Prysmian S.p.a.

Prysmian Cavi E Sistemi Energia S.r.l.

Fibre Ottiche Sud - F.o.s. S.p.a.

Antonio Schiaffo

Franco Cocchini

Valeria Caronna

Stefano Grieco

Alessandro Rossi

Marco Antonio Caiata

Antonio Adigrat

Andrea Mazzotti

Giuseppe Ferri

Mattheus Jacobus Nicolaas Van Stralen

Antonio Collaro

Tonino Caruso

Irene Di Giambattista

Nicola Scafuro

Giuseppe Galasso

Gertjan Krabshuis

Cedric Gonnet

A process and an apparatus for drying and consolidating an optical fibre preform in a furnace tube comprising a heating chamber, wherein an extension tube having an extension chamber configured to house at least a length portion of the preform is removably joined to the furnace tube and the drying process starts with the preform not completely inserted into the furnace tube, an upper length portion of the preform being surrounded by the extension tube joint to the furnace tube.

Method and apparatus for drying and consolidating a preform for optical fibres

The present invention relates to a method for manufacturing a preform for optical fibers, which method comprises the sequential steps of: i) deposition of non-vitrified silica layers on the inner surface of a hollow substrate tube; ii) deposition of vitrified silica layers inside the hollow substrate tube on the inner surface of the non-vitrified silica layers deposited in step i); iii) removal of the hollow substrate tube from the vitrified silica layers deposited in step ii) and the non-vitrified silica layers deposited in step i) to obtain a deposited tube; iv) optional collapsing said deposited tube obtained in step iii) to obtain a deposited rod comprising from the periphery to the center at least one inner optical cladding and an optical core; v) preparation of an intermediate layer by the steps of: * deposition of non-vitrified silica layers on the outside surface of the deposited tube obtained in step iii) or deposited rod obtained in step iv) with a flame hydrolysis process in an outer reaction zone using glass-forming precursors, and subsequently; * drying and consolidating said non-vitrified silica layers into a vitrified fluorine-doped silica intermediate cladding layer; and * in case preceding step iv) was omitted collapsing; to provide a solid rod comprising from the periphery to the center the intermediate layer, at least one inner optical cladding and an optical core; wherein a fluorine-comprising gas is used during the deposition and/or drying and/or consolidating and wherein the intermediate layer has a ratio between the outer diameter of the intermediate cladding layer (C) to the outer diameter of the optical core (A) that is at least 3.5; vi) deposition of natural silica on the outside surface of the intermediate cladding layer of the solid rod obtained in step v) by melting natural silica particles in an outer deposition zone to produce an outer cladding whereby a preform is obtained.

Method for manufacturing a preform for optical fibers

Methods for manufacturing fluorine-doped glass preforms for optical fibers are disclosed. An exemplary method includes exposing a soot preform to an atmosphere containing a fluorine-containing gas in a first elongated chamber of a first furnace. The first elongated chamber typically has a single isothermal hot zone, which may be maintained at a doping temperature of about 800&#xb0; C. to 1200&#xb0; C., to obtain a fluorine-doped soot preform. The exemplary method further includes dehydrating the fluorine-doped soot preform by exposing it to an atmosphere containing a chlorine-containing gas in a second elongated chamber of a second furnace. The second elongated chamber typically has an upper hot zone, which may be maintained at a dehydration temperature of about 1000&#xb0; C. to 1350&#xb0; C., and a lower hot zone, which may be maintained at a consolidation temperature of about 1500&#xb0; C. to 1650&#xb0; C. Dehydration of the fluorine-doped soot preform typically occurs in the upper hot zone of the second furnace. The exemplary method further includes consolidating the fluorine-doped soot preform within the lower hot zone of the second furnace to form a fluorine-doped glass preform.

Method for manufacturing a glass preform for optical fibers

The present invention relates to a method for manufacturing a preform of silica for optical fiber production, as well as to a method for the production of optical fibers comprising a step of drawing the optical fiber from such a preform of silica, the method comprising a step of vaporization of a siloxane feedstock added with a compound having the following formula (I): wherein R, R' and R&#x2033;, equal or different each other, are an alkyl group having from 1 to 5 carbon atoms, and A is a saturated or unsaturated chain of atoms selected from the group consisting of carbon atom, nitrogen atom, and oxygen atom, said chain A forming with the nitrogen atom linked thereto a saturated, unsaturated or aromatic heterocyclic moiety. 

Method for manufacturing silicon dioxide preforms employed in the production of optical fibers

A method of manufacturing a glass core preform for an optical fibre comprising: providing a porous soot core preform having an outer surface) and a central hole extending axially therethrough; dehydrating the porous soot core preform at a first temperature by exposing the outer surface of the preform to an atmosphere containing chlorine, and simultaneously consolidating the soot core preform and closing the central hole at a second temperature higher than the first temperature to form a glass core preform, wherein consolidating and closing comprises sequentially alternating flowing chlorine containing gas into the central hole and reducing the internal pressure of the central hole.

Method of manufacturing preforms for optical fibres having low attenuation loss

Apparatus for applying traction to an elongate cylindrical element produced by fusion of an end portion of a preform of glass material, in which a traction device is capable of being connected to a portion of the elongate cylindrical element to provide traction of the elongate cylindrical element along an axis. A device for the rotation of the elongate cylindrical element applies a twist to the elongate cylindrical element about the axis simultaneously with the traction.

Plant for producing an elongate element usable for producing an optical fibre

An apparatus and method for chemical deposition on a rod member having a support structure for supporting the rod member substantially coaxial to a deposition axis; a burner for depositing chemical substances on the rod member; and a rotation device for imparting a rotation motion to the rod member. The rotation device has a joint member of a type suitable to transmit torque between two misaligned members, for example, a double universal joint or a flexible joint, positioned between a motor and a rod gripping member.

Apparatus and method for chemical deposition on a rod member in an optical fibre manufacturing process

Apparatus and method for applying traction to an elongate element produced by fusing a preform of glass material and usable in a process for producing an optical fibre

A process for manufacturing an optical fiber includes: drawing an optical waveguide from a glass preform; applying a layer of a first coating material on the optical waveguide; curing the first coating layer material to obtain a first coating layer; applying a layer of a second coating material onto the first coating layer; applying a layer of colored coating material onto the second coating layer; curing the second coating material and the colored coating material in a single step to obtain a second coating layer superposed on the first coating layer and a colored coating layer superposed on the second coating material layer, the obtained second coating layer having an elastic modulus higher than that of the first coating layer and lower than that of the colored coating layer. An optical fiber and an apparatus for producing it are also provided.

Process for manufacturing an optical fiber and an optical fiber so obtained

An apparatus and method for forming a optical fiber (,) which includes a furnace (,) for softening an optical fiber blank (,); a tractor (,) for drawing the optical fiber (,) from the softened optical fiber blank (,); and a first applicator (,) for applying a coating of a first coating material to the optical fiber (,), the first applicator having a rotatable die.

Method for producing a coated optical fiber with reduced polarization mode dispersion

An apparatus for forming a optical fiber which includes a furnace for softening an optical fiber blank; a tractor for drawing the optical fiber from the softened optical fiber blank; and a first applicator for applying a coating of a first coating material to the optical fiber, the first applicator having a rotatable die.

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Salerno, Italy

Antonio Schiaffo