Abstract: 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.

Abstract: A method of cooling an optical fiber during drawing through contact with at least one cooling fluid in at least one cooling area, wherein fast cooling, i.e. cooling that is faster than cooling in the surrounding air, from an initial temperature of the fiber to a temperature at the end of fast cooling of said fiber, is followed by slow cooling, i.e. cooling slower than cooling in the surrounding air, from a temperature of said fiber at the start of slow cooling to a temperature of said fiber at the end of slow cooling.

Abstract: The subject-matter of the invention is a fluorinated diol and its process of preparation. The fluorinated diol corresponds to the formula (I): CnF2n+1—A—CH2OCH2—C(CH2OH)2—R in which n has a value from 2 to 20 and A means —CH═CH— or —CH2CH2— and R is an alkyl group comprising 1 to 4 carbon atoms.

Abstract: A method of detecting a critical state of closing of a preform during a phase of closing of the preform following a phase of deposition of layers of material that reduce the radial size of an opening formed in the preform smaller in the radial direction comprises the steps of injecting a gas into the opening, measuring a pressure in a pipe element through which the injected gas flows and detecting the critical state of closing of the optical preform on the basis of a measured pressure.

Abstract: 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.

Abstract: The invention provides a polyurethane type polymeric material for coating optical fibers, based on a fluorinated diol with formula I: CnF2n+1—A—CH2OCH2—C (CH2OH)2—R where n is 2 to 20, and A signifies —CH═CH or —CH2CH2—, and R is an alkyl group containing 1 to 4 carbon atoms. The invention also provides a fiber coated with this polymer which has been light-cured, and a fiber drawing method comprising a step of coating the fiber with a material of the invention.

Abstract: The invention relates to an optical fiber preform comprising an optical core, optical cladding, and an outer sheath, in which the outer sheath includes a peripheral zone containing 20% to 100% by weight alumina and 80% to 0% by weight silica. Such a preform makes it possible to obtain optical fibers having improved mechanical strength and improved impermeability to hydrogen.

Abstract: A method of cooling an optical fiber during drawing through contact with at least one cooling fluid in at least one cooling area,

Abstract: 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.

Abstract: A method of coating an optical fiber, the method including at least one coating step using a coating composition and at least one polymerization step, the composition including a curable formulation and a compound having a low vaporization temperature, the quantity, by weight, of the compound having a low vaporization temperature lying in the range 0.5% to 20% of the composition, the vaporization temperature lying between the coating temperature and the polymerization temperature. The coating composition includes an acrylate resin and an ether, the quantity, by weight, of the ether lying in the range 0.5% to 20% of the composition. The ether can be an alkyl ether, in particular.

Abstract: Device for injecting non-oxidizing gas into a furnace with a graphite concentrator (12) as the heating element used to heat a primary preform in the enclosure of the furnace (14) and moving relative to the furnace in its axial direction, and comprising at the inlet orifice (24) and at the outlet orifice (26) of the enclosure a respective annular injector (40, 42) for injecting two conical curtains of non-oxidizing gas, the gas for each of the curtains being directed towards the apex of the cone and in the direction away from the enclosure (14) so as to prevent any entry into the enclosure of air that could cause combustion of the graphite.