Alcatel

Pierryle Jourdier

Jean-Florent Campion

Jean-Maxime Saugrain

Christelle Lavallade

Jean-Fran&ccedil;ois Chariot

Jacques Jolly

Rosine Meilleur

R&eacute;mi Fauche

Philippe Oskeritsian

Claire Wane Nguila

The invention relates to a method of doping silica with fluorine. The method described comprises mixing a powder of silica granules with a solid fluorine compound, thermally decomposing the solid fluorine compound under an inert atmosphere, and densifying the granules to obtain dense grains of doped silica. It is preferable to use ammonium bifluoride. The invention is applicable to preparing high index silica glass, in particular for fabricating optical fiber preforms.

Method of manufacturing a fluorine-doped silica powder

A method of manufacturing an optical fiber preform ( ) comprising: forming at least one silica-based outer deposition layer ( ) by depositing silica on a primary preform ( ) constituted by a bar mainly comprising silica and including a silica-based outer peripheral portion ( ), the method being characterized in that the viscosity of the outer deposition layer ( ) is adjusted to be substantially identical to the viscosity of the outer peripheral portion ( ) of the primary preform ( ) by adding to the silica, over a substantial portion of the outer deposition layer ( ), at least one compound selected from the group formed by the following compounds: CaF , MgF , AlF , B O , and Al O .

Method of depositing a layer of silica followed by a step of adding dopant to the layer

A process is described for making silica powder by a sol-gel process whereby an aqueous suspension is made of a silica-based raw material which includes particles containing chlorine, the pH of the suspension is adjusted to a value from 3 to 4.5 if necessary, the suspension is gelled, the gel obtained is dried and the dried gel is fractionated into silica granules. The silica-based raw material preferably includes particles containing chlorine having a specific surface area less than 80 m /g and less than 5 wt. % relative to the total quantity of particles containing chlorine of silica particles having a specific surface area from 150 m /g to 300 m /g. The use of such powder to manufacture an optical fiber preform is also described.

Process for making silica powder and use of such powder in the manufacture of an optical fiber preform

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Paris, France

Pierryle Jourdier