Abstract: In a process for producing a low polarization mode dispersion optical fiber, which comprises the steps of drawing a glass preform into an optical fiber and of spinning, during drawing, the optical fiber about an optical fiber axis, the spinning is imparted according to a bidirectional and substantially trapezoidal spin function, which includes zones (P) of substantially constant amplitude (plateau) and zones of transition (T) where inversion of the spin direction takes place, wherein the extension (p) of the zones of substantially constant amplitude is greater than the extension (t) of the zones of transition, and the number of inversions of the direction of spin in a length of fiber of 20 m is at most two.

Abstract: A method of disposing a tubular covering sleeve for electric-cable joints on a supporting element may include arranging the sleeve in a rest and not yet expanded condition; causing radial expansion of the sleeve starting from axially opposite end portions; and arranging the sleeve in a radially expanded condition on the supporting element. Radial expansion of the sleeve may be carried out gradually, starting from the end portions of the sleeve toward an axially intermediate portion of the sleeve. The method of may include arranging the sleeve; arranging a pair of expanders, each at a respective end of the sleeve and at a substantially coaxial position relative to the sleeve; introducing the expanders into the respective ends of the sleeve; abutting distal ends of the expanders against each other at an axially intermediate portion of the sleeve; and arranging the sleeve in a radially expanded condition on the supporting element.

Abstract: Cable for high voltage direct current transmission having at least one conductor and at least one extruded insulating layer consisting of a polymeric composition of a polyethylene and at least one unsaturated fatty acid. Insulating composition having a polyethylene and at least one unsaturated fatty acid.

Abstract: A method and apparatus for manufacturing an optical cable comprising at least one metal tube housing at least one optical fiber and having a predetermined excess fiber length (EFL) is described. In this method the metal tube is plastically deformed and shortened by a predetermined amount (St) greater than the predetermined EFL and is plastically deformed after shortening to provide a controlled elongation thereof so as to reach the predetermined excess fiber length. An optical cable so manufactured has a local excess fiber length (EFL) varying of or less than 0.2 % along the longitudinal extension of the cable with respect to an average EFL of the cable.

Abstract: A method for manufacturing a cable, the cable including at least one transmissive element and at least one coating layer made of a polymeric material and arranged at a radially outer position with respect to the transmissive element. The method includes the steps of: a) feeding the polymeric material to an extrusion apparatus including an extrusion head, the extrusion head including a male die; a female die coaxially arranged with respect to the male die; a conveying channel, at least one portion of which is defined between the male die and the female die; and b) controlling a cross-sectional area of the at least one portion of the conveying channel in response to a detected quantity, the quantity being caused to vary during the manufacturing of the cable as a function of the actual extrusion speed. An extrusion apparatus for carrying out the process.

Abstract: A method of coating the junction area between elongated elements, in particular between electric cables. This method includes the steps of: arranging a rigid tubular support having two axially separable tubular halves; mounting an elastic tubular sleeve in an elastically radially expanded condition on an outer surface of the support; interposing a lubricating material between the support and sleeve; arranging a circumferentially continuous sealing element between the halves to prevent the lubricant from percolating between the halves; positioning the support around the junction area; and moving the halves apart from each other to enable the sleeve to collapse on the junction area. A device for coating the junction area between elongated elements and a method of making the device and a joint for electric cables.

Abstract: A method of coating the junction area between elongated elements, in particular between electric cables. This method includes the steps of: arranging a rigid tubular support having two axially separable tubular halves; mounting an elastic tubular sleeve in an elastically radially expanded condition on an outer surface of the support; interposing a lubricating material between the support and sleeve; arranging a circumferentially continuous sealing element between the halves to prevent the lubricant from percolating between the halves; positioning the support around the junction area; and moving the halves apart from each other to enable the sleeve to collapse on the junction area. A device for coating the junction area between elongated elements and a method of making the device and a joint for electric cables.

Abstract: A cable having a conductor and a flame-retardant coating having (a) a polymer matrix; and (b) natural magnesium hydroxide particles having an average size (d50) of 0.5 ?m to 5.0 ?m and an average pore diameter less than or equal to 0.35 ?m.

Abstract: Optical fiber has a glass portion and at least one coating of crosslinked polymer material surrounding the glass portion, the coating being obtained by crosslinking a composition of (a) at least one radically crosslinkable oligomer containing at least two reactive functional groups and having a number average molecular weight lower than about 1,000, preferably between about 400 and about 900; (b) at least one cationically crosslinkable compound containing at least one reactive functional group; (c) at least one free radical photoinitiator; and (d) at least one cationic photoinitiator. Preferably, the coating is a secondary coating or, in the case of a ribbon of optical fibers, it is a common polymer coating known as a “common coating”.

Abstract: A burner for a vapor deposition process has a cylindrical central gas passage and a plurality of external gas passages surrounding the central gas passage. The burner has a back block defining an initial section of the gas passages, a face block defining a final section of the gas passages and a manifold plate positioned between the back block and the face block and defining an intermediate section of the external gas passages; the face block, the manifold plate and the back block have inner integral walls that define respective sections of the central gas passage.

Abstract: A method for manufacturing an optical cable for communication includes at least one micromodule, said micromodule being blocked with respect to the propagation of water. The method includes the steps of providing at least one optical fiber; embedding the at least one optical fiber in a pseudoplastic filling compound having a viscosity of 3 Pa·s to 30 Pa·s, preferably 7 Pa·s to 25 Pa·s at a shear rate of 10 s?1 and at a temperature of 100° C., and a cross-over lower than 30 Hz, preferably 5 Hz to 25 Hz, at a temperature of 100° C.; and extruding a retaining element made of a thermoplastic polymeric composition around the at least one optical fiber so embedded in the filling compound to obtain a micromodule.

Abstract: An optical cable for communication includes at least one retaining element blocked with respect to the water propagation as well as a process for manufacturing such an optical cable. The optical cable includes, in addition to the retaining element, at least two transmission elements housed within the retaining element and a water swellable yarn housed within the retaining element. The water swellable yarn is selected according to the following equation: V w V TF = k V t + R ( I ) in which Vw is the volume of the water swellable yarn after swelling upon contact with water; VTF is the total free volume in the retaining element; k is a constant?180; R is a constant?1.4; and Vt is the free volume per each transmission element. Advantageously, the optical cable is water-blocked and the water swellable yarn does not induce microbending effects on the transmission elements.

Abstract: An extrusion method and head for depositing by extrusion a polymeric material intended, in particular, for the production of cables includes a core and a coating layer arranged at a radially outer position with respect of the core. The method includes the steps of feeding the polymeric material in a feeding duct of the extrusion head and of conveying a part of the polymeric material towards an undercut extending in the extrusion head in proximity of an end of the feeding duct. The method provides a sealing force between a head body and a conveyor element of the extrusion head exerted by means of the pushing action exerted by the polymeric material in the undercut in a direction substantially perpendicular to the longitudinal axis of the head body.

Abstract: An apparatus for measuring the weight of a preform for optical fibers during a chemical deposition process for the formation of a preform is disclosed. The apparatus has at least one elastic constraint associated with at least one end portion of an elongated element made of a chemical deposition substrate for the formation of the preform, a device for inducing an oscillation, for example axial, on said elongated element, a device for detecting the frequency of oscillation of said elongated element, and a device for calculating the weight of the preform according to the detected frequency of oscillation. Advantageously, the device allows the realisation of a method for measuring the weight of the preform wherein the errors in measurement caused by thermal drift effects, by the axial distribution of the masses on the preform and by loads which are different from the mass of the preform in formation are reduced to below the required precision in measurement.

Abstract: 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.

Abstract: A method for producing an optical fiber having low polarization mode dispersion, by the steps of a) providing an optical fiber perform of glass material; b) heating the glass material of an end portion of the optical fiber perform; c) drawing the heated glass material at a drawing speed V to form an optical fiber, the drawn glass material having a viscous zone; and d) applying to the optical fiber a substantially sinusoidal spin, which is transmitted to the viscous zone, the spin function frequency ?, the viscous zone length L and the drawing speed V being such that both a torsion and at least a 50% detorsion are applied to the viscous zone.

Abstract: A cable includes at least one electrical conductor and at least one extruded covering layer including a thermoplastic polymer material in admixture with a dielectric liquid, wherein the thermoplastic polymer material includes (a) at least 75% by weight, with respect to the total weight of the thermoplastic polymer material, of at least one copolymer of at least two ?-olefin co-monomers, the copolymer having a melting enthalpy lower than 25 J/g; and (b) an amount equal to or less than 25% by weight with respect to the total weight of the thermoplastic polymer material of at least one propylene homopolymer or propylene copolymer with at least one ?-olefin, the at least one propylene homopolymer or propylene copolymer having a melting enthalpy higher than 25 J/g and a melting point higher than 130° C.

Abstract: A tubular covering sleeve for joints of electric cables may include a primary tubular body and a coating sheath. The primary tubular body may include at least one annular insert of semiconductive material integrated into at least one layer of insulating material. The coating sheath may include one or more layers of semiconductive material mechanically engaged in a condition of resilient radial expansion around the primary tubular body so as to exert a centripetal tightening action on the primary tubular body. A junction for electric cables may include devices for mutual connection between the conductors of the cables and a covering sleeve applied around the devices for mutual connection and around the cables. Each cable may include at least one conductor disposed in an insulating coating and a shielding coating externally applied to the insulating coating.

Abstract: Telecommunication cable having an elongated element housing at least one transmitting element. The elongated element has a water-soluble polymeric composition of a vinyl alcohol/vinyl acetate copolymer having a saponification degree of about 60% to about 95%; a plasticizer; a hydrolysis stabilizer compound having a chelant group having two hydrogen atoms bonded to two respective heteroatoms selected from nitrogen, oxygen and sulfur. The two hydrogen atoms have a distance between each other of 4.2×10?10 m to 5.8×10?10 m. The stabilizer compound is present in an amount of at least 0.75 mmoles per 100 g of copolymer. The elongated element is in particular a buffer tube housing a plurality of optical fibers. The presence of the stabilizer reduces the increase of the hydrolysis degree of the copolymer upon aging, thus maintaining the desired water blocking properties of the copolymer.

Abstract: An optical cable for communication includes at least one retaining element blocked with respect to the water propagation as well as a process for manufacturing such an optical cable. The optical cable includes, in addition to the retaining element, at least two transmission elements housed within the retaining element and a water swellable yarn housed within the retaining element. The water swellable yarn is selected according to the following equation: V w V TF = k V t + R ( 1 ) in which Vw is the volume of the water swellable yarn after swelling upon contact with water; VTF is the total free volume in the retaining element; k is a constant ?180; R is a constant ?1.4; and Vt is the free volume per each transmission element. Advantageously, the optical cable is water-blocked and the water swellable yarn does not induce microbending effects on the transmission elements.