Alcatel

Alcatel Alsthom Compagnie Generale D'electricite

Jean-Jacques Girard

Pascal Baniel

Fr&eacute;d&eacute;ric Chiquet

Marylise Le Crom

Frederic Chiquet

Marylise Le Thuaut

The invention provides a monomode optical fiber and a monomode preform ( ) having a mother preform ( ) housed in an outer sleeve tube ( ). It is characterized in that it also includes an intermediate tube ( ) between the mother preform ( ) and the outer tube ( ), the intermediate tube ( ) possessing viscosity at fiber-drawing temperature which is less than the viscosity(ies) at fiber-drawing temperature of the mother preform ( ) and of the outer tube ( ). The invention also provides a method of manufacturing a monomode optical fiber. The fiber has a core that is better centered and less deformed than in the prior art. An application of the invention lies in making an optical amplifier.

Method of manufacturing a monomode fluoride optical fiber, and an optical amplifier using such a fiber

A method of fabricating a fluoride glass optical fiber preform which has a fluoride glass core surrounded by a fluoride glass optical cladding includes the following steps: introducing the cladding glass in the molten state into a bottom part of a mold having a cylindrical inside cross-section, introducing the core glass in the molten state into a top part of the mold above the cladding glass, and inwardly solidifying the core glass and the cladding glass from the interface between the glasses and the mold. The kinetics of solidification of the core glass are such that complete solidification of the cladding glass occurs before complete solidification of the core glass. The method further includes the following operations: centrifuging the content of the mold simultaneously with the solidification, wherein because of the reduction in the volume of the glasses during the solidification, a central portion empty of glass and of substantially cylindrical cross-section is formed around an axis of the mold by the completely solidified cladding glass, which thereby forms the cladding of the preform, wherein the core glass is not completely solidified at the end of the centrifuging, after the centrifuging operation, causing the unsolidified core glass to flow into the central portion,so forming the core of the preform, and removing the solidified preform from the mold.

Method of centrifuging a halide glass and forming an optical fiber

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St Germain les Arpajon, France

Jean-Jacques Girard