# US 4,396,409 A · Method of improving fatigue resistance of optical fibers

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- Number: US 4,396,409 A
- Document ID: US4396409A
- Status: Granted
- Kind: A
- Application number: 06/329,816
- Filed: 1981-12-11
- Granted: 1983-08-02
- Earliest claimed: 1981-12-11
- Assignees: Corning Glass Works
- Inventors: Alan C. Bailey; Robert D. Maurer
- Web page: https://patentgrep.com/patent/US4396409A

## CPC

- C03C 25/104: to obtain optical fibres
- C03B 37/15: with heat application, e.g. for making optical fibres (fusion-splicing of light guides G02B6/255; treatment of light guides to shape optical elements {G02B6/2835, G02B6/2856})
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

Disclosed are a method and apparatus for improving the fatigue characteristics of a glass optical waveguide fiber. After the fiber is drawn and before it is provided with a protective coating it is heated to a temperature within the annealing temperature range. A filtered gas may be flowed over the fiber during the step of heating.

## Claims

### Claim 1

In the method of forming a low loss optical waveguide fiber comprising the steps of
drawing from a source of molten non-devitrifiable glass a fiber having a core and an outer cladding layer, said fiber having a hydroxyl ion content less than 100 ppm, and
applying a protective coating of plastic material to said fiber,
the improvement comprising
heating said fiber, while said fiber is being drawn and prior to applying a coating thereto, to a temperature within the annealing temperature range of the cladding glass to improve the fatigue characteristics of said fiber without devitrifying said core or cladding glass.

### Claim 2 (depends on 1)

A method in accordance with claim 1 further comprising the step of flowing a filtered gas over said fiber during the step of heating.

### Claim 3 (depends on 2)

A method in accordance with claim 2 wherein, during the step of heating said fiber, the temperature of said fiber is between 900.degree. C. and 1300.degree. C.