Patents by Inventor Fred L. Heismann

Fred L. Heismann has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20190149232
    Abstract: A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
    Type: Application
    Filed: January 11, 2019
    Publication date: May 16, 2019
    Applicant: VIAVI SOLUTIONS INC.
    Inventor: Fred L. HEISMANN
  • Patent number: 10218436
    Abstract: A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
    Type: Grant
    Filed: October 18, 2017
    Date of Patent: February 26, 2019
    Assignee: VIAVI SOLUTIONS INC.
    Inventor: Fred L. Heismann
  • Publication number: 20180138974
    Abstract: A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
    Type: Application
    Filed: October 18, 2017
    Publication date: May 17, 2018
    Applicant: VIAVI SOLUTIONS INC.
    Inventor: Fred L. HEISMANN
  • Patent number: 9825698
    Abstract: A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
    Type: Grant
    Filed: December 9, 2014
    Date of Patent: November 21, 2017
    Assignee: VIAVI SOLUTIONS INC.
    Inventor: Fred L. Heismann
  • Publication number: 20160164599
    Abstract: A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
    Type: Application
    Filed: December 9, 2014
    Publication date: June 9, 2016
    Inventor: Fred L. HEISMANN
  • Patent number: 8294896
    Abstract: A method and apparatus for improving the accuracy of in-band OSNR measurements using a conventional polarization extinction or polarization-nulling method. In particular, the severe degradations of the polarization extinction that result from slow and fast polarization fluctuations in the optical signal components during the in-band OSNR measurement are substantially mitigated by rapidly and/or randomly changing the state of polarization prior to conventional polarization control and filtering.
    Type: Grant
    Filed: June 16, 2009
    Date of Patent: October 23, 2012
    Assignee: Acterna LLC
    Inventor: Fred L. Heismann
  • Patent number: 8135275
    Abstract: Two intensity modulated test signals are generated with precise frequency offset from a single laser source, and multiplexed into a combined test signal. The two modulated signals are demultiplexed at a receiver using a fixed periodic optical filter with complementary output ports. Group velocity dispersion/chromatic dispersion is measured over a large dynamic range, using pseudo-random intensity modulation and digital demodulation techniques.
    Type: Grant
    Filed: May 29, 2009
    Date of Patent: March 13, 2012
    Inventors: Fred L. Heismann, Brandon C. Collings
  • Patent number: 8131157
    Abstract: An optical transmitter is disclosed wherein a modulating signal, such as an NRZ signal, encoding data is combined with a time derivative of the modulating signal and coupled to a directly modulated laser in order to generate artificial transient chirp in the output of the laser effective to substantially compensate for dispersion experienced by the output of the laser traveling through a dispersive medium such as an optical fiber. In some embodiments, the time derivative is added to the modulating signal only at the falling edges of the modulating signal.
    Type: Grant
    Filed: January 22, 2008
    Date of Patent: March 6, 2012
    Assignee: Finisar Corporation
    Inventors: Fred L. Heismann, Daniel Mahgerefteh, Parviz Tayebati
  • Publication number: 20090316153
    Abstract: A method and apparatus for improving the accuracy of in-band OSNR measurements using a conventional polarization extinction or polarization-nulling method. In particular, the severe degradations of the polarization extinction that result from slow and fast polarization fluctuations in the optical signal components during the in-band OSNR measurement are substantially mitigated by rapidly and/or randomly changing the state of polarization prior to conventional polarization control and filtering.
    Type: Application
    Filed: June 16, 2009
    Publication date: December 24, 2009
    Applicant: Acterna LLC
    Inventor: Fred L. HEISMANN
  • Publication number: 20090297140
    Abstract: Two intensity modulated test signals are generated with precise frequency offset from a single laser source, and multiplexed into a combined test signal. The two modulated signals are demultiplexed at a receiver using a fixed periodic optical filter with complementary output ports. Group velocity dispersion/chromatic dispersion is measured over a large dynamic range, using pseudo-random intensity modulation and digital demodulation techniques.
    Type: Application
    Filed: May 29, 2009
    Publication date: December 3, 2009
    Applicant: Actena LLC
    Inventors: Fred L. HEISMANN, Brandon C. Collings
  • Publication number: 20080181619
    Abstract: An optical transmitter is disclosed wherein a modulating signal, such as an NRZ signal, encoding data is combined with a time derivative of the modulating signal and coupled to a directly modulated laser in order to generate artificial transient chirp in the output of the laser effective to substantially compensate for dispersion experienced by the output of the laser traveling through a dispersive medium such as an optical fiber. In some embodiments, the time derivative is added to the modulating signal only at the falling edges of the modulating signal.
    Type: Application
    Filed: January 22, 2008
    Publication date: July 31, 2008
    Applicant: FINISAR CORPORATION
    Inventors: Fred L. Heismann, Daniel Mahgerefteh, Parviz Tayebati
  • Patent number: 6411750
    Abstract: A distortion analyzer for generating a distortion signal based on an input signal. For example, the distortion signal may be generated by adding a first signal corresponding to the entire spectrum of the input signal to a second signal corresponding to a low-frequency component of the input signal and then subtracting from the result of addition a third signal corresponding to a specific frequency band of the input signal. The effect of polarization mode dispersion that an optical signal experiences as it propagates through an optical transmission fiber may be compensated for at a receiver using a birefringent compensator, in which the distortion analyzer continuously examines the signal outputted by the compensator and supplies the distortion signal to the compensator, which causes the compensator to reduce the effect of such polarization mode dispersion based on the level of the distortion signal.
    Type: Grant
    Filed: November 29, 2001
    Date of Patent: June 25, 2002
    Assignee: Lucent Technologies Inc.
    Inventors: Daniel A. Fishman, Fred L. Heismann, David L. Wilson
  • Publication number: 20020051619
    Abstract: A distortion analyzer for generating a distortion signal based on an input signal. For example, the distortion signal may be generated by adding a first signal corresponding to the entire spectrum of the input signal to a second signal corresponding to a low-frequency component of the input signal and then subtracting from the result of addition a third signal corresponding to a specific frequency band of the input signal. The effect of polarization mode dispersion that an optical signal experiences as it propagates through an optical transmission fiber may be compensated for at a receiver using a birefringent compensator, in which the distortion analyzer continuously examines the signal outputted by the compensator and supplies the distortion signal to the compensator, which causes the compensator to reduce the effect of such polarization mode dispersion based on the level of the distortion signal.
    Type: Application
    Filed: November 29, 2001
    Publication date: May 2, 2002
    Applicant: Lucent Technologies Inc.
    Inventors: Daniel A. Fishman, Fred L. Heismann, David L. Wilson
  • Patent number: 6330375
    Abstract: The effect of polarization mode dispersion that an optical signal experiences as it propagates through an optical transmission fiber is compensated for at a receiver using a birefringent compensator, in which a distortion analyzer repeatedly examines the signal outputted by the compensator and causes the compensator to reduce the effect of such polarization mode dispersion based on the results of such examination.
    Type: Grant
    Filed: December 16, 1999
    Date of Patent: December 11, 2001
    Assignee: Lucent Technologies Inc.
    Inventors: Daniel A. Fishman, Fred L. Heismann, David L. Wilson
  • Patent number: 5611005
    Abstract: Two separate electrooptic phase modulators are used in a modified Mach-Zehnder interferometer to vary the absolute and relative optical phases of two orthogonally polarized modes of an input signal independently of each other. A conventional Y-branch splitter on lithium niobate splits the input signal equally into the two waveguide phase modulators and an external polarization splitter recombines the two phase modulated signals in orthogonal polarization states. The polarization in the interferometer is maintained by connecting the outputs of the two phase modulators to polarization maintaining fibers. An alternate embodiment of the present invention uses an additional 3-dB directional coupler to mix the two phase modulated signals before they are combined in orthogonal polarization states.
    Type: Grant
    Filed: April 26, 1996
    Date of Patent: March 11, 1997
    Assignee: Lucent Technologies, Inc.
    Inventors: Fred L. Heismann, Robert W. Smith
  • Patent number: 5600738
    Abstract: An optical device having a first substrate having a fast optical axis and a slow optical axis and a first end and a second substrate having a fast optical axis and a slow optical axis and a second end, the second end is positioned adjacent to the first end such that the fast optical axis of the first substrate is coupled to the slow optical axis of the second substrate and the slow optical axis of the first substrate is coupled to the fast optical axis of the second substrate, thereby permitting an optical signal to pass between the first and second substrates. The first substrate and the second substrate have substantially equal length to thereby substantially eliminate polarization dispersion.
    Type: Grant
    Filed: December 30, 1994
    Date of Patent: February 4, 1997
    Assignee: Lucent Technologies Inc.
    Inventors: Glenn D. Bergland, Fred L. Heismann, Steven K. Korotky, Edmond J. Murphy
  • Patent number: 5495543
    Abstract: A double-periodic grating is described for obtaining polarization-independent filtering and coupling. The grating may be viewed as a combination of two gratings with slightly different grating periods. The two periods are carefully chosen to match the difference in propagation constants of the TE and TM polarization modes such that both modes are coupled at the same wavelength.A novel method of obtaining a double-periodic grating is described.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: February 27, 1996
    Assignee: AT&T Corp.
    Inventors: Rodney C. Alferness, Fred L. Heismann
  • Patent number: 5388170
    Abstract: An interferometric modulator comprising a substrate of titanium-doped lithium niobate (Ti:LiNbO.sub.3) having top and bottom surfaces and a waveguide formed in the top surface is disclosed. A conductive layer is formed on the bottom surface of the substrate and electrically coupled to a top-surface ground plane or simply to ground potential. The bottom surface conductive layer functions to thermally stabilize the modulator during operation.
    Type: Grant
    Filed: November 22, 1993
    Date of Patent: February 7, 1995
    Assignee: AT&T Corp.
    Inventors: Fred L. Heismann, Steven K. Korotky, John J. Veselka
  • Patent number: 5361270
    Abstract: The effects of polarization dependent hole burning and/or polarization dependent loss are reduced by modulating the state of polarization (SOP) of an arbitrarily polarized optical signal being launched into the transmission path periodically through a predetermined sequence of polarization states. The sequence of polarization states is selected such that on average the launched modulated signal excites substantially all possible polarization states with substantially equal probability, independent of the input SOP to the polarization modulator. In one exemplary embodiment, the SOP is modulated by a combination cascade of a rotating half-wave plate followed by a quarter-wave plate, which rotates at a different angular speed. In another exemplary embodiment, the SOP is modulated by a combination cascade of two variable phase retarders oriented at fixed angles of 0.degree. and 45.degree., where the modulation frequencies of the two retarders are substantially different from each other.
    Type: Grant
    Filed: August 18, 1993
    Date of Patent: November 1, 1994
    Assignee: AT&T Bell Laboratories
    Inventor: Fred L. Heismann
  • Patent number: 5359678
    Abstract: The effects of polarization dependent hole burning and/or polarization dependent loss are reduced by modulating the state of polarization (SOP) of an optical signal being launched into the transmission path periodically between first and second states of polarization of at least one pair of orthogonal states of polarization. Ideally, the launched modulated signal should spend equal time intervals in both states of the orthogonal pair. In one exemplary embodiment, the SOP is modulated such that it moves along a great circle on the Poincare sphere. In another exemplary embodiment, the SOP is modulated such that it traces a complete great circle on the Poincare sphere. In a preferred embodiment, a complete great circle is traced at a uniform speed on the Poincare sphere.
    Type: Grant
    Filed: June 18, 1993
    Date of Patent: October 25, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Fred L. Heismann, Robert L. Rosenberg