート母材のコア相当部9内にフッ素
が添加されぬような条件でフッ素系ガスを投入するため
には、スート母材の焼結処理において、コア部の少なく
とも最外周部11Bの相対密度が高くなった時点で、フ
ッ素系ガスの投入を開始すれは良い。具体的にはコア部
の少なくとも最外周部11Bの相対密度が0.45以上
が好ましい。In other words, in order to inject fluorine-based gas under conditions such that fluorine is not added into the core-corresponding part 9 of the soot base material, at least the outermost periphery of the core part must be added during the sintering process of the soot base material. It is advisable to start introducing the fluorine-based gas when the relative density of the portion 11B becomes high. Specifically, the relative density of at least the outermost peripheral portion 11B of the core portion is preferably 0.45 or more.
従って、温度分布が均一で昇温速度がα(℃/分)の炉
心管で加熱処理した場合、コア相当部の少なくとも最外
周部11Bの相対密度が045となった温度T1からク
ラッド相当部の相対密度がα45となる温度T3 まで
の間にフッ素系ガスを投入すれば良い。この場合、温度
差ΔT = T、 −T、が大きい程、フッ素系ガスを
投入する温度の許容誤差も大きいことになり、温度制御
が容易になる。逆に言えば、△Tが小さい程、投入温度
の厳密な制御が要求され、不利でるる。Therefore, when heat treatment is performed in a furnace tube with a uniform temperature distribution and a heating rate of α (°C/min), the temperature T1 at which the relative density of at least the outermost peripheral part 11B of the core-corresponding part becomes 045, and the cladding-corresponding part The fluorine gas may be introduced until the temperature T3 at which the relative density becomes α45. In this case, the larger the temperature difference ΔT = T, −T, the larger the tolerance for the temperature at which the fluorine-based gas is introduced, making temperature control easier. Conversely, the smaller ΔT is, the more precise control of the charging temperature is required, which is disadvantageous.
ΔTを大きくするには、第6図で示すp、o。In order to increase ΔT, p and o shown in FIG.
濃度のコア部の高さΔ1が高い程好ましい。It is preferable that the height Δ1 of the concentration core portion is higher.
しかしながら1.へ、を高くしすぎると焼結時に気泡が
発生し易くなり、好ましくない。そのためΔ1−α01
〜5 重量%(P、O,のガラス母材に対する比)の範
囲となるよう火炎加水分解を行うこ左が好ましい。However, 1. If f is too high, bubbles are likely to be generated during sintering, which is not preferable. Therefore Δ1−α01
It is preferable to carry out flame hydrolysis so that the ratio of P, O, to the glass base material is in the range of -5% by weight.
例えば、第4図に示すようなドーパントのP801濃度
分布が(A) 、 CB)の2つの場合を比較する。こ
こでrはスート母材の中心軸からの径方向距離であり、
rlはスート母材のコア相当部の半径、即ち、コア相当
部9の最外周部11Bの位置であり、Δrは微小距離で
、rI+Δrは第5図でのクラッド相当部10の最内周
部11A の半径である。なお、Δrは約1〜2■程度
であるが、この値に限定されるものでもない。For example, two cases in which the dopant P801 concentration distribution is (A) and CB) as shown in FIG. 4 will be compared. Here, r is the radial distance from the central axis of the soot base material,
rl is the radius of the core equivalent part of the soot base material, that is, the position of the outermost peripheral part 11B of the core equivalent part 9, Δr is a minute distance, and rI+Δr is the innermost peripheral part of the cladding equivalent part 10 in FIG. It has a radius of 11A. Incidentally, Δr is approximately 1 to 2 cm, but is not limited to this value.
第5図はこれら添加物のp、o、濃度の相違する2つの
スート母材(A)、■)を昇温速度16ヅ分の加熱炉に
て加熱した場合のスート母材(イ))。Figure 5 shows two soot base materials (A) and (■) with different p, o, and concentrations of these additives, which are heated in a heating furnace with a heating rate of 16㎜ (A)). .
CB)の温度に対する相対密度の変化を示す。第5図中
の曲線Ar1及びBr1はそれぞれスート母材(、k)
および申)のコア相当部の最外周部11Bの相対密度の
変化を示し、曲線ArI+Δr1Brl+Δrはそれぞ
れスート母材(A)及びCB)のクラッド相当部の最内
周部11A の相対密度の変化を示す。CB) shows the change in relative density with respect to temperature. Curves Ar1 and Br1 in Fig. 5 are the soot base material (,k), respectively.
The curves ArI+Δr1Brl+Δr show the changes in the relative density of the innermost periphery 11A of the cladding-equivalent parts of the soot base materials (A) and CB), respectively. .
第5図に示す如く、スート母材内のコア相当部の最外周
部11Bの相対密度がcL45に達してからクラッド相
当部の最内周部11Aの相対密度が(L45に達する迄
の温度差ΔTは、cA)のスート母材のΔTA方が(B
)のスート母材の温度差ΔTBよりも大きい。その分だ
け、(A)のスート母材の温度制御が容易となる。カサ
密度分布についても同様のことが言える。As shown in FIG. 5, the temperature difference from when the relative density of the outermost peripheral part 11B of the core equivalent part in the soot base material reaches cL45 until the relative density of the innermost peripheral part 11A of the cladding equivalent part reaches (L45) ΔT is cA) soot base material ΔTA is (B
) is larger than the temperature difference ΔTB of the soot base material. Accordingly, the temperature control of the soot base material (A) becomes easier. The same can be said about the bulk density distribution.
コア部の少なくとも最外周部11BでのpcOs濃度及
びカサ密度を同時に高くするのが最も有利であるが、ど
ちらかを選択しても本発明の効果を達成することが可能
である。Although it is most advantageous to simultaneously increase the pcOs concentration and the bulk density at least in the outermost peripheral portion 11B of the core portion, the effects of the present invention can be achieved by selecting either one.
なお、コア部へのGem、等屈折率調整剤の添加の有無
にかかわらず、以−Fに示した効果は達成できる。Note that the effects shown below can be achieved regardless of whether or not Gem and a constant refractive index adjusting agent are added to the core portion.
又、コア相当部のOD基量を調整する必要がある場合は
、重水素化前後もしくは重水素化時に塩素系ガスを含ん
だ雰囲気とし、1000〜1200℃ の温度でスート
母材の急激な収縮が起きないように処理すれば良い。In addition, if it is necessary to adjust the amount of OD groups in the core-corresponding part, use an atmosphere containing chlorine-based gas before or during deuteration to cause rapid contraction of the soot base material at a temperature of 1000 to 1200°C. It is best to take measures to prevent this from happening.
実施例1
第6図(a)、(b)にそれぞれ示すP、0.濃度及び
相対カサ密度分布を有するシングルモードファイバ用ス
ート母材を800℃ の加熱炉に投入し、第7図のグラ
フに示す如く、D、Oガスを100cc/分、H6ガス
を10t/分の割合で供給する雰囲気下で60分間保持
し、1000℃まで昇温し、途中でり、Oガスのみを止
め、次いで塩素ガスを200 cc/分流し60分間保
持した後、87・ガス150cc/分をさらに添加しな
がら1時間かけて1300℃まで昇温し、次いで純粋H
θガスの雰囲気で1500℃以上に昇温して透明ガラス
化を行った。Example 1 P, 0. A soot base material for a single mode fiber having a concentration and relative bulk density distribution was put into a heating furnace at 800°C, and as shown in the graph of Figure 7, D and O gases were fed at 100cc/min and H6 gas was heated at 10t/min. Hold for 60 minutes in an atmosphere supplied at a rate, raise the temperature to 1000°C, stop only the O gas halfway through, then flow chlorine gas at 200 cc/min and hold for 60 minutes, then 87.gas at 150 cc/min. The temperature was raised to 1300°C over 1 hour while further adding H, and then pure H
Transparent vitrification was performed by raising the temperature to 1500° C. or higher in an atmosphere of θ gas.
得られたガラス母材の屈折率分布を、第6図(C)に示
す。コア相当部は純粋石英の屈折率分布を有しており、
一方、クラッド相当部はフッ素添加量に対応する屈折率
の低下を示した。XMA元素分析(エックス線マイクロ
アナライザー)を行ったところ、コア相当部は全くフッ
素元素を含まないことが確認された。製品ファイバのコ
ア部は△n値でOX、クラッド部は−[130Xであっ
た。OD基はi ppm存在していた。また波長江63
μm 域に存在する紫外吸収はなく、200℃ に高温
加熱処理してもOH基の吸収増は全くみられなかった。The refractive index distribution of the obtained glass base material is shown in FIG. 6(C). The core equivalent part has a refractive index distribution of pure quartz,
On the other hand, the portion corresponding to the cladding showed a decrease in refractive index corresponding to the amount of fluorine added. When XMA elemental analysis (X-ray microanalyzer) was performed, it was confirmed that the portion corresponding to the core did not contain any fluorine element. The core part of the product fiber had a Δn value of OX, and the cladding part had a -[130X. OD groups were present at i ppm. Also, Nagoe 63
There was no ultraviolet absorption in the μm region, and no increase in OH group absorption was observed even after high-temperature heat treatment at 200°C.
従来のファイバーでは上記条件での加熱処理によってO
H基の吸収増がみられている。With conventional fibers, O is reduced by heat treatment under the above conditions.
Increased absorption of H groups is observed.
比較例1
実施例1の効果を確認するため、第2図のコア用バーナ
ー(下バーナ−)3Bを用い、供給ロアからP、0.を
全く供給しないでスート母材を製造した。Comparative Example 1 In order to confirm the effect of Example 1, P, 0. The soot base material was manufactured without supplying any soot.
このスート母材を実施例1と同様な焼結条件で透明ガラ
ス化を行い、得られたガラス母材のXMA分析を行った
ところ、コア相当部とクラッド相当部に関係なく均一に
フッ素が分布していた。そのため屈折率分布は実効的に
Δnを高めることができないことが確認できた。This soot base material was transparently vitrified under the same sintering conditions as in Example 1, and XMA analysis of the obtained glass base material revealed that fluorine was uniformly distributed regardless of the core-corresponding part and the cladding-corresponding part. Was. Therefore, it was confirmed that the refractive index distribution cannot effectively increase Δn.
実施例2
第6図(a) 、 (b)に示すドーパント濃度、相対
カサ密度分布を有するシングルモードファイバ用スート
母材を800℃の加熱温度に投入し、塩素ガスを100
cc/分及びHeガスを5t1分の割合で供給し、し
かもり、Oが2容量%存在する雰囲気で5℃/分の昇温
速度で1050℃まで加熱し、次いでり、Oの供給のみ
を止め、8N+’、ガスを150cc/分の流量で投入
して1300℃まで加熱し、次いで、純粋He 雰囲気
で1600℃以上に加熱して透明ガラス化を行った。Example 2 A soot base material for a single mode fiber having the dopant concentration and relative bulk density distribution shown in FIGS. 6(a) and 6(b) was heated to 800°C, and chlorine gas was
cc/min and He gas was supplied at a rate of 5t/min, and heated to 1050°C at a temperature increase rate of 5°C/min in an atmosphere containing 2% by volume of O, and then only O was supplied. The tube was stopped, 8N+' gas was introduced at a flow rate of 150 cc/min and heated to 1300° C., and then heated to 1600° C. or higher in a pure He 2 atmosphere to perform transparent vitrification.
得られたガラス母材の屈折率分布は第8図に示すとお9
で、コア相当部は純石英に対応する屈折率を有し、△n
値で0%、一方クラッド相当部はフッ素添加量に対応す
る屈折率の低下を示し、Δn値は−α15%であった。The refractive index distribution of the obtained glass base material is shown in Figure 8.
The core equivalent part has a refractive index corresponding to pure quartz, and △n
On the other hand, the portion corresponding to the cladding showed a decrease in refractive index corresponding to the amount of fluorine added, and the Δn value was −α15%.
XMA分析を行ったところ、コア相当部には全くフッ素
元素が含まれていないことが確認された。When XMA analysis was performed, it was confirmed that the core-corresponding portion contained no fluorine element at all.
実施例3
第6図(a) 、 (b)に夫々示すP、0.濃度及び
相対カサ密度分布を有するシングルモードファイバー用
スート母材を 800℃の加熱炉に投入し、D、0を1
cc/分、塩素ガスを100 ccZ分、Heガスを
101/分の割合で供給する雰囲気下で5℃/分の割合
で1100″Cまで昇温し、次いでD20ガスと塩素ガ
スを止め、BF−ガスを150CC/分の速度で投入し
て1300℃まで昇温し、次いで純粋Ha ガス101
/分に8F、を1ace/分添加した雰囲気で1500
℃以上に昇温して透明ガラス化を行った。Example 3 P, 0. A soot base material for single mode fiber with concentration and relative bulk density distribution was put into a heating furnace at 800℃, and D, 0 was set to 1.
cc/min, chlorine gas was supplied at a rate of 100 cc/min, He gas was supplied at a rate of 101/min, and the temperature was raised to 1100''C at a rate of 5°C/min. - Inject gas at a rate of 150 CC/min and raise the temperature to 1300 °C, then pure Ha gas 101
1500 in an atmosphere containing 1ace/min of 8F/min.
Transparent vitrification was performed by raising the temperature above ℃.
得られたガラス母材の屈折率分布を第9図に示す。ガラ
ス母材の周辺部は第9図中に波線に示すよう垂直となっ
ていた。これは透明化する際、フッ素添加雰囲気とする
ことでガラス中のフッ素の揮散が抑えられることを意味
している。The refractive index distribution of the obtained glass base material is shown in FIG. The peripheral portion of the glass base material was vertical as shown by the dotted line in FIG. This means that when making the glass transparent, the volatilization of fluorine in the glass can be suppressed by creating a fluorine-added atmosphere.
コア相当部は純石英の屈折率を有しており、一方、クラ
ッド相当部はフッ素添加量に対応する屈折率の低下を示
した。XMム分析を行ったところ、コア相当部は全くフ
ッ素元素を含まないことが確認された。製品ファイバの
コア部は、氏値で0%、クラッド部は−a25チであっ
た。The portion corresponding to the core had a refractive index of pure silica, while the portion corresponding to the cladding showed a decrease in refractive index corresponding to the amount of fluorine added. When XM analysis was carried out, it was confirmed that the core portion did not contain any fluorine element. The core part of the product fiber had a molar value of 0%, and the cladding part had a value of -a25.
またこのファイバ中の重水量は約2 ppmであった。Further, the amount of heavy water in this fiber was about 2 ppm.
比較例3
実施例3の効果を確認するため、上バーナ3ムの供給口
5から水素を24/分供給する一方、供給ロアからP!
0.を全く供給しないでスート母材を製造した。その結
果、カサ密度分布は第6図(b)のような分布になった
。このスート母材を実施例1と同様な焼結条件で透明ガ
ラス化を行い、得られたガラス母材のXMA分析を行っ
たところ、コア相当部とクラッド相当部に関係表く均一
にフッ素が分布していた。Comparative Example 3 To confirm the effect of Example 3, hydrogen was supplied from the supply port 5 of the upper burner 3m at 24/min, while P!
0. The soot base material was manufactured without supplying any soot. As a result, the bulk density distribution was as shown in FIG. 6(b). This soot base material was transparently vitrified under the same sintering conditions as in Example 1, and XMA analysis of the obtained glass base material revealed that fluorine was uniformly present in the core-corresponding part and the cladding-corresponding part. It was distributed.
実施例4
第6図(a) 、 (b)にそれぞれ示すP2O,濃度
(a)および相対カサ密度分布を有するシングルモード
ファイバ用スーF母材を800℃の加熱炉に投入し、a
t、ガスを50007分、D、Oガスを10 cc/分
、Heガスを10t/分の割合で供給する雰囲気下で、
15分間保持した後、40℃/分の昇温速度にて100
0℃まで昇温し、1000℃に到達した時点でり、Oガ
スの供給のみを止める。次いでat、ガスを200 c
c/分流しながら1100℃まで昇温した後、sy、ガ
ス150cc/分 をさらに添加しながら1時間かけて
1300℃まで昇温し、次いで純粋Heガス雰囲気とし
てさらに1500℃以上に昇温して透明ガラス化を行っ
た。Example 4 A single-mode fiber Sou-F base material having the P2O concentration (a) and relative bulk density distribution shown in FIGS. 6(a) and 6(b), respectively, was placed in a heating furnace at 800°C.
In an atmosphere where gas was supplied at a rate of 50,007 minutes, D, O gas was supplied at a rate of 10 cc/min, and He gas was supplied at a rate of 10 t/min,
After holding for 15 minutes, the temperature was increased to 100°C at a heating rate of 40°C/min.
The temperature is raised to 0°C, and when it reaches 1000°C, only the supply of O gas is stopped. Then at 200 c of gas
The temperature was raised to 1100°C with c/splitting flow, and then the temperature was raised to 1300°C over 1 hour while adding sy gas at 150cc/min, and then the temperature was further raised to 1500°C or higher in a pure He gas atmosphere. Transparent vitrification was performed.
得られたガラス母材の屈折率分布を、第6図(C)に示
す。コア相当部は純石英の屈折率分布を示しておし、一
方クラッド相当部はフッ素添加量に対応する屈折率の低
下を示した。XMA元素分析(X線マイクロアナライザ
ー)を行ったところ、コア相当部は全くフッ素元素を含
まないことが確認された。製品ファイバのコア部はΔn
値でOX1クラッド部は−0,30Xであった。The refractive index distribution of the obtained glass base material is shown in FIG. 6(C). The core-corresponding part showed a refractive index distribution of pure silica, while the cladding-corresponding part showed a decrease in refractive index corresponding to the amount of fluorine added. When XMA elemental analysis (X-ray microanalyzer) was performed, it was confirmed that the portion corresponding to the core did not contain any fluorine element. The core part of the product fiber is Δn
The value of the OX1 cladding part was -0.30X.
OD基は1 ppm存在していた。また波長α65μm
域に存在する紫外部吸収はなく、200℃に高温加熱処
理してもOH基の吸収増は全くみられなかった。従来の
ファイバーでは上記条件での加熱処理によってOH基の
吸収増がみられている。OD groups were present at 1 ppm. Also, the wavelength α65μm
There was no ultraviolet absorption present in the region, and no increase in absorption of OH groups was observed even after high-temperature heat treatment at 200°C. Conventional fibers show increased absorption of OH groups by heat treatment under the above conditions.
実施例5
第7図(a)に示すドーパント濃度を有するシングルモ
ードファイバ用スート母材ヲ800℃の加熱温度を投入
し、塩素ガスを100 cc/分及びHeガスを5t/
分の割合で供給する雰囲気で、5℃/分の昇温速度で1
000℃まで加熱し、1000℃においてり、Oを1
cc/分1分間時間供給その後塩素ガスとり、Oを止め
、再び昇温を開始するが、この時8F、ガスを150
cc/分の流量で投入して1500℃まで加熱し、次い
で純粋Hθ雰囲気で1600℃以上に加熱して透明ガラ
ス化を行った。Example 5 A soot base material for single mode fiber having the dopant concentration shown in FIG.
At a heating rate of 5°C/min in an atmosphere supplied at a rate of 1.
Heat to 1,000℃, leave at 1,000℃, and add 1
After supplying cc/min for 1 minute, remove the chlorine gas, stop the O, and start raising the temperature again, but at this time, the temperature is 8F and the gas is 150℃.
It was charged at a flow rate of cc/min and heated to 1500°C, and then heated to 1600°C or higher in a pure Hθ atmosphere to perform transparent vitrification.
なお、以上の実施例ではシングルモードファイバ用スー
ト母材についての場合を説明したが、マルチモードファ
イバ用スート母材についても、同様に本発明の方法を実
施して同じように効果を得られる。In the above embodiments, the soot base material for a single mode fiber was described, but the method of the present invention can be applied to a soot base material for a multimode fiber to obtain the same effect.
以上から明らかな如く、本発明の光フアイバ用ガラス母
材の製造方法によると、高温加熱中にスート母材のコア
相当部にフッ素が添加されず、スート母材のクラッド相
当部のみにフッ素を容易に添加できる。従って、実効的
にΔnが大きな光ファイバを製造することができる。As is clear from the above, according to the method for manufacturing a glass base material for optical fiber of the present invention, fluorine is not added to the core-corresponding portion of the soot base material during high-temperature heating, and fluorine is added only to the cladding-corresponding portion of the soot base material. Can be easily added. Therefore, it is possible to effectively manufacture an optical fiber with a large Δn.
まだ、本発明の光フアイバ用ガラス母材の製造方法によ
ると、スート母材を高温加熱焼結する際にクラッド相当
部にフッ素を添加するために少なくとも一時刻フッ素系
ガスを用いる場合において、その製造条件の調整が極め
て容易である。However, according to the method for producing a glass base material for optical fiber of the present invention, when fluorine-based gas is used for at least one time to add fluorine to a portion corresponding to the cladding when the soot base material is heated and sintered at high temperature, Adjustment of manufacturing conditions is extremely easy.
第1図は光ファイバの屈折率分布構造を説明する図。
第2図は本発明を実施するだめの火炎加水分解法による
スート母材製造方法の概略図。
第5図はスート母材内のドーパント分布を説明する図。
第4図(A)及び(B)はスート母材内のP、0.濃度
分布例を示す図。
第5図は、第4図体)及び0)の場合のスート母材内の
径方向の相対密度の昇温(16℃/分)による変化を示
す。
第6図(a) 、 (b)及び(C)は、本発明の実施
例におけるスート母材のP、0.濃度分布、相対密度分
布及び屈折率差分布を示すグラフ。
第7図は、本発明の実施例1におけるスート母材の処理
条件を説明する図。
第8図は、本発明の実施例2のスート母材の屈折率差分
布を示す図。
第9図は、本発明の実施例5のスート母材の屈折率差分
布を示す図。
第10図は、ガラス母材中のp、o、量(motX)と
透明ガラス化温度の関係を示すグラフ。
代理人 内 1) 明
代 理 人 萩 原 亮 −
ン五(’14炉0乙dFIG. 1 is a diagram explaining the refractive index distribution structure of an optical fiber. FIG. 2 is a schematic diagram of a method for producing a soot base material by a flame hydrolysis method according to the present invention. FIG. 5 is a diagram illustrating the dopant distribution within the soot base material. FIGS. 4(A) and 4(B) show P in the soot base material, 0. A diagram showing an example of concentration distribution. FIG. 5 shows the change in the relative density in the radial direction within the soot base material in the cases of (4) and (0) due to temperature increase (16° C./min). FIGS. 6(a), (b), and (C) show the P, 0. Graph showing concentration distribution, relative density distribution, and refractive index difference distribution. FIG. 7 is a diagram illustrating processing conditions for the soot base material in Example 1 of the present invention. FIG. 8 is a diagram showing the refractive index difference distribution of the soot base material of Example 2 of the present invention. FIG. 9 is a diagram showing the refractive index difference distribution of the soot base material of Example 5 of the present invention. FIG. 10 is a graph showing the relationship between the amounts of p, o, and (motX) in the glass base material and the transparent vitrification temperature. Agents 1) Osamu Akiyo Ryo Hagiwara - Ngo ('14
Claims (4)
、クラッド相当部が純石英である光フアイバ用石英系多
孔質母材を焼結して透明ガラス母材を製造する方法にお
いて、該多孔質母材を重水素系ガスを含むガス雰囲気に
て加熱処理した後、フッ素系ガスを含むガス雰囲気にて
加熱処理し、それによりコア相当部にはOD基を少なく
とも1〜20 ppm添加し、クラッド部にのみフッ素
を添加することを特徴とする光フアイバ用ガラス母材の
製造方法。(1) The core equivalent part is P, 0. In a method for manufacturing a transparent glass base material by sintering a quartz-based porous base material for an optical fiber, the porous base material is made of quartz containing quartz and the cladding portion is pure quartz. After heat treatment in a gas atmosphere containing fluorine-based gas, heat treatment is performed in a gas atmosphere containing fluorine-based gas, thereby adding at least 1 to 20 ppm of OD groups to the core-corresponding portion, and adding fluorine only to the cladding portion. A method for producing a glass base material for optical fiber, characterized by:
むガス雰囲気にて加熱処理する特許請求の範囲の第(1
)項に記載の光フアイバ用ガラス母材の製造方法。(2) Claim (1) in which the porous base material is heat-treated in a gas atmosphere containing deuterium-based gas and chlorine-based gas
) A method for producing a glass base material for optical fibers as described in item 1.
くは重水素系ガスと塩素系ガスとを含む雰囲気にて加熱
処理を行うより前または後に、塩素系ガスを含む雰囲気
にて加熱処理する特許請求の範囲の第(1)項または第
(2)項に記載の光フアイバ用ガラス母材の製造方法。(3) Heat treatment in an atmosphere containing chlorine gas before or after heat treating the porous base material in an atmosphere containing deuterium gas, or in an atmosphere containing deuterium gas and chlorine gas. A method for manufacturing a glass preform for optical fiber according to claim (1) or (2).
る以前に、コア相当部が収縮する温度に達するまで加熱
処理しておく特許請求の範囲の第(1)〜(3)項のい
ずれかに記載される光フアイバ用ガラス母材の製造方法
。(4) Any one of claims (1) to (3), in which the core portion is heat-treated until it reaches a temperature at which it contracts before being heat-treated in a gas atmosphere containing a fluorine-based gas. A method for producing a glass base material for optical fiber described in .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59100639A JPS60246233A (en) | 1984-05-21 | 1984-05-21 | Manufacture of glass preform for optical fiber |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59100639A JPS60246233A (en) | 1984-05-21 | 1984-05-21 | Manufacture of glass preform for optical fiber |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS60246233A true JPS60246233A (en) | 1985-12-05 |
Family
ID=14279394
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP59100639A Pending JPS60246233A (en) | 1984-05-21 | 1984-05-21 | Manufacture of glass preform for optical fiber |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS60246233A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001092923A1 (en) * | 2000-05-29 | 2001-12-06 | Zenastra Photonics Inc. | Application of deuterium oxide in producing silicon containing and metal containing materials for optical communication |
-
1984
- 1984-05-21 JP JP59100639A patent/JPS60246233A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001092923A1 (en) * | 2000-05-29 | 2001-12-06 | Zenastra Photonics Inc. | Application of deuterium oxide in producing silicon containing and metal containing materials for optical communication |
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