Prysmian S.p.a.

Prysmian Cavi E Sistemi Energia S.r.l.

Valeria Caronna

Stefano Grieco

Franco Cocchini

Antonio Schiaffo

Antonio Adigrat

Antonio Collaro

Ida Nivelli

Marco Ruzzier

Giuseppe Ferri

Marco Antonio Caiata

Susanna Cattelan

Andrea Macchetta

Irene Di Giambattista

Tonino Caruso

Angelo Mascolo

An apparatus for drying and/or consolidating an at least partially porous optical fibre preform.

Apparatus for drying and/or consolidating a preform for optical fibres

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

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

A method of manufacturing at least one optical fibre preform comprising: providing a plurality of partially porous intermediate preforms, each partially porous intermediate preform having a longitudinal axis and comprising a respective soot intermediate clad layer formed around a respective glass core rod comprising a central core region of radius a and an inner clad region of radius b to define a first core-to-clad ratio a/b; consolidating the formed soot intermediate clad layers to form a respective plurality of intermediate glass preforms, each of the plurality of intermediate glass preforms comprising an intermediate clad region having an external radius c to define a second core-to-clad ratio a/c of from 0.20 to 0.30 , and overcladding at least one intermediate glass preform by forming an overclad region surrounding the intermediate clad region to form an optical fibre glass preform, wherein consolidating comprises exposing the plurality of intermediate preforms to a consolidation hot zone of a single furnace body while rotating each of the intermediate preforms about its respective longitudinal axis.

Method of manufacturing preforms for optical fibres having low water peak

A method of manufacturing an optical fibre preform comprising: providing a glass core rod comprising a central core region of radius a and an inner clad region of external radius b to define a first core-to-clad ratio a/b; forming an intermediate glass preform comprising an intermediate clad region surrounding the inner clad region of the glass rod and having an external radius c to define a second core-to-clad ratio a/c, and overcladding the intermediate glass preform by forming an overclad region surrounding the intermediate clad region to form an optical fibre preform, wherein the first core-to-clad ratio a/b is equal to or less than 0.40 and the second core-to-clad ratio a/c is of from 0.20 to 0.25.

A method for detecting faulty laying down of an optical cable exhibiting a measured cut-off wavelength includes providing an optical cable for transmitting optical signals including at least one single-mode optical fiber having an attenuation equal to or larger than a first threshold value as measured when wound for one turn around a bending radius equal to or smaller than 5 mm at at least one predetermined test wavelength, the test wavelength being smaller than the measured cut-off wavelength, and an attenuation smaller than a second threshold value as measured when wound for one turn around a bending radius equal to at least a minimum bending radius at an operative wavelength equal to or larger than the measured cut-off wavelength; laying the optical cable; and measuring the attenuation in the at least one optical fiber at the predetermined test wavelength. An optical cable includes at least one optical fiber that is bend sensitive at a predetermined test wavelength not larger than the measured cut-off wavelength and is bend insensitive at an operative wavelength larger than the measured cut-off wavelength, where the cable operates in single-mode regime.

Method for checking the correct installation of a bend-insensitive optical cable and optical cable suitable for the method thereof

A process for producing a low-attenuation optical fiber by producing a soot core preform by chemical deposition on a substrate; removing the substrate from the soot core preform, thereby forming a central hole along the soot preform; drying and consolidating the soot core preform in a consolidation furnace to form a glass core preform; heating the glass preform in the consolidation furnace above a glass melting temperature to produce a reduction of the diameter of the central hole; and stretching the glass core preform to completely close the central hole.

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Milan, Italy

Valeria Caronna