JPH0450255B2 - - Google Patents
Info
- Publication number
- JPH0450255B2 JPH0450255B2 JP1102584A JP1102584A JPH0450255B2 JP H0450255 B2 JPH0450255 B2 JP H0450255B2 JP 1102584 A JP1102584 A JP 1102584A JP 1102584 A JP1102584 A JP 1102584A JP H0450255 B2 JPH0450255 B2 JP H0450255B2
- Authority
- JP
- Japan
- Prior art keywords
- furnace
- base material
- fluorine
- gas
- inner cylinder
- 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.)
- Expired - Lifetime
Links
- 239000007789 gas Substances 0.000 claims description 53
- 239000000463 material Substances 0.000 claims description 42
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 32
- 229910052731 fluorine Inorganic materials 0.000 claims description 32
- 239000011737 fluorine Substances 0.000 claims description 32
- 239000011521 glass Substances 0.000 claims description 29
- 238000009826 distribution Methods 0.000 claims description 28
- 150000002222 fluorine compounds Chemical class 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 24
- 239000004071 soot Substances 0.000 claims description 18
- 239000013307 optical fiber Substances 0.000 claims description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000010453 quartz Substances 0.000 claims description 6
- 238000004017 vitrification Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 5
- 239000000835 fiber Substances 0.000 description 5
- 239000001307 helium Substances 0.000 description 5
- 229910052734 helium Inorganic materials 0.000 description 5
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 5
- 239000002019 doping agent Substances 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 229910005793 GeO 2 Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000036760 body temperature Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000005373 porous glass Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
- C03B37/0146—Furnaces therefor, e.g. muffle tubes, furnace linings
-
- 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
Description
【発明の詳細な説明】
本発明は、光フアイバ用母材の製造方法及び製
造装置に関し、特にフツ素を含んだ石英系光フア
イバの製造方法及び装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing a base material for optical fiber, and more particularly to a method and apparatus for manufacturing a silica-based optical fiber containing fluorine.
（従来技術）
第１図に代表的な光フアイバの屈折率分布構造
を示す。第１図ａはグレーデイツド型フアイバ、
ｂはシングルモード・フアイバの屈折率分布であ
る。従来このような屈折率分布を形成するために
は、屈折率を高める添加剤（ドーパント）をコア
部に添加する方法が多く取られていた。屈折率を
高める添加剤としてはGeO2、P2O5、Al2O3など
の酸化物が用いられることが多いが、これらの酸
化物を用いると、レイリー散乱の増加により光
の伝送損失が増加する、ガラス母材中に該酸化
物に起因する気泡発生や結晶相析出などが起り易
い、ガラスの熱膨張係数が大きくなりガラス母
材が割れ易くなる、等の問題を生じる。したがつ
て、ガラス母材中に添加されるドーパント量は少
ない方が望ましい。(Prior Art) FIG. 1 shows the refractive index distribution structure of a typical optical fiber. Figure 1a shows a gray-dated fiber;
b is the refractive index distribution of the single mode fiber. Conventionally, in order to form such a refractive index distribution, many methods have been used to add an additive (dopant) that increases the refractive index to the core portion. Oxides such as GeO 2 , P 2 O 5 , and Al 2 O 3 are often used as additives to increase the refractive index, but when these oxides are used, optical transmission loss increases due to increased Rayleigh scattering. This causes problems such as the occurrence of bubbles and crystal phase precipitation in the glass base material due to the oxide, and the increase in the coefficient of thermal expansion of the glass, making the glass base material more likely to break. Therefore, it is desirable that the amount of dopant added to the glass base material be small.
このため、クラツド部に屈折率を低めるドーパ
ント、たとえばB2O3、フツ素などを添加し、コ
アとクラツド間の屈折率差を大きくする方法が取
られることがある。しかしながら、B2O3はシリ
カガラスの熱膨張係数を大きくし、また長波長領
域に固有の吸収損失を持つ。そこで屈折率低下成
分としてはフツ素を用いることが望ましい。 For this reason, a method is sometimes taken in which a dopant that lowers the refractive index, such as B 2 O 3 or fluorine, is added to the cladding to increase the difference in refractive index between the core and the cladding. However, B 2 O 3 increases the coefficient of thermal expansion of silica glass and also has absorption loss specific to long wavelength regions. Therefore, it is desirable to use fluorine as the refractive index lowering component.
一方光フアイバの製造法としてVAD法は生産
性に優れ経済的な方法として知られている。しか
しながら、VAD法のように火炎加水分解を利用
した方法で石英ガラス中に十分な量のフツ素を添
加することはきわめて困難である。たとえば特開
昭55−15682号公報にはフツ素をガラス母材中に
添加する方法が記載されているが、この方法によ
ればフツ素の添加による屈折率の低下は、高々
0.2〜0.3％程度にすぎず添加されるフツ素の量に
限界がある。 On the other hand, the VAD method is known as a highly productive and economical method for manufacturing optical fibers. However, it is extremely difficult to add a sufficient amount of fluorine into quartz glass using a method that uses flame hydrolysis, such as the VAD method. For example, JP-A-55-15682 describes a method of adding fluorine into a glass base material, but according to this method, the decrease in the refractive index due to the addition of fluorine is at most
There is a limit to the amount of fluorine that can be added, which is only about 0.2 to 0.3%.
また一方では、特開昭55−67533号公報には、
火炎加水分解法で形成されたガラス微粒子の積層
体をフツ素化合物ガスの雰囲気中で加熱すること
により、効率的にフツ素を添加する方法が開示さ
れている。しかしながら、この方法ではガラス微
粒子積層体にほぼ均一に、フツ素が添加されるの
で、フツ素のみを用いて第１図ａのコア部のよう
な連続的に変化するような屈折率分布を形成する
ことは難しい。 On the other hand, in Japanese Patent Application Laid-open No. 55-67533,
A method for efficiently adding fluorine by heating a laminate of glass particles formed by flame hydrolysis in an atmosphere of fluorine compound gas is disclosed. However, in this method, fluorine is added almost uniformly to the glass particle laminate, so only fluorine is used to form a continuously changing refractive index distribution like the core part in Figure 1a. It's difficult to do.
（発明の目的）
本発明の目的は、上記に示したような従来法に
於ける欠点を克服し、光フアイバ用ガラス母材に
フツ素を効率よく添加し、かつ半径方向に連続的
に変化する屈折率分布を形成せしめる方法及び装
置を提供するものである。(Objective of the Invention) The object of the present invention is to overcome the drawbacks of the conventional methods as shown above, to efficiently add fluorine to the glass base material for optical fiber, and to continuously change the fluorine in the radial direction. The present invention provides a method and apparatus for forming a refractive index distribution.
（発明の構成）
本発明者らは鋭意研究の結果、スート母材の焼
結時にフツ素をドープする方法において、炉内の
フツ素ガス濃度を空間的に分布をつけることによ
つて、ガラス母材内にフツ素濃度分布をつける
（すなわち屈折率分布をつける。）ことを考えつ
き、本発明の方法及び装置に到達した。(Structure of the Invention) As a result of intensive research, the present inventors have found that, in a method of doping fluorine during sintering of the soot base material, by spatially distributing the fluorine gas concentration in the furnace, We came up with the idea of creating a fluorine concentration distribution (that is, creating a refractive index distribution) in the base material, and arrived at the method and apparatus of the present invention.
すなわち本発明の要旨とするところは、石英を
主成分とした、スート母材を高温炉内にて透明ガ
ラス化する際に、炉内の雰囲気ガス中に、フツ素
化合物ガスを共存させ、かつ炉内高温部に於ける
フツ素化合物ガスの濃度を炉中心部から半径方向
に連続的に変化させることにより、ガラス母材中
へのフツ素添加量をガラス母材の半径方向に変化
させることを特徴とする光フアイバ母材の製造方
法にあり、さらにそのための装置にある。 In other words, the gist of the present invention is that when a soot base material mainly composed of quartz is transformed into transparent vitrification in a high-temperature furnace, a fluorine compound gas is allowed to coexist in the atmospheric gas in the furnace, and By continuously changing the concentration of fluorine compound gas in the high temperature part of the furnace in the radial direction from the center of the furnace, the amount of fluorine added to the glass base material can be changed in the radial direction of the glass base material. The present invention provides a method for manufacturing an optical fiber base material, and further provides an apparatus for the same.
まず「スート母材焼結時に、フツ素をドープす
る方法において、炉内のフツ素化合物ガス濃度に
空間的な分布をつけることによつて、ガラス母材
内にフツ素濃度分布（すなわち屈折率分布）をつ
ける」という本発明の基本的な考え方について、
実験事実に基づき説明する。 First, in the method of doping fluorine during sintering of the soot base material, by creating a spatial distribution of the fluorine compound gas concentration in the furnace, the fluorine concentration distribution (i.e., refractive index Regarding the basic idea of the present invention, which is "to attach a distribution)",
I will explain based on experimental facts.
本発明者らは、炉内のフツ素化合物ガスの濃度
とガラス母材中に添加される、フツ素濃度との相
関関係を調べるために、次のような実験を行つ
た。即ち、第２図に模式的に示す実験系に於い
て、純石英からなる多孔質ガラス体１をフツ素化
合物ガスであるSF6とヘリウムガスからなる雰囲
気中で1200℃に加熱した状態で３時間保持し、次
いでヘリウムガス雰囲気中で透明ガラス化したの
ち、得られた透明ガラス体の屈折率を測定した。
２は電気炉、３はフツ素化合物ガスSF6及びヘリ
ウムガスの導入口、４は排気口である。第３図
に、フツ素化合物ガスSF6濃度Ｐの1/4乗と得ら
れたガラス体の石英ガラスに対する比屈折率差
Δn（％）との関係を示す。ガラス体中へのフツ素
添加量は、フツ素添加量と比屈比率差Δnがほぼ
比例するとすると、フツ素化合物ガスSF6の濃度
の1/4乗に比例することが判る。さらに保持時間
を倍の６時間としても、フツ素添加量は変化しな
い。このことから、フツ素添加反応のメカニズム
は平衡反応であり、フツ素化合物ガス濃度の1/4
乗に比例した量のフツ素がガラス中に添加される
ことが判つた。そこで炉内のフツ素化合物ガス濃
度に空間的な分布をつけることによつて、ガラス
母材内に添加されるフツ素の量も空間的に変化さ
せることができる。 The present inventors conducted the following experiment in order to investigate the correlation between the concentration of fluorine compound gas in the furnace and the concentration of fluorine added to the glass base material. That is, in the experimental system schematically shown in Fig. 2, a porous glass body 1 made of pure quartz was heated to 1200°C in an atmosphere consisting of SF 6 , which is a fluorine compound gas, and helium gas. After holding the glass body for a period of time and then converting it into transparent glass in a helium gas atmosphere, the refractive index of the obtained transparent glass body was measured.
2 is an electric furnace, 3 is an inlet for fluorine compound gas SF 6 and helium gas, and 4 is an exhaust port. FIG. 3 shows the relationship between the 1/4th power of the fluorine compound gas SF 6 concentration P and the relative refractive index difference Δn (%) of the obtained glass body with respect to quartz glass. It can be seen that the amount of fluorine added into the glass body is proportional to the 1/4th power of the concentration of the fluorine compound gas SF 6 , assuming that the amount of fluorine added and the specific refractive ratio difference Δn are approximately proportional. Furthermore, even if the holding time was doubled to 6 hours, the amount of fluorine added did not change. From this, the mechanism of the fluorine addition reaction is an equilibrium reaction, and 1/4 of the fluorine compound gas concentration
It was found that the amount of fluorine added to the glass was proportional to the power of Therefore, by spatially distributing the fluorine compound gas concentration in the furnace, the amount of fluorine added to the glass base material can also be spatially varied.
上記のフツ素化合物ガスの炉内に於ける濃度分
布を形成する方法を実現するための装置の一実施
態様例を第４図に示す。第４図において５はリン
グ状のヒーターであつて、炉心管６の外部に環状
に設けられている。炉心管６はガス導入口７、ガ
ス排出口８及び母材９を中心軸方向に回転引上げ
る装置を備えており、該炉心管６の内部には、ほ
ぼヒーター部近傍の高温部Ａ−A′付近に達する
高さを有し、該炉心管６とその中心軸をほぼ同じ
くし、ガス導入口１０を有する内円管１１が設け
られて二重構造となつている。該内円筒１１の内
部に入れられたスート母材９は、回転引上装置に
より必要に応じて回転させつつ、上方へ引き上げ
られ、ヒーター５近傍の高温部Ａ−A′を通過す
る際に透明ガラス化される。１２はスート母材が
透明ガラス化された部分である。 FIG. 4 shows an example of an embodiment of an apparatus for realizing the method of forming the concentration distribution of fluorine compound gas in a furnace as described above. In FIG. 4, reference numeral 5 denotes a ring-shaped heater, which is annularly provided outside the furnace core tube 6. The furnace core tube 6 is equipped with a gas inlet 7, a gas outlet 8, and a device for rotating and pulling up the base material 9 in the direction of the central axis. An inner circular tube 11 having a height reaching approximately 100 mm, whose central axis is substantially the same as that of the furnace core tube 6, and having a gas inlet 10 is provided to form a double structure. The soot base material 9 placed inside the inner cylinder 11 is pulled upward while being rotated as necessary by a rotary pulling device, and becomes transparent when passing through a high temperature area A-A' near the heater 5. Become vitrified. 12 is a portion where the soot base material is made into transparent vitrification.
炉心管６にはガス導入口７よりフツ素化合物ガ
スを導入し、一方、内円筒１１にはヘリウム等の
不活性ガスを導入口１０より導入する。フツ素化
合物ガスはヒーター部近傍まで内円筒１１と炉心
管６の間隙を通過し、内円筒１１の上端部におい
て、内円管１１の内部を通過してきた不活性ガス
と半径方向に拡散混合しつつ上方に流れ、ガス排
出口８より排気される。この際、内円筒１１と炉
心管６の径、内円筒１１上端部の高さ、フツ素化
合物と内円筒１１内を流れるガスの流量、ガス排
出口８での排気圧等を最適化することにより、ス
ート母材が透明化する位置Ａ−A′に於けるフツ
素化合物ガスの濃度を、第５図に示すように半径
方向に連続的に変化したものにすることができ
る。 A fluorine compound gas is introduced into the furnace core tube 6 through a gas introduction port 7, while an inert gas such as helium is introduced into the inner cylinder 11 through an introduction port 10. The fluorine compound gas passes through the gap between the inner cylinder 11 and the furnace core tube 6 to the vicinity of the heater section, and is diffused and mixed in the radial direction with the inert gas that has passed through the inner cylinder 11 at the upper end of the inner cylinder 11. The gas flows upward and is exhausted from the gas exhaust port 8. At this time, the diameters of the inner cylinder 11 and the furnace core tube 6, the height of the upper end of the inner cylinder 11, the flow rate of the fluorine compound and the gas flowing inside the inner cylinder 11, the exhaust pressure at the gas outlet 8, etc. should be optimized. As a result, the concentration of the fluorine compound gas at the position A-A' where the soot base material becomes transparent can be made to vary continuously in the radial direction as shown in FIG.
その結果透明ガラス母材中に含まれるフツ素の
濃度の半径方向の分布は第６図に示すように連続
的に変化するものにすることが可能となる。 As a result, the radial distribution of the concentration of fluorine contained in the transparent glass base material can be made to vary continuously as shown in FIG.
フツ素化合物ガスとしては、C2F6、SF6、
CF4、F2、SiF4、CCl2F2など、高温で分解しガラ
スにフツ素を添加する効果のあるものなら、いず
れを用いてもよい。 Fluorine compound gases include C 2 F 6 , SF 6 ,
Any material such as CF 4 , F 2 , SiF 4 , CCl 2 F 2 may be used as long as it decomposes at high temperatures and has the effect of adding fluorine to glass.
また、内円筒１１内に流すガスとしては、ヘリ
ウムの不活性ガスの他に、スート母材の脱水効果
を高める為に塩素、或いは塩素化合物のような脱
水作用を有するものを混合させた不活性ガスを流
すことも、低損失な光フアイバを得るためには効
果的である。 In addition to the inert gas of helium, the gas flowing into the inner cylinder 11 is an inert gas mixed with chlorine or a substance having a dehydrating effect such as a chlorine compound in order to enhance the dehydrating effect of the soot base material. Flowing a gas is also effective in obtaining a low-loss optical fiber.
本発明装置の別の実施態様例を第７図に示す。
第７図の装置では第４図装置における内円筒１１
を炉心管６とほぼ同軸の多重円筒構造とし各円筒
には各別にガス導入口を設けてある。第７図は説
明を簡単にするため２重円筒構造１１および１
１′の場合であつて、夫々にガス導入口１０およ
び１０′がある以外は第４図と同じである。炉心
管６と内円筒１１の間隙および内円筒内各層に流
すガスの流量、組成を調節することにより、フツ
素化合物濃度分布をより細かく調整し、添加され
るフツ素の濃度分布をよりスムースにできる。 Another embodiment of the device of the present invention is shown in FIG.
In the device shown in FIG. 7, the inner cylinder 11 in the device shown in FIG.
has a multi-cylindrical structure substantially coaxial with the furnace core tube 6, and each cylinder is provided with a separate gas inlet. FIG. 7 shows double cylindrical structures 11 and 1 for ease of explanation.
1', which is the same as in FIG. 4 except that there are gas inlets 10 and 10', respectively. By adjusting the flow rate and composition of the gas flowing into the gap between the furnace core tube 6 and the inner cylinder 11 and each layer inside the inner cylinder, the concentration distribution of the fluorine compound can be adjusted more finely, and the concentration distribution of the added fluorine can be made smoother. can.
またフツ素化合物ガスの炉内での空間的濃度分
布を形成するに用いる本発明装置のさらなる実施
態様例を第８図に示す。第８図の装置では内円筒
は設けられておらず、ヒーター近傍の高温部付近
にフツ素化合物ガス吹出口１３が設けられてい
る。図中第４，７図と共通する符号は第４，７図
の場合と同じを意味する。スート母材９は回転し
つつ上方に引上げられるが、吹出口１３よりフツ
素化合物ガスが吹込まれるので、図中Ｂ−B′で
示したスート母材９が透明化される位置において
は、フツ素ガス濃度分布は第９図に示したように
不均一となつている。しかし、スート母材９は軸
を中心として回転しているため、透明ガラス母材
中に含まれるフツ素濃度の半径方向の分布は、第
５図に示したような連続的かつ軸対称なものとす
ることができる。 FIG. 8 shows a further embodiment of the apparatus of the present invention used to form a spatial concentration distribution of fluorine compound gas in the furnace. In the apparatus shown in FIG. 8, an inner cylinder is not provided, and a fluorine compound gas outlet 13 is provided in the vicinity of the high temperature part near the heater. In the figure, the same reference numerals as in FIGS. 4 and 7 have the same meanings as in FIGS. 4 and 7. The soot base material 9 is pulled upward while rotating, and since the fluorine compound gas is blown in from the outlet 13, at the position where the soot base material 9 is made transparent, indicated by B-B' in the figure, The fluorine gas concentration distribution is non-uniform as shown in FIG. However, since the soot base material 9 rotates around its axis, the radial distribution of the fluorine concentration contained in the transparent glass base material is continuous and axially symmetrical as shown in Figure 5. It can be done.
なお、本発明に用いられるスート母材は、純粋
なSiO2からなるもの、又はフツ素以外のGeO2等
のドーパントを多少含むもののいずれでもかまわ
ない。 The soot base material used in the present invention may be made of pure SiO 2 or may contain some dopant other than fluorine, such as GeO 2 .
（実施例 １）
第４図に示す装置を用いて炉体温度を1650℃と
し、スート径80φ、長さ50cmのVAD法で作製し
た純粋石英からなるスート母材を２mm／minの速
度で上方に移動しつつ、透明ガラス化した。炉心
管内径は140mmφ、内円筒外径110mmφ、内径100
mmφとして、炉心管下部のガス導入口７からSF6
を150c.c.／分、内円筒下部のガス導入口１０から
Heを5l／minの流量で導入した。その結果第１０
図に示すようなシングルモード・フアイバに適し
た屈折率分布を持つ透明ガラス母材を得た。(Example 1) Using the apparatus shown in Fig. 4, the furnace body temperature was set at 1650°C, and a soot base material made of pure quartz made by the VAD method with a soot diameter of 80φ and a length of 50 cm was moved upward at a speed of 2 mm/min. While moving, it became transparent glass. The inner diameter of the core tube is 140mmφ, the outer diameter of the inner cylinder is 110mmφ, and the inner diameter is 100mm.
SF 6 from the gas inlet port 7 at the bottom of the core tube as mmφ
150 c.c./min from gas inlet 10 at the bottom of the inner cylinder.
He was introduced at a flow rate of 5 l/min. As a result, the 10th
We obtained a transparent glass base material with a refractive index distribution suitable for a single-mode fiber as shown in the figure.
（実施例 ２）
第７図に示した装置において、炉体温度を1650
℃とし、スート径60mmφ、長さ50cmのVAD法で
作製した純粋石英からなるスート母材を３mm／
minの速度で上方に移動しつつ透明ガラス化し
た。炉心管内径は140φ、外側の内円筒５の外径
110mmφ、内径100mmφ、内側の内円筒１１′の外
径が85mmφ、内径が79mmφとし、炉心管下部のガ
ス導入口７からSF6を500c.c.／min、内円筒１１下
部のガス導入口１０から酸素を500c.c.／min、内
円筒１１′下部のガス導入口７′からHeを5l／min
の流量で導入した。その結果、第１１図に示すよ
うな、グレーデイツド型フアイバに適した屈折率
分布をもつ透明ガラス母材を得た。(Example 2) In the apparatus shown in Fig. 7, the furnace temperature was set to 1650.
℃, a soot base material made of pure quartz made by VAD method with a soot diameter of 60 mmφ and a length of 50 cm is 3 mm/
It turned into transparent glass while moving upward at a speed of min. The inner diameter of the core tube is 140φ, and the outer diameter of the outer inner cylinder 5
110 mmφ, inner diameter 100 mmφ, inner cylinder 11' has an outer diameter of 85 mmφ, inner diameter 79 mmφ, SF 6 from gas inlet 7 at the bottom of the core tube at 500 c.c./min, and gas inlet 10 at the bottom of inner cylinder 11. Oxygen is supplied at 500c.c./min from the inner cylinder 11', and He is supplied at 5l/min from the gas inlet 7' at the bottom of the inner cylinder 11'.
It was introduced at a flow rate of As a result, a transparent glass base material having a refractive index distribution suitable for a graded fiber as shown in FIG. 11 was obtained.
（実施例 ３）
上記実施例２に示した方法に際し、さらに内側
の内円筒１１′内にCl2ガスを50c.c.／minの流量で
流すことにより、第１０図に示したものと同様の
屈折率分布の母材を得、この母材を石英パイプ中
に挿入、一体化したのち線引してフアイバとし、
伝送損失−波長特性を測定した結果残留OH基濃
度が10ppbという極めて低濃度の光フアイバが得
られた。(Example 3) In the method shown in Example 2 above, by further flowing Cl 2 gas into the inner cylinder 11' at a flow rate of 50 c.c./min, the same as that shown in Fig. 10 was obtained. A base material with a refractive index distribution of
As a result of measuring the transmission loss-wavelength characteristics, an optical fiber with an extremely low residual OH group concentration of 10 ppb was obtained.
（実施例 ４）
第８図に示した装置において、炉体温度を1650
℃とし、スート径80mmφ、長さ50cmのVAD法に
より作製した。純粋石英からなるスート母材を３
mm／minの速度で上方に移動しつつ透明ガラス化
した。炉心管６内径は140mmφ、炉心管６内の外
径10mmφ、内径６mmφの吹出口１３からC2F6を
800c.c.／min、炉心管下部のガス導入口７からHe
を5l／minの流量で導入した。(Example 4) In the apparatus shown in Fig. 8, the furnace temperature was set to 1650.
It was prepared using the VAD method with a soot diameter of 80 mmφ and a length of 50 cm. Soot base material made of pure quartz
Transparent vitrification was achieved while moving upward at a speed of mm/min. The inner diameter of the furnace core tube 6 is 140 mmφ, and the C 2 F 6 is connected from the outlet 13, which has an outer diameter of 10 mmφ and an inner diameter of 6 mmφ inside the furnace core tube 6 .
800c.c./min, He from gas inlet 7 at the bottom of the reactor tube.
was introduced at a flow rate of 5 l/min.
その結果、第１１図に示すようなグレーデイツ
ド型フアイバに適した屈折率分布を持つ透明ガラ
ス母材を得た。 As a result, a transparent glass base material having a refractive index distribution suitable for a graded fiber as shown in FIG. 11 was obtained.
第１図ａ，ｂ：光フアイバの代表的な屈折率分
布。第２図：本発明の基本的実験を模式的に説明
する図。第３図：フツ素化合物ガス濃度Ｐの1/4
乗と、得られたガラス体の比屈折率差Δn（％）の
関係を示す図。第４図：本発明の一実施態様例の
説明図。第５図：第４図の装置の炉内高温部Ａ−
A′におけるフツ素化合物ガス濃度分布。第６
図：本発明方法で得られた光フアイバ母材の屈折
率分布例。第７図：本発明の別の実施態様例の説
明図。第８図：本発明のさらなる実施態様例の説
明図。第９図：第６図に示した装置の炉内高温部
Ｂ−B′におけるフツ素化合物ガスの濃度分布。
第１０図：実施例１で得られた光フアイバー母材
の屈折率分布。第１１図：実施例２，３，４で得
られた光フアイバー母材の屈折率分布。
Figure 1 a, b: Typical refractive index distribution of optical fiber. FIG. 2: A diagram schematically explaining the basic experiment of the present invention. Figure 3: 1/4 of fluorine compound gas concentration P
FIG. 3 is a diagram showing the relationship between the power and the relative refractive index difference Δn (%) of the obtained glass body. FIG. 4: An explanatory diagram of one embodiment of the present invention. Figure 5: Furnace high temperature section A- of the equipment in Figure 4
Fluorine compound gas concentration distribution at A′. 6th
Figure: Example of refractive index distribution of optical fiber base material obtained by the method of the present invention. FIG. 7: An explanatory diagram of another embodiment of the present invention. FIG. 8: An explanatory diagram of a further embodiment of the present invention. Figure 9: Concentration distribution of fluorine compound gas in the high temperature section B-B' in the furnace of the apparatus shown in Figure 6.
FIG. 10: Refractive index distribution of the optical fiber base material obtained in Example 1. FIG. 11: Refractive index distribution of the optical fiber base materials obtained in Examples 2, 3, and 4.
Claims (1)
にて透明ガラス化する際に、炉内の雰囲気ガス中
にフツ素化合物ガスを共存させ、かつ炉内高温部
に於けるフツ素化合物ガスの濃度を炉中心部から
半径方向に連続的に変化させることにより、ガラ
ス母材中へのフツ素添加量をガラス母材の半径方
向に変化させることを特徴とする光フアイバ母材
の製造方法。 ２ リング状のヒーターの内側に内管状の炉心管
を設け、該炉心管内に炉心管とその軸をほぼ同じ
くし、その上端が炉内高温部近傍に達する内円筒
を設け、上記炉心管と該内円筒の間隙と内円筒内
にそれぞれ組成の異なるガスを流すことにより、
炉内高温部のフツ素化合物ガス濃度の分布を調整
する光フアイバ母材の製造装置。[Claims] 1. When converting a soot base material mainly composed of quartz into transparent vitrification in a high-temperature furnace, a fluorine compound gas is allowed to coexist in the atmospheric gas in the furnace, and a high-temperature section in the furnace is It is characterized by changing the amount of fluorine added into the glass base material in the radial direction of the glass base material by continuously changing the concentration of the fluorine compound gas in the radial direction from the center of the furnace. A method for manufacturing an optical fiber base material. 2. An inner tube-shaped furnace core tube is provided inside the ring-shaped heater, and an inner cylinder is provided within the furnace core tube, the axis of which is approximately the same as that of the furnace core tube, and whose upper end reaches near the high temperature part of the furnace, and which is connected to the furnace core tube. By flowing gases with different compositions into the gap between the inner cylinder and inside the inner cylinder,
Optical fiber base material manufacturing equipment that adjusts the distribution of fluorine compound gas concentration in the high temperature section of the furnace.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1102584A JPS60204634A (en) | 1984-01-26 | 1984-01-26 | Production of base material for optical fiber and apparatus for producing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1102584A JPS60204634A (en) | 1984-01-26 | 1984-01-26 | Production of base material for optical fiber and apparatus for producing same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60204634A JPS60204634A (en) | 1985-10-16 |
| JPH0450255B2 true JPH0450255B2 (en) | 1992-08-13 |
Family
ID=11766556
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1102584A Granted JPS60204634A (en) | 1984-01-26 | 1984-01-26 | Production of base material for optical fiber and apparatus for producing same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60204634A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0660030B2 (en) * | 1985-12-23 | 1994-08-10 | 住友電気工業株式会社 | Method for manufacturing glass base material for optical fiber |
-
1984
- 1984-01-26 JP JP1102584A patent/JPS60204634A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60204634A (en) | 1985-10-16 |
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