Patents Assigned to Cselt Centro Studi E Laboratori
  • Frequency modulation coherent optical communications system with continuous polarization scrambling
    Patent number: 5329394
    Abstract: A coherent optical communications system with continuous polarization scrambling, wherein such scrambling is obtained by combining orthogonally polarized radiations at different frequencies emitted by two independent sources. The two sources may be employed to build the transmitted or the local oscillator of the system.
    Type: Grant
    Filed: May 15, 1992
    Date of Patent: July 12, 1994
    Assignee: CSELT-Centro Studi E Laboratori Telecomunicationi S.p.A.
    Inventors: Riccardo Calvani, Renato Caponi, Giuseppe Marone
  • High-resolution spectroscopy system
    Patent number: 5305077
    Abstract: The radiation to be analyzed is sent onto an interference filter which selects different portions of the radiation spectrum in correspondence with different incidence angles. The intensity values of the radiation outgoing from the element are stored by a measuring and data processing unit which processes such values with the transfer function of the element to obtain the information on the spectrum.
    Type: Grant
    Filed: March 30, 1992
    Date of Patent: April 19, 1994
    Assignee: CSELT-Centro Studi E Laboratori Telecommunicazioni S.p.A.
    Inventors: Giorgio Grego, Luigi Tallone
  • Gain-coupled distributed-feedback semiconductor laser
    Patent number: 5276702
    Abstract: In a distributed feedback semiconductor laser, the active medium has a periodic thickness variation in the light propagation direction so as to generate a periodic gain variation, while maintaining the effective refractive index constant, and has a discrete multi-quantum wire structure.
    Type: Grant
    Filed: May 13, 1992
    Date of Patent: January 4, 1994
    Assignee: CSELT-Centro Studi e Laboratori Telecommunicazioni S.p.A.
    Inventor: Marina Meliga
  • Method of fabricating integrated optical devices by means of field-assisted ion exchange
    Patent number: 5269888
    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.
    Type: Grant
    Filed: April 2, 1991
    Date of Patent: December 14, 1993
    Assignee: CSELT - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventor: Salvatore Morasca
  • Method of fabricating integrated optical guides of glass
    Patent number: 5271082
    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.
    Type: Grant
    Filed: February 27, 1992
    Date of Patent: December 14, 1993
    Assignee: CSELT - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Marco Braglia, Giuseppe Cocito, Roberto De Franceschi
  • Pump system for waveguide lasers or amplifiers
    Patent number: 5263036
    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.
    Type: Grant
    Filed: January 17, 1992
    Date of Patent: November 16, 1993
    Assignee: Cselt-Centro Studi E Laboratori Telecomunicazioni S.p.A.
    Inventors: Carlo De Bernardi, Salvatore Morasca
  • Coherent optical fiber communications system using polarization modulation
    Patent number: 5257126
    Abstract: A coherent optical communications system using polarisation modulation, wherein the polarisation modulation of the optical signals is obtained by using two lasers (1, 2) emitting orthogonally polarised radiations at different frequencies, which are combined without losses prior to transmission over the line (FIG. 1).
    Type: Grant
    Filed: May 15, 1992
    Date of Patent: October 26, 1993
    Assignee: CSELT-Centro Studi e Laboratori Telecommunicazioni S.p.A.
    Inventors: Riccardo Calvani, Renato Caponi, Giuseppe Marone
  • Device for introducing reagents into an organometallic vapor phase deposition apparatus
    Patent number: 5224513
    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.
    Type: Grant
    Filed: March 25, 1992
    Date of Patent: July 6, 1993
    Assignee: Cselt - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventor: Daniele Bertone
  • Orthomode transducer between a circular waveguide and a coaxial cable
    Patent number: 5212461
    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).
    Type: Grant
    Filed: May 9, 1991
    Date of Patent: May 18, 1993
    Assignee: CSELT-Centro Studi E Laboratori Telecomunicazioni S.P.A.
    Inventors: Antonello Aicardi, Piercarlo Massaglia
  • Apparatus and method for the generation of modulated optical signals using a semiconductor laser
    Patent number: 5197075
    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.
    Type: Grant
    Filed: December 10, 1991
    Date of Patent: March 23, 1993
    Assignee: Cselt - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Fortunato T. Arecchi, Massimo Calzavara, Giovanni Giacomelli
  • Method of measuring the nonlinear refractive index coefficient of a bistable resonant cavity optical component
    Patent number: 5166744
    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.
    Type: Grant
    Filed: June 21, 1991
    Date of Patent: November 24, 1992
    Assignee: Cselt - Centro Studi E Laboratori Telecomunicazioni S.P.A.
    Inventors: Riccardo Calvani, Renato Caponi
  • System for measuring the refractive index profile of optical components
    Patent number: 5160973
    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.
    Type: Grant
    Filed: October 18, 1991
    Date of Patent: November 3, 1992
    Assignee: CSELT - Centro Studi E Laboratori Telecomunicazioni S.p.A.
    Inventors: Giuseppe Cocito, Giorgio Greco
  • C-MOS differential sense amplifier
    Patent number: 5155397
    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.
    Type: Grant
    Filed: December 19, 1990
    Date of Patent: October 13, 1992
    Assignee: Cselt - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Mario Fassino, Mario Sartori
  • Optical spectroscopy system
    Patent number: 5144374
    Abstract: An optical spectroscopy system, wherein a pulse of a radiation to be analyzed is sent to a diffractive element presenting high temporal chromatic dispersion, and information relevant to the radiation spectrum is obtained from pulse broadening in the time domain.
    Type: Grant
    Filed: April 11, 1991
    Date of Patent: September 1, 1992
    Assignee: Cselt - Centro Studi e Laboratori Telecommunicazioni S.p.A.
    Inventor: Giorgio Grego
  • Method of hydrid digital coding distinguishing motion pictures from still pictures
    Patent number: 5142362
    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.
    Type: Grant
    Filed: February 20, 1991
    Date of Patent: August 25, 1992
    Assignee: CSELT - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Lorenzo Masera, Fernando Pereira
  • Method of adjusting the operation characteristics of integrated optical devices
    Patent number: 5139556
    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.
    Type: Grant
    Filed: February 20, 1991
    Date of Patent: August 18, 1992
    Assignee: CSELT - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Claudio Caldera, Carlo De Bernardi, Salvatore Morasca
  • Vapor effusion source for epitaxial deposition plants
    Patent number: 5128538
    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.
    Type: Grant
    Filed: April 2, 1991
    Date of Patent: July 7, 1992
    Assignee: Cselt - Centro Studi e Laboratori Telecomunicazioni S.p.A.
    Inventors: Fernando Genova, Giuliana Morello
  • Coherent optical-fiber communication system using polarization diversity transmission
    Patent number: 5127066
    Abstract: A coherent optical-fiber transmission system is rendered insensitive to fluctuations of the state of polarization of the electromagnetic field due to propagation along the fiber by varying at the transmitting side the state of polarization of the optical carrier modulated by the information signal to be transmitted. The variation is such that spectral broadening of the intermediate frequency signal at the receiver is kept limited, while reception of half the power outgoing from the fiber is ensured.
    Type: Grant
    Filed: November 2, 1990
    Date of Patent: June 30, 1992
    Assignee: CSELT - Centro Studi e Laboratori Telecommunicazioni S.p.A.
    Inventor: Pierluigi Poggiolini
  • Coupled quantum-well electro-optical modulator
    Patent number: 5105301
    Abstract: A coupled quantum well electro-optical modulator, whose semiconductor structure is composed of one or of a plurality of successions formed by two layers capable of forming quantum wells, of a barrier layer which separates the two layers and of an intrinsic layer which separates the succession from other possible successions, where in presence of an electric field the absorption threshold of the light radiation shifts towards shorter wavelengths.
    Type: Grant
    Filed: December 14, 1989
    Date of Patent: April 14, 1992
    Assignee: CSELT - Centro Studi e Laboratori Telecommunicazioni S.p.A.
    Inventor: Domenico Campi
  • Method of and device for moving image contour recognition
    Patent number: 5103488
    Abstract: The recognition method is applied to visual telephony image coding. Matrices of digital samples relevant to the individual frames of the video transmission are submitted to a first processing whereby the foreground region containing the figure is identified. The information concerning the elements of such a region is then processed by edge recognition algorithms to detect a group of elements possibly belonging to the contour. The group of elements is analyzed to select a sequence of elements distributed on the average along a line. The sequency of elements is processed by a neural network to build up the continuous contour which is then coded.
    Type: Grant
    Filed: June 7, 1990
    Date of Patent: April 7, 1992
    Assignee: CSELT Centro Studi e Laboratori Telecommunicazioni SpA
    Inventors: Roberto Gemello, Cataldo Lettera, Lorenzo Masera