WO2001020370A2 - Method for creating codoped layers and fibers containing codoped layers - Google Patents
Method for creating codoped layers and fibers containing codoped layers Download PDFInfo
- Publication number
- WO2001020370A2 WO2001020370A2 PCT/US2000/020120 US0020120W WO0120370A2 WO 2001020370 A2 WO2001020370 A2 WO 2001020370A2 US 0020120 W US0020120 W US 0020120W WO 0120370 A2 WO0120370 A2 WO 0120370A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- layer
- creating
- dopant
- consolidating
- layers
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01861—Means for changing or stabilising the diameter or form of tubes or rods
- C03B37/01869—Collapsing
-
- 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]
- C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01853—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/10—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with boron
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/28—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with phosphorus
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
- G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
- G02B6/02114—Refractive index modulation gratings, e.g. Bragg gratings characterised by enhanced photosensitivity characteristics of the fibre, e.g. hydrogen loading, heat treatment
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Definitions
- the present invention is directed to a method of creating codoped layers, particularly codoped layers in fibers, more particularly codoped layers having high dopant concentrations serving as cores in fibers.
- a photosensitive optical device is a device whose refractive index may be altered by exposing the device to optical radiation, typically in the ultraviolet region of the spectrum.
- Photosensitive optical devices have been known for a number of years.
- Large photosensitivity is desired for allowing the creation of large photo induced index changes.
- Improved photosensitivity allows numerous new applications, such as very broadband reflectors /filters, ultra-short gratings, cladding mode suppression gratings, and other photonic bandgap devices, to be realized.
- codoping fibers e.g., with germanium and boron or germanium and tin, enhances the photosensitivity of the best photosensitive single dopant fiber, i.e., doped with germanium.
- high concentrations of codopants in the core were typically not needed.
- codoped fibers may be employed for other uses and the problems with achieving codoped fibers with high levels of dopant concentrations are the same regardless of end use of the fiber.
- codoped refers to two or more types of dopants being present in the same region, as opposed to fibers such as gradient index fibers which may have different dopant concentrations in different stratified layers.
- all dopants are introduced into the process simultaneously to form a codoped fiber core.
- different dopants require different, conditions, e.g., temperature, inside atmosphere, etc., for optimum collection efficiency.
- B doping requires a relatively lower temperature than Ge dopant deposition.
- BC1 3 oxidation generates locally high concentrated Cl environment, which dramatically reduces GeCl oxidation.
- B O 3 decreases the glass viscosity, which in tun accelerates GeO thermal decomposition. In the worst case scenario, the Ge incorporation is prevented to such a degree that the core index change relative to the initial material is negative.
- the present invention may be realized by a method of making a codoped layer including creating a first layer having a first dopant, creating a second layer having a second dopant over the first layer, the creating of the second layer being sequential to the creating of the first layer, and interdiffusing the first layer and the second layer to substantially eliminate layer structuretherebetween.
- the creating of each of the first and second layers may include depositing a dopant and consolidating the layer.
- the consolidating may include sintering the layer.
- the depositing and the consolidating may be performed sequentially.
- the consolidating may be performed under different conditions, e.g., temperature, atmosphere, than the depositing. Both the depositing and the consolidating may be performed under different conditions, e.g., temperature, atmosphere, for the first and second layers.
- a third layer having a third dopant may be created over the second layer.
- the third dopant may be the same as one of the first and second dopants. Adjacent layers need not have different dopants. Layers may have more than one dopant present.
- a region on which a layer is to be created may be cooled.
- the invention may be realized by a method of making a fiber having a codoped layer therein including creating a first layer having a first dopant in a fiber structure, creating a second layer having a second dopant over the first layer, the creating of the second layer being sequential to the creating of the first layer, interdiffusing the first layer and the second layer to substantially eliminate layer structure therebetween, and processing the fiber having the codoped layer therein to form a fiber having a desired dimensions.
- the method of creating of the first layer and the of the second layer may occur in a core region of the fiber structure.
- Fig. 1 a shows an end face cross-section of a tube and cladding in which the core is to be formed
- Fig. lb shows a longitudinal cross-section of the tube and cladding of Fig. la;
- Fig. lc shows a longitudinal cross-section of the tube and cladding of Fig. lb with a first layer deposited thereon-
- Fig. Id shows a longitudinal cross-section of the structure of Fig. lc with a second layer deposited thereon;
- Fig. le shows a the structure of Fig. Id after collapsing
- Fig. 2 is a flow chart of the method in accordance with the present invention.
- dopants are incorporated independently.
- This independent incorporation eliminates one feature of the modified chemical vapor deposition (MCVD) commonly employed to make fibers, e.g., a single pass creation of the core, including simultaneous deposition and consolidation. When doping the core with more than one dopant, this single pass creation is still used for all the dopants at the same time.
- MCVD modified chemical vapor deposition
- independent creation of layers in accordance with the present invention allows the creation conditions for each layer to be optimized, since conditions tailored for each dopant can be used. Then, interdiffusing of the created layers allows a substantially homogeneous dopant distribution to be achieved.
- the optimization of the collection of the dopants may be further improved by also sequentially performing the deposition and the consolidation involved in the creation of each layer. While sequential deposition and sintering have been employed to increase throughput of single dopant fibers or to create fibers with distinct dopant regions, such sequential deposition has not been used in conjunction with manufacturing codoped fibers having a continuous distribution of the dopants. In accordance with the present invention, sequential deposition and consolidating allows the collection efficiency of the dopants to be further optimized. The optimization of the collecting of the dopants may be realized since efficient deposition typically occurs at temperatures below a temperature required for consolidation.
- the separation of the depositing and consolidating allows the consolidation environment to be altered from the typical oxidizing conditions to a condition which may further aid in enhancing photosensitivity.
- a condition which may further aid in enhancing photosensitivity For example, when Ge is one of the dopants being incorporated, performing sintering in a reducing condition is believed to create more Ge related oxygen deficient centers, which increase the photosensitivity.
- the present invention may be used to create fibers having increased photosensitivity both by increasing the amount of dopants incorporated into the fiber and by altering the sintering environment to enhance photosensitivity.
- Fig. la shows an end cross-section
- Fig. lb shows a longitudinal cross section of a tube 10 and a clad 12 in which the core material is to be deposited in accordance with the present invention.
- the creation of the structure in which the codoped layer is to be formed is conventional up to this point. It is noted that all of the structural figures are for illustration purposes only. They are not to scale and the thickness thereof, including relative thickness, may be exaggerated for clarity. Further, the longitudinal cross-sections s ⁇ own in Figs, lb-le are only partial cross sections, as indicated by the break lines at the ends thereof.
- a first dopant is supplied under the optimum conditions for such deposition and consolidated under the optimum conditions to form a first layer as shown in Fig. lc.
- another dopant is supplied under its optimum conditions for deposition and consolidated under the optimum conditions to form a second layer 16 as shown in Fig. Id.
- the deposition and consolidation of various dopants under their respective optimum conditions may be repeating any desired number of times. Further, to insure homogeneity of the final codoped layer and/or to provide sufficient deposition of the dopants, varying layers of the same dopants may be supplied, e.g., first a Ge layer, then a B layer, then another Ge layer, then another
- a layer may have more than one type of dopant therein. Additionally, adjacent layers do not have to have different dopants, although more than one dopant will be provided over the plurality of layers.
- Fig. le once all the desired layers have been deposited and consolidated, the structure is then collapsed to form a preform having a homogeneous core 18, i.e., no layer structure remaining from the alternating deposition can be discerned. This preform is then ready to be drawn into a fiber of desired parameters or otherwise further processed to achieve desired core/clad ratios.
- Fig. 2 A summary of the process of the present invention is illustrated in Fig. 2. The summary begins after the tube structure of Fig. la, or other appropriate structure in which the codoped layer is to be created, has been formed.
- the tube is allowed to cool down to increase soot collection efficiency and stabilize chemical reactant flows.
- the maximum temperature of the tube for the deposition is below 200°C.
- a first dopant is deposited under desired conditions.
- the desired conditions will be conditions for obtaining maximum collection efficiency of the desired dopant.
- the layer is consolidated, e.g., by sintering, which may be performed under different conditions then the depositing.
- the tube with the first layer therein as shown in Fig. I c is allowed to cool if it is not already at the desired temperature.
- another layer with another dopant is deposited under desired conditions.
- the other dopant will typically be different from the first dopant.
- the deposition conditions will typically be different from the previous conditions in 22, and will typically be the deposition conditions for realizing the maximum collection efficiency of the other dopant.
- the other layer is then consolidated in 30, e.g., by sintering, under conditions which may be different from the previous sintering in 24.
- any additional number of layers of any desired combination e.g., all of which may be different dopants, some of which may be the same dopant as previously deposited, some may contain more than one dopant, etc., may be deposited and consolidated under their respective desired conditions.
- layers are to be sequentially created, the creation of each layer may be achieved in a single pass, rather in the sequential manner shown.
- 22, 24 may be simultaneous and 28, -30, while subsequent to 22, 24, may be simultaneous with each other. If all desired layers have been created, the flow proceeds to 32.
- the entire structure is collapsed to form the preform shown in Fig. le.
- the collapsing promotes the interdiffusion of the dopants and homogenizes the composition across the core layers.
- the presence of layers in the core should not be discernible in the resulting structure in terms of the refractive index profile.
- This collapsing may be performed in a conventional manner, preferably at a temperature above the consolidating temperatures for the layers.
- the maximum thickness for a layer above which sufficient inter-diffusion will not result depends on the specific dopant diffusion coefficients. However, under most deposition processes, any resultant thickness will allow sufficient inter-diffusion by collapsing the preform. A specific example is discussed below.
- a standard clad containing Ge, F and P as well as Si is deposited.
- the O flow in the SiCl 4 bubbler is about 600 seem, 70 seem in the GeCl 4 bubbler, 75 seem in POCl 3 bubbler and 5 seem of SiF .
- Such a formation creates a barrier layer to prevent water diffusion from the Tube and the H /0 burner.
- F and P are introduced in order to reduce the processing temperature.
- Ge is introduced to compensate for the index decrease and to reduce draw induced attenuation.
- Core deposition begins with Ge deposition.
- the Ge soot layer is deposited at the preferred temperature, e.g.,1550°C.
- this soot layer is consolidated by sintering. Since the deposition and consolidating are performed sequentially in accordance with this example, the conditions under which consolidating are performed may be different from those for the deposition to optimize the photosensitivity or other desired property of the resulting fiber without increasing dopant concentration. Such an increase may be realized, for example, when using Ge as one of the dopants, by consolidating including sintering using a reducing environment or an oxidizing environment.
- this sintering is performed by flowing O and/or He and/or CO and/or Cl 2 and/or other gases depending on the environment requirement at, e.g., 1880°C.
- the next deposition is of B, and is actually a B/Ge codeposition. In this deposition pass, both Bcl 3 and GeCl 4 gases are flowed in.
- the processing conditions are optimized for B deposition. Therefore, the temperature is reduced to, e.g., 1450°C.
- the consolidating includes sintering at a reduced temperature, e.g.,17000C.
- each layer typically preferably includes cooling, depositing and consolidating. Using this method, concentrations of B 2 -O 3 and GeO of greater than around 15 weight percent each can be realized.
- the tube is then collapsed into a preform.
- a high temperature in the collapsing function i.e., above the consolidating temperatures, e.g., 2000-2100°C, interdiffusion of the dopants is promoted.
- This collapsing substantially homogenizes the composition of the core, i.e., eliminates the alternating layer structure.
- a number of layers with different dopants can be separately created, preferably including separate deposition and consolidation for each layer, under optimized conditions.
- the resulting, structure may then be interdiffused to eliminate the layered structure.
- the present invention may be employed to create a codoped fiber for any desired application.
- the process of the present invention can be used to form any desired codoped layer.
- any desired codoped layer may be created using the present invention.
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- 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)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
- Glass Compositions (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU24220/01A AU2422001A (en) | 1999-09-17 | 2000-07-24 | Method for creating codoped layers and fibers containing codoped layers |
CA002385567A CA2385567A1 (en) | 1999-09-17 | 2000-07-24 | Method for creating codoped layers and fibers containing codoped layers |
EP00987951A EP1230036A2 (en) | 1999-09-17 | 2000-07-24 | Method for creating codoped layers and fibers containing codoped layers |
JP2001523898A JP2003509326A (en) | 1999-09-17 | 2000-07-24 | Co-doped layer and method for forming a fiber containing the co-doped layer |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US39929199A | 1999-09-17 | 1999-09-17 | |
US09/399,291 | 1999-09-17 |
Publications (3)
Publication Number | Publication Date |
---|---|
WO2001020370A2 true WO2001020370A2 (en) | 2001-03-22 |
WO2001020370A3 WO2001020370A3 (en) | 2002-01-10 |
WO2001020370A9 WO2001020370A9 (en) | 2002-09-12 |
Family
ID=23578966
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2000/020120 WO2001020370A2 (en) | 1999-09-17 | 2000-07-24 | Method for creating codoped layers and fibers containing codoped layers |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1230036A2 (en) |
JP (1) | JP2003509326A (en) |
CN (1) | CN1402655A (en) |
AU (1) | AU2422001A (en) |
CA (1) | CA2385567A1 (en) |
WO (1) | WO2001020370A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004002910A1 (en) | 2002-06-29 | 2004-01-08 | Lg Cable Ltd. | Method for fabricating optical fiber preform without hydroxyl group in core |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4620861A (en) * | 1985-11-04 | 1986-11-04 | Corning Glass Works | Method for making index-profiled optical device |
US4975102A (en) * | 1979-10-25 | 1990-12-04 | Nippon Telegraph & Telephone Public Corporation | Optical transmission fiber and process for producing the same |
US5364429A (en) * | 1991-07-25 | 1994-11-15 | Alcatel Fibres Optiques | Method of manufacturing active optical fibers |
US5448673A (en) * | 1993-08-12 | 1995-09-05 | Center For Innovative Technology | Controlled dopant diffusion for fiber optic coupler |
US5778129A (en) * | 1996-01-12 | 1998-07-07 | Fujitsu Limited | Doped optical fiber having core and clad structure for increasing the amplification band of an optical amplifier using the optical fiber |
US5892876A (en) * | 1995-10-31 | 1999-04-06 | Alcatel Submarine Networks | Optical fiber including a fluorescent dopant |
-
2000
- 2000-07-24 WO PCT/US2000/020120 patent/WO2001020370A2/en not_active Application Discontinuation
- 2000-07-24 JP JP2001523898A patent/JP2003509326A/en not_active Withdrawn
- 2000-07-24 AU AU24220/01A patent/AU2422001A/en not_active Abandoned
- 2000-07-24 CA CA002385567A patent/CA2385567A1/en not_active Abandoned
- 2000-07-24 CN CN00815627A patent/CN1402655A/en active Pending
- 2000-07-24 EP EP00987951A patent/EP1230036A2/en not_active Withdrawn
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4975102A (en) * | 1979-10-25 | 1990-12-04 | Nippon Telegraph & Telephone Public Corporation | Optical transmission fiber and process for producing the same |
US4620861A (en) * | 1985-11-04 | 1986-11-04 | Corning Glass Works | Method for making index-profiled optical device |
US5364429A (en) * | 1991-07-25 | 1994-11-15 | Alcatel Fibres Optiques | Method of manufacturing active optical fibers |
US5448673A (en) * | 1993-08-12 | 1995-09-05 | Center For Innovative Technology | Controlled dopant diffusion for fiber optic coupler |
US5892876A (en) * | 1995-10-31 | 1999-04-06 | Alcatel Submarine Networks | Optical fiber including a fluorescent dopant |
US5778129A (en) * | 1996-01-12 | 1998-07-07 | Fujitsu Limited | Doped optical fiber having core and clad structure for increasing the amplification band of an optical amplifier using the optical fiber |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004002910A1 (en) | 2002-06-29 | 2004-01-08 | Lg Cable Ltd. | Method for fabricating optical fiber preform without hydroxyl group in core |
EP1517864A1 (en) * | 2002-06-29 | 2005-03-30 | LG Cable Ltd. | Method for fabricating optical fiber preform without hydroxyl group in core |
EP1517864A4 (en) * | 2002-06-29 | 2009-12-16 | Ls Cable Ltd | Method for fabricating optical fiber preform without hydroxyl group in core |
Also Published As
Publication number | Publication date |
---|---|
CN1402655A (en) | 2003-03-12 |
AU2422001A (en) | 2001-04-17 |
CA2385567A1 (en) | 2001-03-22 |
JP2003509326A (en) | 2003-03-11 |
WO2001020370A3 (en) | 2002-01-10 |
WO2001020370A9 (en) | 2002-09-12 |
EP1230036A2 (en) | 2002-08-14 |
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