Patents Examined by Kinfe-Michael Negash
  • Patent number: 7095961
    Abstract: An optical transmitter transmits a data signal developing a specific spectrum at a predetermined frequency, while an optical receiver detects amplitude information on the spectrum included in the data signal to control the received data signal to a constant amplitude on the basis of the detected amplitude information. This can provide an optical communication system and an optical receiver capable of functioning well even if the optical S/N is in a poor condition.
    Type: Grant
    Filed: September 10, 2001
    Date of Patent: August 22, 2006
    Assignee: Fujitsu Limited
    Inventor: Sadao Ibukuro
  • Patent number: 7006766
    Abstract: A system for controlling the demultiplexing process in an optical backplane device has application to optical switching in high-speed digital communication routers and switches. In demultiplexing, a selected compressed data packet is extracted from a multiplexed stream of compressed packets by a modulator and decompressed. The modulator is controlled by a control signal. An error in the timing of the modulator control signal corresponds to a characteristic distortion in the decompressed signal. By monitoring the effect of timing errors on decompressed signals, steps can be taken to correct the timing errors by controlling delays in either the optical or the electronic parts of the switching device. The timing of modulator control pulses is thus continuously adjusted to minimize timing errors. Instead of monitoring just decompressed signals, calibration pulse trains of known value and suitable form can be inserted.
    Type: Grant
    Filed: April 26, 2001
    Date of Patent: February 28, 2006
    Assignee: Roke Manor Research Limited
    Inventor: John Mansbridge
  • Patent number: 6978091
    Abstract: Generating oscillator signals with which selected signals may be mixed. Such oscillator signals may be generated by dividing a pilot tone, such as a 120 MHz pilot tone found on many cable TV systems. Oscillator signals for demodulating received selected signals may be similarly generated.
    Type: Grant
    Filed: September 21, 2000
    Date of Patent: December 20, 2005
    Assignee: Verizon Services Corp.
    Inventor: Jacob Needle
  • Patent number: 6972880
    Abstract: An apparatus for transmitting and receiving optical signals and which is independent of the optical transmission bit rate. The apparatus includes an optical transmitting unit and an optical receiving unit. The optical transmitting unit receives a clock signal and transmits an optical signal at a bit rate corresponding to the frequency of the clock signal. The optical receiving unit receives an optical signal, converts the received optical signal into an electrical signal and processes the electrical signal to be an electrical representation of the received optical signal. The optical receiving unit has frequency characteristics which are controllable in accordance with the frequency of the clock signal to control the processing of the electrical signal. For example, the optical receiving unit can include an amplifying unit which amplifies the electrical signal, wherein the gain and band of the amplifier are controllable in accordance with the frequency of the clock signal.
    Type: Grant
    Filed: October 15, 1996
    Date of Patent: December 6, 2005
    Assignee: Fujitsu Limited
    Inventor: Hiroki Kanesaka
  • Patent number: 6934477
    Abstract: Erbium doped fiber amplifiers (ERDAs) optically couple optical signals between free-space and fiber optic links of a terrestrial optical communication network. The optical gain of transmitting and receiving ERDAs is controlled to achieve good optical signal communication. Control occurs in response to signals received at the transmitting and receiving ends of the links. Control, status and management information may be communicated optically between link head stations. The physical position of transceivers at opposite ends of the link optical signal paths is also controlled.
    Type: Grant
    Filed: July 3, 2002
    Date of Patent: August 23, 2005
    Assignee: LightPointe Communications, Inc.
    Inventor: Heinz Willebrand
  • Patent number: 6934472
    Abstract: An optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and data payload propagate through network elements with the same path and the associated delays. The technique effects survivability and security of the optical networks by encompassing conventional electronic security with an optical security layer by generating replicated versions of the input data payload at the input node, and the transmission of each of the replicated versions over a corresponding one of the plurality of links. Moreover, each of the links is composed of multiple wavelengths to propagate optical signals or optical packets, and each of the replicated versions of the data payload may be propagated over a selected one of the wavelengths in each corresponding one of the plurality of links.
    Type: Grant
    Filed: January 30, 2001
    Date of Patent: August 23, 2005
    Assignee: The Regents of the University of California
    Inventors: Gee-Kung Chang, Arshad M. Chowdhury, Georgios Ellinas
  • Patent number: 6931211
    Abstract: The present invention is directed to a reconfigurable data communications system. The system includes a removable optical backplane connector with a first end and a second end, a first data communications card, and a switch fabric card. The first data communications card includes an optical port configured to receive the first end of the removable optical backplane connector. The switch fabric card has a plurality of optical ports adapted to receive the second end of the removable optical backplane connector.
    Type: Grant
    Filed: August 23, 2001
    Date of Patent: August 16, 2005
    Assignee: Cedarpoint Communications, Inc.
    Inventors: Daniel W. English, Mark Galvin
  • Patent number: 6925256
    Abstract: A bi-directional communication assembly is provided with commonly available optoelectronic components in a compact package. Diplex functionality is achieved by orienting the receiving detector at an angle with respect to the transmitting beam. An interference coating inside the detector, on the detector surface, or on a surface in intimate contact with the detector, reflects the transmitted beam while simultaneously allowing the receiving beam to pass through the coating to the light absorbing region. The combined function of the receiving detector, providing advantages of a common beam path and close proximity of the components, enable a compact package that can be placed within the space usually occupied by the transmitter light source alone.
    Type: Grant
    Filed: February 18, 2000
    Date of Patent: August 2, 2005
    Assignee: DiPlex
    Inventor: Allan Heiney
  • Patent number: 6922531
    Abstract: A system and method for identifying one or more characteristics of an optical signal, in which a transmitter is operable to transmit an optical signal and a receiving unit is operable to receive the optical signal. The transmitter has a laser for generating the optical signal and an encoding unit adapted to control the laser to activate and deactivate the optical signal during a laser shutdown state based on a predetermined code. The receiving unit has an optical receiver optically coupled to the transmitter by a light transmission medium and is operable to receive the optical signal from the transmitter. The receiving unit also has a decoder measuring at least one of an active time of the optical signal and the inactive time between active times of the optical signal. The decoder determines at least one of the one or more characteristics of the optical system based on at least one of the active time or the inactive time.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: July 26, 2005
    Assignee: Nortel Networks Limited
    Inventor: Paul A. Smeulders
  • Patent number: 6917764
    Abstract: An apparatus and associated method for generating predistortion IMD in a predistortion circuit. The method comprising adjusting the bias voltage, adjusting the bias current; adjusting the gain of the amplifier; and adjusting the differential bias current flowing through each diode in an antiparallel diode pair. In one aspect, the bias voltage, the bias current, the gain of the amplifier, and the differential bias current can be iteratively adjusted to generate both even-order and odd-order predistortion IMD.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: July 12, 2005
    Assignee: Emcore Corporation
    Inventor: Gordon C. Wilson
  • Patent number: 6917762
    Abstract: An optical transmission system for compensating for transmission loss includes a transmitting apparatus for serializing a plurality of n (n is a natural number)-bit channel data received from the outside in response to a predetermined clock signal, converting the serialized channel data and the predetermined clock signal into a current signal whose magnitude changes corresponding to an error detection signal, and outputting optical signals having optical output power corresponding to the magnitude of the current signal, a first optical fiber for transmitting the optical signals, a receiving apparatus for recovering the n-bit channel data and the predetermined clock signal from the optical signals received through the first optical fiber, detecting transmission loss generated when the optical signals are transmitted and received, optically converting the transmission loss, and outputting the optically converted transmission loss as the error detection signal, and a second optical fiber for transmitting the opt
    Type: Grant
    Filed: December 29, 2000
    Date of Patent: July 12, 2005
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Yong-Sub Kim
  • Patent number: 6915078
    Abstract: An optical cross-connect switch (12) includes and optical matrix 14 for passing optical communication data between an origination I/O port (20) and a destination I/O port (22). Control information is passes between the origination I/O port (20) and the destination I/O port (22) in transport frames 24. The transport frames include multiple framing bytes indicative of the start of a frame (24) and stuff bytes at regular intervals to ensure adequate bit transitions in the control information data stream. Payload bytes carrying control information are positioned between stuff bytes. The stuff bytes have different bit values from the framing bytes in multiple bit positions to allow false framing only if there are multiple bit errors in the stuff frame.
    Type: Grant
    Filed: August 15, 2000
    Date of Patent: July 5, 2005
    Assignee: Alcatel
    Inventor: Anthony Mazzurco
  • Patent number: 6912359
    Abstract: A suite of optical performance monitoring (OPM) methods, based on optical subcarrier multiplexing, are described by the invention. The strength of this approach lies in the simplicity of double sideband subcarrier signals and the fact that these signals travel the complete optical path with the baseband signal of interest. The subcarrier signals can be recovered using techniques described in the application and are immune to fiber dispersion induced fading.
    Type: Grant
    Filed: September 7, 2001
    Date of Patent: June 28, 2005
    Assignee: The Regents of the University of California
    Inventors: Daniel J. Blumenthal, Bengt-Erik Olsson, Giammarco Rossi, Timothy Eugene Dimmick
  • Patent number: 6912075
    Abstract: A node for satellite system communications between a ground station and a satellite includes a fiber optic bus on the satellite. An optical drop is coupled to the bus. The optical drop resolves an optical signal destined to the given satellite from the optical bus. An uplink and downlink receive and transmit communications from a ground terminal. A router is coupled to the optical drop and the uplink and downlink. An address reader and a table are used by the router to determine the destination of the received RF signals. The received RF signals are converted to optical signals by an optical source. The optical source has a wavelength that corresponds with the destination satellite. The optical signals are transmitted to an adjacent satellite by an optical transmitter such as a transmitting telescope.
    Type: Grant
    Filed: May 17, 1999
    Date of Patent: June 28, 2005
    Assignee: The DIRECTV Group, Inc.
    Inventors: Stanislav I. Ionov, George C. Valley
  • Patent number: 6907196
    Abstract: An arrangement and a method for testing a telecommunications circuit over Dense Wavelength Division Multiplexing (DWDM). A transmitter, which is optically coupled to the circuit, transmits a test-drive signal on the circuit. Through a network, a performance of the circuit is monitored at points along the circuit based on the transmitted test-drive signal.
    Type: Grant
    Filed: June 23, 2004
    Date of Patent: June 14, 2005
    Assignee: Sprint Communications Company L.P.
    Inventors: Douglas L. Richards, David W. Williams, Francis R. Yarkosky
  • Patent number: 6907198
    Abstract: A high-speed and small-sized optical interconnection device uses wavelength-multiplexed light suitable therefor in order to make compatible between an increase in high-speed communication capacity of the optical interconnection device and an increase in high-speed communication distance thereof. A signal processing LSI is placed within a central portion of a main surface of a semiconductor substrate, and input/output units for transmitting and receiving optical wavelength-multiplexed lights are multi-chip integrated on the periphery of the main surface of the semiconductor substrate into a single package, and a wiring length can be reduced and a physical signal band for each connecting wiring can be enlarged. Further, the signal processing LSI is made up of CMOS and a driver circuit for each optical transmitting/receiving element is comprised of a Si—Ge transistor circuit, whereby a modulated signal band can be enlarged and the performance of the input/output optical signals from the device can be improved.
    Type: Grant
    Filed: July 31, 2001
    Date of Patent: June 14, 2005
    Assignee: Hitachi, Ltd.
    Inventor: Shinji Nishimura
  • Patent number: 6901225
    Abstract: A device is provided for detecting polarization mode dispersion of an optical data signal, wherein the device includes at least two filters, each of which is respectively followed by a power detector. A better compensation can ensue due to the combination of a large monotony range and great steepness in the employment of a number of filters.
    Type: Grant
    Filed: July 1, 1999
    Date of Patent: May 31, 2005
    Assignee: Siemens Aktiengesellschaft
    Inventor: Reinhold Noe
  • Patent number: 6898379
    Abstract: An interference-reducing optoelectronic device determines the value of a current data bit in an optical data stream. A receiver receives the optical data stream, which is converted to a series of samples by a D/A converter. A set of adaptive filters, each filter corresponding to a unique possible value for one or more prior data bits, filters the series of samples utilizing variable tap coefficients to generate filtered output values. The variable tap coefficients are at least partially different than the variable tap coefficients of another adaptive filter. Comparators compare the filtered output values against filter-specific adaptive threshold values to generate tentative values for the current data bit. A delay mechanism delays a determined value for the prior data bits, and a selection mechanism determines the value of the current data bit by selecting the tentative value corresponding to the delayed determined value of the prior data bits.
    Type: Grant
    Filed: November 5, 2002
    Date of Patent: May 24, 2005
    Assignee: Finisar Corporation
    Inventors: Thomas J. Lenosky, Jan Lipson, Giorgio Giaretta
  • Patent number: 6895187
    Abstract: A branching unit, for use in optical communication systems, has three branches A, B and C each including a connection for a power feed and several inputs/outputs for optical fibers. Optical switches are provided for selectively coupling inputs/outputs of different branches to enable a routeing of optical signals through the unit. The routeing is effected in dependence upon the way in which each of the three branch connections are provided with an electrical power feed.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: May 17, 2005
    Assignee: Alcatel
    Inventor: Stephen Michael Webb
  • Patent number: 6892032
    Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.
    Type: Grant
    Filed: December 20, 2002
    Date of Patent: May 10, 2005
    Assignee: Nortel Networks Limited
    Inventors: David Milton, Tomas Valis, Gino Totti, Kexing Liu, Michel Pigeon