Patent ID: 6718800
Filing Date: 2004-04-13
Classification: C03B,Y02P

Abstract:
A method of preparing a preform for an optical fiber, the preform having a central duct with a last-deposited core layer on a surface of the duct, an intake end and an exhaust end, comprising:first heating the preform at a first temperature of at least about 2150+/âˆ’100Â° C. and which is sufficient to initiate a partial collapse of the central duct; partially collapsing the central duct while performing the first heating step until the central duct has a diameter between approximately 3 and 1.5 mm; etching the partially collapsed duct at a second temperature of approximately 1600Â° C. to 2000Â° C. and which is lower than the first temperature by an amount sufficient to keep the duct in an open condition while removing a portion of the core layer last-deposited on the surface of the duct; and second heating the preform at a temperature sufficient to collapse the duct of the preform fully after the etching step, thus forming a solid preform rod.