Patents Assigned to Opnext Subsystems, Inc.
  • Automatic gain control for high-speed coherent optical receivers
    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
  • Alignment of in-phase and quadrature data in quadrature phase shift keying optical transmitters
    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
  • Polarization and differential-group-delay insensitive digital timing error detection for polarization-multiplexed coherent optical systems
    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
  • Quadrature time skew detection for coherent optical signals
    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
  • Multiplexer lane alignment for high-speed data systems
    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
  • Coherent optical receiver with adaptive equalizer initialization system
    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
  • Optical Coherent Receiver Optimization
    Publication number: 20130170829
    Abstract: Coherent optical receiver performance is optimized and made adaptable to changing optical channel conditions by providing feedback loops to adjust receiver parameters based on measured receiver performance.
    Type: Application
    Filed: December 30, 2011
    Publication date: July 4, 2013
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventor: Sunil Kumar Singh Khatana
  • Polarization monitoring in polarization division multiplexing in optical communications
    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
  • In-phase and quadrature pattern alignment for quadrature phase shift keying optical transmitters
    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
  • Automatic Gain Control for High-Speed Coherent Optical Receivers
    Publication number: 20130071109
    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: Application
    Filed: September 15, 2011
    Publication date: March 21, 2013
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Sunil Kumar Singh Khatana, George Zarris
  • Polarization and Differential-Group-Delay Insensitive Digital Timing Error Detection for Polarization-Multiplexed Coherent Optical Systems
    Publication number: 20120288275
    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: Application
    Filed: May 14, 2012
    Publication date: November 15, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Bo Zhang, Sunil Kumar Singh Khatana
  • Multiplexer Lane Alignment for High-Speed Data Systems
    Publication number: 20120251099
    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: Application
    Filed: April 1, 2011
    Publication date: October 4, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Sunil Kumar Singh Khatana, Hong Jiang
  • In-Phase and Quadrature Pattern Alignment for Quadrature Phase Shift Keying Optical Transmitters
    Publication number: 20120250793
    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: Application
    Filed: April 1, 2011
    Publication date: October 4, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Sunil Kumar Singh Khatana, Edem Ibragimov
  • Alignment of In-phase and Quadrature Data in Quadrature Phase Shift Keying Optical Transmitters
    Publication number: 20120250792
    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: Application
    Filed: April 1, 2011
    Publication date: October 4, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Sunil Kumar Singh Khatana, Lee Dardis
  • Quadrature Time Skew Detection for Coherent Optical Signals
    Publication number: 20120224847
    Abstract: A method for detecting and measuring time skew in high-speed DP-QPSK coherent optical receivers is described.
    Type: Application
    Filed: September 23, 2011
    Publication date: September 6, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Edem Ibragimov, Sunil Kumar Singh Khatana
  • Optical receiver having fractional sampling
    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
  • Balanced phase-shaped binary transmission in optical communications
    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
  • Polarization Monitoring in Polarization Division Multiplexing in Optical Communications
    Publication number: 20120020659
    Abstract: Systems and techniques for optical communications based on polarization division multiplexing are described.
    Type: Application
    Filed: October 3, 2011
    Publication date: January 26, 2012
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Edem Ibragimov, Theodore J. Schmidt
  • Polarization monitoring in polarization division multiplexing in optical communications
    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
  • SUB-RATE SAMPLING IN COHERENT OPTICAL RECEIVERS
    Publication number: 20110236025
    Abstract: Apparatus and methods for optimizing the interplay between the sampling rate of an ADC of a receiver system and a bandwidth of analog anti-aliasing filters are described. The described technology can be used to mitigate aliasing for receiver systems that operate at fractional sampling rates by optimizing a bandwidth of optical and electrical filters included in the receiver systems.
    Type: Application
    Filed: March 25, 2011
    Publication date: September 29, 2011
    Applicant: OPNEXT SUBSYSTEMS, INC.
    Inventors: Andrew Wagner, Christian Malouin, Theodore J. Schmidt