Abstract: The process of the invention to make miniaturized multipolar cables includes the steps of combining together a plurality of individually insulated conductors, inserting a filling in a pasty state and containing mineral fillers into the gaps existing between the conductors, partly hardening the filling and disposing the other cable components, in particular the sheath, around the conductors-filling assembly, and letting the filling become completely hard within the produced cable.

Abstract: The optical node comprises two working directional switches (22,27) connected serially in a primary ring line (2), respectively ahead of and after an extracting and/or inserting unit (11), and further connected serially in a secondary ring line (3), which are adapted to controllably switch the optical signal path between the primary ring line (2) and the secondary ring line (3), and to the extracting and/or inserting unit (11). The node further comprises two backup directional switches associated with the working directional switches and connected operatively in the primary (2) and secondary (3) ring lines to restore the optical node (10) to proper operation on the occurrence of a failure at the working directional switches.

Abstract: An optical telecommunication system has at least two sources of optical modulated signals at different wavelengths in a predetermined transmission wavelength band, together with a multiplexer for the signals, an optical fibre line connected at one end to the multiplexer, and a demultiplexer/receiver for the signals. The line comprises an optical fibre having a chromatic dispersion value lower than a predetermined value in the transmission wavelength band and increasing as wavelength increases. The fibre also has a zero value of chromatic dispersion at a wavelength lower than the minimum wavelength of the transmission wavelength band by such an amount that no local wavelength zero value of the chromatic dispersion present in the fibre and capable of generating a four-wave-mixing phenomenon is included in the band.

Abstract: The support is designed to keep in expanded condition an elastic covering sleeve for elongated cylindrical elements such as electric cable joints and the like. The support comprises a tape wound spirally in side-by-side turns so as to take on a cylindrical tubular form and mutual constraint means between the turns to keep the tape in wound condition. In accordance with the invention the tape and the constraint means are provided in different materials.

Abstract: A multi-wavelength optical telecommunication method includes the steps of generating at least one optical transmission signal in a predetermined wavelength band, transmitting the optical transmission signal through an optical fibre to a receiving station, receiving the optical transmission signal through a passband filter and filtering the signal to let the transmission signal alone pass. The wavelength band is scanned in order to identify in the band a recognizable portion of the optical spectrum being received, thus determining, based on the operating conditions corresponding to the recognizable spectrum portion, a search range of the transmission signal within which the transmission signal is searched out and recognized based on its spectral profile.

Abstract: A method of selectively compensating for the chromatic dispersion of optical signals in an optical telecommunication network, comprising the steps of transmitting at least two signals over a common portion of said network, separating at least one of the signals from the remaining signals at at least one point of the network, compensating for the chromatic dispersion of this signal and recombining said signal with the remaining signals at said one point of the network. Preferably this method further comprises the steps of detecting the chromatic dispersion of each of the signals at at least one point of the network, identifying, among the signals, the signals to be compensated, for which the detected dispersion value does not fall within a range of predetermined values and compensating for the dispersion of said signals so as to make them fall within this range of predetermined values.

Abstract: An optoelectronic apparatus comprising a casing (110) inside which an electronic unit and an optical unit electrically interconnected are disposed; the optical unit comprises an element (100) on which at least one component is housed, which can be of an optical type, of optical connection, of an electro-optical type (270, 275, 300), said element (100) comprising a plurality of separate areas (190, 195), so that each area houses components substantially of a single type.

Abstract: An optical communication system is described which includes an optical source; an optical modulator, receiving a transmission signal having frequencies included within a signal band and adapted to emit a modulated optical signal of a predetermined optical bandwidth; an optical transmission line comprising an optical fiber portion; and an optical receiver adapted to receive the optical signal in the presence of a predetermined SNR in the signal band, measured in a 5 MHz band. The telecommunication system further comprises, optically connected between the optical modulator and the optical transmission line, a depolarizer comprising two polarization-maintaining optical fiber portions, optically connected with each other in such a manner that the respective polarization axes form an angle of 45.degree.

Abstract: A self-extinguishing cable releasing low quantities of toxic and corrosive smokes and gases for optical or electrical applications, comprises a self-extinguishing coating (3), releasing low quantities of toxic and corrosive fumes and gases, comprising:a) a polymer base including from 30 to 60 parts of a thermoplastic polyester and from 40 to 70 parts of a silicone-polyimide polymer;b) at least 0.5 parts of an anti-hydrolysis agent of the thermoplastic polyester and at least 0.25 parts of a selected antioxidant agent per each 100 parts by weight of the polymer base.Advantageously, the antioxidant agent is so selected that the coating (3) has a value of percent elongation at break not lower than 80% of the starting value and in any case not lower than 250%, after a 10-day aging at 175.degree. C. in a hot air oven.

Abstract: An optical self-healing-ring communication network is described which include: a first optical communication line, forming a closed optical path; at least two add/drop nodes for optical signals, optically connected along the line; a second optical communication line forming a closed optical path and optically connected to the optical-signal add/drop nodes. Defined in the network are first and second mutually opposite travel directions of the optical signals, with respect to the position of the optical-signal add/drop nodes. At least one of said nodes further comprises selection means, controlled by the optical signals, for the selective dropping of the optical signals from one of the communication lines. At least one of the optical-signal add/drop nodes further include means for the simultaneous input of at least one optical signal in the first direction along the first communication line and in the second direction along the second communication line.

Abstract: An optoelectronic apparatus includes a casing and an optical unit (300) on which at least one component (300) having high heat emission is disposed. This component is initially linked with clearance with the optical unit, by first fastening means, and in a second step by second fastening means the component is fixedly secured to the casing in a thermal contact state.

Abstract: An optical telecommunication system including a transmitting station and a receiving station for optical signals, connected with each other by an optical fiber line including optical line amplifiers having a rare-earth-doped active fiber and connected in series, in which the transmitting station includes signal generator for generating signals at several wavelengths, and connections for conveying the signals to a single optical fiber line. The optical signal receiving station includes apparatus for separating the signals. At least one of the optical line amplifiers has dopants, fiber length and pumping power capable of determining, at the input of the receiving station, an optical signal/noise ratio which for the different wavelengths has a difference less than 2 dB, and for each signal is greater than 15 dB.

Abstract: An acousto-optical waveguide device with compensation of polarization mode dispersion (PMD) comprises at least one first and one second optical path in optical waveguide and at least one compensation optical path connected to the first and second optical path. The compensation optical path has a prefixed PMD such that the passage time of a first polarization component of an optical signal in the first optical path and in the compensation optical path is substantially equal to the passage time of a second polarization component in the second optical path and in the compensation optical path.

Abstract: Electrical cable for high and very high voltages includes a plurality of conductors, at least one semiconductive layer, a stratified insulation impregnated with an insulating fluid and an external metal sheath. The insulation is constituted by a paper/polypropylene/paper laminate, wherein polypropylene has been subjected to a treatment such as to allow the laminate to swell up by less than 5% after immersion in decylbenzene at 100.degree. C. for at least 3 days.

Abstract: A double-stage acousto-optical waveguide device comprises two polarization conversion stages, a polarization selective input element, a polarization selective output element and two intermediate polarization selective elements that have two branches connected together and two branches not connected together that are located on opposite sides of the branches connected together and extend in lateral waveguides that reach the edges of the substrate.

Abstract: An acousto-optical waveguide device for the wavelength selection of an optical signal comprises two polarization conversion stages, one polarization selective input element, one polarization selective output element and two intermediate polarization selective elements located at the output of the first conversion stage and at the input of the second conversion stage, respectively; the intermediate polarization selective elements have two branches connected together and two branches not connected together located on opposite sides with respect to the branches connected together.

Abstract: An analog-external-modulation optical, emitter is described which comprises an electro-optical modulator and a piloting circuit. The piloting circuit comprises a pilot-tone-generating circuit; an electric control signal generated by the optical signal coming out of the modulator and a predetermined bias voltage are fed to the input of a differential amplifier the output of which is added to the pilot tone to feed an electric input of the electro-optical modulator. The RF input of the analog electric signal is connected to a linearizer circuit to which the pilot-tone-generating circuit is also connected. The output of the linearizer circuit is sent to an electric input of the electro-optical modulator through a band-stop filter adapted to eliminate the pilot tone downstream of the linearizer circuit.

Abstract: The present invention relates to an optical amplifier and a telecommunication system including a plurality of the optical amplifiers connected in cascade, particularly adapted for a wavelength division multiplexing transmission, in which a combination of dopants in the active fiber core of the optical amplifiers enables a high signal/noise ratio to be achieved for all channels in a predetermined wavelength band, even in the presence of several simultaneously fed signals.

Abstract: An optical telecommunication system has at least two sources of optical modulated signals at different wavelengths in a predetermined transmission wavelength band, together with a multiplexer for the signals, an optical fiber line connected at one end to the multiplexer, and a demultiplexer/receiver for the signals. The line comprises an optical fiber having a chromatic dispersion value lower than a predetermined value in the transmission wavelength band and increasing as wavelength increases. The fiber also has a zero value of chromatic dispersion at a wavelength lower than the minimum wavelength of the transmission wavelength band by such an amount that no local wavelength zero value of the chromatic dispersion present in the fiber and capable of generating a four-wave-mixing phenomenon is included in the band.

Abstract: A multi-wavelength optical telecommunication method includes the steps of generating at least one optical transmission signal in a predetermined wavelength band, transmitting the optical transmission signal through an optical fibre to a receiving station, receiving the optical transmission signal through a passband filter and filtering the signal to let the transmission signal alone pass. The wavelength band is scanned in order to identify in the band a recognizable portion of the optical spectrum being received, thus determining, based on the operating conditions corresponding to the recognizable spectrum portion, a search range of the transmission signal within which the transmission signal is searched out and recognized based on its spectral profile.