JPH04295026A - Production of mother mateiral for single-mode optical fiber - Google Patents
Production of mother mateiral for single-mode optical fiberInfo
- Publication number
- JPH04295026A JPH04295026A JP8309991A JP8309991A JPH04295026A JP H04295026 A JPH04295026 A JP H04295026A JP 8309991 A JP8309991 A JP 8309991A JP 8309991 A JP8309991 A JP 8309991A JP H04295026 A JPH04295026 A JP H04295026A
- Authority
- JP
- Japan
- Prior art keywords
- base material
- optical fiber
- temperature
- quartz glass
- mode optical
- 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.)
- Granted
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 26
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 45
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000005373 porous glass Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 239000011521 glass Substances 0.000 claims abstract description 14
- 208000005156 Dehydration Diseases 0.000 claims abstract description 11
- 230000018044 dehydration Effects 0.000 claims abstract description 11
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 11
- 238000005245 sintering Methods 0.000 claims abstract description 5
- 238000000151 deposition Methods 0.000 claims abstract 2
- 239000002245 particle Substances 0.000 claims description 6
- 239000010419 fine particle Substances 0.000 abstract description 2
- 230000007423 decrease Effects 0.000 description 11
- 238000005253 cladding Methods 0.000 description 7
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 239000005049 silicon tetrachloride Substances 0.000 description 6
- IEXRMSFAVATTJX-UHFFFAOYSA-N tetrachlorogermane Chemical compound Cl[Ge](Cl)(Cl)Cl IEXRMSFAVATTJX-UHFFFAOYSA-N 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000004031 devitrification Methods 0.000 description 5
- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium oxide Inorganic materials O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- PVADDRMAFCOOPC-UHFFFAOYSA-N oxogermanium Chemical compound [Ge]=O PVADDRMAFCOOPC-UHFFFAOYSA-N 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910006113 GeCl4 Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000004017 vitrification Methods 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Thermal Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明はシングルモ−ド光ファイ
バ用母材の製造方法、特にはロット間において長手方向
に安定した比屈折率差（△ｎ）を有するシングルモ−ド
光ファイバ製造用のガラス母材の製造方法に関するもの
である。[Industrial Application Field] The present invention relates to a method for manufacturing a preform for single-mode optical fiber, and in particular a method for manufacturing a single-mode optical fiber having a stable relative refractive index difference (△n) in the longitudinal direction between lots. The present invention relates to a method for manufacturing a glass base material.
【０００２】0002
【従来の技術】シングルモ−ド光ファイバ用母材の製造
は四塩化けい素などの気体状ガラス原料と四塩化ゲルマ
ニウムなどのド−プ剤とを酸水素火炎バ−ナ−に導入し
、ついでこの火炎加水分解で発生したガラス微粒子を担
体上に堆積し、これを軸方向に成長させて多孔質ガラス
母材を作る、いわゆるＶＡＤ 法で製造し、ついでこれ
を高温で脱水、焼結して透明ガラス化することによって
製造されている。[Prior Art] In the production of a single mode optical fiber base material, a gaseous glass raw material such as silicon tetrachloride and a dopant such as germanium tetrachloride are introduced into an oxyhydrogen flame burner, and then Glass particles generated by this flame hydrolysis are deposited on a carrier and grown in the axial direction to create a porous glass matrix, the so-called VAD method, which is then dehydrated and sintered at high temperatures. Manufactured by transparent vitrification.
【０００３】0003
【発明が解決しようとする課題】しかして、このＶＡＤ
法で製造されたシングルモ−ド光ファイバ用母材には
引上げ速度の変動のために比屈折率差（△ｎ）がロット
間で大きくバラ付くという不利がある。これはガラス微
粒子の堆積、成長で一定直径の多孔質ガラス母材が得ら
れるように成長しつつある多孔質ガラス母材は徐々に上
方に引上げられるのであるが、多くの場合、多孔質ガラ
ス母材の製造初期や後期では引上げ速度が外径が一定に
なったときの引上げる速度に比較して変化し易く、また
その他の要因で作業中に引上げ速度が変化することもあ
る。[Problem to be solved by the invention] However, this VAD
The single-mode optical fiber preform manufactured by the method has the disadvantage that the relative refractive index difference (Δn) varies greatly from lot to lot due to variations in the pulling speed. This is because the growing porous glass base material is gradually pulled upwards so that a porous glass base material with a constant diameter is obtained through the accumulation and growth of glass particles, but in many cases, the porous glass base material In the early and later stages of material production, the pulling speed is more likely to change than the pulling speed when the outer diameter is constant, and the pulling speed may change during work due to other factors.
【０００４】このように引上げ速度が変化するとこれを
脱水、焼結して得られるガラス母材の比屈折率差（△ｎ
）が変化し、このために比屈折率差（△ｎ）の安定した
ガラス母材を得ることが難しく、一本のガラス母材から
目的とする屈折率分布をもつ部分の割合が６０％以下に
もなるという欠点がある。When the pulling speed changes in this way, the relative refractive index difference (△n
) changes, and for this reason, it is difficult to obtain a glass base material with a stable relative refractive index difference (△n), and the proportion of the portion with the desired refractive index distribution from one glass base material is less than 60%. It also has the disadvantage of becoming
【０００５】そのため、この引上げ速度の安定化につい
ては大気圧による原料ガス供給量の変動を補正する方法
が提案されており、本発明者らもクラッド用バ−ナ−に
供給する水素量を制御する方法を提案している（特願平
２−３８０３９号明細書参照）が、多孔質ガラス母材の
引上げ速度を一定にしても石英ガラス製の炉芯管を用い
て脱水、焼結した場合には各ロット毎に比屈折率差（△
ｎ）が異なる値となるために、比屈折率差（△ｎ）がロ
ット間で均一である光ファイバ用母材を得ることが難し
いという問題がある。[0005] Therefore, in order to stabilize the pulling speed, a method has been proposed that corrects the fluctuation in the amount of raw material gas supplied due to atmospheric pressure, and the present inventors have also proposed a method of controlling the amount of hydrogen supplied to the cladding burner. However, even if the pulling speed of the porous glass base material is kept constant, if dehydration and sintering are performed using a quartz glass furnace core tube, The relative refractive index difference (△
Since n) has different values, there is a problem that it is difficult to obtain an optical fiber base material in which the relative refractive index difference (Δn) is uniform among lots.
【０００６】[0006]
【課題を解決するための手段】本発明はこのような不利
を解決したシングルモ−ド光ファイバ用母材の製造方法
に関するもので、これはゲルマニウムド−プしたガラス
微粒子をタ−ゲット基材に堆積し、これを軸方向に引上
げて多孔質ガラス母材を作り、これを石英ガラス製炉芯
管を用いて高温で脱水、焼結してなる光ファイバ用母材
の製造方法において、多孔質ガラス母材の脱水処理工程
における該石英ガラス製炉芯管の加熱ヒ−タ−の温度を
該石英ガラス製炉芯管の使用回数に応じて制御して加熱
ゾ−ンの温度を一定に保つことを特徴とするものである
。[Means for Solving the Problems] The present invention relates to a method for manufacturing a single mode optical fiber base material that overcomes these disadvantages. In the method for producing an optical fiber base material, the porous glass base material is produced by pulling it in the axial direction, which is then dehydrated and sintered at high temperature using a quartz glass furnace core tube. The temperature of the heater for the quartz glass furnace core tube in the dehydration treatment process of the glass base material is controlled according to the number of times the quartz glass furnace core tube is used to keep the temperature of the heating zone constant. It is characterized by this.
【０００７】すなわち、本発明者らはロット間での比屈
折率差（△ｎ）が一定であるシングルモ−ド光ファイバ
用母材の製造方法について種々検討した結果、ＶＡＤ
法で製られたゲルマニウムド−プされた多孔質ガラス母
材の屈折率が脱水、焼結工程における脱水処理温度に依
存し、この脱水処理温度の下降と共に上昇するというこ
と、またこの脱水、焼結工程を行なう石英ガラス製炉芯
管についてはその加熱ヒ−タ−の温度が使用回数の増加
と共に低下することを見出し、この加熱ゾ−ンの温度を
一定にするためにはこの石英ガラス製炉芯管の加熱ヒ−
タ−の温度をこの炉芯管の使用回数に応じて制御すれば
よいということを確認して本発明を完成させた。以下に
これをさらに詳述する。[0007] In other words, as a result of various studies on the method of manufacturing a base material for a single mode optical fiber in which the relative refractive index difference (△n) is constant between lots, the inventors found that VAD
The refractive index of the germanium-doped porous glass base material produced by this method depends on the dehydration temperature in the dehydration and sintering processes, and increases as the dehydration temperature decreases. It has been discovered that the temperature of the quartz glass furnace core tube used in the silica heating process decreases as the number of times it is used increases, and in order to keep the temperature of this heating zone constant, Furnace core tube heating
The present invention was completed by confirming that the temperature of the furnace can be controlled according to the number of times the furnace core tube is used. This will be explained in further detail below.
【０００８】[0008]
【作用】本発明は比屈折率差（△ｎ）がロット間で均一
とされたシングルモ−ド光ファイバ−用母材の製造方法
に関するものである。The present invention relates to a method of manufacturing a base material for single mode optical fiber in which the relative refractive index difference (Δn) is made uniform from lot to lot.
【０００９】本発明による光ファイバ−用母材の製造は
基本的には公知のＶＡＤ 法で行なわれる。したがって
、これは一本のコア用酸水素火炎バ−ナ−と複数個のク
ラッド用酸水素火炎バ−ナ−を用いて、このコア用酸水
素火炎バ−ナ−に四塩化けい素とド−プ剤としての四塩
化ゲルマニウムからなる原料ガスと酸素ガス、水素ガス
を導入し、四塩化けい素と四塩化ゲルマニウムの火炎加
水分解で発生した酸化ゲルマニウムでド−プされたシリ
カガラス微粒子をタ−ゲット基材上に堆積させて軸方向
にコア部を成長させ、クラッド用酸水素火炎バ−ナ−に
四塩化けい素、酸素ガス、水素ガスを供給して四塩化け
い素の火炎加水分解で発生したシリカガラス微粒子をこ
のコア部上に堆積成長させクラッド部を形成させて多孔
質ガラス母材を作り、ついてこれを石英ガラス製炉芯管
を用いて脱水、焼結させればよい。The production of the optical fiber preform according to the present invention is basically carried out by the known VAD method. Therefore, this method uses one oxyhydrogen flame burner for the core and a plurality of oxyhydrogen flame burners for the cladding. - A raw material gas consisting of germanium tetrachloride as a propagating agent, oxygen gas, and hydrogen gas are introduced, and silica glass fine particles doped with germanium oxide generated by flame hydrolysis of silicon tetrachloride and germanium tetrachloride are heated. - Deposit on the target substrate to grow the core part in the axial direction, and supply silicon tetrachloride, oxygen gas, and hydrogen gas to an oxyhydrogen flame burner for cladding to flame hydrolyze silicon tetrachloride. The silica glass particles generated in step 1 are deposited and grown on this core portion to form a cladding portion to form a porous glass base material, which is then dehydrated and sintered using a quartz glass furnace core tube.
【００１０】しかし、この場合多孔質ガラス母材の脱水
、焼結によって得られる光ファイバ用母材の比屈折率差
（△ｎ）とロット間との相関についてしらべたところ、
この多孔質ガラス母材の脱水、処理工程は従来一般に
Ｃｌ２、 Ｆ２などのハロゲンガスの存在下で行なわれ
るのであるが、これを例えば Ｃｌ２ガスの存在下で行
なうとド−プ剤としての酸化ゲルマニウム（ＧｅＯ２）
が Ｃｌ２と反応して揮発性の ＧｅＣｌ４となって揮
発するので比屈折率差（△ｎ）が低下するようになるの
であるが、この反応がこの反応温度に依存するものであ
るためにこの加熱ゾ−ンの温度が低下すると ＧｅＣｌ
４の発生が抑えられて母材中の結晶性ＧｅＯ２が徐々に
増加し、比屈折率差（△ｎ）が上昇するので、この比屈
折率差（△ｎ）を均一にするためには脱水処理工程にお
いて加熱ゾ−ンの温度を一定にすればよいということが
見出された。However, in this case, when we investigated the correlation between lots and the relative refractive index difference (Δn) of the optical fiber base material obtained by dehydrating and sintering the porous glass base material, we found that
The dehydration and treatment process for this porous glass base material has traditionally been
This is carried out in the presence of halogen gas such as Cl2, F2, etc. If this is carried out in the presence of Cl2 gas, for example, germanium oxide (GeO2) as a dopant will be removed.
reacts with Cl2 to form volatile GeCl4 and evaporate, resulting in a decrease in the relative refractive index difference (△n), but since this reaction depends on the reaction temperature, this heating When the temperature of the zone decreases, GeCl
4 is suppressed, crystalline GeO2 in the base metal gradually increases, and the relative refractive index difference (△n) increases. Therefore, in order to make this relative refractive index difference (△n) uniform, dehydration It has been found that it is sufficient to maintain a constant temperature in the heating zone during the treatment process.
【００１１】他方、この多孔質ガラス母材の脱水処理工
程は石英ガラス製炉芯管を用いて行なわれるのであるが
、この石英ガラス製炉芯管についてはこれを使用してい
ると石英ガラスの失透が徐々に進み、この失透が進むに
したがってこれに比例して輻射熱の放射量が徐々に落ち
、加熱ゾ−ンの温度が徐々に低下するために、炉芯管に
供給する電力を一定にして多孔質ガラス母材を複数個脱
水処理し焼結すると、このようにして得られた光ファイ
バ用母材の比屈折率差（△ｎ）は加熱ゾ−ンの温度が徐
々に低下するために各ロット間では図２に示したように
ロット毎に徐々に上昇し、一定にならないということが
見出された。On the other hand, this dehydration process of the porous glass base material is carried out using a quartz glass furnace core tube. Devitrification progresses gradually, and as this devitrification progresses, the amount of radiant heat gradually decreases in proportion to this, and the temperature of the heating zone gradually decreases, so the power supplied to the furnace core tube is reduced. When a plurality of porous glass preforms are dehydrated and sintered at a constant temperature, the relative refractive index difference (△n) of the optical fiber preforms thus obtained gradually decreases as the temperature of the heating zone gradually decreases. It has been found that, as shown in FIG. 2, the temperature increases gradually from lot to lot and does not remain constant.
【００１２】したがって、各ロット間における光ファイ
バ用母材の比屈折率差（△ｎ）を均一にするためには加
熱ゾ−ンの温度を一定にする必要があるが、これには石
英ガラス製炉芯管での石英ガラスの失透による輻射熱の
放射量の減少があるので、これについてはこの失透化度
に比例して徐々に加熱ヒ−タ−に供給する電力を例えば
炉内温度を１，１００ ℃と一定にするときには図３に
示したようにロット数の増加と共に徐々に上昇させれば
、これを所定の一定温度に保つことができ、得られる光
ファイバ用母材の比屈折率差（△ｎ）をロット間で均一
にすることができることが確認されたので、この加熱ゾ
−ンの温度を一定にするためにはここに使用する石英ガ
ラス製炉芯管の使用回数に応じて加熱ヒ−タ−の温度を
制御すること、換言すれば加熱ヒ−タ−給する電力を製
炉芯管の使用回数に応じて徐々に増加させればよい。Therefore, in order to make the relative refractive index difference (△n) of the optical fiber base material uniform between lots, it is necessary to keep the temperature of the heating zone constant. Since the amount of radiant heat decreases due to the devitrification of the quartz glass in the furnace core tube, the power supplied to the heater is gradually increased in proportion to the degree of devitrification, for example, by increasing the furnace temperature. When keeping the temperature constant at 1,100 °C, if the temperature is gradually increased as the number of lots increases as shown in Figure 3, this can be maintained at a predetermined constant temperature, and the ratio of the resulting optical fiber base material can be reduced. It has been confirmed that the refractive index difference (△n) can be made uniform between lots, so in order to keep the temperature of this heating zone constant, it is necessary to use the quartz glass furnace core tube used here several times. In other words, the electric power supplied to the heater may be gradually increased in accordance with the number of times the furnace core tube is used.
【００１３】なお、本発明により光ファイバ用母材を得
るために多孔質ガラス母材を脱水処理するための加熱ゾ
−ンの温度はを８００〜１，４００ ℃の範囲で一定温
度に保持すればロット間での比屈折率差（△ｎ）の変動
を少なくすることができる。[0013] According to the present invention, the temperature of the heating zone for dehydrating the porous glass base material to obtain the optical fiber base material must be maintained at a constant temperature in the range of 800 to 1,400°C. This makes it possible to reduce variations in the relative refractive index difference (Δn) between lots.
【００１４】[0014]
【実施例】つぎに本発明の実施例、比較例を示す。
実施例、比較例
コア用バ−ナ−に四塩化けい素３０ｃｃ／分、四塩化ゲ
ルマニウム ３．５ｃｃ／分、酸素ガス３．０ リット
ル／分、水素ガス１．０ リットル／分を供給すると共
に、クラッド用バ−ナ−に四塩化けい素 ４００ｃｃ／
分、酸素ガス１０リットル／分、水素ガス８リットル／
分を供給し、この火炎加水分解で発生した酸化ゲルマニ
ウムでド−プされたコア用ガラス微粒子および酸化ゲル
マニウムを含まないクラッド用ガラス微粒子を基材の先
に設置した２０ｒｐｍ で回転している合成石英ガラス
棒に堆積し、その軸方向に成長させてコア部、クラッド
部からなる多孔質ガラス母材を作り、軸方向にこの多孔
質ガラス母材を引上げ装置を用いて０．６５±０．００
５ｍｍ／分の一定速度で引上げて、外径 １００ｍｍ、
長さ８００ｍｍ の多孔質ガラス母材を作った。[Examples] Next, examples of the present invention and comparative examples will be shown. Examples and Comparative Examples 30 cc/min of silicon tetrachloride, 3.5 cc/min of germanium tetrachloride, 3.0 liter/min of oxygen gas, and 1.0 liter/min of hydrogen gas were supplied to the core burner. , 400cc/silicon tetrachloride in the cladding burner
minutes, oxygen gas 10 liters/minute, hydrogen gas 8 liters/minute
Glass particles for the core doped with germanium oxide generated by this flame hydrolysis and glass particles for the cladding that do not contain germanium oxide were placed at the tip of the base material, and synthetic quartz was rotated at 20 rpm. It is deposited on a glass rod and grown in the axial direction to create a porous glass base material consisting of a core part and a cladding part, and the porous glass base material is pulled up in the axial direction using a pulling device to 0.65 ± 0.00.
Pull it up at a constant speed of 5 mm/min to an outer diameter of 100 mm.
A porous glass base material with a length of 800 mm was made.
【００１５】ついで、これを Ｃｌ２ガスを１０容量％
含有するＨｅガス雰囲気中において長さ２，０００ ｍ
ｍの石英ガラス製炉管を用い、この加熱ヒ−タ−に供給
する電力をロット毎に図３に示したように徐々に上昇さ
せて加熱ゾ−ンの温度を１，１００ ℃±１ ℃に保つ
ようにして脱水処理し、１，６００ ℃で焼結して外径
４０ｍｍ、長さ４００ｍｍ のシングルモ−ド光ファイ
バ用母材を作り、このもののロット毎に比屈折率差（△
ｎ）をしらべたところ、図１に示したように略々均一で
あることが確認された。[0015] Then, add 10% by volume of Cl2 gas to this
Length 2,000 m in He gas atmosphere containing
Using a quartz glass furnace tube of 500 m in diameter, the temperature of the heating zone was raised to 1,100°C ± 1°C by gradually increasing the power supplied to the heater for each lot as shown in Figure 3. The material was dehydrated at a temperature of
n), it was confirmed that it was substantially uniform as shown in FIG.
【００１６】しかし、比較のために上記における加熱ヒ
−タ−に供給される電力を各ロットごとに変えずに一定
にしたところ、この場合にはロット数の増加と共に光フ
ァイバ用母材の屈折率分布が増加し、両者の関係は図２
に示したとおりのものとなった。However, for comparison, when the power supplied to the heater in the above was kept constant for each lot, the refraction of the optical fiber base material increased as the number of lots increased. The rate distribution increases, and the relationship between the two is shown in Figure 2.
The results were as shown in the figure.
【００１７】[0017]
【発明の効果】本発明はロット間において長手方向の比
屈折率差（△ｎ）が安定しているシングルモ−ド光ファ
イバ用多孔質ガラス母材の製造方法に関するもので、こ
れは前記したように公知のＶＡＤ 法で多孔質ガラス母
材を作り、ついでこれを石英ガラス製炉芯管を用いて高
温で脱水、焼結してなる光ファイバ用母材の製造方法に
おいて、多孔質ガラス母材の脱水処理工程における該石
英ガラス製炉芯管の加熱ヒ−タ−の温度を該石英ガラス
製炉芯管の使用回数に応じて制御して加熱ゾ−ンの温度
を一定に保つことを特徴とするものであり、これによれ
ば使用回数の増加に伴なって発生する石英ガラス製炉芯
管の石英ガラスの失透に伴なう輻射熱の放射量減少が炉
芯管に供給される電力の増加によって補償されるので、
加熱ゾ−ンの温度が一定となり、 ＧｅＣｌ４の揮発
量も一定となって得られる光ファイバ用母材の比屈折率
差（△ｎ）がロット間で変動せず、均一なものになると
いう有利性が与えられる。[Effects of the Invention] The present invention relates to a method for manufacturing a porous glass base material for a single mode optical fiber in which the relative refractive index difference (△n) in the longitudinal direction is stable between lots. In a method for manufacturing an optical fiber base material, a porous glass base material is produced by a VAD method known in the art, and then dehydrated and sintered at high temperature using a quartz glass furnace core tube. The temperature of the heater for the quartz glass furnace core tube in the dehydration process is controlled according to the number of times the quartz glass furnace core tube is used to keep the temperature of the heating zone constant. According to this, the decrease in the amount of radiant heat due to devitrification of the quartz glass of the quartz glass furnace core tube that occurs as the number of times it is used increases, and the electric power supplied to the furnace core tube decreases. is compensated by an increase in
The temperature of the heating zone is constant, and the amount of GeCl4 volatilized is also constant, which has the advantage that the relative refractive index difference (△n) of the optical fiber base material does not vary from lot to lot and becomes uniform. gender is given.
【図１】本発明により得られたシングルモ−ド光ファイ
バ−用母材のロット数と屈折率（△ｎ）との相関グラフ
である。FIG. 1 is a correlation graph between the lot number and refractive index (Δn) of a single-mode optical fiber preform obtained according to the present invention.
【図２】比較例で作られたシングルモ−ド光ファイバ−
用母材のロット数と屈折率（△ｎ）との相関グラフであ
る。[Figure 2] Single mode optical fiber made as a comparative example
It is a correlation graph between the lot number of the base material for use and the refractive index (Δn).
【図３】ロット数と石英ガラス製炉芯管に供給するヒ−
タ−電力（ｋｗ）との相関グラフである。[Figure 3] Number of lots and heat supplied to the quartz glass furnace core tube
It is a correlation graph with tar power (kw).
Claims (1)
−ゲット基材上に堆積し、これを軸方向に引上げて多孔
質ガラス母材を作り、これを石英ガラス製炉芯管を用い
て高温で脱水、焼結してなる光ファイバ用母材の製造方
法において、多孔質ガラス母材の脱水処理工程における
該石英ガラス製炉芯管の加熱ヒ−タ−の温度を該石英ガ
ラス製炉芯管の使用回数に応じて制御して加熱ゾ−ンの
温度を一定に保つことを特徴とするシングルモ−ド光フ
ァイバ用母材の製造方法。Claim 1: Depositing germanium-doped glass particles on a target base material, pulling this up in the axial direction to create a porous glass base material, and using a quartz glass furnace core tube to heat the porous glass base material at high temperature. In the method for producing an optical fiber preform by dehydrating and sintering the porous glass preform, the temperature of the heater of the quartz glass furnace core tube in the dehydration treatment step of the porous glass preform is adjusted to the temperature of the heater of the quartz glass furnace core. A method for manufacturing a base material for a single mode optical fiber, characterized in that the temperature of a heating zone is kept constant by controlling it according to the number of times the tube is used.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8309991A JP3071235B2 (en) | 1991-03-22 | 1991-03-22 | Method of manufacturing preform for single mode optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8309991A JP3071235B2 (en) | 1991-03-22 | 1991-03-22 | Method of manufacturing preform for single mode optical fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04295026A true JPH04295026A (en) | 1992-10-20 |
| JP3071235B2 JP3071235B2 (en) | 2000-07-31 |
Family
ID=13792744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8309991A Expired - Lifetime JP3071235B2 (en) | 1991-03-22 | 1991-03-22 | Method of manufacturing preform for single mode optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3071235B2 (en) |
-
1991
- 1991-03-22 JP JP8309991A patent/JP3071235B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP3071235B2 (en) | 2000-07-31 |
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