Abstract: A telecommunication optical fiber cable and in particular a reduced diameter optical cable with improved installation features for use in the end part of an access telecommunication network. The optical fiber cable has a number of optical fibers; at least a core tube containing the optical fibers; a jacket surrounding the core tube; and at least one strength rod spaced from the central axis, the cable having a twisting stiffness G*Jp, wherein G is the elastic shear modulus; and Jp is the polar moment of inertia of a cable section, wherein the twisting stiffness G*Jp is lower than or equal to 0.10 Nm2, preferably lower than or equal to 0.05 Nm2, and more preferably lower than or equal to 0.02 Nm2. The cable is profitably installable by a blown method.

Abstract: A telecommunication fiber optic cable for gas pipeline application has a built-in leakage detecting device. The cable has an optical core including a number of telecommunication optical fibers, an outer jacket covering the optical core, and one or more gas leakage detector optical fibers. One or more gas leakage detector optical fibers are enclosed within the outer jacket. Preferably, the cable has a linearly extending rod reinforcing system having strength rods that force the cable to bend in a preferential bending place. Preferably, the leakage detector optical fibers are located at, or close to, a plane that is substantially orthogonal to the preferential bending plane and passing through the cable neutral axis.

Abstract: A telecommunication optical cable has a number of optical fibers; at least a microsheath loosely containing the optical fibers, the at least one microsheath loosely containing the optical fibers therein forming at least one corresponding microbundle, wherein the optical fibers are stranded according to an open helix trajectory.

Abstract: Optical fiber ribbon having an optical fiber with a radiation curable internal coating and a radiation curable colored coating disposed to surround the internal coating, and a radiation curable matrix material surrounding one or more of the optical fibers to form a ribbon, in which: the colored coating has a degree of adhesion to the inner coating which is higher than the degree of adhesion to the matrix material; and the optical fiber in the optical fiber ribbon shows, upon aging of the ribbon for at least two weeks in water at 60° C., an increase in the attenuation of the transmitted signal at 1550 nm of less than 0.05 db/km with respect to the attenuation of the assembled optical fiber measured before aging.

Abstract: A telecommunication optical cable has a number of optical fibers; at least a microsheath loosely containing the optical fibers, the at least one microsheath loosely containing the optical fibers therein forming at least one corresponding microbundle, wherein the optical fibers are stranded according to an open helix trajectory.

Abstract: An optical cable having an optical core with a strength member and optical fibers embedded in a thermoplastic material. The optical core has a joint section having substantially the same diameter as the one of the optical core. The joint section has a jointed strength member and a plurality of spliced optical fibers, the jointed portion of the strength member and the spliced portion of the optical fibers being embedded into a cured polymeric material. A method for manufacturing an optical core is also disclosed.

Abstract: An optical cable having at least one element for the transmission of optical signals and a structure that is able to protect the at least one element. The structure is a multilayer structure and is arranged in a position radially external to the at least one element and has a) at least one first covering layer of polymeric material in a position radially external to the at least one element; b) at least one covering layer of foamed polymeric material in a position radially external to the at least one first covering layer, and c) at least one second covering layer of polymeric material in a position radially external to the at least one covering layer of foamed polymeric material. The foamed polymeric material has a density between 0.3 and 0.7 kg/dm3 and tensile modulus at 20° C. between 300 and 700 MPa.

Abstract: The invention relates to a radiation curable colored coating composition for coloring a coated optical fiber wherein the coating, when disposed and cured to surround an optical fiber coated with an internal coating, and when said colored fiber is coated with a matrix material and assembled into an optical fiber ribbon, said colored coating has a degree of adhesion to the internal coating which is higher than the degree of adhesion to the matrix material and said optical fiber assembled into said optical fiber ribbon shows, upon aging for at least two weeks in water at 60° C., an increase in the attenuation of the transmitted signal at 1550 nm of less than 0.05 db/km with respect to the attenuation of the assembled optical fiber measured before aging. The invention also relates to said colored coating composition when used in an optical fiber ribbon.

Abstract: Optical fiber ribbon having an optical fiber with a radiation curable internal coating and a radiation curable colored coating disposed to surround the internal coating, and a radiation curable matrix material surrounding one or more of the optical fibers to form a ribbon, in which: the colored coating has a degree of adhesion to the inner coating which is higher than the degree of adhesion to the matrix material; and the optical fiber in the optical fiber ribbon shows, upon aging of the ribbon for at least two weeks in water at 60° C., an increase in the attenuation of the transmitted signal at 1550 nm of less than 0.05 db/km with respect to the attenuation of the assembled optical fiber measured before aging.

Abstract: A submarine optical cable resistant to a longitudinal flow of water accidentally penetrated inside it and a method for controlling the longitudinal flow of water inside the cable. The cable has a longitudinal cavity disposed along a deformable elongated hollow body. The longitudinal cavity is suitable dimensioned so that the head losses of the water flowing through the cavity are lower than the head losses of the water flowing inside the buffer tubes. Thus, in case of accidental ingress of water inside the submarine cable, the water flow inside the buffer tubes is prevented from reaching long penetration lengths by the hydrostatic pressure of the water inside the longitudinal cavity acting onto the outer surface of the buffer tube.

Abstract: A submarine optical cable having a central polymeric buffer tube, said cable being particularly suitable for long-haul repeatered systems. A longitudinal reinforcing element is embedded into the walls of the central polymeric buffer tube which is of relatively small dimensions. The presence of said reinforcing element allows a precise control over the excess fiber length within the buffer tube. This reinforcing element is of relatively small diameter, in order to comply with the requirements of reduced dimensions of the buffer tube. Notwithstanding this relatively small diameter, said longitudinal reinforcing element allows for a good control over the longitudinal shrinkage of the polymeric buffer tube within the submarine cable.

Abstract: The invention relates to a radiation curable colored coating composition for coloring a coated optical fiber wherein the coating, when disposed and cured to surround an optical fiber coated with an internal coating, and when said colored fiber is coated with a matrix material and assembled into an optical fiber ribbon, said colored coating has a degree of adhesion to the internal coating which is higher than the degree of adhesion to the matrix material and said optical fiber assembled into said optical fiber ribbon shows, upon aging for at least two weeks in water at 60° C., an increase in the attenuation of the transmitted signal at 1550 nm of less than 0.05 db/km with respect to the attenuation of the assembled optical fiber measured before aging. The invention also relates to said colored coating composition when used in an optical fiber ribbon.

Abstract: The present invention relates to a submarine optical cable comprising a central polymeric buffer tube, said cable being particular suitable for long-haul repeatered systems. A longitudinal reinforcing element is embedded into the walls of the central polymeric buffer tube which is of relatively small dimensions. The presence of said reinforcing element allows a precise control over the excess fiber length within the buffer tube. This reinforcing element is of relatively small diameter, in order to comply with the requirements of reduced dimensions of the buffer tube. Notwithstanding this relatively small diameter, said longitudinal reinforcing element allows for a good control over the longitudinal shrinkage of the polymeric buffer tube within the submarine cable.

Abstract: A submarine optical cable resistant to a longitudinal flow of water accidentally penetrated inside it and a method for controlling the longitudinal flow of water inside the cable. The cable has a longitudinal cavity disposed along a deformable elongated hollow body. The longitudinal cavity is suitable dimensioned so that the head losses of the water flowing through the cavity are lower than the head losses of the water flowing inside the buffer tubes. Thus, in case of accidental ingress of water inside the submarine cable, the water flow inside the buffer tubes is prevented from reaching long penetration lengths by the hydrostatic pressure of the water inside the longitudinal cavity acting onto the outer surface of the buffer tube.

Abstract: The described ribbon optical fibre cable comprises a cylindrical core (9) provided, on the outer surface thereof, with parallel grooves (10) extending in a helical manner along the cable axis, at least a pair of ribbons (1) being radially superposed within at least one of said grooves (10). Each ribbon (1a, 1b, 1c, 1d, 1e) comprises a plurality of optical fibres (2) each of which is covered with a primary layered coating (3), and a common coating (4) covers all the optical fibres of the ribbon. The primary coating (3) is formed with a first layer (5) directly in contact with the fibres (2) and a second layer (6) external to the first layer (5), the modulus of elasticity of said first layer (5) being lower than the modulus of elasticity of said second layer (6). Applied to each ribbon (1a, 1b, 1c, 1d, 1e) is a longitudinal tension greater than the longitudinal tension applied to the ribbon radially overlying the former.

Abstract: A joint, and a method for forming such joint, between two optical fiber cables or cores having closed-helix grooves each loosely receiving at least one optical fiber. A cylindrical body having open-helix grooves is interposed between the two cores so that the latter grooves interconnect corresponding grooves of the cores. The ends of the optical fibers are joined, and the fibers are then placed in the grooves of the cylindrical body.