Abstract: The device for the phase realignment of ATM cells in an optical ATM switching node is associated with each input line (Fe) of node and includes a circuit for recognizing the beginning of a cell, a circuit for evaluating the time shift between of a cell and a reference instant and for generating an error signal (ER) depending on the amount of time difference, and a delay line for compensating the time difference, driven by the error signal (ER). The time difference compensator means includes a logarithmic optical delay line that is connected upstream of the device for recognizing the beginning of a cell and for evaluating the amount of the time difference.

Abstract: In a radio communication system, in particular a mobile communication system, variable-rate information flows originating from different sources (CV1, CS1; CV2, CS2) and relative to a same communication are transmitted on a same radio channel. Each mobile station (M1 . . . Mh) and the fixed part (B1 . . . Bn; RNC) of the system comprise a unit for the control of the variable-rate transmission, which dynamically allocates the available bits to the different streams by taking into account the needs of the sources (CV1, CS1; CV2, CS2), the conditions of the channel (6) and the system occupancy. (FIG. 1).

Abstract: The device includes a first and a second optical circulator (C1, C2) having an input port and an output port that are the inputs and the outputs of the switch, as well as an optical bandpass filter (FP) placed between the two circulators (C1, C2) and connected with means for switching its state so that the filter either reflects or transmits a given wavelength, thus allowing a carrier with this wavelength at the input port of one of the circulators (C1, C2) to reach the output port of the same circulator or the output port of the other circulator.

Abstract: The vapour generator for chemical vapour deposition plants allows the extraction of metalorganic vapours from liquid or solid sources. It mainly consists of a container into which a gas flows in, and as it passes near the reagent, it is saturated with the vapours produced and transports them to the reaction chamber. Only the generator is brought to a temperature which is higher than room temperature so as to obtain a vapour which is saturated with a high quantity of reagent. To avoid vapour condensation in the pipe system transporting it from the generator to the reaction chamber, it is diluted with a carrier gas directly in the body of the heated generator, reducing in this way the condensation temperature of vapour which becomes unsaturated. For this purpose, the generator contains a dilution bypass-line in the upper base into which the carrier gas is made to flow. The pipe system going from the generator to the reaction chamber can be held at room temperature without any condensation risks.

Abstract: A method of adjusting the operation of optical networks in terms of propagation constants of guided modes in integrated optical devices, allowing a considerable number of out of tolerance devices to be recovered by depositing on the surface where the optical guides are manufactured, once the normal fabrication process is completed, a further layer of transparent material of suitable size and refractive index.

Abstract: Apparatus for measuring the effective refractive index in optical fibers, in which a source sends light radiation, the wavelength of which can be varied within a predetermined interval, into a fiber span, and a detector collects the radiation intensity of the radiation collected by the detector as the wavelength varies, in order to determine the oscillation period of the fiber transmittance or reflectivity and to obtain the effective refractive index from such period.

Abstract: Integrated optical devices are fabricated by field-assisted ion exchange on a starting substrate, wherein the substrate is first prepared to be connected to a source of potential difference, is duly masked as a function of the optical circuit to be implemented and is dipped in a melted salt, which is an ion source for the exchange, with another electrode for applying the electric field capable of inducing ion exchange.

Abstract: Refractive index change in a glass substrate, necessary to obtain a guiding region, is obtained by bombarding the substrate surface with an electron beam. An electric field induced by negative charge accumulation is created under the surface, whereby sodium ions present in glass are made to migrate towards the inside of the substrate.

Abstract: A pump system for lasers or amplifiers made of a waveguide presenting a monomode active region, in which the pump radiation is launched into a multimode guide surrounding the active region. The radiation is obtained as a sum of the radiations emitted by a plurality of independent sources.

Abstract: The device for introducing reagents into an organometallic vapor phase deposition apparatus consists of a valve body having two chambers, each of which can be placed in communication with a passage for the introduction of the reagent and is permanently connected with two passages traversed by carrier gas.

Abstract: The orthomode transducer between a circular waveguide and a coaxial cable consists of a circular waveguide section, into which two probes externally connected to coaxial connectors penetrate. The probe placed close to the input aperture of the waveguide is tuned by a screw and a metal plate belonging to the same axial plane and the other probe is tuned by a screw and a circular disc which closes the waveguide. The shapes of the plate and of the probes are such as to allow the best power coupling between the waveguide and the coaxial line over a wide operating band (10% of the mid-band frequency).

Abstract: A system for the generation of modulated optical signals, wherein to the d.c. bias current of a semiconductor laser (1) associated with an opto-electronic feedback circuit (2) including a delay, there are superimposed the variations of a current obtained by detecting an optical signal resulting from the combination of an optical, amplitude-modulated input signal and of the optical signal present in the feedback circuit. By a suitable choice of the modulation frequency (f2) of the input signal and of the low-frequency gain (B) of the feedback loop (2), the laser output signal is amplitude-modulated at a frequency equal to the modulation frquency (f2) of the input signal.

Abstract: In order to determine the nonlinear refractive index coefficient of a material which, once inserted into a Fabry-Perot cavity (1), has an optically bistable behavior, the output power (12; 13) of the cavity (1) is measured in function of the power (1) of an amplitude-modulated optical input signal to obtain the material hysteresis loop; the hysteresis loop saturation region is detected, where the phase (.phi.) of the electromagnetic field associated with the signal within the cavity is a linear function of the output power; the values of the phase (.phi.) in said region are obtained from the output and input power values (12; 13; 11) and the nonlinear refractive index coefficient (n2) is obtained from the angular coefficient of the straight line representing said phase.

Abstract: The system uses a monochromatic radiation source (1) and an acousto-optic modulator (2), which is driven by a periodically variable frequency. The modulator emits a first beam having the same wavelength as the source and a second beam, whose wavelength and emission direction vary with the modulating frequency. After the second beam has been collimated, radiations of both beams are sent towards the component under test and an electrical signal with varying frequency is generated representative of the beat between such radiations at the output from the component. A spectral analysis of the beat signal is carried out, and the refractive index value is derived from the position taken by the various frequencies of the beat signal on a detection plane.

Abstract: A C-MOS sense amplifier capable of detecting voltage differences between the signals applied to its inputs in correspondence with the clock signal transitions. The amplifier has a level converter, a sense circuit and a feedback block which are inactive in a first inactive phase of the clock signal, while in a second active phase, immediately after clock signal transition, the sense amplifier attains the operating point necessary to activate the level converter and the sense circuit. Hence a high positive feedback is started which switches the sense circuit. Finally, after the level transition of a delayed clock signal, the feedback signal generated by the feedback block reduces to zero the dissipation of the whole differential sense amplifier.

Abstract: Still and moving picture components of a motion video transmission are coded by using the same algorithm. The system provides a posteriori recognition of still pictures on memorization of the quantization step used to code groups of pixels of a still picture which belong to a certain hierarchical level (e.g. the macroblock level), and allows convergence of the quantization step towards a minimum predetermined value.

Abstract: A method of adjusting the operation of bimodal optical networks in terms of propagation constants of guided modes in integrated optical devices, allowing a considerable number of out of tolerance devices to be recovered by depositing on the surface where the optical guides are manufactured, once the normal fabrication process is completed, a further layer of transparent material of suitable size and refractive index.

Abstract: An effusion source for epitaxial deposition plants wherein molecular vapor beams are directed towards a substrate to be grown in ultrahigh vacuum environment, which has a first tube, which is airtightly closed at one end by flanges allowing the passage of vapor inlet tubes and is equipped at the the other end with baffle plates and a nozzle for mixing vapors and shaping the molecular beam. A second tube, coaxially joined to the first tube, allows an interstice at ambient pressure and temperature to be obtained in the zone of the vapor mixing and molecular beam shaping, wherein a heating can be located.

Abstract: A fast packet and frequency switch, with inputs and outputs connected to optical fibers, each allowing the transit of a certain number of different-wavelength optical carriers, modulated by serial information flows organized into packets. The packets are phase-realigned and their labels are converted under the control of external processors designed to set-up and break connections. Then a frequency conversion of the optical carriers allotted to packets is carried out and the packets are recombined into a single fiber by a passive recombination network in order to be stored into an optical loop memory, which is an optical fiber delay line. Each optical packet flow is extracted at suitable times, is frequency-converted and, among the various frequencies obtained, there are selected only those to be sent to corresponding output fibers outgoing from the switch, after having been recombined with those of the other converted flows.

Abstract: An automatic system for adjusting the output impedance of fast CMOS drivers, wherein the output impedance of a plurality of slaved drives is adjusted by a circuit for measuring and correcting mismatch between the output impedance of one of the drivers, taken as reference and dedicated for this purpose, and the impedance at the input of a reference transmission line, equal to the lines connected to the other drivers. The measuring of the output impedance of the reference drive is indirectly effected by inserting at the reference drive input a clock signal and by periodically measuring the output on the reference transmission line in correspondence with the positive half-period center.