Alcatel

Alcatel Fibres Optiques

Alcatel N.v.

Draka Comteq B.v.

Jean-Florent Campion

Christelle Lavallade

Jean-Maxime Saugrain

Jacques Jolly

Pierryle Jourdier

Yves Lumineau

Pierre Ripoche

Alain Drouart

Pierre Rebreyend

Jacques Goudeau

Remi Fauche

Philippe Oskeritsian

R&eacute;mi Fauche

Pierre Sillard

Louis-Anne De Montmorillon

Pascale Nouchi

Ludovic Fleury

Maxime Gorlier

Laurent Gasca

Florent Beaumont

Beno&icirc;t Gouez

Philippe Dupont

G&eacute;rard Orcel

Jean-Fran&ccedil;ois Chariot

Jean-Philippe Francois

Roger Charlton

Bernard Jouvenel

Rosine Meilleur

Helene Jameron

Benoit Gouez

Jean-Francois Chariot

Marc Nicolardot

Sophie Dubois

Jos&eacute; G Piffaretti

Claire Wane Nguila

Isabelle DeCaux

Gérard Orcel

Terry Voots

Eric Tutin

Rémi Fauche

Virginie Herchuelz

Christine Labatut

The present invention provides an installation for fabricating or overcladding an optical fiber preform, which installation includes an inductive torch for producing a plasma from a plasma generating gas and material feed means and is characterized in that said plasma generating gas is a mixture of a first gas chosen from diatomic gases and mixtures of at least two gases and argon in a proportion by volume from 0.5% to 10%.

Overcladding an optical fiber preform using an air-argon plasma torch

The invention provides a low cost method of manufacturing high capacity preforms by chemical vapor deposition. More particularly, there is described a method of manufacturing an optical fiber preform, which method comprises the steps of providing a substrate tube of silica doped with sufficient chlorine to obtain an OH concentration of less than 100 ppb and doped with sufficient fluorine proportional to the chlorine doping to obtain a refractive index that is lower than that of a natural silica, depositing inner cladding and an optical core inside the substrate tube, collapsing the substrate tube to form a primary preform, and depositing outer cladding of said natural silica on the resulting primary preform. The invention is applicable to manufacturing optical fibers.

Method of manufacturing large capacity preforms by MCVD

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

The invention provides a step index optical fiber which presents cladding having an index lower than the index of silica and a core with an index higher than the index of silica. The fiber is obtained by drawing a preform made by chemical vapor deposition using a deposition tube of index lower than the index of silica. Inner cladding of index substantially equal to the index of the deposition tube, and then a core of index higher than the index of the inner cladding are deposited in succession therein. The invention makes it possible to obtain a fiber having a large effective area, reduced attenuation, and suitable for being fabricated at low cost by chemical vapor deposition.

Step index optical fiber with doped cladding and core, a preform, and a method of fabricating such a fiber

The method is designed to be implemented in an installation provided with means enabling a preform held between two points by supporting end-pieces to be rotated and to be moved in translation. Heater means for heating the preform by means of a plasma torch are associated with material supply means, so as to enable the preform to be manufactured in layers. Preform/torch relative displacements, with or without material being supplied, lead either to a new layer of material being deposited on the preform, or to the most recent layer deposited being glazed. Said method interposes a one-ended reduction in layer length, starting from one of the intermediate layers, while a succession of concentric layers are being deposited on the preform in a manner such that the lengths of the layers are progressively reduced so that the preform tapers towards it ends. The one-ended reduction leads to a limitation of the thickness of a determined segment at the level of the layer deposited immediately prior to the reduction.

Making an optical fiber preform including reducing the length of a deposition layer

A method for reducing the hydrogen aging loss of silica optical fibers by irreversible reaction of the peroxide defects with deuterium is described. This method comprises the step of contacting the optical fiber with deuterium by exposure to a gas mixture containing deuterium at a temperature compatible with the fiber without exposing the fiber to any further activation, and subsequently the step of degassing the fiber in a neutral atmosphere. The invention relates further to a process of producing optical fibers with low hydrogen aging loss wherein an optical fiber is treated using the method for reducing the hydrogen aging loss. Finally, the invention relates to optical fibers with low hydrogen aging loss obtainable by this process and telecommunication cables produced using these optical fibers. Using the new method, an activation step using intense light and/or elevated temperature is not necessary to achieve the reaction of peroxide defects in silica with deuterium. The process according to the invention allows reaction at temperatures such as the ambient temperature without any further activation.

Method for reducing the hydrogen sensitivity of optical fibers at 1380nm-1410 nm

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

Natural or synthetic silica is deposited on a preform set into rotation in front of a plasma torch which moves back and forth substantially parallel to a longitudinal direction of the preform, a first feed duct feeds the plasma with grains of natural or synthetic silica while a second feed duct feeds the plasma with a fluorine or chlorine compound, preferably a fluorine compound, mixed with a carrier gas. Any sodium or lithium contained in the grains of natural or synthetic silica react with the fluorine or chlorine of the fluorine or chlorine compound, thereby making it possible to improve the optical quality of fibers drawn from a preform built up with natural or synthetic silica, and to do so at reduced cost.

Method of purifying natural or synthetic silica, and application thereof to depositing purified natural or synthetic silica on an optical fiber preform

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

Silica granules made up of mutually agglomerated silica soot particles are treated by placing the granules in a crucible inside a furnace which contains an inert gas mixed with a chlorine-containing compound and in which the temperature lies in the range 1000&deg; C. to 1500&deg; C. According to the invention, a crucible is used that is made of porous graphite firstly to increase the surface area of the crucible through which the chlorine-containing compound diffuses. This gives rise to faster exchange between the granules and the gas for given partial pressure of the chlorine-containing compound, thereby improving purification. Secondly, the difference between the chemical natures of the silicas and the crucible make the two materials inert relative to each other so that the granules do not adhere to the walls of the crucible, thereby making it possible to recover the granules without having to apply any mechanical operation that might contaminate them.

Method and apparatus for treating silica granules using porous graphite crucible

Method of purifying silica and depositing on an optical fiber preform

An optical fiber preform comprising a core of radius R, and a sheath comprising cladding and outer sheath, wherein the outer sheath comprises an inner zone, and a peripheral zone made of silica doped with alumina and of thickness lying in the range 0.08 R to 2.2 R, and the proportion by weight of alumina in the peripheral zone is such that the equivalent concentration of alumina in the outer sheath as a whole lies in the range 100 ppm to 1000 ppm by weight of aluminum relative to silica. A method of manufacturing said preform, and an associated optical fiber.

Preform including a barrier layer preventing hydrogen from diffusing into optical fiber manufactured from said perform, and a method of preparing such a preform

In the method, a suspension of silica particles in water is provided, the suspension is gelled, the resulting gel is dried under microwaves, the dried gel is fractioned into silica granules having a diameter lying in the range 10 .mu.m to 1000 .mu.m, having an apparent density of about 0.5 g/cm.sup.3 to 0.6 g/cm.sup.3, and a porosity of less than 20%, and the granules are screened in the range 100 .mu.m to 500 .mu.m. The suspension in water of silica particles is made by mixing silica soots having a size of less than 0.1 .mu.m and silica grains having a size greater than 1 .mu.m. Its maximum concentration in total weight is greater than that of a suspension of synthetic soots on their own, thereby making it possible to increase the production capacity of the method. Advantageously, the out-of-range granules rejected by the screening are recycled as silica grains for the aqueous suspension, thereby making it possible to increase the accumulated production efficiency of the method.

Method of manufacturing a silica powder

A method of manufacturing a silica powder using a sol-gel technique, wherein a suspension consisting of synthetic silica soot, having a specific surface area of less than 80 m.sup.2 /g, is made in water to form a concentration of 50% to 75% by weight of silica; the suspension is gelled; the resulting gel is dried without forming a crust and with microwaves and broken up into silica grains having an apparent density of 0.5 g/cm.sup.3 to 0.6 g/cm.sup.3 ; and screening of the dry gel is performed to provide grains having a desired size.

Method of manufacturing a silica powder and use of such a powder in

A device for doping silica powder with a dopant includes an arrangement for receiving silica soot particles or previously fabricated silica granules. The particles or granules contained in the receiving arrangement are heated to a temperature sufficient to allow agglomeration of the soot particles into granules followed by densification of the granules. The receiving arrangement is fed with a precursor gas of the dopant so that the granules are heated in an atmosphere containing the precursor gas, which causes the dopant to be incorporated into the granules during their densification to produce densified and doped silica grains. The receiving arrangement is mobile so that, during their movement, each of the granules that it contains is subject to movement such that substantially all of its outside surface is exposed to the atmosphere containing the precursor gas.

Device for doping silica powder

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Conflans St Honorine, France

Jean-Florent Campion