Having Feedback Patents (Class 398/213)
  • Patent number: 9515859
    Abstract: A system for communicating modulated EHF signals may include a modulation circuit responsive to a bi-level transmit information signal for generating a transmit output signal. The transmit output signal may have an EHF frequency when the transmit information signal is at a first information state and may be suppressed when the transmit information signal is at a second information state. A transmit transducer operatively coupled to the modulation circuit may be responsive to the transmit output signal for converting the transmit output signal into an electromagnetic signal.
    Type: Grant
    Filed: August 18, 2014
    Date of Patent: December 6, 2016
    Assignee: Keyssa, Inc.
    Inventors: Gary D. McCormack, Ian A. Kyles
  • Patent number: 9166702
    Abstract: A signal level detect circuit configured to assess an input signal with varying amplitude signal levels and to generate an indicator signal includes an input circuit configured to receive the input signal and to process the input signal, the input circuit including a first node on which the input signal is sampled; a comparator configured to compare the processed input signal to a signal level threshold and generate a comparator output signal; and an active discharge circuit configured to provide a first discharge current to the first node in response to the comparator output signal. The comparator output signal changes from a low output state to a high output state in response to the comparator input signal, and the active discharge circuit generates the first discharge current to discharge the sampled input signal on the first node after the comparator output signal changes to the high output state.
    Type: Grant
    Filed: November 4, 2013
    Date of Patent: October 20, 2015
    Assignee: Micrel, Inc.
    Inventors: Ulrich Bruedigam, Tomislav Kapucija
  • Patent number: 8989576
    Abstract: A method of processing optical signal (TE) whose power (PE) varies in a random manner in a range of variation of power (?PE) around a mean power (PE?), the processing of the optical signal (TE) generating processing noise (GELECTRONIC), characterized in that the relative variation of power (GE) of at least a temporal part at said optical signal (TE) is optically amplified.
    Type: Grant
    Filed: March 24, 2011
    Date of Patent: March 24, 2015
    Assignees: Universite de Bourgogne, CNRS—Centre National de Recherche Scientifique
    Inventors: Christophe Finot, Julien Fatome
  • Patent number: 8971721
    Abstract: A method for bidirectional optical communication comprising the steps of:—at a first optical line terminal, directly modulating a laser source to generate a downstream optical signal which has an optical power spectrum comprising two peaks having a frequency separation and a non zero power difference at generation;—propagating said downstream optical signal at a distance along an optical line comprising at least a first optical fiber propagating said downstream optical signal to a second optical line terminal;—at the second optical line terminal: power splitting said downstream optical signal to generate a first and a second power portion of said downstream optical signal, spatially separated; passive filtering said first power portion of said downstream optical signal so as to increase in absolute value a respective power difference of said two peaks, so as to obtain a filtered optical signal which is thereafter detected; and amplitude modulating the second power portion of the downstream optical signal so a
    Type: Grant
    Filed: May 20, 2009
    Date of Patent: March 3, 2015
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Rinaldo Mazzone, Francesco Martini, Mauro Rudi Casanova
  • Patent number: 8953950
    Abstract: A ultra high speed photonic Analog to Digital Converted (ADC) for sampling and quantizing an electrical voltage signal, internally enabled by photonics uses coherent optical detection architectures for photonic quantization. Coherent light is phase modulated by the test signal. Using an interferometer, or an array of interferometers the phase of modulated light is compared with a reference light. Flash ADC, successive approximation ADC and delta-sigma ADC configurations are presented.
    Type: Grant
    Filed: July 25, 2010
    Date of Patent: February 10, 2015
    Assignee: Technion Research and Development Foundation Ltd.
    Inventors: Moshe Nazarathy, Igor Zelniker
  • Patent number: 8948613
    Abstract: In part, aspects of the invention relate to methods, apparatus, and systems for intensity and/or pattern line noise reduction in a data collection system such as an optical coherence tomography system that uses an electromagnetic radiation source and interferometric principles. In one embodiment, the noise is intensity noise or line pattern noise and the source is a laser such as a swept laser. One or more attenuators responsive to one or more control signals can be used in conjunction with an analog or digital feedback network in one embodiment.
    Type: Grant
    Filed: March 17, 2011
    Date of Patent: February 3, 2015
    Assignee: Lightlab Imaging, Inc.
    Inventors: Joseph M. Schmitt, Victor Grinberg
  • Patent number: 8948615
    Abstract: There is provided an optical receiver including a variable-ratio splitter to split an input signal light into a plurality of signal lights, based on a variable ratio, a plurality of photo detectors to receive the plurality of signal lights respectively, an operation circuit to output a reception electrical signal, based on a reception processing on one of the plurality of signal lights, a calculation circuit to calculate a total power of the plurality of signal lights received by the plurality of photo detectors, and an output unit to output a signal regarding the total power.
    Type: Grant
    Filed: March 29, 2011
    Date of Patent: February 3, 2015
    Assignee: Fujitsu Optical Components Limited
    Inventor: Hiromasa Tanaka
  • Patent number: 8897657
    Abstract: To stabilize power to an optical multimode receiver a multimode variable optical attenuator is connected to the receiver with the attenuator's voltage being controlled using a feedback signal provided by an output detector, the signal being processed using a control algorithm based on proportional-integrate-differential theory.
    Type: Grant
    Filed: February 17, 2011
    Date of Patent: November 25, 2014
    Assignee: The Johns Hopkins University
    Inventors: Joseph E. Sluz, Juan C. Juarez, David W. Young
  • Patent number: 8891978
    Abstract: At least one cell implementing a sensor array embraces a photoelectric-conversion accumulation element configured to generate and accumulate signal charges, a potential detection circuit configured to detect the signal charges generated by the photoelectric-conversion accumulation element as a potential change, and an amplification circuit configured to amplify the potential change and to transmit to an output-signal line. The photoelectric-conversion accumulation element and the potential detection circuit are connected in series between a first potential terminal and a second potential terminal, and the potential detection circuit has an insulated-gate transistor, which detects the potential change in a weak inversion state, in a period when an optical-communication signal is received.
    Type: Grant
    Filed: September 18, 2009
    Date of Patent: November 18, 2014
    Assignee: National University Corporation Shizuoka University
    Inventors: Shoji Kawahito, Isamu Takai, Michinori Ando
  • Patent number: 8861982
    Abstract: When designing a demodulator for a DPSK-modulated signal, it is required that optical phase modulation is performed fast and the demodulator has a long lifetime. To achieve this object, a delay line interferometer inside the demodulator performs adjustment of phase difference between two split lights caused to interfere, using a first optical phase modulation unit such as a Piezo actuator and a second optical phase modulation unit such as a heating element that operates slower in modulation speed than the first optical phase modulation unit and is slower in deterioration speed.
    Type: Grant
    Filed: January 6, 2011
    Date of Patent: October 14, 2014
    Assignee: Oclaro Japan, Inc.
    Inventors: Hideharu Mikami, Taichi Kogure
  • Patent number: 8755696
    Abstract: A control apparatus for controlling an optical receiver having delay paths comprises an optical variable attenuator configured to generate a variable signal and provide the variable signal to the optical receiver; a fine control voltage controller configured to generate a variable fine control voltage and input the variable fine control voltage to one path of the delay paths of the optical receiver; a photo-diode voltage monitor configured to detect a first voltage value and a second voltage value; a bit error rate (BER) checker configured to estimate a bit error rate (BER) according to a signal output from the optical receiver; and a controller configured to set a value of the variable signal and a value of the variable fine control voltage and to estimate the fine control voltage that makes the bit error rate a minimum according to the first voltage value and the second voltage value.
    Type: Grant
    Filed: May 30, 2012
    Date of Patent: June 17, 2014
    Assignee: Electronics and Telecommunications Research Institute
    Inventor: Jyung-Chan Lee
  • Patent number: 8737848
    Abstract: An optical receiver includes: an optical amplifier amplifying an optical signal fed thereinto according to an operating current fed thereinto, the optical signal being a wavelength-multiplexed optical signal, a demultiplexer demultiplexing an optical signal output from the optical amplifier; and an operating-current control circuit selecting a monitoring target from a plurality of wavelength signals output from the demultiplexer and controlling the operating current of the optical amplifier so that optical power of the monitoring target is controlled to be a predetermined value.
    Type: Grant
    Filed: January 21, 2011
    Date of Patent: May 27, 2014
    Assignees: Fujitsu Limited, Fujitsu Optical Components Limited
    Inventors: Tadashi Ikeuchi, Naoki Kuwata
  • Patent number: 8718476
    Abstract: There is provided a method and apparatus for tuning an optical discriminator to the carrier frequency of an optical signal to allow superior reception of said signal. The carrier frequency of the signal is dithered during a test phase in order to provide information that allows a subsequent tuning phase to optimise the reception of the optical signal, as measured by a signal quality metric. The tuning phase may comprise adjustment of one or both of the carrier frequency and the optical discriminator.
    Type: Grant
    Filed: February 27, 2008
    Date of Patent: May 6, 2014
    Assignee: Xtera Communications, Inc.
    Inventors: Steven Webb, David Winterburn
  • Patent number: 8705983
    Abstract: An optical communication system for generating and transmitting a modulated optical signal in which light emitted by a light source is modulated by an optical modulator in accordance with an input electrical signal. A bias signal generator applies a bias electrical signal to bias the optical modulator at a bias angle away from quadrature. The bias signal generator monitors the input electrical signal and adjusts the applied bias electrical signal in dependence on the input electrical signal. The system further includes a receiver which may include an equalizer coupled to the photodetector of the receiver.
    Type: Grant
    Filed: March 25, 2011
    Date of Patent: April 22, 2014
    Assignee: Emcore Corporation
    Inventors: Ronald T. Logan, Jr., Eva Peral, Patrick J. Cawthorne, Gustav Witzel, Frank Weiss
  • Patent number: 8705985
    Abstract: A method and an optical receiver implementing this method suitable for robustly receiving unencoded optical data. The method sets the threshold for the receiver using values relating to the high and low values of a binary signal. However, for some data patterns these values may not be accurately determined, such as for extended periods of constant high or low values being transmitted. In this case the method, in one embodiment, assumes that the extinction ratio of the signal is substantially constant and is thereby able to track the threshold for the signal.
    Type: Grant
    Filed: June 2, 2011
    Date of Patent: April 22, 2014
    Assignee: Mellanox Technologies Denmark APS
    Inventor: Steen Bak Christensen
  • Patent number: 8676054
    Abstract: There is provided an optical transmission receiver includes an optical switch configured to switch between optical transmission channels, the optical transmission channels being gradually switched from one to the other, an optical amplifier configured to amplify a light propagating in the other of the optical transmission channels which is in a state subsequent to switching, and a switching speed controller configured to control a switching speed of the optical switch based on a level of the light amplified by the optical amplifier.
    Type: Grant
    Filed: July 13, 2010
    Date of Patent: March 18, 2014
    Assignee: Fujitsu Limited
    Inventors: Yuichi Suzuki, Toshihiro Ohtani
  • Patent number: 8655196
    Abstract: This invention relates to a phase control circuit for an optical receiver (1). The phase control circuit (9, 19) comprises a non-linear element (22) and a power detector (24). The non-linear element (22) has a rectifying characteristic, inputs the received electrical signal (7, 17) and provides a rectified signal at its output. The power detector (24) provides an error signal which is used to obtain a phase control signal (5) which is output by the phase control circuit. The invention further relates to a corresponding method for phase control of an optical receiver (1).
    Type: Grant
    Filed: March 3, 2009
    Date of Patent: February 18, 2014
    Assignee: Cisco Technology, Inc.
    Inventor: Christopher Fludger
  • Patent number: 8649690
    Abstract: A system configured to maintain a consistent local-oscillator-power-to-primary-signal-power ratio (LO/SIG ratio).
    Type: Grant
    Filed: May 30, 2012
    Date of Patent: February 11, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Soren Gehrke, Theodor Kupfer, James Whiteaway
  • Patent number: 8606120
    Abstract: The present invention provides a system, apparatus and method to control an optical polarization beam splitter. A portion of an optical output of the polarization beam splitter is converted into a corresponding electrical signal. The electrical signal is then provided to the polarization beam splitter as a control signal via a feedback loop. The polarization beam splitter controls a characteristic of the optical output of the polarization beam splitter in response to the received control signal. The characteristic, for example, may be controlled through thermo-optically or electro-optically. The control system may be used over a period of time to maintain the characteristic at a desired value, for example as the components of the polarization beam splitter, or other elements used in the control of the polarization beam splitter, age.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: December 10, 2013
    Assignee: Infinera Corporation
    Inventors: Mehrdad Ziari, Masaki Kato, Radhakrishnan L. Nagarajan
  • Patent number: 8577225
    Abstract: Provided is an optical receiver which accurately demodulates an optical signal obtained by the differential phase shift modulation method. The optical receiver includes: an interferometer which branches the inputted optical signal into two parts and gives a one-bit phase difference to the resultant two optical signals so that the two optical signals after addition of the phase difference are made to interfere each other to output two output lights; reflection means which reflects one of the output lights from the interferometer so as to return to the interferometer; detection means which detects the return light which has been reflected by the reflection means and propagates through the interferometer in the different direction from the inputted optical signal, for output; and phase difference control means which adjusts the phase difference given by the interferometer according to the intensity of the return light detected by the detection means.
    Type: Grant
    Filed: March 25, 2009
    Date of Patent: November 5, 2013
    Assignee: Sumitomo Osaka Cement Co., Ltd.
    Inventors: Masahito Mure, Norikazu Miyazaki, Toshio Kataoka, Kaoru Higuma
  • Patent number: 8543004
    Abstract: In one aspect, the present invention embraces a wavelength locking method for causing a narrow-band wavelength spectrum of an optical transmit signal of an optical transceiver device to track a narrow-band wavelength spectrum of an optical receive signal received by the optical transceiver device Further, the present invention embraces a wavelength lockable optical transceiver device, especially for a passive optical transmission network, using this wavelength locking method.
    Type: Grant
    Filed: December 16, 2011
    Date of Patent: September 24, 2013
    Assignee: ADVA Optical Networking SE
    Inventor: Michael Eiselt
  • Patent number: 8538271
    Abstract: An apparatus comprising an optical receiver configured to receive an optical signal, and a combined level and clock recovery circuit coupled to the optical receiver and configured to update a signal threshold and a clock phase substantially simultaneously. Also included is an apparatus comprising at least one processor configured to implement a method comprising recognizing reception of a signal, and adjusting a threshold and a clock phase associated with the signal using a rising time for the signal and a falling time for the signal. Also included is a method comprising receiving a signal, and adjusting a threshold level of the signal to establish level recovery using a clock recovery scheme.
    Type: Grant
    Filed: November 23, 2009
    Date of Patent: September 17, 2013
    Assignee: Futurewei Technologies, Inc.
    Inventor: Frank J. Effenberger
  • Publication number: 20130216241
    Abstract: A technique is provided for configuring an optical receiver. A photo detector is connected to a load resistor, and the photo detector includes an internal capacitance. A current source is connected through a switching circuit to the load resistor and to the photo detector. The current source is configured to discharge the internal capacitance of the photo detector. The switching circuit is configured to connect the current source to the internal capacitance based on a previous data bit.
    Type: Application
    Filed: February 16, 2012
    Publication date: August 22, 2013
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Jonathan E. Proesel, Alexander V. Rylyakov, Clint L. Schow, Yurii A. Vlasov
  • Patent number: 8515291
    Abstract: The light receiving device includes a pixel array, such as a two-dimensional pixel array, of pixels each having a light-receiving element for receiving input signal light, an output selecting unit for selecting the outputs of pixels within the pixel array, a selected output adding unit for adding and outputting the selected outputs of the pixels, and an amplifying unit for amplifying the output of the selected output adding unit.
    Type: Grant
    Filed: August 13, 2009
    Date of Patent: August 20, 2013
    Assignee: Fujitsu Semiconductor Limited
    Inventor: Tadao Inoue
  • Patent number: 8503891
    Abstract: There is a need to provide a multirate burst mode receiver for an OLT to be capable of receiving a high-speed burst signal without the need for a special capability of an ONU in a PON system including a mix of ONUs at different transmission bit rates. A multirate burst mode receiver according to the invention includes a signal input discrimination section and a bit rate discrimination section. The signal input discrimination section detects an average amplitude to discriminate signal input. The bit rate discrimination section detects an envelope curve for a high-frequency component to discriminate a signal bit rate. Based on a discrimination result from the signal input discrimination section and the bit rate discrimination section, the multirate burst mode receiver switches a setting for an optical signal reception section and a serial-parallel converter corresponding to the reception bit rate.
    Type: Grant
    Filed: January 21, 2011
    Date of Patent: August 6, 2013
    Assignee: Hitachi, Ltd.
    Inventors: Daisuke Mashimo, Masahito Takei, Jun Sugawa, Hiroki Ikeda
  • Patent number: 8498545
    Abstract: A demodulator for a DPSK-modulated optical signal of bit frequency 1/T, comprises an interferometric structure (3) having an input port (1) for receiving the DPSK-modulated optical signal, an output port (8), and first and second arms (4, 5) extending from said input port (1) to said output port (8), adjustment means (5, 7, 14, 16) for fine tuning a propagation delay difference of said two arms (4, 5) in a range comprising T, an optical/electrical converter (10) connected to the output port (8) of the interferometric structure (3), and a bandpass filter (12) connected to an output of the optical/electrical converter (10), the passband of which does not include 1/T. The adjustment means (5, 7, 14, 16) is adapted to tune the propagation delay according to the output power level of the bandpass filter (12).
    Type: Grant
    Filed: December 21, 2005
    Date of Patent: July 30, 2013
    Assignee: Alcatel Lucent
    Inventors: Loïc Becouarn, Georges Grandpierre, Thierry Boissau
  • Patent number: 8472802
    Abstract: Various embodiments of the present invention are directed to methods and systems for transmitting optical signals from a source to a plurality of receiving devices. In one method embodiment, an optical enablement signal is transmitted (401) from the source to the plurality of receiving devices. The target receiving device responds to receiving the optical enablement signal by preparing to receive one or more optical data signals. The source transmits the one or more optical data signals to the target receiving device. The remaining receiving devices do not receive the one or more optical data signals.
    Type: Grant
    Filed: March 10, 2008
    Date of Patent: June 25, 2013
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Jung Ho Ahn, Moray McLaren, Alan L. Davis
  • Patent number: 8472813
    Abstract: A polarization-multiplexed (POLMUX) optical orthogonal frequency division multiplexing (OFDM) system with direct detection includes an adaptive dual POLMUX carrier OFDM transmitter; and a block symmetric (B-S) MIMO equalizer coupled to the adaptive dual POLMUX carrier OFDM transmitter through a standard single-mode-fiber (SSMF) feedback path.
    Type: Grant
    Filed: June 18, 2010
    Date of Patent: June 25, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Neda Cvijetic, Narayan Prasad, Dayou Qian, Ting Wang
  • Patent number: 8472812
    Abstract: Transmission-side communication apparatus 100 using a DQPSK (differential quadrature phase-shift keying) scheme is provided with: optical carrier generation section 102 which generates an optical carrier the frequency of which switches among a plurality of different frequencies within one symbol period; and modulation section 103 with which DQPSK-modulates the optical carrier generated by the optical carrier generation means in accordance with a modulation signal at an interval of the symbol period. There are provided: single delay interference section 121 which receives an optical signal obtained by DQPSK-modulating an optical carrier the frequency of which switches among a plurality of different frequencies within one symbol period and outputs an output light obtained by causing the optical signal 104 and a delay optical signal thereof to interfere with each other; and photoelectric conversion section 124 which converts the output light outputted by the delay interference means to an electric signal.
    Type: Grant
    Filed: February 18, 2009
    Date of Patent: June 25, 2013
    Assignee: NEC Corporation
    Inventors: Satomi Shioiri, Toshiharu Ito, Kiyoshi Fukuchi
  • Patent number: 8433200
    Abstract: A quantum key delivery system includes an optical circulator, an optical low-pass filter, optical splitters, and first and second optical couplers arranged for outputting various wavelength components including correlated-photon pair wavelength components outputted from an optical loop path. The first and second optical couplers output light beams, which are sent over first and second quantum channels to first and second recipients, respectively. Other optical splitters are adapted to output light rays, from which first and second control signals are produced. From auxiliary idler light components transmitted over the first and second quantum channels, clock signals are extracted. The system thus extracts a clock signal for detecting arrival of photons, and stably operates with an expected value of the number of generated correlated photon pairs maintained at a substantially constant value.
    Type: Grant
    Filed: August 16, 2011
    Date of Patent: April 30, 2013
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Shin Arahira
  • Patent number: 8412054
    Abstract: An optical receiver includes a first interferometer having a plurality of arms. The optical receiver further includes first tunable optical filters connected in series with the arms of the first interferometer, where each first tunable optical filter is tuned to filter a region of overlap in the optical frequency spectrum between adjacent optical channels.
    Type: Grant
    Filed: August 4, 2011
    Date of Patent: April 2, 2013
    Assignee: Verizon Patent and Licensing Inc.
    Inventors: David Zhi Chen, E. Evert Basch
  • Patent number: 8396375
    Abstract: A method for enabling bidirectional data communication using a single optical carrier and a single laser source with the aid of an integrated, colorless demodulator and detector for frequency modulated signals, and a reflective modulator. A receiving optical system holds a technique for demodulation and detection of optical frequency modulated signals, enabling remodulation of the incoming signal to establish bidirectional communication with the transmitting optical system, without introducing a high penalty. A colorless demodulator and detector, which provides the functionality of a periodic filtering device for demodulation of the downstream, and also detection capability. The principle of operation of the CDD relies on the introduction of a comb transfer function with the help of a Semiconductor Optical Amplifier, by providing a reflected feedback signal to the CDD's active element.
    Type: Grant
    Filed: February 18, 2010
    Date of Patent: March 12, 2013
    Assignee: Universitat Politecnica de Catalunya
    Inventors: Bernhard Schrenk, José Antonio Lázaro Villa, Christophe Kazmierski, Josep Joan Prat Gomà
  • Patent number: 8326160
    Abstract: A dispersion compensation device includes: an optical branching unit to branch an optical signal to be received; a first dispersion compensator to perform dispersion compensation on one part of the optical signal branched by the optical branching unit with a variable compensation amount; a second dispersion compensator to perform dispersion compensation on another part of the optical signal branched by the optical branching unit; a monitoring unit to monitor the communication quality of an output optical signal of the second dispersion compensator; and a controlling unit to determine the direction of variation in chromatic dispersion of the optical signal based on the direction of variation in communication quality monitored by the monitoring unit and control the compensation amount of the first dispersion compensator based on the result of the determination.
    Type: Grant
    Filed: November 22, 2010
    Date of Patent: December 4, 2012
    Assignee: Fujitsu Limited
    Inventors: Makoto Murakami, Toshihiro Ohtani
  • Patent number: 8320779
    Abstract: A receiver includes wavelength demultiplexer for demultiplexing a received WDM light into light signals at respective central frequencies thereof, delay interferometer for converting a light signal output from wavelength demultiplexer into an intensity signal, and light detector for converting an output signal from delay interferometer into an electric signal. The interval between interferential frequencies of delay interferometer is 2/(2n+1) times the interval between the central frequencies of the WDM light. Logic inverting circuit outputs the output signal from the light detector while non-inverting or inverting the logic level thereof depending on the received central frequency.
    Type: Grant
    Filed: October 4, 2006
    Date of Patent: November 27, 2012
    Assignee: NEC Corporation
    Inventors: Kiyoshi Fukuchi, Toshiharu Ito
  • Patent number: 8306439
    Abstract: A communication apparatus in accordance with an embodiment comprises a reception unit configured to demodulate a received signal to output a first demodulated signal in dependence on a reception condition. The communication apparatus further comprises a pattern detection unit configured to detect a characteristic pattern in the first demodulated signal to output a pattern detection signal, and a pitch detection unit configured to detect a pitch of the characteristic pattern based on the pattern detection signal to output a first signal detection signal indicating that the first demodulated signal is one of an in-phase signal and a quadrature signal, or an inverted version of the one of the in-phase signal and the quadrature signal.
    Type: Grant
    Filed: June 16, 2009
    Date of Patent: November 6, 2012
    Assignee: Fujitsu Limited
    Inventors: Naoki Kuwata, Tadashi Ikeuchi, Toru Katagiri
  • Patent number: 8301039
    Abstract: A delay device that provides a delay amount to at least one of the in-phase signal and the quadrature signal, and a delay control section that controls the delay amount provided by the delay device based on a quality of the signals when the in-phase signal and the quadrature signal, to the at least one of which the delay amount is provided, at the delay device are converted into digital signals by the analog-digital converter, and the digital signal processing is carried out at the processor are provided. Thereby, the signal quality of recovered data at a receiving end of a multi-level phase modulation communication system is improved.
    Type: Grant
    Filed: November 17, 2009
    Date of Patent: October 30, 2012
    Assignee: Fujitsu Limited
    Inventors: Masato Nishihara, Tomoo Takahara, Hisao Nakashima
  • Patent number: 8295712
    Abstract: An optical device comprising an optical device comprising a Mach-Zehnder interferometer having a first 2×2 optical coupler, a second 2×2 optical coupler, a first optical arm, and a second optical arm. The first and second arms connecting corresponding pairs of optical ports of the first and second 2×2 optical couplers. The second optical arm has a longer optical path than the first arm. The device also comprises one or more optical resonators optically coupled to the first optical arm and an optical splitter. The optical splitter is coupled to deliver a portion of an input optical signal to one port of the first 2×2 optical coupler and to deliver a remaining portion of the input optical signal to one port of the second optical coupler.
    Type: Grant
    Filed: November 10, 2009
    Date of Patent: October 23, 2012
    Assignee: Alcatel Lucent
    Inventors: Young Kai Chen, Mahmoud Rasras
  • Patent number: 8270847
    Abstract: Polarization multiplexing with different differential phase shift keying (DPSK) schemes generally uses DPSK modulated signals modulated using different DPSK modulation schemes and combined with orthogonal polarizations relative to each other. The different DPSK modulation schemes may use different DPSK phase shifts to represent data, such as a regular DPSK modulation scheme and a ?/2 DPSK modulation scheme. By using different DPSK modulation schemes to represent data on the orthogonally polarized signals, the DPSK demodulators may effectively separate the orthogonally polarized signals using the property of the DPSK receivers. To optimize performance, the DPSK modulated signals may also be bit-interleaved when combined with orthogonal polarization.
    Type: Grant
    Filed: February 2, 2009
    Date of Patent: September 18, 2012
    Assignee: Tyco Electronics Subsea Communications LLC
    Inventors: Hongbin Zhang, Jin-Xing Cai
  • Patent number: 8270850
    Abstract: A demodulator includes: a splitter that branches a differential phase shift keying optical signal into a first branched optical signal passing through a first optical path and a second branched optical signal passing through a second optical path; a multiplexer that multiplexes the first branched optical signal having passed through the first optical path and the second branched optical signal having passed through the second optical path and makes interference between the first branched optical signal and the second branched optical signal; and a double refraction medium that reduces difference between phase differences between each polarized wave between the first branched optical signal and the second branched optical signal multiplexed by the multiplexer.
    Type: Grant
    Filed: November 19, 2009
    Date of Patent: September 18, 2012
    Assignee: Fujitsu Limited
    Inventors: Takashi Shimizu, Koji Terada, Kiyomi Narita, Kazuyuki Mori
  • Patent number: 8254793
    Abstract: A tunable element of a tuning module is receptive to optical data channels of a multiplexed optical data signal, each optical data channel having a different respective wavelength. The tunable element is responsive to different stimuli such that multiple passbands of the tunable element are defined, each passband corresponding to a respective stimulus and including no more than one wavelength of the optical data channels. An optical detector communicates with the tunable element and is receptive to no more than one optical data channel from the tunable element at any given time, an output of the optical detector is an electrical data signal that corresponds to the optical data channel received by the optical detector from the tunable element. A controller communicates with the tunable element and tunes the tunable element from one optical data channel to the other by causing application of a corresponding stimulus to the tunable element.
    Type: Grant
    Filed: May 27, 2008
    Date of Patent: August 28, 2012
    Assignee: Finisar Corporation
    Inventors: Gayle L. Noble, Lucy G. Hosking, Luke Ekkizogloy, James L. Noble
  • Patent number: 8249466
    Abstract: A polarization multiplexing optical receiver includes a polarization controller configured to control a polarization state of a polarization multiplexed optical signal; a polarization splitter configured to split the polarization multiplexed optical signal for which the polarization state is controlled by the polarization controller into a first polarization signal and a second polarization signal; a first detector configured to detect an optical power of the first polarization signal and output a first optical power signal representing the optical power of the first polarization signal; a second detector configured to detect an optical power of the second polarization signal and output a second optical power signal representing the optical power of the second polarization signal; and a controller configured to control the polarization controller on the basis of the first optical power signal and the second optical power signal.
    Type: Grant
    Filed: November 16, 2009
    Date of Patent: August 21, 2012
    Assignee: Fujitsu Limited
    Inventor: Takeshi Hoshida
  • Patent number: 8249447
    Abstract: The present invention provides systems and methods for a receiver threshold optimization loop to provide self-contained automatic adjustment in a compact module, such as a pluggable optical transceiver. The receiver threshold optimization loop utilizes a performance metric associated with the receiver, such as FEC, to optimize performance of the receiver. The receiver is optimized through a change in the receiver threshold responsive to the performance metric. Advantageously, the present invention provides improved receiver performance through a continuous adjustment that is self-contained within the receiver, such as within a pluggable optical transceiver compliant to a multi-source agreement (MSA). The receiver threshold optimization loop can include a fine and a coarse sweep of adjustment from an initial setting.
    Type: Grant
    Filed: April 29, 2008
    Date of Patent: August 21, 2012
    Assignee: Menara Networks, Inc.
    Inventors: Qingzhong Cai, Xiaoguang Sun, Gabriel E. Cardona
  • Patent number: 8238762
    Abstract: The invention relates to a bandpass filter (OFI) which is mounted downstream of an optical amplifier (OV) and allows noise to be largely reduced. In order for said bandpass filter to be able to optimally receive burst signals (BS1, BS2, . . . , BSN) transmitted by several user devices (ONT1, ONT2, . . . , ONTN) also in a central node (OLT), the bandpass filter is set to the respective received carrier frequencies (TF1to TFN). Because of time constraints, this is possible only if the carrier frequencies (TF1, . . . ) or associated filter setting values (FE1, . . . ) have already been stored and the bandpass filter is preset.
    Type: Grant
    Filed: July 11, 2007
    Date of Patent: August 7, 2012
    Assignee: Nokia Siemens Networks GmbH & Co.
    Inventor: Michael Rasztovits-Wiech
  • Patent number: 8218975
    Abstract: A demodulator comprises an input splitter, optical device sets, and couplers. The input splitter splits an input signal comprising symbols to yield a number of signals. A first optical device set directs a signal of along a first path. A second optical device set directs another signal along a second path to yield a delayed signal. At least a portion of the second path is in free space. A path length difference between the first path and the second path introduces a delay between the first signal and the second signal. A coupler receives a portion of the signal and a portion of the delayed signal to generate interference, where the interference indicates a phase shift between a phase corresponding to a symbol and a successive phase corresponding to a successive symbol.
    Type: Grant
    Filed: December 31, 2009
    Date of Patent: July 10, 2012
    Assignee: Fujitsu Limited
    Inventors: Cechan Tian, Takao Naito
  • Patent number: 8208816
    Abstract: An optical communications system includes an optical transmitter that generates a modulated optical signal at an output. The modulated optical signal propagates through an optical link where the dispersion of the optical link is imprinted onto an optical spectrum of the modulated optical signal. A demodulator receives the modulated optical signal and filters at least a portion of the optical spectrum with the imprinted dispersion of the optical link, thereby mitigating effects of dispersion in the modulated optical signal and generating a demodulated optical signal at an output. An optical detector generates an electrical data signal from the demodulated optical signal.
    Type: Grant
    Filed: April 19, 2008
    Date of Patent: June 26, 2012
    Assignee: Finisar Corporation
    Inventor: Heider Ereifej
  • Patent number: 8184972
    Abstract: Data is encrypted onto an electromagnetic beam by providing an electromagnetic beam having a signal component having a modal state, wherein the signal component is susceptible to accumulation of a geometric phase, and a reference component, transmitted along a path over at least part of which the signal component accumulates a geometric phase by transformation of its modal state from a first to a second modal state, from the second to at least one further modal state, and then back to the first modal state; and modulating with the data the geometric phase so accumulated, by modulating the modal state transformations. Data is decrypted from a received electromagnetic beam by corresponding processing of the received electromagnetic beam and by comparing an overall phase of the signal component with an overall phase of the reference component so as to retrieve the modulation.
    Type: Grant
    Filed: July 24, 2008
    Date of Patent: May 22, 2012
    Assignee: Fujitsu Limited
    Inventors: Michael Charles Parker, Stuart Douglas Walker
  • Patent number: 8155535
    Abstract: An optical receiver for stably reproducing packets having different light receiving levels is disclosed. The optical receiver includes: a light receiving element for outputting a current in response to a light receiving level of an optical signal; a preamplifier for converting the current signal outputted from the light receiving element into a voltage signal; a circuit for detecting a consecutive same binary symbols portion from a binary symbols stream of the voltage signal outputted from the preamplifier to output a time constant switching signal in response to a detection result thereof; a level detecting circuit for detecting a voltage level of the voltage signal outputted from the preamplifier based upon a time constant which is switched/controlled in response to the time constant switching signal; and an amplifier for amplifying an output voltage of the level detecting circuit to apply a control voltage for controlling the gain to the preamplifier.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: April 10, 2012
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masaki Noda, Masamichi Nogami, Junichi Nakagawa
  • Patent number: 8145072
    Abstract: According to an aspect of an embodiment, a DQPSK optical receiver, comprising: a first LPF connected to a line branching off from between a first optical-electrical converter and a first data recovery circuit; a second LPF connected to a line branching off from between a second optical-electrical converter and a second data recovery circuit; a first LIA for amplifying a signal output from the first LPF and also limiting an amplitude of an output signal thereof; a second LIA for amplifying a signal output from the second LPF and also limiting an amplitude of an output signal thereof; a first mixer for multiplying the output signal from the first LIA by a signal output from the second LPF; and a second mixer for multiplying the output signal from the second LIA by a signal output from the first LPF.
    Type: Grant
    Filed: September 4, 2008
    Date of Patent: March 27, 2012
    Assignee: Fujitsu Limited
    Inventors: Yuichi Akiyama, Toshiki Tanaka
  • Patent number: 8131161
    Abstract: A DPSK optical receiver includes a DPSK demodulation circuit, an optical bandpass filter, a first photodetector, and a first control circuit. The DPSK demodulation circuit demodulates a DPSK optical signal and outputs the DPSK demodulated optical signal. The optical bandpass filter extracts a demodulated optical signal near the center wavelength from the DPSK demodulated optical signal output from the DPSK demodulation circuit. The first photodetector detects the optical power level of the DPSK demodulated optical signal extracted by the optical bandpass filter. The first control circuit performs phase control on the DPSK demodulation circuit so as to optimize the DPSK demodulation circuit with respect to the center wavelength of the DPSK optical signal on the basis of the optical power level detected by the first photodetector.
    Type: Grant
    Filed: April 25, 2008
    Date of Patent: March 6, 2012
    Assignee: NEC Corporation
    Inventor: Yoshihisa Inada
  • Patent number: 8121494
    Abstract: Apparatus and methods are provided for receiving differential phase-shift keyed (DPSK) optical signals subjected to tight optical filtering, such as may be experienced by 40 Gb/s and 100 Gb/s channels in a dense wavelength division multiplexing (DWDM) communications system with 50 GHz channel spacing. An optical DPSK receiver is described which employs an optical delay interferometer (ODI) demodulator having a free spectral range (FSR) that is larger than the symbol rate (SR) of the DPSK signal to be demodulated. The receiver includes means for introducing an additional power imbalance between the outputs of the ODI demodulator, and the additional power imbalance may be related to the ratio of FSR to SR. The additional power imbalance increases the signal tolerance to tight optical filtering, thereby achieving high spectral efficiency in applications such as DWDM.
    Type: Grant
    Filed: August 19, 2008
    Date of Patent: February 21, 2012
    Assignee: Alcatel Lucent
    Inventors: Chraplyvy R Andrew, Xiang Liu, Chandrasekhar Sethumadhavan