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US 7,565,820 B2Granted
Methods and apparatus for forming heat treated optical fiber
AssigneeCorning Incorporated
InventorsJohn D. Foster, Hazel B. Matthews, III
Life of this patent
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Abstract
A method for forming an optical fiber includes drawing the optical fiber from a glass supply and treating the fiber by maintaining the optical fiber within a treatment temperature range for a treatment time. Preferably also, the fiber is cooled at a specified cooling rate. The optical fiber treatment reduces the tendency of the optical fiber to increase in attenuation due to Rayleigh scattering, and/or over time following formation of the optical fiber due to heat aging. Apparatus are also provided.
Claims23
A method of manufacturing optical fiber, comprising the steps of:
- drawing the optical fiber from a heated glass source at a draw rate of greater than or equal to 10 m/s,
- heat treating the optical fiber by maintaining the optical fiber in a heated treatment zone for a total residence time greater than 0.07 seconds and less than 0.25 seconds while subjecting the optical fiber to an average cooling rate in the heated treatment zone, defined as a fiber entry surface temperature minus a fiber exit surface temperature divided by the total residence time of the optical fiber in the heated treatment zone, of greater than 2,500° C./s and less than 3,500° C./s;
- wherein the method further comprises subjecting the fiber to at least two heating zones during heat treating, wherein a first zone closer to the draw furnace is controlled to have a temperature between 1,100°C. and 1,300°C. and a second zone further downstream from the draw furnace is controlled to a temperature between 1,400°C. and 1,500°C.
A method of manufacturing optical fiber, comprising the steps of:
- providing a heated glass preform having a germania-doped central core region and a substantially pure silica cladding region,
- drawing the optical fiber from a heated glass preform at a draw rate of greater than or equal to 15 m/s and at a draw tension between 25 and 200 grams, and
- heat treating the optical fiber in a heated treatment zone having an atmosphere containing helium flowing at greater than 10 liters/minute, and having a fiber entry surface temperature of the optical fiber into the heated treatment zone is greater than 1,600° C., a fiber exit surface temperature of the optical fiber from the heated treatment zone between 1,300° C. and 1,400° C., and the optical fiber is maintained in the heated treatment zone for a total residence time of greater than 0.07 and less than 0.15 seconds while controlling an average cooling rate of the optical fiber in the heated treatment zone to be greater than 2,000° C./s and less than 3,500° C./s.
A method of manufacturing optical fiber, comprising the steps of:
- drawing the optical fiber from a heated glass source at a draw rate of greater than or equal to 10 m/s, and
- heat treating the optical fiber by maintaining the optical fiber in a heated treatment zone for a total residence time greater than 0.07 seconds and less than 0.25 seconds while subjecting the optical fiber to an average cooling rate in the heated treatment zone, defined as a fiber entry surface temperature minus a fiber exit surface temperature divided by the total residence time of the optical fiber in the heated treatment zone, of greater than 1,200° C./s and less than 5,000°C./s,
- wherein during the step of heat treating, the optical fiber is exposed to a furnace temperature in at least a part of the heated treatment zone of greater than 1,300° C., and
- wherein the fiber is subjected to multiple heating zones during the step of heat treating, at least one heating zone of the multiple heating zones being set to different temperature as compared to another of the multiple heating zones;
- wherein the at least one heating zone of the multiple heating zones is controlled to have a temperature of between 1,400° C. and 1,600° C;
- and
- wherein a first zone closer to the draw furnace is controlled to have a temperature between 1,100° C. and 1,300° C. and a second zone further downstream from the draw furnace to a temperature between 1,400° C. and 1,500° C.
4 more elements
Dependencies are inferred from the claim text.