Graded start rods for the production of optical waveguides

• US 4,298,366 A
• Filed: 07/13/1979
• Issued: 11/03/1981
• Est. Priority Date: 07/13/1979
• Status: Expired due to Term

• Current Assignee: Times Fiber Communications Incorporated (Amphenol Corporation)
• Original Assignee: Times Fiber Communications Incorporated (Amphenol Corporation)
• Inventors: Dabby, Franklin W., Chesler, Ronald B.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US06/057,519
• Time in Patent Office: 844 Days
• Field of Search: 350/96.30, 350/96.31, 350/96.34, 65/2, 65/3 R, 65/3 A, 65/13, 65/3.1, 65/3.11, 65/3.12
• US Class Current: 65/421
• CPC Class Codes: C03B 2201/10 doped with boron C03B2201/14 takes precedence
• CPC Class Codes: C03B 2203/24 Single mode [SM or monomode]
• CPC Class Codes: C03B 37/01205 starting from tubes, rods, fibres or filaments C03B37/014 takes precedence
• CPC Class Codes: C03B 37/01466 Means for changing or stabilising the diameter or form of tubes or rods C03B37/01861 takes precedence
• CPC Class Codes: C03B 37/01493 Deposition substrates, e.g. targets, mandrels, start rods or tubes

Abstract

A process for preparing a glass rod having a graded refractive index for use as the start rod in the production of optical waveguides is disclosed. The process comprises depositing and sintering borosilicate particles on a glass rod to form a rod having a larger diameter than the original fused silica rod and drawing this rod to obtain a start rod having the same diameter as the original glass rod but exhibiting a partially radially graded refractive index. Optical waveguides prepared from such graded start rods have a more uniformly graded radial index of refraction profile.

Claims

1. A process for the production of optical waveguides which comprises preparing a preform by depositing and sintering borosilicate particles on a cylindrical glass rod, heating said preform to the drawing temperature and drawing said preform into optical waveguides, wherein said cylindrical glass rod comprises a central area of constant refractive index and an outer region of varying refractive index and wherein said cylindrical glass rod is prepared by the process comprising depositing and sintering borosilicate particles on a pure fused silica glass rod and drawing the resulting composite to obtain a graded start rod of about the same diameter as the original pure fused silica rod.

2. The process as defined by claim 1, wherein said cylindrical glass rod comprises a pure fused silica central area and a borosilicate outer region having radially increasing proportions of boron oxide relative to silica.

3. The process as defined by claim 2, wherein said borosilicate outer region exhibits an increasing ratio of boron oxide to silica with radial distance from the pure fused silica core.

4. The process as defined by claim 1, wherein the diameter of said pure fused silica rod is about 3 to 6 mm.

5. The process as defined by claim 1, wherein the diameter of said composite prior to drawing is about 6 to 12 mm.

6. The process as defined by claim 1, wherein said borosilicate particles are produced by high temperature pyrolysis of a first gaseous reactant selected from the group consisting of SiH₄, SiCl₄ and SiBr₄ and a second gaseous reactant selected from the group consisting of B₂ H₆, BCl₃ and BBr₃.

7. The process as defined by claim 6, wherein said reactants are SiCl₄ and BCl₃.

8. The process as defined by claim 6, wherein said high temperature pyrolysis is conducted as a flame pyrolysis by burning natural gas in the presence of oxygen.