International Standard Electric Corporation

John Irven

Philip W Black

Andrew Peter Harrison

Henley F Sterling

Carl Peter Sandbank

Paul E Lighty

A rod of silica 14 is inserted into a substrate tube 10 whose bore is lined with a layer 11 of material having a refractive index less than that of silica. This layer 11 is itself covered with a layer 12 of silica. The assembly of the rod and tube is drawn into fibre, or its components are fused together to form a solid cross-section optical fibre preform.

Optical fibre preform manufacture

An optical glass fiber is formed of an inner layer of germania doped glass within the bore of the outer cladding tube of silica. The tube with the higher index of refraction inner layer is rotated while being heated to collapse the bore to form an optical fiber preform. The preform is then drawn into fiber in a separate operation. A first silica layer can be deposited within the tube bore before the germania doped layer. The deposition of germania takes place under hydrogen free conditions. Appropriate heat treatment of the tube avoids excessive evaporation of germania and provides a graded transition of the refractive index in the boundary between core and cladding.

Method of making solid preforms and optical fibers drawn therefrom

Single mode optical fibre for operation in the wavelength range 1.5 to 1.7 microns is made by depositing a cladding glass layer and then a core glass layer upon the bore of a silica substrate tube. The bore of the coated tube is then collapsed to form a solid cross-section optical fibre preform. The cladding glass has an index matching that of silica and either contains no oxide of phosphorus or the minimal amount to provide a low enough deposition temperature and high enough deposition rate to provide an acceptably low diffusion of hydroxyl groups from the material of the substrate tube. Optionally the deposition of the cladding may be preceded by the deposition of a diffusion barrier layer which may contain a higher proportion of oxide of phosphorus.

Single mode fibre and method of making

A method for making an optical fiber solid rod preform wherein a vapor reaction deposit process is used to form a localized deposit on an end face of a rod or disc by relative movement in which the position of the localized deposit is scanned over the end face of the solid rod or disc and at the same time the reaction is progressively changed to cause the deposit building up on the end face to have a radially graded refractive index profile.

Optical fiber manufacture

A method of manufacturing a continuous preform for an optical fibre of the type produced from glass or silica tubes or rods, the method including arranging the tubes or rods end to end in a rectilinear array, placing glass or silica sleeving tubes over the joints between the rods or tubes, and fusion sealing the joints between the rods or tubes.

Method of manufacturing a continuous optical preform

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 continuous flow process is disclosed in which optical fibre is made by a method involving the chemical vapor deposition of material upon the bore of a tube. The tube is fabricated from an annular crucible around a vertical gas feed and is lowered through a hot zone where it is softened and drawn into fibre. The gas deposits one or more layers on the inside of the tube prior to drawing so as to provide the drawn fibre with optical waveguide properties.

Optical fibre manufacture

High numerical aperture optical fibers are produced by the chemical vapor deposition of core material on the inner surface of a borosilicate glass tube and collapsing and drawing the tube into a fiber.

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.

A fiber optic preform is provided by depositing phosphorus pentoxide as a dopant on the bore of a silica tube to form a high refractive index layer and collapsing the tube to form a core of high index phosphorus pentoxide doped silica.

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Stansted, United Kingdom

John Irven