CA1218270A - Method of fabricating optical fiber preforms - Google Patents
Method of fabricating optical fiber preformsInfo
- Publication number
- CA1218270A CA1218270A CA000430834A CA430834A CA1218270A CA 1218270 A CA1218270 A CA 1218270A CA 000430834 A CA000430834 A CA 000430834A CA 430834 A CA430834 A CA 430834A CA 1218270 A CA1218270 A CA 1218270A
- Authority
- CA
- Canada
- Prior art keywords
- soot
- stream
- torch
- forming
- precursor materials
- 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
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]
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01413—Reactant delivery systems
- C03B37/0142—Reactant deposition burners
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/04—Multi-nested ports
- C03B2207/06—Concentric circular ports
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/04—Multi-nested ports
- C03B2207/14—Tapered or flared nozzles or ports angled to central burner axis
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/42—Assembly details; Material or dimensions of burner; Manifolds or supports
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/50—Multiple burner arrangements
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geochemistry & Mineralogy (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
- Glass Melting And Manufacturing (AREA)
- Surface Treatment Of Glass Fibres Or Filaments (AREA)
Abstract
METHOD OF FABRICATING OPTICAL FIBER PREFORMS
Abstract An improved method of forming a soot form (from which fiber preforms are made) involves focussing the stream of particulate precursor materials, and directing the focussed stream downward onto a rotating supporting member.
Abstract An improved method of forming a soot form (from which fiber preforms are made) involves focussing the stream of particulate precursor materials, and directing the focussed stream downward onto a rotating supporting member.
Description
METHOD OF FABRICATING OPTICAL FIBER PREFORMS
Technical Field This invention relates to the Axial Vapor-phase Deposition (AVD) method of fabricating optical fiber preforms.
Background of the Invention In the typical prior art method of fabricating optical fiber preforms by the AVD process (alternatively referred to as Vapor-phase Axial Deposition [VAD]), a porous soot for~ is grown while being pulled in an upward axial direction. See, for example, the paper by T. Izawa et al. entitled "Material and Processes for Fiber Preform Fabrication-Vapor-Phase Axial Deposition" published in the October 1980 issue of the Proceedings of the IEEE, Vol. 68, No. 10, pp. 1184-1187. As illustrated in this article, the Elames are directed upward and, hence, the soot is deposited in an upward direction. While this is consistent with the direction of convection flow, due to the hot gasses produced by the torch, it is opposite to the downward pull of gravity. Thus, two of the para~eters controlling the efficiency with which soot is deposited are tending to operate in opposite directions. For a discussion of the effect of gravity on this process see "Influence of Gravity on Chemical Vapor Deposition Processes" by G. Wahl Prog. Astronaut Aeronut 52 lMater.
Sci. Space Appl. Space Processes,) 451-~82, 1977.
In addition to the opposing influences of convection flow and gravity on the deposition efficiency, the convection flow carries "fluff" (i.e., random density particles) upward toward the growing soot form and deposits it about the outer surface of the rotating form. This can have an adverse effect upon the refractive index profile of the resulting preform made from the soot form.
~ZlB~70
Technical Field This invention relates to the Axial Vapor-phase Deposition (AVD) method of fabricating optical fiber preforms.
Background of the Invention In the typical prior art method of fabricating optical fiber preforms by the AVD process (alternatively referred to as Vapor-phase Axial Deposition [VAD]), a porous soot for~ is grown while being pulled in an upward axial direction. See, for example, the paper by T. Izawa et al. entitled "Material and Processes for Fiber Preform Fabrication-Vapor-Phase Axial Deposition" published in the October 1980 issue of the Proceedings of the IEEE, Vol. 68, No. 10, pp. 1184-1187. As illustrated in this article, the Elames are directed upward and, hence, the soot is deposited in an upward direction. While this is consistent with the direction of convection flow, due to the hot gasses produced by the torch, it is opposite to the downward pull of gravity. Thus, two of the para~eters controlling the efficiency with which soot is deposited are tending to operate in opposite directions. For a discussion of the effect of gravity on this process see "Influence of Gravity on Chemical Vapor Deposition Processes" by G. Wahl Prog. Astronaut Aeronut 52 lMater.
Sci. Space Appl. Space Processes,) 451-~82, 1977.
In addition to the opposing influences of convection flow and gravity on the deposition efficiency, the convection flow carries "fluff" (i.e., random density particles) upward toward the growing soot form and deposits it about the outer surface of the rotating form. This can have an adverse effect upon the refractive index profile of the resulting preform made from the soot form.
~ZlB~70
- 2 -Summary of the Invention The various disadvantages and limitations in the prior art AVD method of fabricating soot Eorms for con-solidation into optical fiber preforms are mitigated, in accordance with the present invention, by the downward deposition of the precursor materials. While the effects of gravity and convection flow still tend to operate in opposite directions, the natural tendency of the heated gas to flow upward can be minimized by focussing the gas flow onto the growing soot form. However, it has been found that enough of the convection 10w away from the downward directed gas stream remains so as to minimize the accumulation of fluff.
In accordance with an aspect of -the invention there is provided a method of forming a glass soot form suitable for production of optical ~ibers, which comprises forming a stream of precursor materials by flowing flame-producing reactants through an outer portion of a torch and by flowing soot-forming raw materials throug~ at least one portion of the torch located internally of t~e flame producing reactants, focusing said stream of precursor materials by flo~ing flame-producing reactants so as to form a converging flame and flowing said soot-forming raw materials through the converging Elame so as to produce a collimated stream of precursor materials; directing said stream of precursor materials onto a support member or a soot form, and forming from said stream of precursor materials a soot which is deposited so as to produce said soot form.
3Q These and other advantages of the invention are described hereinbelow in connection with the following figures.
Brief Description of the Drawings FIG. 1 shows an arrangement for fabricating soot :12~ 7(:~
forms in accordance with the present invention;
FIG. 2 shows the effect of convection upon a downward directed flame produced by a ~orch of uniform diameter;
FIG. 3 shows an arrangement for simultaneously depositing core and cladding layers; and FIGS. 4 and 5 illustrate the use of tapered adapters for focussing the gas flow from a conventional torch.
Detailed Description Referring to the drawings, FIG. 1 shows an arrangement 10 for fabricating soot forms employing the Downward Axial Vapor-phase Deposition (DAVD) method in accordance with the present invention. The form is grown on a silica starting member 11 which is rotated about its vertical axis by a motor 12 which is connected to member 11 by means of a shaft 9. A second motor 13 causes the starting member to move in a downward direction as the soot form grows, so as to maintain the growing surface at a fixed location relative to the focal point of the flame.
~aw materials, such as SiC14, GeC14, POCL3, oxygen and hydrogen, are fed into the base chamber 15 of torch 14, which produces fine glass particles by the flame hydrolysis reaction. The particles are, initially, deposited onto the end of starting member 11. As the soot form grows, the glass particles are deposited onto the upper surface of the downward drawn, axially growing form.
If one attempts to practice the DAYD process employing a conventional torch 20 of uniform cross section, 3Q the situation depicted in FIG. 2 is produced. In this case, the convention effect is so pronounced as to cause the flame 21 to bend upward and completely away from the starting member 11. As a result, deposition is erratic and totally unsatisfactory if at all. To avoid this, the ~ ' .~ i~
~, ~2~ 70 - 3a -gas flow must be focussed in the manner produced, for example, by the tapered torch disclosed in United States Patent No. 4,368,063 which issued to H.M. Presby on January 11, 1983. When the torch is tapered, as shown in FIG. 1, the flame configuration is subs~antially independent of orientation and, hence, the torch can be directed downward at any angle ~ to the vertical where 0~90 degrees. A
further advantage of the use of the tapered torch is that it provides a means for controlling the diameter of the soot form. The smaller the torch diameter at the output end, the smaller the diameter of the resulting form. As an example, a 3/4" diameter form was grown in accordance with the invention using a 3/8" diameter torch. The resulting form is considerably smaller than the typical 2" to 3"
diameter forms produced by the upward AVD process using conventional torches. In additionr the form grew with a flat upper surface, was of uniform diameter, and free of fluff.
The use of a focussing torch further permits the simultaneous deposition of one or more cladding layers using additional torches. FIG. 3 shows a soot form 35 comprising a core region 31 being deposited by a first --- lZ~ 70 torch 32, and a single cladding region 33 being deposited by a second torch 34. The latter can be directed perpendicular to the vertical (i.e., ~=90 degrees).
Experience has shown that the precise location of the focal point is not critical. FIG. 3 also shows the well controlled manner in which the soot form grows with clean vertical lines and a flat upper surface. Additional torches can be similarly employed to simultaneously deposit additional cladding layers.
After the soot form is fabricated, it is consolidated by heating to form the optical fiber preform.
The fiber is then drawn from the preform.
As noted in connection with FIGS. 1 and 3, the res~ ting soot forms have well defined upper and side boundaries. This is the result of the focussing action of the tapered torch. The latter generates a converging gas flow whose focal point is advantageously located near the center of the upper surface of the growing form. This tends to produce a well defined temperature gradient across the upper surface of the form and a well defined cutoff temperature below which deposition does not occur. This, plus the fact that the convection flow carries the nondeposited particles away from the growing soot form, accounts for the well defined boundaries.
A further advantage of a focussed flame is that the cladding flame operates substantially independently of the core producing flame thus permitting their simultaneous use. The simultaneous deposition of a cladding layer is not normally practical with the upward AVD process.
FIGS. 4 and 5 illustrate the use of tapered adapters for focussing the gas flow from a conventional torch. The tapered tip 41, illustrated in FIG. 4, is a single tapered tube which fits over the end of the torch ~0. In the embodiment of FIG. 5, the tapered focussing tip 43 comprises a plurality of concentric cylindrical sections 44, 45 and 46 which serve to preserve the separate flow of the constituent materials. Tip 43 can f ~ 70 be made in the manner described in the above mentioned United States Patent number 4,368,063.
~hi
In accordance with an aspect of -the invention there is provided a method of forming a glass soot form suitable for production of optical ~ibers, which comprises forming a stream of precursor materials by flowing flame-producing reactants through an outer portion of a torch and by flowing soot-forming raw materials throug~ at least one portion of the torch located internally of t~e flame producing reactants, focusing said stream of precursor materials by flo~ing flame-producing reactants so as to form a converging flame and flowing said soot-forming raw materials through the converging Elame so as to produce a collimated stream of precursor materials; directing said stream of precursor materials onto a support member or a soot form, and forming from said stream of precursor materials a soot which is deposited so as to produce said soot form.
3Q These and other advantages of the invention are described hereinbelow in connection with the following figures.
Brief Description of the Drawings FIG. 1 shows an arrangement for fabricating soot :12~ 7(:~
forms in accordance with the present invention;
FIG. 2 shows the effect of convection upon a downward directed flame produced by a ~orch of uniform diameter;
FIG. 3 shows an arrangement for simultaneously depositing core and cladding layers; and FIGS. 4 and 5 illustrate the use of tapered adapters for focussing the gas flow from a conventional torch.
Detailed Description Referring to the drawings, FIG. 1 shows an arrangement 10 for fabricating soot forms employing the Downward Axial Vapor-phase Deposition (DAVD) method in accordance with the present invention. The form is grown on a silica starting member 11 which is rotated about its vertical axis by a motor 12 which is connected to member 11 by means of a shaft 9. A second motor 13 causes the starting member to move in a downward direction as the soot form grows, so as to maintain the growing surface at a fixed location relative to the focal point of the flame.
~aw materials, such as SiC14, GeC14, POCL3, oxygen and hydrogen, are fed into the base chamber 15 of torch 14, which produces fine glass particles by the flame hydrolysis reaction. The particles are, initially, deposited onto the end of starting member 11. As the soot form grows, the glass particles are deposited onto the upper surface of the downward drawn, axially growing form.
If one attempts to practice the DAYD process employing a conventional torch 20 of uniform cross section, 3Q the situation depicted in FIG. 2 is produced. In this case, the convention effect is so pronounced as to cause the flame 21 to bend upward and completely away from the starting member 11. As a result, deposition is erratic and totally unsatisfactory if at all. To avoid this, the ~ ' .~ i~
~, ~2~ 70 - 3a -gas flow must be focussed in the manner produced, for example, by the tapered torch disclosed in United States Patent No. 4,368,063 which issued to H.M. Presby on January 11, 1983. When the torch is tapered, as shown in FIG. 1, the flame configuration is subs~antially independent of orientation and, hence, the torch can be directed downward at any angle ~ to the vertical where 0~90 degrees. A
further advantage of the use of the tapered torch is that it provides a means for controlling the diameter of the soot form. The smaller the torch diameter at the output end, the smaller the diameter of the resulting form. As an example, a 3/4" diameter form was grown in accordance with the invention using a 3/8" diameter torch. The resulting form is considerably smaller than the typical 2" to 3"
diameter forms produced by the upward AVD process using conventional torches. In additionr the form grew with a flat upper surface, was of uniform diameter, and free of fluff.
The use of a focussing torch further permits the simultaneous deposition of one or more cladding layers using additional torches. FIG. 3 shows a soot form 35 comprising a core region 31 being deposited by a first --- lZ~ 70 torch 32, and a single cladding region 33 being deposited by a second torch 34. The latter can be directed perpendicular to the vertical (i.e., ~=90 degrees).
Experience has shown that the precise location of the focal point is not critical. FIG. 3 also shows the well controlled manner in which the soot form grows with clean vertical lines and a flat upper surface. Additional torches can be similarly employed to simultaneously deposit additional cladding layers.
After the soot form is fabricated, it is consolidated by heating to form the optical fiber preform.
The fiber is then drawn from the preform.
As noted in connection with FIGS. 1 and 3, the res~ ting soot forms have well defined upper and side boundaries. This is the result of the focussing action of the tapered torch. The latter generates a converging gas flow whose focal point is advantageously located near the center of the upper surface of the growing form. This tends to produce a well defined temperature gradient across the upper surface of the form and a well defined cutoff temperature below which deposition does not occur. This, plus the fact that the convection flow carries the nondeposited particles away from the growing soot form, accounts for the well defined boundaries.
A further advantage of a focussed flame is that the cladding flame operates substantially independently of the core producing flame thus permitting their simultaneous use. The simultaneous deposition of a cladding layer is not normally practical with the upward AVD process.
FIGS. 4 and 5 illustrate the use of tapered adapters for focussing the gas flow from a conventional torch. The tapered tip 41, illustrated in FIG. 4, is a single tapered tube which fits over the end of the torch ~0. In the embodiment of FIG. 5, the tapered focussing tip 43 comprises a plurality of concentric cylindrical sections 44, 45 and 46 which serve to preserve the separate flow of the constituent materials. Tip 43 can f ~ 70 be made in the manner described in the above mentioned United States Patent number 4,368,063.
~hi
Claims (9)
1. A method of forming a glass soot form suit-able for production of optical fibers, which comprises forming a stream of precursor materials by flowing flame producing reactants through an outer portion of a torch and by flowing soot-forming raw materials through at least one portion of the torch located internally of the flame producing reactants, focusing said stream of precursor materials by flowing flame-producing reactants so as to form a converging flame and flowing said soot-forming raw materials through the converging flame so as to produce a collimated stream of precursor materials;
directing said stream of precursor materials onto a support member or a soot form, and forming from said stream of precursor materials a soot which is deposited so as to produce said soot form.
directing said stream of precursor materials onto a support member or a soot form, and forming from said stream of precursor materials a soot which is deposited so as to produce said soot form.
2. The method according to claim 1, which comprises orienting said focused stream to locate the focal point of said stream on the upper surface of said soot form.
3. The method according to claim 1, which comprises forming, from at least one other stream of precursor materials, a second soot capable of being consolidated into a glass, said second soot forming being in a manner similar to that of the first mentioned soot-forming, focusing said at least one other stream of precursor materials similarly to the first stream;
and directing said at least one other focused stream onto the side of the soot from produced by said first precursor materials.
and directing said at least one other focused stream onto the side of the soot from produced by said first precursor materials.
4. The method according to claim 1, wherein said directing is in a generally downward direction at an angle of .PHI. degrees with the vertical, where 0<.PHI.<90 degrees.
5. The method according to claim 1 or 3, wherein said focusing is by means of a torch the diameter of which tapers from a first diameter along the input end of its length to a second smaller diameter at its output end.
6. The method according to claim 1 or 3, wherein said focusing is by means of a tapered section of tubing adapted to fit over an output end of said torch.
7. The method according to claim 1 or 3, wherein said focusing is by means of a tapered assembly of coaxially aligned tubes adapted to fit over the end of said torch and to align with a corresponding assembly of co-axially aligned tubes forming said torch.
8. The method according to claim 1 or 3, which comprises rotating said support member relative to the focused stream and translating said support member vertically at a rate proportional to the growth rate of said soot form.
9. The method according to claim 1 wherein said soot is formed by means of a hydrolysis torch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40161082A | 1982-07-26 | 1982-07-26 | |
| US401,610 | 1982-07-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218270A true CA1218270A (en) | 1987-02-24 |
Family
ID=23588455
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000430834A Expired CA1218270A (en) | 1982-07-26 | 1983-06-21 | Method of fabricating optical fiber preforms |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5935036A (en) |
| CA (1) | CA1218270A (en) |
| DE (1) | DE3326928A1 (en) |
| FR (1) | FR2530613B1 (en) |
| GB (1) | GB2124205B (en) |
| NL (1) | NL8302641A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000191337A (en) * | 1998-12-25 | 2000-07-11 | Furukawa Electric Co Ltd:The | Torch for synthesizing glass particulate with hood |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2272342A (en) * | 1934-08-27 | 1942-02-10 | Corning Glass Works | Method of making a transparent article of silica |
| US3565345A (en) * | 1968-07-11 | 1971-02-23 | Texas Instruments Inc | Production of an article of high purity metal oxide |
| GB1368093A (en) * | 1972-10-17 | 1974-09-25 | Post Office | Silica-based vitreous material |
| GB1450123A (en) * | 1973-11-27 | 1976-09-22 | Post Office | Doped vitreous silica |
| US4135901A (en) * | 1974-12-18 | 1979-01-23 | Sumitomo Electric Industries, Ltd. | Method of manufacturing glass for optical waveguide |
| FR2313327A1 (en) * | 1975-06-06 | 1976-12-31 | Quartz & Silice | VERY HIGH PURITY GLASS PREPARATION PROCESS USED IN PARTICULAR FOR THE MANUFACTURE OF OPTICAL FIBERS |
| IT1091498B (en) * | 1977-11-25 | 1985-07-06 | Cselt Centro Studi Lab Telecom | PROCEDURE AND EQUIPMENT FOR THE CONTINUOUS PRODUCTION OF OPTICAL FIBERS |
| US4231774A (en) * | 1978-04-10 | 1980-11-04 | International Telephone And Telegraph Corporation | Method of fabricating large optical preforms |
| GB1574115A (en) * | 1978-05-18 | 1980-09-03 | Standard Telephones Cables Ltd | Optical fibre manufacture |
| US4230473A (en) * | 1979-03-16 | 1980-10-28 | Bell Telephone Laboratories, Incorporated | Method of fabricating optical fibers |
| GB2071644B (en) * | 1980-02-22 | 1984-03-14 | Sumitomo Electric Industries | Radiation resistant optical fibres and a process for the production thereof |
| US4310339A (en) * | 1980-06-02 | 1982-01-12 | Corning Glass Works | Method and apparatus for forming an optical waveguide preform having a continuously removable starting member |
| GB2083806B (en) * | 1980-09-11 | 1984-08-08 | Nippon Telegraph & Telephone | Fabrication methods of doped silica glass and optical fibre preform by using the doped silica glass |
| NL8103648A (en) * | 1981-08-03 | 1983-03-01 | Philips Nv | METHOD FOR MANUFACTURING FORMS FOR DRAWING OPTICAL FIBERS AND FORMS ACCORDING TO THIS METHOD AND FOR APPARATUS FOR MANUFACTURING OPTICAL FIBERS |
-
1983
- 1983-06-21 CA CA000430834A patent/CA1218270A/en not_active Expired
- 1983-07-20 GB GB08319566A patent/GB2124205B/en not_active Expired
- 1983-07-21 FR FR8312063A patent/FR2530613B1/en not_active Expired
- 1983-07-25 NL NL8302641A patent/NL8302641A/en not_active Application Discontinuation
- 1983-07-26 JP JP13529183A patent/JPS5935036A/en active Pending
- 1983-07-26 DE DE19833326928 patent/DE3326928A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5935036A (en) | 1984-02-25 |
| GB2124205B (en) | 1986-12-10 |
| NL8302641A (en) | 1984-02-16 |
| DE3326928A1 (en) | 1984-02-02 |
| FR2530613A1 (en) | 1984-01-27 |
| GB2124205A (en) | 1984-02-15 |
| FR2530613B1 (en) | 1987-11-13 |
| GB8319566D0 (en) | 1983-08-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |