Patents Assigned to Opnext Subsystems, Inc.
  • Patent number: 8768178
    Abstract: Feed-forward and feedback strategies are used to control local oscillator power and transimpedance amplifier gain in a high-speed coherent optical receiver.
    Type: Grant
    Filed: September 15, 2011
    Date of Patent: July 1, 2014
    Assignee: Opnext Subsystems, Inc.
    Inventors: Sunil Kumar Singh Khatana, George Zarris
  • Patent number: 8644420
    Abstract: I/Q data skew in a QPSK modulator may be detected by sending identical or complementary data streams to I and Q channel PSK modulators, setting the relative carrier phase between I and Q to zero or ?, and monitoring the average QPSK output power, where the data streams sent to the I and Q channels include streams of alternating ones and zeroes.
    Type: Grant
    Filed: April 1, 2011
    Date of Patent: February 4, 2014
    Assignee: Opnext Subsystems, Inc.
    Inventors: Sunil Kumar Singh Khatana, Lee Dardis
  • Patent number: 8634726
    Abstract: Digital timing error detection systems and techniques are described. The described techniques are independent of polarization and differential-group-delay and are used to perform timing recovery of polarization-multiplexed coherent optical systems.
    Type: Grant
    Filed: May 14, 2012
    Date of Patent: January 21, 2014
    Assignee: Opnext Subsystems, Inc.
    Inventors: Bo Zhang, Sunil Kumar Singh Khatana
  • Patent number: 8565621
    Abstract: A method for detecting and measuring time skew in high-speed DP-QPSK coherent optical receivers is described.
    Type: Grant
    Filed: September 23, 2011
    Date of Patent: October 22, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Edem Ibragimov, Sunil Kumar Singh Khatana
  • Patent number: 8565271
    Abstract: Patterns detected by a low-speed receiver at the output of a high-speed multiplexer are used to determine when multiplexer input lanes are deskewed.
    Type: Grant
    Filed: April 1, 2011
    Date of Patent: October 22, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Sunil Kumar Singh Khatana, Hong Jiang
  • Patent number: 8532504
    Abstract: An adaptive-equalizer initialization system performs three functions: frequency offset estimation, taps estimation for chromatic dispersion filters, and taps initialization for an adaptive equalizer. The system contains hardware FFT and peak detector units that sense a pure tone that marks the beginning of a known, short data sequence.
    Type: Grant
    Filed: October 28, 2010
    Date of Patent: September 10, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Andrew Wagner, Christian Malouin, Theodore J. Schmidt
  • Patent number: 8437632
    Abstract: Systems and techniques for optical communications based on polarization division multiplexing are described.
    Type: Grant
    Filed: October 3, 2011
    Date of Patent: May 7, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Edem Ibragimov, Theodore J. Schmidt
  • Patent number: 8428183
    Abstract: I/Q data skew in a QPSK modulator may be detected by sending identical or complementary data streams to I and Q channel PSK modulators, setting the relative carrier phase between I and Q to zero or ?, and monitoring the average QPSK output power, where the data streams sent to the I and Q channels include pseudorandom streams of ones and zeroes.
    Type: Grant
    Filed: April 1, 2011
    Date of Patent: April 23, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Sunil Kumar Singh Khatana, Edem Ibragimov
  • Patent number: 8244142
    Abstract: Apparatus and methods for receiving and processing optical signals carrying symbols that represent data, including an optical receiver having fractional sampling analog-to-digital conversion and interpolation timing recovery synchronization for processing an optical signal.
    Type: Grant
    Filed: October 28, 2009
    Date of Patent: August 14, 2012
    Assignee: Opnext Subsystems, Inc.
    Inventors: Andrew Wagner, Christian Malouin, Theodore J. Schmidt
  • Patent number: 8126337
    Abstract: Optical communication apparatus, methods, systems are provided based on balanced-detection phase-shaped binary transmission (BD-PSBT).
    Type: Grant
    Filed: October 16, 2008
    Date of Patent: February 28, 2012
    Assignee: Opnext Subsystems, Inc.
    Inventors: Christian Malouin, Theodore J. Schmidt
  • Patent number: 8032025
    Abstract: Systems and techniques for optical communications based on polarization division multiplexing are described.
    Type: Grant
    Filed: October 22, 2008
    Date of Patent: October 4, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Edem Ibragimov, Theodore J. Schmidt
  • Patent number: 8023833
    Abstract: Techniques, devices and systems based on optical receivers with controllable transfer function bandwidth and gain imbalance.
    Type: Grant
    Filed: March 26, 2010
    Date of Patent: September 20, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Christian Malouin, Theodore J. Schmidt, Brian L. Heffner, Yannick Keith Lize, Gordon Ries
  • Patent number: 7991300
    Abstract: Apparatus and techniques for receiving and processing an optical signal. In one implementation, an optical receiver is provided to include a delay line interferometer, an etalon, and a data estimator for estimating the data carried on a differentially modulated optical input signal. The delay line interferometer receives the input signal and issues differentially decoded constructive and destructive signals. The etalon filters the constructive signal with a transmission stopband imposed over the passband of the constructive signal. The bandwidth of the etalon stopband is selected based on the bandwidth of the modulation of the input signal in order to maximize received signal quality. The data estimator uses a difference between signals derived from the filtered constructive signal and the destructive signal for estimating data.
    Type: Grant
    Filed: November 5, 2007
    Date of Patent: August 2, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Brian L. Heffner, Christian Malouin, Theodore J. Schmidt
  • Patent number: 7986878
    Abstract: Techniques, apparatus and systems to provide adjustable bit rate optical transmission using programmable signal modulation in optical communication systems.
    Type: Grant
    Filed: February 5, 2008
    Date of Patent: July 26, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Ross Alexander Saunders, Roberto Marcoccia, Steven Keck, Theodore J. Schmidt, Christian Malouin
  • Patent number: 7983573
    Abstract: An optical receiver apparatus and methods for mitigating intersymbol interference (ISI) in a differentially-encoded modulation transmission system by controlling constructive and destructive transfer functions. The receiver includes a bandwidth control element for controlling transfer function bandwidth, a transfer phase controller for controlling transfer function phase and/or an imbalancer for imbalancing the transfer functions for compensating for intersymbol interference and optimizing the quality of the received optical signal.
    Type: Grant
    Filed: March 14, 2007
    Date of Patent: July 19, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Christian Malouin, Theodore J. Schmidt, Brian L. Heffner
  • Patent number: 7970289
    Abstract: An optical receiver apparatus and methods for mitigating intersymbol interference (ISI) in a differentially-encoded modulation transmission system by controlling constructive and destructive transfer functions. The receiver includes a bandwidth control element for controlling transfer function bandwidth, a transfer phase controller for controlling transfer function phase and/or an imbalancer for imbalancing the transfer functions for compensating for intersymbol interference and optimizing the quality of the received optical signal.
    Type: Grant
    Filed: May 30, 2007
    Date of Patent: June 28, 2011
    Assignee: Opnext Subsystems, Inc.
    Inventors: Brian L. Heffner, Christian Malouin, Theodore J. Schmidt