DE3941863A1 - Light wave conductors mfr. for optical fibres - by coating internal surface of tube with diffusion layer to remove impurities prior to coating when glass core layer and drawing - Google Patents
Light wave conductors mfr. for optical fibres - by coating internal surface of tube with diffusion layer to remove impurities prior to coating when glass core layer and drawingInfo
- Publication number
- DE3941863A1 DE3941863A1 DE19893941863 DE3941863A DE3941863A1 DE 3941863 A1 DE3941863 A1 DE 3941863A1 DE 19893941863 DE19893941863 DE 19893941863 DE 3941863 A DE3941863 A DE 3941863A DE 3941863 A1 DE3941863 A1 DE 3941863A1
- Authority
- DE
- Germany
- Prior art keywords
- diffusion layer
- layer
- impurities
- diffusion
- tube
- 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.)
- Withdrawn
Links
- 238000009792 diffusion process Methods 0.000 title claims abstract description 36
- 239000012535 impurity Substances 0.000 title claims abstract description 22
- 239000011521 glass Substances 0.000 title claims abstract description 9
- 238000000576 coating method Methods 0.000 title claims abstract description 6
- 230000003287 optical effect Effects 0.000 title claims abstract description 6
- 239000010410 layer Substances 0.000 title abstract description 22
- 239000011248 coating agent Substances 0.000 title abstract description 5
- 239000004020 conductor Substances 0.000 title abstract 2
- 239000012792 core layer Substances 0.000 title description 2
- 238000010438 heat treatment Methods 0.000 claims abstract 2
- 238000000034 method Methods 0.000 claims description 30
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 11
- 239000000758 substrate Substances 0.000 claims description 10
- 238000005530 etching Methods 0.000 claims description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 239000011574 phosphorus Substances 0.000 claims description 5
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 4
- 239000000460 chlorine Substances 0.000 claims description 4
- 229910052731 fluorine Inorganic materials 0.000 claims description 4
- 239000011737 fluorine Substances 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- -1 B 2 O 3 Inorganic materials 0.000 claims description 3
- 239000002019 doping agent Substances 0.000 claims description 3
- 229910004261 CaF 2 Inorganic materials 0.000 claims description 2
- 229910003902 SiCl 4 Inorganic materials 0.000 claims description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 230000008021 deposition Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 2
- 235000012239 silicon dioxide Nutrition 0.000 claims 2
- 239000000377 silicon dioxide Substances 0.000 claims 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims 1
- 229910005793 GeO 2 Inorganic materials 0.000 claims 1
- 229910052783 alkali metal Inorganic materials 0.000 claims 1
- 150000001340 alkali metals Chemical class 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 claims 1
- 229910052801 chlorine Inorganic materials 0.000 claims 1
- 238000011109 contamination Methods 0.000 claims 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 229910052723 transition metal Inorganic materials 0.000 claims 1
- 150000003624 transition metals Chemical class 0.000 claims 1
- 239000012808 vapor phase Substances 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims 1
- 239000013307 optical fiber Substances 0.000 abstract description 5
- 238000013016 damping Methods 0.000 abstract description 3
- 239000000835 fiber Substances 0.000 abstract description 3
- 239000002344 surface layer Substances 0.000 abstract 1
- 239000010453 quartz Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000005253 cladding Methods 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000005049 silicon tetrachloride Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/018—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
- C03B37/01876—Means for heating tubes or rods during or immediately prior to deposition, e.g. electric resistance heaters
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Herstellen einer Vorform für Lichtwellenleiter nach dem Oberbegriff des Anspruchs 1.The invention relates to a method for producing a preform for Optical waveguide according to the preamble of claim 1.
Es ist bekannt, Lichtwellenleiter (LWL = optische Fasern) zum Zweck der optischen Nachrichtenübertragung durch Innenbeschichtung eines Rohres aus reinem Quarzglas, Kollabieren und Ziehen zur Faser herzustellen. Die für die Lichtausbreitung verantwortlichen Moden werden nicht nur im Kern des Lichtwellenleiters geführt, sondern auch im Mantelbereich, in dem sie exponentiell abklingen. Es muß deshalb dafür Sorge getragen werden, daß weder der Mantel- noch der Kernbereich Verunreinigungen enthalten, welche im Bereich der zu Übertragung vorgesehenen Frequenzen eine hohe Zusatzdämpfung bewirken.It is known to use optical fibers (LWL = optical fibers) for the purpose of optical transmission of messages by coating the inside of a pipe made of pure quartz glass, collapsing and pulling to the fiber. The Modes responsible for light propagation are not just at the core of the optical waveguide, but also in the cladding area, in which they subside exponentially. Therefore care must be taken that neither the jacket nor the core area contain impurities, which is high in the range of the frequencies intended for transmission Cause additional damping.
Handelsüblich hergestellte Quarzrohre enthalten soviele Verunreini gungen, daß sie als Mantelmaterial für eine optische Faser für Fern übertragungszwecke nicht infrage kommen. Es wird daher auf das Quarzrohr innen zunächst ein Mantel höchster Reinheit abgeschieden. Dann werden die Schichten für den späteren Kernbereich abgeschieden. Diese Schichten werden mittels des sog. MVCD-Verfahrens hergestellt. Beim Kollabieren des Rohres und beim Ziehen der Faser aus dem Vorformstab ist allerdings die Temperatur so hoch, daß Verunreinigungen aus dem Substratrohr in den Mantel und sogar den Kernbereich gelangen können. Die Dämpfungserhöhung beruht dabei hauptsächlich auf Wasserstoff- oder OH-Ionen, wobei der leicht diffundierende Wasserstoff in der SiO2-Matrix mit dem Matrix sauerstoff zu einem OH⁻-Radikal rekombinieren kann.Commercially available quartz tubes contain so many impurities that they are not suitable as a cladding material for an optical fiber for long-distance transmission purposes. Therefore, a jacket of the highest purity is first deposited on the inside of the quartz tube. Then the layers for the later core area are deposited. These layers are produced using the so-called MVCD process. When the tube collapses and the fiber is pulled out of the preform rod, however, the temperature is so high that contaminants from the substrate tube can get into the jacket and even the core area. The increase in damping is mainly based on hydrogen or OH ions, the slightly diffusing hydrogen in the SiO 2 matrix being able to recombine with the matrix to form an OH⁻ radical.
Aus diesem Grunde ist ein hochreines Substratrohr aus Quarz erforder lich. Zur Reinigung wird meistens die Innenfläche mit halogenhaltigen Gasen bei höherer Temperatur gespült. Dieses Verfahren ist allerdings nicht geeignet, die im Volumen des Quarzrohres befindlichen Wasserstoff ionen zu entfernen. Auch Metallionen sind schädlich und müssen ebenfalls entfernt werden.For this reason, a high-purity quartz substrate tube is required Lich. For cleaning, the inner surface is usually covered with halogen Gases purged at a higher temperature. However, this procedure is not suitable, the hydrogen in the volume of the quartz tube remove ions. Metal ions are also harmful and must also be removed.
Der Erfindung liegt die Aufgabe zugrunde, bei einem Substratrohr der eingangs genannten Art ein zur Entfernung von Verunreinigungen besonders wirksames Verfahren anzugeben, das die Verunreinigungen auch im Volumen weitgehend zu entfernen gestattet.The invention has for its object in a substrate tube type mentioned above to remove impurities particularly effective method to specify that the impurities also in volume allowed to remove largely.
Die Aufgabe wird erfindungsgemäß durch die im Kennzeichen des Anspruchs 1 aufgeführten Merkmale gelöst. Weiterbildungen der Erfindung sind in den Unteransprüchen beschrieben.The object is achieved by the characterizing part of the claim 1 listed features solved. Developments of the invention are in described the subclaims.
Die mit der Erfindung erzielten Vorteile bestehen nicht nur in einer schnelleren Reinigung der Substratrohre, sondern auch darin, daß Ver unreinigungen weitgehend entfernt werden können.The advantages achieved by the invention are not only one faster cleaning of the substrate tubes, but also that Ver impurities can largely be removed.
Dabei macht sich die Erfindung auch einen sog. Getter-Effekt zunutze, bei dem Verunreinigungs-Bestandteile eine chemische Bindung mit dem Gettermaterial eingehen. Zeitbestimmend für den Vorgang ist die Diffu sion der Verunreinigungen zum Gettermaterial. Deshalb ist es auch von Vorteil, wenn die Schicht, in die die Verunreinigungen hineindiffun dieren sollen, auf beiden Seiten des Rohres aufgebracht wird. Ein besonderer Vorteil des Verfahrens ergibt sich dadurch, daß auch für längere Zeiten eine niedrige Dämpfung der übertragenen Moden in der optischen Faser gewährleistet ist. Vorzugsweise wird als Diffusions schicht ein Material aufgebracht, welches einen hohen Phosphorgehalt aufweist. Phosphor bildet mit Hydroxylionen bekanntlich eine stabile Verbindung. Durch Ätzen mit Gasen hoher Reinheit wird die Diffusions schicht entfernt und auf der Innenseite des Rohres in üblicher Weise durch das MCVD-Verfahren erst die Mantelschicht und dann die hochreine Kernschicht abgeschieden.The invention also makes use of a so-called getter effect, a chemical bond with the impurity constituents Enter getter material. The Diffu is decisive for the process sion of impurities to getter material. That is why it is from Advantage if the layer into which the impurities diffuse dieren, is applied to both sides of the tube. A The particular advantage of the method results from the fact that long periods of low attenuation of the transmitted modes in the optical fiber is guaranteed. Preferably as a diffusion layer applied a material that has a high phosphorus content having. As is known, phosphorus forms a stable one with hydroxyl ions Connection. The diffusion is made by etching with gases of high purity layer removed and on the inside of the tube in the usual way with the MCVD process, first the cladding layer and then the high-purity one Core layer deposited.
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und wird im folgenden näher beschrieben. Die Fig. 1 zeigt einen Quer schnitt durch ein Quarzrohr 1 mit Diffusionsschicht 2 und Verunreini gungen 5, die Fig. 2 das fertig beschichtete Rohr vor dem Kollabieren. Die Diffusionsschicht 2 besteht entweder aus SiO2 oder aus SiO2 mit Dotierungskomponente. Als Dotierungsstoff kommt in erster Linie Phosphor infrage, da er insbesondere mit OH-Gruppen reagiert. Weitere bevorzugte Komponenten für die Dotierung sind Fluor oder Bor. Als Diffusionsschicht 2 kann man aber auch einen anderen Glasbildner als Silizium heranziehen; hier sind Phosphor, Germanium, Bor oder auch CaF2 geeignet. Sollten Alkali-, Erdalkalimetalle oder Aluminium im Rohr aus handelsüblichem Quarz vorhanden sein, so empfiehlt es sich, in die Glassubstanz Stoffe einzubringen, welche mit diesen Atomen eine Reaktion eingehen. Die Diffusionsschicht wird also als Glas aufgefaßt, wobei auch andere Glasbildner als Silizium zugelassen sind. Wichtig ist nur, daß die Diffusion der Verunreinigungen 5 aus dem Rohr mit genügend hoher Ge schwindigkeit erfolgen kann. Deshalb ist es erforderlich, den Diffu sionsvorgang bei einer erhöhten Temperatur ablaufen zu lassen. Vorzugs weise ist diese Temperatur 1500 bis 1700°C. Eine solche Temperatur wird bei der Abscheidung des durch das MCVD-Verfahren aufgebrachten Diffu sionsschicht ohnehin angewendet.An embodiment of the invention is shown in the drawing and will be described in more detail below. Fig. 1 shows a cross section through a quartz tube 1 with diffusion layer 2 and impurities 5 , Fig. 2 shows the finished coated tube before collapsing. The diffusion layer 2 consists either of SiO 2 or of SiO 2 with a doping component. Phosphorus is primarily considered as a dopant, since it reacts in particular with OH groups. Other preferred components for the doping are fluorine or boron. However, a glass former other than silicon can also be used as the diffusion layer 2 ; here phosphorus, germanium, boron or also CaF 2 are suitable. If there are alkali, alkaline earth metals or aluminum in the tube made of commercially available quartz, it is advisable to incorporate substances into the glass substance that react with these atoms. The diffusion layer is thus understood as glass, although glass formers other than silicon are also permitted. It is only important that the diffusion of the impurities 5 from the tube can take place at a sufficiently high speed. It is therefore necessary to let the diffusion process take place at an elevated temperature. This temperature is preferably 1500 to 1700 ° C. Such a temperature is used anyway in the deposition of the diffusion layer applied by the MCVD process.
Es ist aber von Vorteil, den für das MCVD-Verfahren verwendeten Ofen nach der Abscheidung der Diffusionsschicht zusätzlich ein paarmal in Längsrichtung des Rohres hin und her zu führen. Bei diesen Ofendurch läufen diffundieren die Verunreinigungen in dem gewünschtem Maße in die Diffusionsschicht 2.However, it is advantageous to additionally move the furnace used for the MCVD process back and forth a couple of times in the longitudinal direction of the tube after the diffusion layer has been deposited. In these furnace runs, the impurities diffuse into the diffusion layer 2 to the desired extent.
Die Diffusionsschicht 2 kann eine unterschiedliche Konzentration an Dotierstoffen aufweisen. In einer vorteilhaften Ausgestaltung der Erfin dung nimmt der Phosphorgehalt mit jeder abgeschiedenen Schicht zu. Die Schichtdicke beträgt 50 bis 800 µm, vorzugsweise 60 bis 300 µm. The diffusion layer 2 can have a different concentration of dopants. In an advantageous embodiment of the inven tion, the phosphorus content increases with each deposited layer. The layer thickness is 50 to 800 microns, preferably 60 to 300 microns.
Nachdem die Verunreinigungen 5 in die Diffusionsschicht gewandert sind, wird diese Schicht weggeätzt. Dies kann ganz oder teilweise geschehen.After the impurities 5 have migrated into the diffusion layer, this layer is etched away. This can be done in whole or in part.
Nach dem Wegätzen kann erneut eine Diffusionsschicht aufgebracht werden, welche dann nach erfolgter Diffusion wieder weggeätzt wird. Als Ätz mittel werden fluorhaltige Verbindungen eingesetzt. Insbesondere kommen SF6 und/oder CCl2F2 infrage. Diesen Stoffen wird Sauerstoff und/oder Cl2 und/oder CCl4 und/oder Helium oder ein anderes Edelgas beigemischt. Auch mit Beimischungen von Siliciumtetrachlorid (SiCl4) und GeCl4 bzw. BCl3 sind gute Ätzergebnisse zu erzielen.After the etching away, a diffusion layer can be applied again, which is then etched away again after the diffusion has taken place. Fluorine-containing compounds are used as etching agents. SF 6 and / or CCl 2 F 2 are particularly suitable. Oxygen and / or Cl 2 and / or CCl 4 and / or helium or another noble gas is mixed with these substances. Good etching results can also be achieved with admixtures of silicon tetrachloride (SiCl 4 ) and GeCl 4 or BCl 3 .
Claims (23)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893941863 DE3941863A1 (en) | 1989-12-19 | 1989-12-19 | Light wave conductors mfr. for optical fibres - by coating internal surface of tube with diffusion layer to remove impurities prior to coating when glass core layer and drawing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893941863 DE3941863A1 (en) | 1989-12-19 | 1989-12-19 | Light wave conductors mfr. for optical fibres - by coating internal surface of tube with diffusion layer to remove impurities prior to coating when glass core layer and drawing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE3941863A1 true DE3941863A1 (en) | 1991-06-20 |
Family
ID=6395769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DE19893941863 Withdrawn DE3941863A1 (en) | 1989-12-19 | 1989-12-19 | Light wave conductors mfr. for optical fibres - by coating internal surface of tube with diffusion layer to remove impurities prior to coating when glass core layer and drawing |
Country Status (1)
| Country | Link |
|---|---|
| DE (1) | DE3941863A1 (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2746949A1 (en) * | 1976-10-19 | 1978-04-20 | Thomson Csf | METHOD FOR MANUFACTURING GLASS FIBERS WITH A RADIAL REFRACTIVE INDEX GRADIENT |
| WO1986001193A1 (en) * | 1984-08-14 | 1986-02-27 | Hughes Aircraft Company | Process for the removal of impurities from optical component materials |
| EP0197585A1 (en) * | 1985-03-29 | 1986-10-15 | Philips Patentverwaltung GmbH | Method for making glass bodies |
| EP0198510A1 (en) * | 1985-04-18 | 1986-10-22 | Sumitomo Electric Industries Limited | Method of producing glass preform for optical fiber |
| DE3235465C2 (en) * | 1981-10-01 | 1987-11-19 | At & T Technologies, Inc., New York, N.Y., Us | |
| DE3619510A1 (en) * | 1986-06-10 | 1987-12-17 | Philips Patentverwaltung | METHOD FOR PRODUCING GLASS OR CERAMIC BODIES |
| US4729777A (en) * | 1985-08-22 | 1988-03-08 | Kokusai Denshin Denwa Kabushiki Kaisha | Method and apparatus for manufacturing preform for fluoride glass fiber |
| DE3630479A1 (en) * | 1986-09-06 | 1988-03-17 | Schott Glaswerke | Process for the production of a planar, polarising, monomodal optical waveguide |
| DE2946011C2 (en) * | 1978-11-20 | 1989-01-12 | Mitsubishi Kinzoku K.K., Tokio/Tokyo, Jp |
-
1989
- 1989-12-19 DE DE19893941863 patent/DE3941863A1/en not_active Withdrawn
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2746949A1 (en) * | 1976-10-19 | 1978-04-20 | Thomson Csf | METHOD FOR MANUFACTURING GLASS FIBERS WITH A RADIAL REFRACTIVE INDEX GRADIENT |
| DE2946011C2 (en) * | 1978-11-20 | 1989-01-12 | Mitsubishi Kinzoku K.K., Tokio/Tokyo, Jp | |
| DE3235465C2 (en) * | 1981-10-01 | 1987-11-19 | At & T Technologies, Inc., New York, N.Y., Us | |
| WO1986001193A1 (en) * | 1984-08-14 | 1986-02-27 | Hughes Aircraft Company | Process for the removal of impurities from optical component materials |
| EP0197585A1 (en) * | 1985-03-29 | 1986-10-15 | Philips Patentverwaltung GmbH | Method for making glass bodies |
| EP0198510A1 (en) * | 1985-04-18 | 1986-10-22 | Sumitomo Electric Industries Limited | Method of producing glass preform for optical fiber |
| US4729777A (en) * | 1985-08-22 | 1988-03-08 | Kokusai Denshin Denwa Kabushiki Kaisha | Method and apparatus for manufacturing preform for fluoride glass fiber |
| DE3619510A1 (en) * | 1986-06-10 | 1987-12-17 | Philips Patentverwaltung | METHOD FOR PRODUCING GLASS OR CERAMIC BODIES |
| DE3630479A1 (en) * | 1986-09-06 | 1988-03-17 | Schott Glaswerke | Process for the production of a planar, polarising, monomodal optical waveguide |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| OM8 | Search report available as to paragraph 43 lit. 1 sentence 1 patent law | ||
| 8127 | New person/name/address of the applicant |
Owner name: KABEL RHEYDT AG, 4050 MOENCHENGLADBACH, DE |
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| 8139 | Disposal/non-payment of the annual fee |