Patents Represented by Attorney Gregory C. Ranieri
  • Patent number: 5412754
    Abstract: Trajectories are generated in response to an input label by using a reverse time delay neural network. The reverse time delay neural network comprises an input layer, a plurality of hidden layers, and an output layer, all arranged in succession so that the number of frames per layer increases as the network is traversed from the input layer to the output layer. Additionally, the number of features decreases as the network is traversed from the input layer to the output layer. Features of the trajectory are created from the input label so that a time series of frames can be output by the network. Frames generally relate to particular epochs of time or time units and a frame includes a plurality of features.Interconnection between layers is accomplished using differential neuron units. In the differential neuron unit, standard neuron weighting, summing, and nonlinear squashing functions are performed on the inputs thereto.
    Type: Grant
    Filed: June 30, 1992
    Date of Patent: May 2, 1995
    Assignee: AT&T Corp.
    Inventors: Yann A. Le Cun, Patrice Y. Simard
  • Patent number: 5390200
    Abstract: A monolithically integrated laser which is rapidly tunable over a wide optical frequency range comprises a frequency router formed in a semiconductive wafer defining a tuned cavity. A control circuit applies electrical energy to predetermined controllably transmissive waveguides connecting the frequency routing device with reflective elements defined in the wafer. This tunes the laser to a desired one of a plurality of optical frequencies. Application of such electrical energy creates frequency selective pathways through the wafer able to support selected lasing frequencies. Additional optical amplifiers are formed in the frequency router to create lasing action in a preselected pathway. This laser is economical to construct and is useful in high capacity, high speed optical communications networks.
    Type: Grant
    Filed: October 13, 1993
    Date of Patent: February 14, 1995
    Assignee: AT&T Corp.
    Inventor: Martin Zirngibl
  • Patent number: 5357364
    Abstract: Timing jitter problems are effectively eliminated in a soliton transmission system realized in accordance with the principles of the present invention by deploying optical filters whose center frequency intentionally differs from the center frequency of adjacent optical filters. The center frequency of the series of optical filters is translated along the desired length of the system in a predetermined manner such as frequency increasing, frequency decreasing, and combinations of both to create a transmission environment which is substantially opaque to noise while remaining perfectly transparent to solitons.
    Type: Grant
    Filed: June 25, 1992
    Date of Patent: October 18, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: James P. Gordon, Linn F. Mollenauer
  • Patent number: 5333219
    Abstract: The present invention relates to a new tunable filter which, when used as an intracavity mode selecting filter in a semiconductor laser structure, provides a large tuning range. The disclosed filter is, in one embodiment, a two branch asymmetric Y-branch tunable filter where the ends of the two branches terminate at a common plane. In another embodiment, the invention is realized by using a cascade of two or more Y-branches to place several asymmetrical Y-branch filters in parallel.
    Type: Grant
    Filed: December 17, 1992
    Date of Patent: July 26, 1994
    Assignee: AT&T Bell Laboratories
    Inventor: Mark E. Kuznetsov
  • Patent number: 5311344
    Abstract: Bidirectional, non-interfering transmission of broadband services on a single fiber is accomplished by simultaneously combining wavelength-division, time-division, and subcarrier multiplexing on the downstream and upstream transmissions. High speed electrical data signals are time-division multiplexed at the exchange into a composite signal which modulates a standard diode laser operating at a first wavelength. Data signals from an individual subscriber are modulated onto a subcarrier designated solely for the particular subscriber which, in turn, modulates a laser operating at a second wavelength. Extraction and insertion of the upstream and downstream transmissions at the subscriber and exchange locations is accomplished with wavelength selective couplers.
    Type: Grant
    Filed: September 2, 1992
    Date of Patent: May 10, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Peter P. Bohn, Thomas H. Wood
  • Patent number: 5303079
    Abstract: External modulation is accomplished in a dual waveguide device wherein substantially identical input optical beams are supplied to the waveguides and wherein each waveguide through its electrode is subject to individual, mutually exclusive control. Modulation signals are applied to each waveguide via its separate electrode. Control signals are applied to each waveguide for adjusting the modulation chirp parameter to a desired fixed, non-zero value. Typically, the desired value of the chirp parameter is one which provides the lowest fiber dispersion penalty for the system. Modulated lightwave signals emerging from the waveguides are combined to form a single output signal suitable for transmission over an optical fiber. In one embodiment, Mach-Zehnder interferometer having separately controllable waveguides has its input coupled to a CW laser. Both III-V semiconductor and Ti:LiNbO.sub.
    Type: Grant
    Filed: April 9, 1992
    Date of Patent: April 12, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Alan H. Gnauck, Steven K. Korotky, Jane E. Zucker
  • Patent number: 5288659
    Abstract: An improved process for fabricating photonic circuits is disclosed. The inventive process starts with a growth of a base wafer comprising a stack of epitaxial layers of various materials. At least a portion of each of the material layers will ultimately be a functioning part of any of a number of devices which will form the PIC or will serve a role in at least one of the fabrication processing steps. Specific inventive processing steps are addressed to (1) interconnecting passive waveguides, active devices, and grating filtering regions without the substantial optical discontinuities which appear in the prior art, and (2) etching continuous waveguide mesas to different depths in different regions of the PIC so as to optimize the performance of each PIC device.
    Type: Grant
    Filed: September 14, 1992
    Date of Patent: February 22, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Thomas L. Koch, Uziel Koren
  • Patent number: 5278855
    Abstract: Extended wavelength tunability is achieved in a saturable absorber for applications such as modelocking lasers by realizing a semiconductor structure having a tapered energy bandgap profile in a portion of the saturable absorber wherein the profile is given as a function of the distance along the propagation axis of the saturable absorber. For certain applications, at least one mirror is monolithically integrated with the saturable absorber.
    Type: Grant
    Filed: May 11, 1992
    Date of Patent: January 11, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Gloria R. Jacobovitz-Veselka, Ursula Keller
  • Patent number: 5274748
    Abstract: An electronic synapse circuit is disclosed for multiplying an analog weight signal value by a digital state signal value to achieve a signed product value as a current which is capable of being summed with other such synapse circuit outputs. The circuit employs a storage multiplying digital-to-analog converter which provides storage for the analog weight signal value. Additional circuitry permits programming different analog weight signal values into the circuit, performing four-quadrant multiplication, generating a current summable output, and maintaining the stored analog weight signal value at a substantially constant value independent of the digital state signal values.
    Type: Grant
    Filed: December 27, 1991
    Date of Patent: December 28, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Bernhard Boser, Eduard Sackinger
  • Patent number: 5271090
    Abstract: Higher operational speed is obtained without sacrificing computational accuracy and reliability in a neural network by interchanging a computationally complex nonlinear function with a similar but less complex nonlinear function in each neuron or computational element after each neuron of the network has been trained by an appropriate training algorithm for the classifying problem addressed by the neural network. In one exemplary embodiment, a hyperbolic tangent function is replaced by a piecewise linear threshold logic function.
    Type: Grant
    Filed: March 2, 1992
    Date of Patent: December 14, 1993
    Assignee: AT&T Bell Laboratories
    Inventor: Bernhard Boser
  • Patent number: 5258946
    Abstract: A measure of the correlation or degree of closeness between an input data pattern and a stored data pattern is achieved directly from content-addressable memory cells which are realized in accordance with the principles of the present invention to provide a match/non-match output indication which is summable with other such match/non-match output indications on a match bus line for computing the correlation or degree of closeness measure. Each content-addressable memory cell includes a single bit, static random access memory cell and a comparing logic gate connected jointly to the output of the static random access memory cell and the bit bus line for the single bit of the input data pattern. Output of the comparing logic gate is connected to the match bus line and is generated as a fixed amount of current which can be summed with other current on the match bus line. The output stage of the comparing gate is thus operated as a current source.
    Type: Grant
    Filed: February 13, 1991
    Date of Patent: November 2, 1993
    Assignee: AT&T Bell Laboratories
    Inventor: Hans P. Graf
  • Patent number: 5255265
    Abstract: Significant throughput improvement is achieved for an input queued packet switch using output port schedulers by permitting the output schedulers to recycle or reassign cell transmission times from input ports which are unable to use them. When an output scheduler assigns a cell transmission time to an input port and that input port is unable to use the assigned transmission time due to a scheduling conflict, for example, the input port makes a new request for the same output port during the next subsequent request period and then returns the unusable transmission time assignment back to the output scheduler. The output scheduler stores the returned transmission time in a separate queue for assignment to later requests for the particular output port. Throughput performance is improved from 58% (without time slot recycling) to 92% (with time slot recycling) for random packet cell traffic models.
    Type: Grant
    Filed: May 5, 1992
    Date of Patent: October 19, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Kai Y. Eng, Mark J. Karol
  • Patent number: 5243669
    Abstract: Polarization rotation is achieved in an exemplary embodiment in an optical waveguide by augmenting the waveguide structure with a plurality of spaced-apart sections for loading the refractive index of the waveguide to cause a lateral asymmetry in the refractive index profile of the waveguide viewed in the plane transverse to the waveguide longitudinal axis. Each spaced-apart section induces non-zero coupling between the principal orthogonal polarization modes. Phase matched coupling between the principal orthogonal polarization modes is achieved by spacing the sections periodically by a distance .LAMBDA. equal to .lambda./.DELTA.N where .lambda. is the propagation wavelength in the waveguide and .DELTA.N is the difference between the effective refractive indices for the principal orthogonal polarization modes. Realizations of the waveguide structure are shown using Group III-V semiconductor rib waveguide structures.
    Type: Grant
    Filed: April 7, 1992
    Date of Patent: September 7, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Thomas L. Koch, Yosi Shani
  • Patent number: 5241414
    Abstract: For a group of optical amplifiers, pump beams from an array of lasers are mixed together to form a plurality of composite pump beams. Each composite pump beam is distributed to the pump port of a particular optical amplifier. The composite pump beam improves the reliability of each optical amplifier. Rather than having catastrophic failure of an optical amplifier occasioned by the failure of its pump laser, it is now possible to maintain full operation of the group of optical amplifiers even though one or more lasers fail.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: August 31, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Clinton R. Giles, Tingye Li
  • Patent number: 5237577
    Abstract: Saturation intensity and loss of a saturable absorber are substantially independently regulated by positioning the saturable absorber element within a Fabry-Perot etalon defined by first and second reflective elements so that the saturable absorber element responds to light at optical wavelengths in the anti-resonant portion of the Fabry-Perot spectral response, that is, between optical wavelengths corresponding to resonance peaks. The resulting combination of elements is called a Fabry-Perot saturable absorber. Thickness of the saturable absorber element substantially sets the loss of the Fabry-Perot saturable absorber while changes in the reflectivity of the first reflective element onto which the light is incident substantially determines the saturation intensity (degree of nonlinearity) and assists in compensating loss of the saturable absorber element.
    Type: Grant
    Filed: November 6, 1991
    Date of Patent: August 17, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Ursula Keller, David A. B. Miller
  • Patent number: 5220578
    Abstract: A light transmitter comprising a distributed Bragg reflector laser and mode stabilization feedback means is described for maintaining the laser in single longitudinal mode operation.
    Type: Grant
    Filed: November 1, 1991
    Date of Patent: June 15, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Thomas L. Koch, Sheryl L. Woodward
  • Patent number: 5220325
    Abstract: Efficient decoding of an hierarchical, variable length, encoded data sequence containing embedded uncoded data into a sequence of fixed length instructions for subsequent processing by a digital video processor or the like is realized in an apparatus including a decoder having a plurality of variable length code decoding elements and a control structure embedded within each decoding element for transferring the decoding operation to an appropriate one of the decoding elements in response to a prior output from the decoder element. As the encoded data sequence is processed by the apparatus, a predetermined length of the sequence is stored in a register. The control structure further responds to the encoded data sequence to initiate selection of either the predetermined length of the sequence stored in the register or a portion of the decoder output as the fixed length instruction to be output by the apparatus.
    Type: Grant
    Filed: March 28, 1991
    Date of Patent: June 15, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Bryan D. Ackland, Hemant Bheda, Joseph H. Othmer
  • Patent number: 5212743
    Abstract: Wide optical bandwidth and broad wavelength tuning range are achieved in a reset-free, optical, automatic polarization controller by combining three controllable fractional wave elements in cascade and further by controlling the orientations of both outermost fractional wave elements to differ by a prescribed angular amount which is maintained substantially constant. The prescribed angular amount is defined to be between 0 and 2.pi., inclusively. Synchronous control of both outermost fractional wave elements maintains the prescribed angular difference to be maintained constant during operation of the polarization controller. The three fractional wave elements are described as an endlessly rotatable half-wave element and two synchronously rotatable quarter-wave elements wherein the half-wave element is placed between the quarter-wave elements. Each fractional wave element varies the orientation of linear birefringence along its optical wavepath and introduces a specified phase retardation.
    Type: Grant
    Filed: February 12, 1992
    Date of Patent: May 18, 1993
    Assignee: AT&T Bell Laboratories
    Inventor: Fred L. Heismann
  • Patent number: 5210428
    Abstract: Carriers are permitted escape from quantum wells within a semiconductor device in the minimum amount of time by utilizing semiconductor material in the barrier layers around the quantum well wherein the barrier layers exhibit an effective bandgap energy less than the sum of the longitudinal optical phonon energy and the exciton absorption energy.
    Type: Grant
    Filed: November 1, 1991
    Date of Patent: May 11, 1993
    Assignee: AT&T Bell Laboratories
    Inventor: Keith W. Goossen
  • Patent number: 5187610
    Abstract: In an optical arrangement for amplifying an input lightwave signal by a predetermined amount to a desired output level, an optical amplifier is connected to a loss element. The optical amplifier is pumped by an amount exceeding a nominal amount wherein the nominal amount is the amount of pumping needed to attain the desired output level at the optical amplifier output. By attenuating the signal output from the optical amplifier, the loss element generates an output signal from the optical arrangement at the desired output level. This optical arrangement is characterized by an improved noise performance (noise figure) over standard optical amplifiers.
    Type: Grant
    Filed: December 19, 1991
    Date of Patent: February 16, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Isam M. I. Habbab, Adel A. M. Saleh