Abstract: A tubular supporting element for supporting an elastic sleeve for covering a junction of cables which is provided with a wall which has a groove or incision directed according to a helical line and which has a radial depth from the outer surface of the supporting element less than the radial thickness of the supporting element. The incision has a mouth at the outer surface of the supporting element with a width of less than 0.1 mm, preferably less than 0.05 mm, so as to provide a strip between the incision having a substantially rectangular cross-section. Also, a process and an apparatus for making the tubular supporting element.

Abstract: An optical amplifier (1) includes optical components including at least one optical amplifying active fiber and a pump laser supplying pumping power to the amplifying fiber through an optical coupler, light guide sections (14) for connecting the optical components, and electronic and electrical power supply and control components (41,42). The amplifier is characterized in that it includes:an optical unit (15) including all the optical components (2-13) and the connection light guide sections (14),an electronic unit (16) including all the electronic and electrical components (41,42) and being separate from the optical unit (15),a plate between the optical unit and the electronic unit; andelectrical interconnections (43,44) between the optical unit (15) and the electronic unit (16).The clear separation of the electronic components (41,42) from the optical components (2-13) affords size reductions and rationalization of the amplifier (1) implementation procedure.

Abstract: An optical signal generator for telecommunication systems, comprising at least a single-frequency active optical fiber laser as an optical signal source at a signal transmission wavelength, at least an active optical fiber optical amplifier operatively connected to said laser and at least one source of pumping optical power at a pumping wavelength, the pumping optical power source being operatively connected to at least one of said active fibers of said laser and amplifier and transfer-means for said pumping optical power being connected to said active fibers of said laser and amplifier, in order to transfer unabsorbed optical power at the pumping wavelength from one of said active fibers to the other of said active fibers.

Abstract: A passively-mode-locked laser generator having an active optical fibre and fibre pumping means adapted to cause the generation of an emission signal in the fibre, a polarization control means, signal extraction means and at least one optical component with transmissiveness depending on polarization is disclosed. The components are inserted in an optical fibre path that, for a pumping energy lower than a predetermined value corresponding to a linear propagation condition of the signal, gives rise to a polarization rotation of the emission signal through an angle causing the extinction of the signal itself within the optical component with transmissiveness depending on polarization. For a pumping energy of a higher power than the predetermined value, the generator causes a polarization rotation of the emission signal through an angle corresponding to the transmission with low losses of only pulses of high peak power of the emission signal.

Abstract: The enclosure assembly, being particularly but not exclusively conceived for use over electric cable splices, comprises a sleeve of an elastomer material, a support whereover the sleeve is fitted in a condition of elastic expansion, said sleeve being adapted to shrink around the elongate cylindrical objects upon removal of the support. The support comprises two substantially cylindrical, tubular bodies having ends abutted coaxially with each other in mutual continuation relationship; the abutted ends are disposed at substantially inward locations of the sleeve longitudinal extension. Thus, the support removal can begin from a predetermined internal region of the sleeve; the sleeve starts shrinking over the splice within said internal region, and any axial deformations in the sleeve would leave the sleeve positioning relatively to said predetermined internal region unaffected.

Abstract: An optical amplifier which includes an optical fiber having an erbium doped core surrounded by cladding, a pump for pumping the fiber with pump light at a pump wavelength coupled to the fiber, input means for inputting a signal to be amplified to the amplifier and output means for outputting an amplified signal from the amplifier. The fiber has a NA higher than 0.2. The difference in the coefficient of thermal expansion of the core adjacent the core/cladding interface and the coefficient of thermal expansion of the cladding at at least one radius less than 2 .mu.m from said interface is lower than a predetermined value, corresponding to a ratio of erbium loss to background loss, at said pump wavelength, and greater than a minimum ratio of about 20 when erbium loss is 0.15 dB/m and about 120 when erbium loss is 3.5 dB/m.

Abstract: The enclosure assembly particularly, but not exclusively, conceived for spliced electric cables, comprises a sleeve of an elastomer material, a support whereover the sleeve is fitted in a state of elastic expansion, said sleeve being adapted to shrink about the elongate cylindrical objects upon removal of the support. The support comprises a tubular body formed of a strip of a strong flexible material wound into a helix having mutually bonded adjacent turns, the turns being separable by applying a pull force along a substantially longitudinal direction to an end portion of the strip unravelled from the adjacent turns and taken through the interior of the tubular body along a substantially axial direction and out through the opposite end of the tubular body.

Abstract: Method for the preparation of a precursor for a superconductor, comprising the addition of a condensation product to an aqueous solution of metal salts, the total or partial removal of water from the mixture thus obtained, the subsequent processing of the viscous mass obtained after having removed part of the water or the calcination of the solid gel obtained after having substantially removed all the water, wherein the condensation product is a product of esterification of citric acid with ethylene glycol prepared separately and the solution of metal salts substantially is a solution of acetates in water and acetic acid.

Abstract: In a waveguide structure with diffused rare-earth doping in a light channel arranged lithium niobate crystal surface, the rare-earth doping is arranged in an effective rare-earth doping region approximately coaxially with the light guide channel; the light guide channel is diffused directly frown the crystal surface and its expansion is laterally limited.

Abstract: A hydrogen-absorbing composition for optical fiber cables comprises a catalyst selected from the group including the transition metals, their salts and organic and inorganic complexes, and a hydrocarbon compound including at least 90% of a substantially homogeneous, silicon-free hydrocarbon not obtained by polymerization of monomers including conjugate dienes and having double bonds reactive to hydrogen at room temperature in a corresponding amount to an iodine number in the 70 to 1,000 mg/g range; a viscosity in the 500 to 70,000 cSt range at room temperature, and a viscosity at room temperature lower than 70,000 cSt after ageing by exposure to air, in thin layer, for at least 7 days at 100.degree. C. Fiber optic cables according to the invention comprise at least one optical fiber received in a respective housing and, in at least an internal volume portion, an effective amount of said hydrogen-absorbing composition.

Abstract: In a cable in accordance with the invention, capable of working at operating temperatures of 150.degree. C., a conductor coating made of a mixture of a polyphenylsulfide and a silicone ether imide block copolymer is provided. The invention also refers to the mixture in itself and to a method of producing said cable.

Abstract: The amplifier (1) comprises two active light guide sections (7,10), two dichroic couplers (5,8), two pump laser sources (6,8) acting on the active light guide sections (7,10) through the dichroic couplers (5,8), two directional couplers (3,11) associated with two respective optical meters (4,12), and light guide sections (14) for interconnecting the various components. The dichroic (5,8) and directional (3,11) couplers, and the optical meters (4,12), are pre-assembled onto an auxiliary frame (21); the active (7,10) and connection (14) light guide sections are wound on two drums (30) provided on an organizer frame (28). The auxiliary frame (21), organizer frame (28), and pump laser sources (6,9) are accommodated on a main frame (15).

Abstract: An active mode-locking pulse laser generator comprising:an active fibre doped with a fluorescent dopant;active-fibre pumping means;a modulator to be driven from the outside, connected in series to said active fibre;a wavelength selecting filter, to be driven from the outside, connected in series to said active fibre;means for drawing an emission signal from said active fibre;means for defining a laser cavity including the active fibre, pumping means, modulator, filter, and signal drawing means,wherein the drivable modulator is adapted to generate a modulation of the emission signal generated by the active fibre, such as to cause a mode-locking of the oscillating emission signal in the cavity, wherein the wavelength selecting filter consists of an optical-waveguide monolithic filter, in the absence of components subjected to spatial-configuration modifications.

Abstract: A covering for a joint between electric cables, an element including such covering for forming a covered joint and a joint obtained with such covering. The covering includes two radially elastic sleeves of cross-linked polymeric material, one sleeve being inside and co-axial with the other sleeve. In the unassembled state, the diameter of the bore of the outer sleeve is less than the diameter of the outer surface of the inner sleeve so that when assembled, the outer sleeve exerts radially inward pressure on the inner sleeve. Each sleeve may be formed of one or more tubular layers of polymeric material.

Abstract: The telecommunication line comprises at least one terminal station having an optical-signal transmitter and an optical-signal receiver, which are operationally connected by an automatic protection device suitable for shutting down said transmitter in the absence of a received optical signal, at least one opticalfibre line for the transmission of the optical signals transmitted by said transmitter and received by said receiver, and at least one optical amplifier included in said line. With said optical amplifier there are associated means for the detection of the presence of light energy at input and means for causing the shut down of the amplifier, which in the absence of light energy at input are caused by said detection means to interrupt substantially any emission of light energy on the part of said optical amplifier.

Abstract: An electric covering for a joint between a pair of electric cables, a device including such covering in elastically expanded condition on a rigid tubular support and electric cable joints including such covering. The covering includes at least two elastic sleeves of cross-linked polymeric material, a first radially inner sleeve at least partly of insulating material and a second radially outward sleeve. To permit the covering to be elastically expanded and encircling the rigid support for a long period of time, e.g. two years, the two sleeves have different mechanical properties and in particular, the material of the second sleeve has a residual deformation, which is applied by elongation over a period of time, which is less than the residual deformation, similarly applied, to the material of the first sleeve.

Abstract: An extruder head has an inner die member (5) housed in a supporting body (2) and provided with a central duct (6) continuously passed through by a semifinished product (7). An outer die member (9) exhibits a shaped housing (10) defining, in cooperation with the inner die member (5), an outflow port (11) for the mixture to be applied to the semifinished product (7). The shaped housing (10) is defined in a centering element (12) rotatably housed, according to an oblique and incident axis relative to the axis of the central duct (6), within an intermediate collar (13) rotating in the supporting body (2) in coaxial relation with the central duct itself. By rotating the centering element (12), the outflow port (11) moves from a centered position to a maximum-eccentricity position with respect to the central duct (6). The rotation of the intermediate collar (13) modifies the orientation of the common plane containing the axes of the outflow port (11) and central duct (6).

Abstract: An optical fiber telecommunications system having two terminals interconnected by optical fibers and active-fiber optical amplifiers. Each terminal has an optical telecommunication signal transmitter associated with an optical signal receiver which are interconnected by a protective device which causes the transmitter to be inoperative when its associated receiver does not receive an optical signal. Optical switches are provided at the downstream sides of active-fiber optical amplifiers and are controlled by detecting devices coupled to amplifier outputs, each of which detecting devices opens the associated switch in the absence of a signal having the characteristics, e.g. an alternating component, of the optical telecommunication signal whereby the protective devices are operated.

Abstract: Adapters for interconnecting optical fiber lines, including optical amplifiers, with optical transmitters and receivers in which the operating parameters of the optical amplifiers are different from the operating parameters of the transmitters and receivers. The adapters convert the optical signals from a transmitter to those within the operating parameters of the optical amplifier and convert the optical signals from an optical amplifier to those within the operating parameters of the receiver. The adapter receiving the optical signals from the transmitter also has provision for inserting service signals and the adapter receiving signals from an optical amplifier has provision for separating the optical signals from the service signals. Also, switching devices for changing transmitters and/or receivers or lines in the event of component failures.

Abstract: An optical fiber and an optical amplifier, in particular for optical fiber telecommunication lines operating with a transmission signal in a predetermined wavelength range. The amplifier comprises laser emitting active optical fiber doped with erbium and a further doping substance, distributed along the fiber. The further doping substance has an absorption for a light having a wavelength lower than 1,540 nm substantially higher than the absorption that the further doping substance shows for a light having a wavelength varying from 1,540 nm to the upper limit of the predetermined wavelength range of the transmission signal. Preferably, the further doping substance is samarium.