CA1241240A - Method for producing optical fiber preform - Google Patents
Method for producing optical fiber preformInfo
- Publication number
- CA1241240A CA1241240A CA000469884A CA469884A CA1241240A CA 1241240 A CA1241240 A CA 1241240A CA 000469884 A CA000469884 A CA 000469884A CA 469884 A CA469884 A CA 469884A CA 1241240 A CA1241240 A CA 1241240A
- Authority
- CA
- Canada
- Prior art keywords
- nozzle
- optical fiber
- glass
- fiber preform
- fluorine
- 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
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 46
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 52
- 239000011737 fluorine Substances 0.000 claims abstract description 52
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000000463 material Substances 0.000 claims abstract description 35
- 239000002994 raw material Substances 0.000 claims abstract description 29
- 239000011521 glass Substances 0.000 claims abstract description 28
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910001882 dioxygen Inorganic materials 0.000 claims abstract description 27
- 239000002245 particle Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000007789 gas Substances 0.000 claims abstract description 14
- 238000000151 deposition Methods 0.000 claims abstract description 10
- 230000003301 hydrolyzing effect Effects 0.000 claims abstract description 7
- 238000007496 glass forming Methods 0.000 claims description 25
- 239000004071 soot Substances 0.000 claims description 20
- WMIYKQLTONQJES-UHFFFAOYSA-N hexafluoroethane Chemical compound FC(F)(F)C(F)(F)F WMIYKQLTONQJES-UHFFFAOYSA-N 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 4
- PXBRQCKWGAHEHS-UHFFFAOYSA-N dichlorodifluoromethane Chemical compound FC(F)(Cl)Cl PXBRQCKWGAHEHS-UHFFFAOYSA-N 0.000 claims description 3
- 235000019404 dichlorodifluoromethane Nutrition 0.000 claims description 3
- 239000000075 oxide glass Substances 0.000 claims description 2
- 229910004014 SiF4 Inorganic materials 0.000 claims 2
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 claims 2
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 claims 2
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 claims 2
- 239000000203 mixture Substances 0.000 claims 1
- 238000010348 incorporation Methods 0.000 abstract 1
- 238000002474 experimental method Methods 0.000 description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 241000282421 Canidae Species 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000003190 augmentative effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Landscapes
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Abstract:
The invention provides a method for producing an optical fiber preform containing fluorine. The method comprises injecting a glass raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, an inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydrolyzing the glass raw material to synthesize fine glass particles and depositing the fine glass particles on a tip of a rotating seed rod. This method allows effective incorporation of fluorine into the preform.
The invention provides a method for producing an optical fiber preform containing fluorine. The method comprises injecting a glass raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, an inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydrolyzing the glass raw material to synthesize fine glass particles and depositing the fine glass particles on a tip of a rotating seed rod. This method allows effective incorporation of fluorine into the preform.
Description
- ` ~2~2~
Method for producing optical fiber preform The present invention relates to a method for producing an optical fiber preform. More particularly, it relates to a method for producing an optical fiber preform containing fluorine.
The presence of fluorine in a silica glass lowers its refractive index and makes it possible to produce optical fibers having various refractive index distributions and improved light transmission characteristics. For example, it is possible to produce an optical fiber having a large no-fraetive index difference between the core and the cladding and thus a large aperture number and an optical fiber comprising a core made of pure silica glass and having improved resistance against radiation.
Several methods are known for producing a silica glass type optical fiber preform containing fluorine. These methods include a modified chemical vapor deposition (MCVD) method and a plasma outside vapor deposition (POND) method.
Generally, only about 10 Km of an optical fiber can be drawn from a preform produced by these methods. Further, since the production rates of these methods are low, they are not suitable for mass production of the optical fiber preform and thus the optical fiber.
The vapor phase axial deposition method (hereinafter :, I
~29~1~413 referred to as "VAT" method) can provide an optical fiber preform from which an optical fiber of longer length can be drawn. However, optical fiber preforms containing fluorine are rarely produced by the VAT method, since if a fluorine-containing material is simply mixed with gaseous Seiko, which is a raw material of ion many drawbacks arise, i.e., the fluorine is not effectively added to the silica glass, the produced preform tends to crack and the deposition rate of glass soot particles is reduced.
One object of the present invention is to provide an optical fiber preform, particularly a porous optical fiber preform, containing fluorine.
Another object of the present invention is to provide a method for producing an optical fiber preform containing fluorine by the VAT method.
According to one aspect of the invention there is provided a method for producing an optical fiber preform comprising injecting a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, an inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydra-lying the glass-forming raw material to synthesize glass soot particles and depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform it formed and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
According to another aspect of the invention there is provided a method for producing an optical fiber preform comprising injecting at least one member selected from the group consisting of a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, the remaining member of the group and optionally at least one material which is injected from the first nozzle from a second nozzle which surrounds the first nozzle, an inactive gas from a third nozzle which surrounds the second . , .
I
nozzle and hydrogen gas from a fourth nozzle which sun-rounds the third nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
According to a further aspect of the invention there is provided a method for producing an optical fiber preform comprising the steps of: injecting an oxide glass-forming raw material and oxygen gas from a primary nozzle, a gaseous fluorine-containing material and oxygen gas from a first nozzle which surrounds said primary nozzle or is surrounded by said primary nozzle, inert gas from a second nozzle which surrounds said first nozzle and said primary nozzle, and hydrogen gas from a third nozzle which sun-rounds said second nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is former, and fusing the optical fiber preform to produce an oxide glass optical fiber preform containing fluorine.
Preferred embodiments of the invention are described in the following with reference to the accompanying drawings, in which:
Fig. 1 is a schematic view illustrating the VAT method;
and Figs. 2 to 5 show examples of the layout of the nozzles of a burner used in the method of the invention.
In the present invention, the fluorine-containing material is preferably selected from gaseous fluorinated compounds which are readily available. The fluorine-containing material is injected together with a gaseous glass-forming raw material (erg. Seiko, Jackal, etc.), hydrogen gas, oxygen gas and an inactive gas from a multi-nozzle burner (hereinafter referred to as "burner") for synthesizing glass soot particles, and the materials ..~,,~
I
- pa -are flame hydrolyzed in an oxy-hydrogen flame to produce a porous preform containing fluorine.
The first characteristic of the invention resides in that the injection mode of the gaseous materials from the burner is arranged so that the glass soot particles are synthesized in the flame under high oxygen partial pros-sure. The second characteristic of the invention resides in that, in some injecting modes, the fluorine-containing material and the glass-forming raw materials can be separately injected from the burner.
It has been found that when the glass soot particles are synthesized under high oxygen partial pressure, the fluorine-containing material is thoroughly decomposed and a sufficient quantity of glass soot particles are Cynthia-sized and, further, fluorine is effectively incorporated into the produced preform.
If the oxygen partial pressure is reduced by decreasing the flow rate of oxygen gas, component atoms of the fluorine-containing material, such as carbon atoms, are not completely oxidized during the decomposition of the fluorine-containing material and tend to deposit on the porous preform. In addition, the synthesizing rate of the glass soot particles is decreased.
t Lo Lo The characteristics mentioned above are shown by the following experiments.
Preforms were produced according to a generally conventional VAT method illustrated in Fig. 1 in which numeral 1 denotes a produced preform and numeral 2 denotes a burner.
However, the burner employed was a four-nozzle burner, the cross section of which is shown in Fig. 2. CC12F2 is used as the fluorine-containing material. Preforms were produced under various conditions as follows:
Experiment No. 1 First nozzle: Seiko, 250 ml/sec.
CC12F2, 250 ml/sec.
Second nozzle: Ho, 4,000 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: 2' 6,400 ml/sec.
Experiment No 2 First nozzle: Seiko, 250 ml/sec.
CC12F2, 83 ml/sec.
Second nozzle: Ho, 4,000 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: 2' 8,000 ml/sec.
Experiment No. 3 First nozzle: Seiko, 250 ml/see.
CC12F2, 125 ml/see-Second nozzle: Ho, 4,000 ml/see.
Third nozzle: No, 1,500 ml/see.
Fourth nozzle: 2' 8,000 ml/sec.
Experiment No. 4 -First nozzle: Seiko, 250 ml/sec.
CC12F2, 250 ml/sec-
Method for producing optical fiber preform The present invention relates to a method for producing an optical fiber preform. More particularly, it relates to a method for producing an optical fiber preform containing fluorine.
The presence of fluorine in a silica glass lowers its refractive index and makes it possible to produce optical fibers having various refractive index distributions and improved light transmission characteristics. For example, it is possible to produce an optical fiber having a large no-fraetive index difference between the core and the cladding and thus a large aperture number and an optical fiber comprising a core made of pure silica glass and having improved resistance against radiation.
Several methods are known for producing a silica glass type optical fiber preform containing fluorine. These methods include a modified chemical vapor deposition (MCVD) method and a plasma outside vapor deposition (POND) method.
Generally, only about 10 Km of an optical fiber can be drawn from a preform produced by these methods. Further, since the production rates of these methods are low, they are not suitable for mass production of the optical fiber preform and thus the optical fiber.
The vapor phase axial deposition method (hereinafter :, I
~29~1~413 referred to as "VAT" method) can provide an optical fiber preform from which an optical fiber of longer length can be drawn. However, optical fiber preforms containing fluorine are rarely produced by the VAT method, since if a fluorine-containing material is simply mixed with gaseous Seiko, which is a raw material of ion many drawbacks arise, i.e., the fluorine is not effectively added to the silica glass, the produced preform tends to crack and the deposition rate of glass soot particles is reduced.
One object of the present invention is to provide an optical fiber preform, particularly a porous optical fiber preform, containing fluorine.
Another object of the present invention is to provide a method for producing an optical fiber preform containing fluorine by the VAT method.
According to one aspect of the invention there is provided a method for producing an optical fiber preform comprising injecting a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, an inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydra-lying the glass-forming raw material to synthesize glass soot particles and depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform it formed and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
According to another aspect of the invention there is provided a method for producing an optical fiber preform comprising injecting at least one member selected from the group consisting of a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, the remaining member of the group and optionally at least one material which is injected from the first nozzle from a second nozzle which surrounds the first nozzle, an inactive gas from a third nozzle which surrounds the second . , .
I
nozzle and hydrogen gas from a fourth nozzle which sun-rounds the third nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
According to a further aspect of the invention there is provided a method for producing an optical fiber preform comprising the steps of: injecting an oxide glass-forming raw material and oxygen gas from a primary nozzle, a gaseous fluorine-containing material and oxygen gas from a first nozzle which surrounds said primary nozzle or is surrounded by said primary nozzle, inert gas from a second nozzle which surrounds said first nozzle and said primary nozzle, and hydrogen gas from a third nozzle which sun-rounds said second nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is former, and fusing the optical fiber preform to produce an oxide glass optical fiber preform containing fluorine.
Preferred embodiments of the invention are described in the following with reference to the accompanying drawings, in which:
Fig. 1 is a schematic view illustrating the VAT method;
and Figs. 2 to 5 show examples of the layout of the nozzles of a burner used in the method of the invention.
In the present invention, the fluorine-containing material is preferably selected from gaseous fluorinated compounds which are readily available. The fluorine-containing material is injected together with a gaseous glass-forming raw material (erg. Seiko, Jackal, etc.), hydrogen gas, oxygen gas and an inactive gas from a multi-nozzle burner (hereinafter referred to as "burner") for synthesizing glass soot particles, and the materials ..~,,~
I
- pa -are flame hydrolyzed in an oxy-hydrogen flame to produce a porous preform containing fluorine.
The first characteristic of the invention resides in that the injection mode of the gaseous materials from the burner is arranged so that the glass soot particles are synthesized in the flame under high oxygen partial pros-sure. The second characteristic of the invention resides in that, in some injecting modes, the fluorine-containing material and the glass-forming raw materials can be separately injected from the burner.
It has been found that when the glass soot particles are synthesized under high oxygen partial pressure, the fluorine-containing material is thoroughly decomposed and a sufficient quantity of glass soot particles are Cynthia-sized and, further, fluorine is effectively incorporated into the produced preform.
If the oxygen partial pressure is reduced by decreasing the flow rate of oxygen gas, component atoms of the fluorine-containing material, such as carbon atoms, are not completely oxidized during the decomposition of the fluorine-containing material and tend to deposit on the porous preform. In addition, the synthesizing rate of the glass soot particles is decreased.
t Lo Lo The characteristics mentioned above are shown by the following experiments.
Preforms were produced according to a generally conventional VAT method illustrated in Fig. 1 in which numeral 1 denotes a produced preform and numeral 2 denotes a burner.
However, the burner employed was a four-nozzle burner, the cross section of which is shown in Fig. 2. CC12F2 is used as the fluorine-containing material. Preforms were produced under various conditions as follows:
Experiment No. 1 First nozzle: Seiko, 250 ml/sec.
CC12F2, 250 ml/sec.
Second nozzle: Ho, 4,000 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: 2' 6,400 ml/sec.
Experiment No 2 First nozzle: Seiko, 250 ml/sec.
CC12F2, 83 ml/sec.
Second nozzle: Ho, 4,000 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: 2' 8,000 ml/sec.
Experiment No. 3 First nozzle: Seiko, 250 ml/see.
CC12F2, 125 ml/see-Second nozzle: Ho, 4,000 ml/see.
Third nozzle: No, 1,500 ml/see.
Fourth nozzle: 2' 8,000 ml/sec.
Experiment No. 4 -First nozzle: Seiko, 250 ml/sec.
CC12F2, 250 ml/sec-
2' 200 ml/sec.
Second nozzle: 2' 1,800 ml/sec.
Third nozzle: No, 1,500 ml/see.
Fourth nozzle: Ho, 4,000 ml/sec.
which ratios are shown in Table 1. The thus produced porous preforms were sistered to convert them to a transparent pro-form by a per _ conventional method at a temperature of 1,600C
~l2~2~
in a stream of helium at a flow rate of 5 liters/min.
( The refractive indices of the transparent preforms were measured.
The layout of the nozzles is shown in Fig. 2, in which nozzle 3 it for Seiko and CC12F2, nozzle 3' is for Seiko, CC12F2 and oxygen gas, nozzle 4 is for hydrogen gas, nozzle 5 is for an inactive gas and nozzle 6 is for oxygen gas.
Table 1 Exp. ¦ Layout 2 flow rate CC12F2 flow rate refractive 10 No, of _ index nozzles Ho flow rate Suckle flow rate difference 1 [I] 1.6 1.0 -0.09 2 [I] 2.0 0.33 -0.075
Second nozzle: 2' 1,800 ml/sec.
Third nozzle: No, 1,500 ml/see.
Fourth nozzle: Ho, 4,000 ml/sec.
which ratios are shown in Table 1. The thus produced porous preforms were sistered to convert them to a transparent pro-form by a per _ conventional method at a temperature of 1,600C
~l2~2~
in a stream of helium at a flow rate of 5 liters/min.
( The refractive indices of the transparent preforms were measured.
The layout of the nozzles is shown in Fig. 2, in which nozzle 3 it for Seiko and CC12F2, nozzle 3' is for Seiko, CC12F2 and oxygen gas, nozzle 4 is for hydrogen gas, nozzle 5 is for an inactive gas and nozzle 6 is for oxygen gas.
Table 1 Exp. ¦ Layout 2 flow rate CC12F2 flow rate refractive 10 No, of _ index nozzles Ho flow rate Suckle flow rate difference 1 [I] 1.6 1.0 -0.09 2 [I] 2.0 0.33 -0.075
3 [I] 2.0 0.5 -0.09 15 4 ¦ [II¦ 0.5 1.0 -0.13 The refractive index differences shown in Table 1 indicate the following:
Comparing the result of Experiment No. 1, in which the flow rate of oxygen gas was low and the flow rate of CC12F2 was high, and that of Experiment No. 3, in which the flow rate of oxygen gas was high and the flow raze of CC12F2 was low, substantially the same amount of fluorine was added and it is concluded that when the flow rate of oxygen gas is high, fluorine is effectively added even at a low flow rate of CC12F2. Comparing the results of Experiment Nos. 1 and 4 in which the flow rate of CC12F2 is the same but the layout of the nozzles is different, more fluorine is added in Export-mint No. 4 than in Experiment No. 1. These results clearly indicate that it is advantageous to synthesize glass 500t particles by flame hydrolysis under high oxygen partial pressure in order to add fluorine effectively. When the glass-forming raw materials and oxygen gas were injected from adjacent nozzles as in the layout [II] in Fig. 2 or from the same .
I
nozzle, f fluorine was more effectively added. When the nozzle for hydrogen gas and the nozzle for oxygen gas are adjacently arranged, an oxyhydrogen flame is formed very close to the exits of the nozzles so that the tips of the nozzles tend to be heated to a very high temperature and adversely affected.
In order to prevent such deterioration of the nozzles, the nozzle for inactive gas is preferably positioned between the above two nozzles.
By separately injecting the glass-forming raw materials and the fluorine-containing material, the deposition rate of the glass soot particles is greatly improved, which is clear from the results shown in Table 2.
Table 2 Exp. No. Layout of Refractive Ratio of deposition rate nozzles index of fine glass particles difference
Comparing the result of Experiment No. 1, in which the flow rate of oxygen gas was low and the flow rate of CC12F2 was high, and that of Experiment No. 3, in which the flow rate of oxygen gas was high and the flow raze of CC12F2 was low, substantially the same amount of fluorine was added and it is concluded that when the flow rate of oxygen gas is high, fluorine is effectively added even at a low flow rate of CC12F2. Comparing the results of Experiment Nos. 1 and 4 in which the flow rate of CC12F2 is the same but the layout of the nozzles is different, more fluorine is added in Export-mint No. 4 than in Experiment No. 1. These results clearly indicate that it is advantageous to synthesize glass 500t particles by flame hydrolysis under high oxygen partial pressure in order to add fluorine effectively. When the glass-forming raw materials and oxygen gas were injected from adjacent nozzles as in the layout [II] in Fig. 2 or from the same .
I
nozzle, f fluorine was more effectively added. When the nozzle for hydrogen gas and the nozzle for oxygen gas are adjacently arranged, an oxyhydrogen flame is formed very close to the exits of the nozzles so that the tips of the nozzles tend to be heated to a very high temperature and adversely affected.
In order to prevent such deterioration of the nozzles, the nozzle for inactive gas is preferably positioned between the above two nozzles.
By separately injecting the glass-forming raw materials and the fluorine-containing material, the deposition rate of the glass soot particles is greatly improved, which is clear from the results shown in Table 2.
Table 2 Exp. No. Layout of Refractive Ratio of deposition rate nozzles index of fine glass particles difference
4 [II] -0.13 1.0 [III] -0.13 OWE
In the layout [III] of the nozzles in Fig. 2, nozzle 3" is for Seiko and oxygen gas and nozzle 6' is for CC12F2 and oxygen gas. In Experiment 5, the flow rates of the gases were as follows:
First nozzle: Seiko, 250 ml/sec.
2' 200 ml/sec.
Second nozzle: 2' 1,800 ml/sec.
CC12F2, 250 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: Ho, 4,000 ml/sec.
These results may be attributed to the fact that 30 when Seiko and CC12F2 are injected simultaneously, the formation of Sue nuclei is restricted by the formation of Sift and the like, while when they are separately injected, the Sue nuclei are advantageously formed so that the deposition of a solid phase is facilitated.
In order to synthesize the glass soot particles at higher oxygen partial pressure under the above described conditions, the layout of the nozzles as shown in Fig. 3 may preferably be used. The multi-nozzle burner of Fig. 3 has a center nozzle 7 for the glass-forming raw material, the fluorine containing material and oxygen gas, a nozzle 8 for an inactive gas which surrounds the nozzle 7 and a nozzle 9 for hydrogen gas which surrounds the nozzle 8.
A burner shown in Fig. 4 is a modification of the burner of Fig. 3, in which the central nozzle 7 is divided into two, namely a nozzle 7' for at least one of the glass raw material, the fluorine-containing material and oxygen gas and a nozzle 7" for the remainder and optionally at least one material which is injected from the first nozzle. The nozzles 7' and 7" are surrounded by the nozzle 8 and further the nozzle 9 as in Fig. 3. By increasing the number of nozzles for the glass-forming raw material and oxygen gas, it is possible to produce a stable porous preform since the synthesis of the glass soot particles and their flow rate, as well as the distribution of their spatial concentration, can be controlled In addition to the burners of Figs. 3 and 4, the burner of Fig. 2 [III] is preferred.
When hydrogen gas is injected from the outermost nozzle, the flame is not sufficiently concentrated and, under some conditions, the porous preform is not effectively heated so that a preform having a low bulk density is produced which may result in cracking and/or runaway of the produced porous preform. In addition, the fluctuation of the flame is augmented so that a stable porous preform is not produced. In such cases, a nozzle 10 for inactive gas can be provided around the nozzle 9 as shown in Fig. 5 in order to improve the concentration of the flame and to diminish the fluctuation of the flame.
Specific examples of the fluorine-containing material are CCl2F2' CF4, SF6, C2F6, Sift, etc. The amount of fluorine added is increased as the flow rate of the fluorine-containing material is increased. The maximum flow rate may delimited since too large a flow rate causes several problems such as cracking of the produced preform, asymmetry of the ~;~41;~0 preform around its axis, etc. Therefore, a fluorine-containing material containing more fluorine atoms per molecule is more preferred, and Sift, C2F6, CF4 and SF6 are suitable.
Specific examples of the inactive gas are argon, helium, nitrogen, etc.
The flow rates of the glass-forming raw material, the fluorine-containing material, oxygen gas and hydrogen gas are as follows:
Glass-forming raw material 200 - 500 ml/sec.
preferably 300 - 400 ml/sec.
Fluorine-containing material 200 - 500 ml/sec.
preferably 300 - 400 ml/sec.
Oxygen gas 4,000 - 12,000 ml/sec.
preferably 6,000 - 8,000 ml/sec.
Hydrogen gas 4,000 - 15,000 ml/sec.
preferably 5,000 - 8,000 ml/sec.
Usually, the ratio of oxygen flow rate and hydrogen flow rate is from 0.5 to 2, preferably from 0.5 to 1. The ratio of the flow rates of the fluorine-containing material and of the glass-forming raw material is from 0.5 to 1.5, preferably from 0.7 to 1.
The diameter of each nozzle varies with other conditions such as the flow rates of the gases. The figures show typical diameters of the nozzles, but the present invention is not limited to these diameters.
In the layout [III] of the nozzles in Fig. 2, nozzle 3" is for Seiko and oxygen gas and nozzle 6' is for CC12F2 and oxygen gas. In Experiment 5, the flow rates of the gases were as follows:
First nozzle: Seiko, 250 ml/sec.
2' 200 ml/sec.
Second nozzle: 2' 1,800 ml/sec.
CC12F2, 250 ml/sec.
Third nozzle: No, 1,500 ml/sec.
Fourth nozzle: Ho, 4,000 ml/sec.
These results may be attributed to the fact that 30 when Seiko and CC12F2 are injected simultaneously, the formation of Sue nuclei is restricted by the formation of Sift and the like, while when they are separately injected, the Sue nuclei are advantageously formed so that the deposition of a solid phase is facilitated.
In order to synthesize the glass soot particles at higher oxygen partial pressure under the above described conditions, the layout of the nozzles as shown in Fig. 3 may preferably be used. The multi-nozzle burner of Fig. 3 has a center nozzle 7 for the glass-forming raw material, the fluorine containing material and oxygen gas, a nozzle 8 for an inactive gas which surrounds the nozzle 7 and a nozzle 9 for hydrogen gas which surrounds the nozzle 8.
A burner shown in Fig. 4 is a modification of the burner of Fig. 3, in which the central nozzle 7 is divided into two, namely a nozzle 7' for at least one of the glass raw material, the fluorine-containing material and oxygen gas and a nozzle 7" for the remainder and optionally at least one material which is injected from the first nozzle. The nozzles 7' and 7" are surrounded by the nozzle 8 and further the nozzle 9 as in Fig. 3. By increasing the number of nozzles for the glass-forming raw material and oxygen gas, it is possible to produce a stable porous preform since the synthesis of the glass soot particles and their flow rate, as well as the distribution of their spatial concentration, can be controlled In addition to the burners of Figs. 3 and 4, the burner of Fig. 2 [III] is preferred.
When hydrogen gas is injected from the outermost nozzle, the flame is not sufficiently concentrated and, under some conditions, the porous preform is not effectively heated so that a preform having a low bulk density is produced which may result in cracking and/or runaway of the produced porous preform. In addition, the fluctuation of the flame is augmented so that a stable porous preform is not produced. In such cases, a nozzle 10 for inactive gas can be provided around the nozzle 9 as shown in Fig. 5 in order to improve the concentration of the flame and to diminish the fluctuation of the flame.
Specific examples of the fluorine-containing material are CCl2F2' CF4, SF6, C2F6, Sift, etc. The amount of fluorine added is increased as the flow rate of the fluorine-containing material is increased. The maximum flow rate may delimited since too large a flow rate causes several problems such as cracking of the produced preform, asymmetry of the ~;~41;~0 preform around its axis, etc. Therefore, a fluorine-containing material containing more fluorine atoms per molecule is more preferred, and Sift, C2F6, CF4 and SF6 are suitable.
Specific examples of the inactive gas are argon, helium, nitrogen, etc.
The flow rates of the glass-forming raw material, the fluorine-containing material, oxygen gas and hydrogen gas are as follows:
Glass-forming raw material 200 - 500 ml/sec.
preferably 300 - 400 ml/sec.
Fluorine-containing material 200 - 500 ml/sec.
preferably 300 - 400 ml/sec.
Oxygen gas 4,000 - 12,000 ml/sec.
preferably 6,000 - 8,000 ml/sec.
Hydrogen gas 4,000 - 15,000 ml/sec.
preferably 5,000 - 8,000 ml/sec.
Usually, the ratio of oxygen flow rate and hydrogen flow rate is from 0.5 to 2, preferably from 0.5 to 1. The ratio of the flow rates of the fluorine-containing material and of the glass-forming raw material is from 0.5 to 1.5, preferably from 0.7 to 1.
The diameter of each nozzle varies with other conditions such as the flow rates of the gases. The figures show typical diameters of the nozzles, but the present invention is not limited to these diameters.
Claims (11)
1. A method for producing an optical fiber preform comprising injecting a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydro-lyzing the glass-forming raw material to synthesize glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
2. A method according to claim 1, wherein said injecting step further comprises the step of injecting an inactive gas from a fourth nozzle which surrounds the third nozzle.
3. A method according to claim 1, wherein the fluorine-containing material is at least one material member selected from the group consisting of SF6, CF4, C2F6, SiF4 and CCl2F2.
4. A method for producing an optical fiber preform com-prising injecting at least one member selected from the group consisting of a glass-forming raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, the remaining member of the group and optionally at least one material which is injected from the first nozzle from a second nozzle which surrounds the first nozzle, an inactive gas from a third nozzle which surrounds the second nozzle and hydrogen gas from a fourth nozzle which surrounds the third nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glassy optical fiber preform containing fluorine.
5. A method according to claim 4, wherein said injecting step further comprises the step of injecting an inactive as from a fourth nozzle which surrounds the third nozzle.
6. A method according to claim 4, wherein the fluorine-containing material is at least one material member selected from the group consisting of SF6, CF4, C2F6, SiF4, and CCl2F2.
7. A method according to claim 4, wherein the glass-forming raw materials and the fluorine-containing material are independently injected.
8. A method for producing an optical fiber preform comprising the steps of:
injecting an oxide glass-forming raw material and oxygen gas from a primary nozzle, a gaseous fluorine-containing material and oxygen gas from a first nozzle which surrounds said primary nozzle or is surrounded by said primary nozzle, inert gas from a second nozzle which surrounds said first nozzle and said primary nozzle, and hydrogen gas from a third nozzle which surrounds said second nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce an oxide glass optical fiber preform containing fluorine.
injecting an oxide glass-forming raw material and oxygen gas from a primary nozzle, a gaseous fluorine-containing material and oxygen gas from a first nozzle which surrounds said primary nozzle or is surrounded by said primary nozzle, inert gas from a second nozzle which surrounds said first nozzle and said primary nozzle, and hydrogen gas from a third nozzle which surrounds said second nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce an oxide glass optical fiber preform containing fluorine.
9. A method for producing an optical fiber preform comprising steps of:
injecting a glass-forming raw material and oxygen gas simultaneously from a centrally positioned first nozzle, a gaseous fluorine-containing material from a second nozzle which surrounds said centrally positioned nozzle, inert gas from a third nozzle which surrounds said second nozzle, and hydrogen gas from a fourth nozzle which surrounds said third nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glass optical fiber preform containing fluorine.
injecting a glass-forming raw material and oxygen gas simultaneously from a centrally positioned first nozzle, a gaseous fluorine-containing material from a second nozzle which surrounds said centrally positioned nozzle, inert gas from a third nozzle which surrounds said second nozzle, and hydrogen gas from a fourth nozzle which surrounds said third nozzle, flame hydrolyzing the glass-forming raw material to synthesize glass soot particles, depositing the glass soot particles on a tip of a rotating seed rod until an optical fiber preform is formed, and fusing the optical fiber preform to produce a glass optical fiber preform containing fluorine.
10. A method according to claim 9, wherein a mixture of the glass-forming raw material and oxygen gas are injected from said centrally positioned first nozzle.
11. A method according to claim 9, wherein a fifth nozzle is provided around the fourth nozzle to inject inert gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000469884A CA1241240A (en) | 1984-12-12 | 1984-12-12 | Method for producing optical fiber preform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000469884A CA1241240A (en) | 1984-12-12 | 1984-12-12 | Method for producing optical fiber preform |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1241240A true CA1241240A (en) | 1988-08-30 |
Family
ID=4129365
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000469884A Expired CA1241240A (en) | 1984-12-12 | 1984-12-12 | Method for producing optical fiber preform |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1241240A (en) |
-
1984
- 1984-12-12 CA CA000469884A patent/CA1241240A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4627866A (en) | Method for producing optical fiber preform | |
| CA1148341A (en) | Fabrication method of single-mode optical fiber preforms | |
| US5055121A (en) | Method for producing glass preform for optical fiber | |
| US4224046A (en) | Method for manufacturing an optical fiber preform | |
| CA1284921C (en) | Method, apparatus and burner for fabricating an optical fiber preform | |
| US4675040A (en) | Method for producing glass preform for single mode optical fiber | |
| US4610709A (en) | Method for producing glass preform for optical fiber | |
| US4804247A (en) | Quartz glass optical fiber | |
| US4880452A (en) | Method for producing glass preform for optical fiber containing fluorine in cladding | |
| JPH0559053B2 (en) | ||
| CA1241240A (en) | Method for producing optical fiber preform | |
| GB2029400A (en) | An Optical Fibre | |
| US5238479A (en) | Method for producing porous glass preform for optical fiber | |
| CA1240214A (en) | Method for producing glass preform for single mode optical fiber | |
| JPS6048456B2 (en) | Method for manufacturing base material for optical fiber | |
| JPS60264338A (en) | Manufacture of optical fiber preform | |
| EP0251312B1 (en) | Method of manufacturing fiber preform for single-mode fibers | |
| US5366531A (en) | Preparation of a preform of optical fibers | |
| EP1044173A1 (en) | Method of making large scale optical fiber preforms with improved properties | |
| EP0415341B1 (en) | Method for producing porous glass preform for optical fiber | |
| JP3078590B2 (en) | Manufacturing method of synthetic quartz glass | |
| EP0135175B1 (en) | Methods for producing optical fiber preform and optical fiber | |
| JPH0331657B2 (en) | ||
| KR870000609B1 (en) | A method for making of optical fiber preform | |
| JPH01242432A (en) | Production of base material for optical fiber |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |