Optical fiber fabrication and resulting product

• US 4,909,816 A
• Filed: 07/26/1983
• Issued: 03/20/1990
• Est. Priority Date: 02/22/1974
• Status: Expired due to Term

• Current Assignee: Fitel USA Corporation
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: O'Connor, Paul B., MacChesney, John B.
• Primary Examiner(s): Schor, Kenneth M.
• Application Number:
  US06/517,430
• Time in Patent Office: 2,429 Days
• Field of Search: 350/96.30, 350/96.31, 65/3.12, 65/3.11, 65/3.2, 65/18.2, 65/110, 427/163, 427/167, 427/231, 427/237, 264/1.2, 264/1.5
• US Class Current: 65/420
• CPC Class Codes: C03B 37/018 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 rodC03B37/016 takes precedence; bulk deposition of porous glass by OVD or VAD C03B37/014 ; surface treatment of glass by coating C03C17/02
• CPC Class Codes: C03B 37/01861 Means for changing or stabilising the diameter or form of tubes or rods

Abstract

A preform for fabrication of a glass fiber optical transmission line is prepared by chemical reaction of vapor ingredients within a glass tube. Reaction, which may be between chlorides or hydrides of, for example, silicon and germanium with oxygen, occurs preferentially within a constantly traversing hot zone. Flow rates and temperature are sufficient to result in glass formation in the form of particulate matter on the inner surface of the tube. The particulate matter deposits on the tube and is fused with each passage of the hot zone. Continuous rotation of the tube during processing permits attainment of higher temperatures within the heated zone without distortion of the tube.

Claims

1. A method of making an optical fiber preform suitable for drawing into an optical fiber including the steps of:

providing a hollow glass tube of a first refractive index and having a predetermined length with a bore formed therethrough;

introducing into said bore, in unreacted dry vapor form, material that forms a glass layer, coating said bore by thermally depositing said material thereon to form a glass layer of higher refractive index than the refractive index of said tube;

rotating said glass tube about its longitudinal axis by a rotating device, while heating said coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core of said higher index of refraction than the refractive index of said tube.

2. The method of making an optical fiber preform as set forth in claim 1, wherein said tube is made of a silica glass and wherein said material includes germania and silica in order to produce an optical fiber preform having a core of mixed germania-silica composition.

3. The method of claim 1 wherein the coating, rotating and heating steps occur in the order recited.

4. A process for fabrication of a glass optical fiber preform having a core section and a cladding comprising the steps of:

introducing a moving stream of a vapor mixture including at least one compound glass forming precursor together with an oxidizing medium into a tube of a predetermined length, heating the tube and contents by a moving hot zone produced by a correspondingly moving heat source external to the tube so as to react the said mixture and produce a glassy layer on the inner surface of the tube, rotating said glass tube about its longitudinal axis by a rotating device, while heating said coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core having a higher index of refraction than the refractive index of said tube.

5. The process of claim 4 wherein said vapor mixture includes oxygen and chlorides of silicon and germanium.

6. The process of claim 4 wherein the first mentioned heating, the rotating and the second mentioned heating steps occur in the order recited.

7. A method of making an optical fiber preform having a glass core and a glass cladding comprising the steps of:

introducing a stream of vapors into the interior of a glass tube having a first refractive index and a predetermined length, said vapor being chemically reactive in the process of heating to form glass substantially similar to that of said glass core, establishing a localized hot zone in the interior of said glass tube to react vapor within said hot zone, moving said hot zone longitudinally along substantially the same length of said glass tube to coat a layer of glass substantially similar to said glass core on the inside wall of said glass tube, rotating said glass tube about its longitudinal axis by a rotating device, while heating said coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core having a higher index of refraction than the refractive index of said tube.

8. The method of claim 7 wherein the moving, rotating and heating steps occur in the order recited.

9. A method of making an optical fiber preform suitable for drawing into an optical fiber including the steps of:

providing a hollow glass tube of a first refractive index and having a predetermined length with a bore formed therethrough;

introducing into said bore, in unreacted dry vapor form, material that forms a glass layer,

coating said bore by thermally depositing said material thereon to form a glass layer of higher refractive index than the refractive index of said tube;

rotating said coated glass tube about its longitudinal axis by a rotating device; and

heating said rotating coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core of said higher index of refraction than the refractive index of said tube.

10. The method of claim 9 wherein said heating step is accomplished by passing a heat source along the length of said tube.

11. The method of claim 10 wherein said core includes germania and silica.

12. A process for fabrication of a glass optical fiber preform having a core section and a cladding comprising the steps of:

introducing a moving stream of a vapor mixture including at least one compound glass forming precursor together with an oxidizing medium into a tube of a predetermined length,

heating the tube and contents by a moving hot zone produced by a correspondingly moving heat source external to the tube so as to react the said mixture and produce a glassy layer on the inner surface of the tube,

rotating said coated glass tube about its longitudinal axis by a rotating device; and

heating said rotating coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core having a higher index of refraction than the refractive index of said tube.

13. The process of claim 12 wherein the second-mentioned heating step is accomplished by passing a heat source along the length of said tube.

14. The process of claim 12 wherein said core includes germania and silica.

15. A method of making an optical fiber preform having a glass core and a glass cladding comprising the steps of:

introducing a stream of vapors into the interior of a glass tube having a first refractive index and a predetermined length, said vapor being chemically reactive in the process of heating to form glass substantially similar to that of said glass core,

establishing a localized hot zone in the interior of said glass tube to react vapor within said hot zone,

moving said hot zone longitudinally along substantially the same length of said glass tube to coat a layer of glass substantially similar to said glass core on the inside wall of said glass tube,

rotating said coated glass tube about its longitudinal axis by a rotating device; and

heating said rotating coated tube to collapse said tube into a solid preform having substantially the same length as said predetermined length whereby the glass coating layer becomes a core having a higher index of refraction than the refractive index of said tube.

16. The method of claim 15 wherein said heating step is accomplished by passing a heat source along the length of said tube.

17. The method of claim 15 wherein said core includes germania and silica.