International Standard Electric Corporation

Andrew Peter Harrison

John Irven

In the manufacture of silica optical fibers a tube having an internal coating of a volatile dopant is locally heated by a hot zone repeatedly traversed along its length to promote shrinkage and finally collapse of the tube bore. During the shrinkage prior to the final collapse traversal a gas flow of oxygen and a halide of the volatile dopant is maintained through the tube in order firstly to provide a small overpressure to ensure circularity in the shrinkage and secondly to compensate for the tendency for dopant to be lost by volatilization.

Method of manufacturing optical fibre preforms

A method is described of increasing the proportion of chemical vapor reaction deposited material to substrate material in a silica optical fiber preform. The deposited material is deposited upon the bore of a silica substrate tube whose bore is then collapsed to form the preform. The preform is then heated to cause some of the surface of the preform to be driven off by volatilization in order to increase the proportion of chemical vapor reaction deposited material to substrate material up to a predetermined value.

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Stansted, United Kingdom

Andrew Peter Harrison