Patent ID: 7565820

Claim:
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.