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 rare-earth doped, lithium niobate, diffusion Bragg reflector laser having a simplified structure and improved efficiency is disclosed. The laser has a pump source, a wavelength division multiplexer, a substrate of lithium niobate doped with at least one rare earth element and having a feedback element, and a grating reflector. The grating reflector is formed from portions of an optical fibre and abuts one end of the doped substrate, such that the grating reflector and the feedback element of the doped substrate form a cavity for the laser. The doped substrate may include phase or amplitude modulators for FM or AM mode-locking operation.

Abstract: A multi-wavelength optical telecommunication method includes: generating at least two optical transmission signals of wavelengths different from each other, multiplexing the optical signals in a single transmission fibre, forming a multi-wavelength optical signal, transmitting, through the transmission fibre, the multi-wavelength optical signal including the optical transmission signals to a respective receiving station and separating the optical transmission signals, in which the step of separating the optical transmission signals includes: distributing the received multi-wavelength optical signal onto at least two output fibres; selectively reflecting a wavelength band of the multi-wavelength optical signal including at least one of the optical transmission signals, so that the reflected band propagates over the output fibre in an opposite direction to the multi-wavelength optical signal; separating the reflected band from the output fibre and feeding it, through a receiving fibre, to a respective receiver.

Abstract: An acoustooptical wavelength device for wavelength selection includes one substrate of a birefringent and photoelastic material on which there is formed: first and second rotation stages of the polarization plane of an optical signal in a first wavelength interval, wherein each stage comprises at least one optical waveguide traveled over by the signal; at least one optical waveguide, connecting the two stages and carrying one single polarizer consisting of an evanescent-wave polarization coupler; and at least one optical waveguide carrying one polarizer being finally provided downstream of the second stage.

Abstract: The device and method are based on tapping off a predetermined line signal fraction and inputting it, together with a continuous pumping radiation, to a resonant cavity which comprises a non-linear wave guide. The value of the pumping wavelength is related to the wavelength of the line signal pulses to produce therewith a four-wave mixing (FWM) effect in the non-linear wave guide. In travelling the non-linear wave guide, a clone signal is generated by FWM effect which duplicates the pulse sequence of the line signal at a clone wavelength. By adjusting the length of the resonant cavity such that, in inputting the line signal, each of its pulses will come in at exactly a pulse of the clone signal which is being circulated within the cavity, a clone signal can be circulated within the resonant cavity whose pulse sequence represents the optical clock signal sought.

Abstract: Insulating and anticorrosive composition for electrical devices consisting of two semifluid components that are mixed together at the time of application, whereinA) the first component includesfrom 20 to 35 parts (w/w) of a bitumen having a softening point of at least 90.degree. C.,from 1.5 to 7 parts (w/w) of a hydrocarbon resin,from 0.5 to 5 parts (w/w) of an alkylbenzene,from 35 to 60 parts (w/w) of resin oil, andfrom 10 to 30 parts (w/w) of olein,B) the second component includesfrom 40 to 60 parts (w/w) of a mixture of partially hydrogenated terphenyls and quaterphenyls,from 0.5 to 5 parts (w/w) of a styrene/butadiene block copolymer,from 5 to 30 parts (w/w) of calcium oxide, andfrom 10 to 50 parts (w/w) of calcium hydroxide.

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: A wavelength selective acousto-optical waveguide device comprises a first and a second optical path in an optical waveguide having a length different by an amount corresponding to a value d=.+-..lambda.(k +m) where d is the difference between the optical paths of the two waveguides, .lambda. is the wavelength of the optical signal, k is a number greater than 0 and less than 1; and m is 0 or a whole number, so as to create a phase shift between at least two parasitic components of the optical signal, such as to generate a destructive interference between the parasitic components.

Abstract: Optical cable, including (a) at least a closed longitudinal housing containing at least an optical fiber and (b) an outer coating permeable to water, wherein there is a second longitudinal housing comprising a moisture-absorbing composition that after absorption of more than 50% by weight of water releases less than 5% by weight of water at 60.degree. C. in two hours.

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 fiber 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 said recognizable spectrum portion, a search range of said transmission signal within which the transmission signal is searched out and recognized based on its spectral profile.

Abstract: An optical telecommunication system includes means for generating optical signals of different wavelengths, an optical-fibre line with amplifying means, a pre-amplifer, and receiving means. The the pre-amplifier comprises an optical waveguide doped with a rare earth material, differential-attenuation means located at a first position along the doped waveguide and capable of causing an attenuation in the signal band which is greater than the attenuation caused at the pumping wavelength, and filtering means located at a second position and adapted to attenuate by a value higher than a predetermined minimum, the spontaneous emission in a wavelength band contiguous with the signal band.The position and attenuation of the differential-attenuation means and filtering means and the wavelength band are selected in a functional relation with respect to each other in order to limit the output power variations from the pre-amplifier.

Abstract: An optical telecommunication system includes at least two sources of optical signals modulated at different wavelengths, having respective coherence times; a multiplexer for multiplexing said signals in a single common optical fibre; an optical-fibre line connected at one end to the common optical fibre of the multiplexer; a receiver for receiving said signals; an element for reducing the four wave mixing (FWM) between the signals, optically connected in series along the optical-fibre line. The FWM-reducing element includes an optical circuit including at least two-wavelength-selective filters, each relative to a wavelength band including one of the optical signals. The filters are optically connected in series with each other over an optical path, and the length of at least one section of the optical path included between two consecutive filters is greater than the length corresponding to the coherence time of at least one of the sources of optical signals.

Abstract: The container for housing optical components (at least one active fibre, a plurality of passive optical components, a plurality of welds and optionally other special components) within a shell of an active fibre optical amplifier comprises a first box element for reception of the passive optical components, a second box element for reception of the active fibre and a third box element for reception of the welds. The three box elements are constrained in a removable manner one against the other so as to form a monolithic container structure.

Abstract: The optical amplifier (1) comprises optical components (2-13), connection light guide sections (14) between the optical components, and electronic and electrical power supply and control components (41,42). It is characterized in that it comprises:an optical unit (15) comprising the optical components (2-13) and the connection light guide sections (14).an electronic unit (16) comprising the electronic and electrical components (41,42) and being separate from the optical unit (15), andmeans (43,44) of electrical interconnection 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: A cable, self-extinguishing and releasing low quantities of toxic and corrosive smokes and gases, for optical or electrical applications, comprises a coating (3) including an outer layer (5) consisting of a polymeric mixture including 50 to 80 parts (w/w) of an aromatic polyester of the isophthalic and terephthalic acids, with bisphenol A and 20 to 50 parts (w/w) of a polyether-polyester block elastomer copolymer having a Shore hardness D greater than 50 and a Vicat softening point higher than 170.degree. C., as well as a coaxial inner (4) layer comprising an polyester thermoplastic elastomer including a quantity of aromatic groups such that its Shore hardness D is equal to at least 45 and such that the delamination shear force necessary to separate said layers (4, 5) from one another is equal to at least 2,000 g. after ageing in oil ASTM Nr. 3 for 2 hours at 100.degree. C.

Abstract: An optical fiber power amplifier, particularly for telecommunication lines with optical fibers, including an active fiber doped with Erbium as a fluorescing substance, and with Al.sub.2 O.sub.3 as refraction index modifying dopant. The fiber is pumped with a laser providing a wavelength higher than 520 nm and preferably, 980 nm. The amplifier has a particularly high amplification efficiency close to the theoretical maximum efficiency.

Abstract: There is proposed a tubular supporting element of a sleeve for covering a junction of cables provided with a wall that has a non-passing incision directed according to a helical line, having a mouth with a width of less than 0.1 mm, preferably less than 0.05 mm, so as to accomplish a strip having a substantially rectangular cross-section; a process and an apparatus for accomplishing the abovementioned tubular element have also been developed.

Abstract: In an optical amplifier, comprising a rare earth doped optical waveguide, in which signals at signal wavelength and pump power at pump wavelength are coupled together, a differential loss inducing means is located in a predetermined position along the length of the waveguide, causing a loss for the signal greater by a predetermined loss amount than the loss for the pump wavelength, said predetermined loss amount and said predetermined loss position being chosen in a mutual relationship to cause an amplification of lower power input signals, in said signal input power range, greater than the amplification of higher power input signals in said range, by an amount causing a substantially constant output power in a dynamic range of input signals greater than 15 dB.

Abstract: A high-transmission-speed optical connection comprising a pulse-generation laser source, optical-fibre transmission means and a receiver, in which said optical-fibre means forms an optical fibre path, such that a pulsed signal of the soliton type is subjected to a broadening in time greater than 50% by effect of the chromatic dispersion, in which said laser source comprises an active and harmonic mode-locking optical-fibre laser wherein the fibre length, filter pass-band and power in the cavity are selected for emitting pulses of a Gaussian temporal profile having such a duration and bandwidth that, at the receiver, the duration of the pulses themselves is not more than 15% higher than the duration at the emission.

Abstract: A unit for amplifying light signals in optical fiber transmission lines includes a fiber optical amplifier to which light signals are transmitted through an input optical fiber line, and from which the signals, after having been amplified, are introduced into an output optical fiber line. First and second optical insulators are interposed between the fiber optical amplifier and the input and output lines to prevent the transmission of optical noise signals from the input and output lines, respectively, to the amplifier.