Thomas R Mcdonald, Age 953786 Oak Trail Rd, Abbott, MS 39773

6834516, Dec 28, 2004

Apr 24, 2002

10/131700

Donald P. Jablonowski - Dunwoody GA
Thomas E. McDonald - Acworth GA
Fengqing Wu - Duluth GA

Furukawa Electric North America Inc - Norcross GA

C03B 3707

65389

Dynamically controlling the reaction temperature at the tip of a soot preform by controlling the flow of hydrogen gas to the core torch provides a wide latitude of control over the temperature range necessary to produce uniform composition of the preform.

7021083, Apr 4, 2006

Jan 29, 2003

10/353354

Thomas E. McDonald - Acworth GA, US
Fengqing Wu - Duluth GA, US

Fitel USA Corp. - Norcross GA

C03B 37/018

65404, 65 23, 65414, 65433, 65427

A glass tube for use in an optical fiber preform is produced by applying a first soot on an end face of a starting member to form an elongated, porous cylindrical soot core having a first density, and applying a second soot including SiOon the periphery of the soot core to form a porous soot cladding having a second density greater than that of the soot core at the periphery of the core. The core and the cladding are later heated together at a temperature sufficient for sintering to form a core glass and a cladding glass. Because the soot core collapses at a greater rate than the soot cladding during sintering, the core glass separates or delaminates radially from the cladding glass. The core glass is then removed from the surrounding cladding glass, and the latter is treated to provide a high purity glass tube suitable for use as part of an optical fiber preform.