Optical fiber draw furnace system and method

1. A method of operating an optical fiber draw furnace, the method comprising:

positioning a downfeed handle for supporting an optical fiber preform within a furnace such that the downfeed handle is movable within the furnace; and

operating one or more heating elements to thermally heat at least a portion of an upper muffle extension disposed within the furnace, the one or more heating elements being moveable with the downfeed handle,

wherein operating the one or more heating elements comprises heating at least a portion of the downfeed handle to a temperature ranging from about 400° C. to about 1000° C.

2. The method of claim 1 , further comprising injecting a process gas around the downfeed handle.

3. The method of claim 2 , wherein the process gas is at least one of nitrogen and argon.

4. The method of claim 1 , further comprising operating a lower heater within the furnace, the upper muffle extension being disposed above the lower heater within the furnace.

5. The method of claim 1 , wherein operating the one or more heating elements comprises heating the downfeed handle such that only a portion of the downfeed handle that is disposed within the upper muffle extension is heated.

6. The method of claim 1 , wherein operating the one or more heating elements comprises heating at least the portion of the downfeed handle to a temperature of about 800° C.

7. The method of claim 1 , wherein operating the one or more heating elements comprises sequentially heating a plurality of zones of the downfeed handle.

8. The method of claim 7 , wherein:

the plurality of zones comprises a first zone that is disposed closest to a lower heater of all the zones of the plurality of zones, and

sequentially heating the plurality of zones comprises heating the first zone after moving the downfeed handle relatively closer to the lower heater.

9. The method of claim 8 , wherein:

the plurality of zones further comprises a second zone, the first zone being located relatively closer to the lower heater than the second zone, and

sequentially heating the plurality of zones comprises heating the second zone after heating the first zone and after moving the downfeed handle relatively closer to the lower heater.

10. The method of claim 9 , wherein:

the plurality of zones further comprises a third zone, the first zone and the second zone being located relatively closer to the lower heater than the third zone, and

sequentially heating the plurality of zones comprises heating the third zone after heating the first zone and the second zone and after moving the downfeed handle relatively closer to the lower heater.

11. The method of claim 10 , further comprising reducing power applied to the first zone after moving the downfeed handle to a predetermined position relative to the lower heater while maintaining the power applied to the second zone and to the third zone.

12. The method of claim 7 , wherein sequentially heating the plurality of zones comprises heating one or more additional zones as the downfeed handle moves relatively closer to a lower heater.

13. The method of claim 12 , wherein sequentially heating the plurality of zones further comprises reducing power applied to at least one zone when the downfeed handle moves to a predetermined position relative to the lower heater.

14. The method of claim 1 , further comprising:

supporting an optical fiber preform from the downfeed handle, and

drawing an optical fiber from the optical fiber preform.

15. The method of claim 1 , wherein the one or more heating elements are coupled to the downfeed handle.

16. The method of claim 15 , wherein the one or more heating elements are disposed on the downfeed handle.