Patents by Inventor Inwoong Kim

Inwoong Kim 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: 20140079391
    Abstract: According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes receiving supervisory data and adjusting a characteristic of a carrier of the optical signal for at least one of a first polarization component of the optical signal and a second polarization component of the optical signal based on the received supervisory data. The characteristic may be adjusted such that there is a relative difference between the characteristic for the first polarization component and the second polarization component. The relative difference of the characteristic between the first polarization component and the second polarization component may indicate the supervisory data. Alternately, the characteristic may be adjusted such that there is a change in a polarization orientation of the carrier on a Poincaré sphere that indicates the supervisory data.
    Type: Application
    Filed: September 14, 2012
    Publication date: March 20, 2014
    Applicant: FUJITSU LIMITED
    Inventors: Inwoong KIM, Olga VASSILIEVA, Paparao PALACHARLA, Motoyoshi SEKIYA
  • Patent number: 8639120
    Abstract: A system is provided for electrical domain optical spectrum shaping. The system may include a laser, a modulator, a first electrical filter, and a second electrical filter. The laser may be configured to output an optical carrier signal. The modulator may be configured to modulate the optical carrier signal to output a modulated optical signal based on a first filtered input signal and a second filtered input signal received by the modulator. The first electrical filter may be configured to filter a first input signal to produce the first filtered input signal. The second electrical filter may be configured to filter a second input signal to produce the second filtered input signal.
    Type: Grant
    Filed: January 20, 2010
    Date of Patent: January 28, 2014
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Paparao Palacharla, Takao Naito
  • Publication number: 20140023362
    Abstract: An apparatus including a polarization controller is described. The polarizer controller is communicatively coupled via a feedback loop to an evaluation module located near an optical receiver. The evaluation module is configured to measure polarization dependent loss (PDL) of an optical signal received at the optical receiver. The polarization controller is configured to receive feedback control data regarding the PDL from the evaluation module. Additionally, the polarization controller is configured to modify a state of polarization of the optical signal at an optical transmitter, which is communicatively coupled to the optical receiver, based on the feedback control data.
    Type: Application
    Filed: July 18, 2012
    Publication date: January 23, 2014
    Applicant: FUJITSU LIMITED
    Inventors: Olga VASSILIEVA, Inwoong KIM, Motoyoshi SEKIYA
  • Publication number: 20130272710
    Abstract: According to an aspect of an embodiment, a method of spectrum defragmentation in an optical network may include assigning an optical signal within an optical network to a first frequency slot that spans a first portion of an optical spectrum of the optical network. The method may also include constructing a frequency slot dependency map based on the assignation of the optical signal to the frequency slot. The method may also include reassigning, as a result of an optical signal departure event, the optical signal to a second frequency slot based on the frequency slot dependency map. The second frequency slot may span a second portion of the optical spectrum of the optical network.
    Type: Application
    Filed: April 12, 2012
    Publication date: October 17, 2013
    Applicant: FUJITSU LIMITED
    Inventors: Xi WANG, Inwoong KIM, Paparao PALACHARLA, Motoyoshi SEKIYA
  • Publication number: 20130272702
    Abstract: A method for regenerating optical signal includes determining a source optical signal to be regenerated, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, creating a first conjugate optical signal and a second conjugate optical signal from the intermediate optical signal, and performing degenerate phase-sensitive amplification utilizing the first conjugate optical signal, the second conjugate optical signal and the source optical signal to yield an output optical signal. The source optical signal is modulated with a multilevel modulation format. Each conjugate optical signal has a phase that is a conjugate of a multiple of the phase of the source optical signal.
    Type: Application
    Filed: June 18, 2012
    Publication date: October 17, 2013
    Applicant: FUJITSU NETWORK COMMUNICATIONS, INC.
    Inventors: Jeng-yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Inwoong Kim
  • Patent number: 8559829
    Abstract: In accordance with some embodiments of the present disclosure a method for receiving and processing an optical orthogonal frequency-division multiplexed signal containing a plurality of traffics comprises receiving the optical orthogonal frequency-division multiplexed signal.
    Type: Grant
    Filed: July 5, 2011
    Date of Patent: October 15, 2013
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Paparao Palacharla, Xi Wang, Motoyoshi Sekiya
  • Publication number: 20130251368
    Abstract: An optical network for reassigning a carrier wavelength of an optical signal may include first and second optical nodes. The first optical node may be configured to transmit an optical signal along an optical path. The first optical node may also be configured to tune a carrier wavelength of the optical signal from a first wavelength to a second wavelength, according to a continuous function, to reassign the carrier wavelength of the optical signal. The second optical node may be configured to receive the optical signal and may include a feedback loop configured to adjust a wavelength of a reference optical signal to approximate the carrier wavelength of the optical signal.
    Type: Application
    Filed: March 22, 2012
    Publication date: September 26, 2013
    Applicant: FUJITSU LIMITED
    Inventors: Inwoong KIM, Paparao PALACHARLA, Xi WANG, Motoyoshi SEKIYA
  • Publication number: 20130253896
    Abstract: According to an aspect of an embodiment, a method of modeling an optical signal transmission path may include obtaining first transmission characteristics of an optical signal transmission path within an optical network based on a parameter of the optical network and randomly changing states of polarization of an optical signal within the optical signal transmission path. The method may also include obtaining second transmission characteristics of the optical signal transmission path based on the parameter and a first fixed state of polarization of the optical signal. The method may also include correlating the first transmission characteristics with the second transmission characteristics to obtain an effective state of polarization of the optical signal. A simulation of the optical signal transmission path based on the parameter and the effective state of polarization of the optical signal may produce transmission characteristics that may approximate the first transmission characteristics.
    Type: Application
    Filed: March 22, 2012
    Publication date: September 26, 2013
    Inventors: Olga VASSILIEVA, Inwoong KIM, Motoyoshi SEKIYA
  • Patent number: 8543000
    Abstract: In accordance with the present disclosure a system for reducing polarization dependent loss (PDL) of an optical signal comprises a delay module coupled to one or more PDL inducing network elements of an optical network. The delay module is configured to time interleave a first polarization component with respect to a second polarization component of the optical signal. The time interleaving reduces interference caused by cross-talk components associated with the first and second polarization components and induced by the PDL of the PDL inducing elements.
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: September 24, 2013
    Assignee: Fujitsu Limited
    Inventors: Olga I Vassilieva, Inwoong Kim
  • Patent number: 8488979
    Abstract: An apparatus for use with an optical computation system may comprise a monolithic device with no free space optical components and may include a phase modulator and a polarization modulator. The phase modulator may be configured to receive a beam of light and two digital data streams and operable to modulate the phase of the beam of light to at least four phase states, the at least four phase states representing the two digital data streams. The polarization modulator may be configured to receive two additional digital data streams and the modulated beam of light from the phase modulator and operable to modulate the polarization of the beam of light to at least four polarization states, the at least four polarization states representing the two additional digital data streams.
    Type: Grant
    Filed: December 23, 2009
    Date of Patent: July 16, 2013
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Takao Naito
  • Patent number: 8467690
    Abstract: Methods and systems are provided for cancellation of chromatic dispersion combined laser phase noise. A method may include measuring a differential of laser phase noise using two optical pilot signals, the pilot signals each having a different optical frequency, or using an optical carrier and a pilot signal. The method may also include determining an approximate laser phase noise present in an optical system based on the measured differential of laser phase noise. The method may further include compensating for laser phase noise based on the determined approximate laser phase noise.
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: June 18, 2013
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Takao Naito, Olga I. Vassilieva
  • Patent number: 8447182
    Abstract: According to one embodiment, a system for transmitting an optical signal comprises a traffic distribution circuit configured to distribute traffic to a plurality of wavelength division multiplexer (WDM) modules. The system further comprises a first WDM module and a second WDM module. The first and second WDM modules each comprise a plurality of tunable optical transmitters, with each transmitter associated with a different wavelength band of a plurality of wavelength bands. Each transmitter in the first and second WDM modules is also tuned to transmit optical signals in channels included within the associated wavelength band of the transmitter. The first and second WDM modules each comprise a multiplexer configured to combine the optical signals transmitted from the plurality of transmitters into optical signals. The system further comprises a cyclic multiplexer configured to combine the optical signals from the first and second WDM modules into an optical output signal.
    Type: Grant
    Filed: September 30, 2010
    Date of Patent: May 21, 2013
    Assignee: Fujitsu Limited
    Inventors: Martin Bouda, Inwoong Kim, Takao Naito
  • Publication number: 20130011138
    Abstract: In accordance with some embodiments of the present disclosure a method for receiving and processing an optical orthogonal frequency-division multiplexed signal containing a plurality of traffics comprises receiving the optical orthogonal frequency-division multiplexed signal.
    Type: Application
    Filed: July 5, 2011
    Publication date: January 10, 2013
    Applicant: FUJITSU LIMITED
    Inventors: Inwoong Kim, Paparao Palacharla, Xi Wang, Motoyoshi Sekiya
  • Publication number: 20120328286
    Abstract: A system and method are provided for monitoring traffic in a network comprising a plurality of links, wherein each of the plurality of links comprises a plurality of neighboring pairs of slots. The system and method may include identifying a first usage status and a second usage status, calculating a utilization entropy value based at least on the difference between the first and second usage status, iteratively calculating a set of utilization entropy values for a portion of the network, and calculating an overall utilization entropy value for the portion of the network under analysis based at least on a statistical analysis of the set of utilization entropy values.
    Type: Application
    Filed: June 21, 2011
    Publication date: December 27, 2012
    Applicant: FUJITSU LIMITED
    Inventors: Xi Wang, Inwoong Kim, Qiong Zhang, Paparao Palacharla, Motoyoshi Sekiya
  • Patent number: 8335438
    Abstract: According to particular embodiments, a signal communicated from a transmitter to a receiver is received. A frequency offset estimate of the signal is determined. The frequency offset estimate indicates a frequency difference between the transmitter and the receiver. The frequency offset estimate is provided as feedback. A next frequency offset is compensated for according to the feedback.
    Type: Grant
    Filed: October 30, 2009
    Date of Patent: December 18, 2012
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Takao Naito
  • Publication number: 20120263455
    Abstract: In accordance with embodiments of the present disclosure, a method may include determining individual spectrum requirements for each of a plurality of signals to be communicated in an optical network, wherein a first signal of the plurality of signals has a first spectrum requirement and a second signal of the plurality of signals has a second spectrum requirement. The method may also include calculating a minimum spectrum granularity based on the individual spectrum requirements. The method may further include assigning each particular signal a channel spectrum equal to an integer multiple of the minimum spectrum granularity.
    Type: Application
    Filed: July 1, 2011
    Publication date: October 18, 2012
    Applicant: FUJITSU LIMITED
    Inventors: Xi Wang, Qiong Zhang, Inwoong Kim, Paparao Palacharla, Motoyoshi Sekiya
  • Patent number: 8270835
    Abstract: A method for reducing cross-phase modulation in an optical signal includes receiving an optical signal comprising a plurality of channels, wherein the information being communicated in a first set of one or more of the channels is modulated using one or more single-polarization modulation techniques and wherein the information being communicated in a second set of one or more of the channels is modulated using one or more dual-polarization modulation techniques. The method also includes splitting the optical signal into at least a first copy of the optical signal and a second copy of the optical signal and terminating the second set of channels in the first copy. Furthermore, the method includes applying a differential group delay to the second copy, the differential group delay introducing a walk-off between symbols communicated in a first polarization component of the second set of channels and the symbols of a second polarization component of the second set of channels.
    Type: Grant
    Filed: March 31, 2010
    Date of Patent: September 18, 2012
    Assignee: Fujitsu Limited
    Inventors: Kevin Croussore, Inwoong Kim, Olga I. Vassilieva
  • Patent number: 8204389
    Abstract: Systems and method of compensating for transmission impairment are disclosed. One such method comprises: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel.
    Type: Grant
    Filed: January 9, 2009
    Date of Patent: June 19, 2012
    Assignee: University of Central Florida Research Foundation, Inc.
    Inventors: Guifang Li, Eduardo Mateo, Likai Zhu, Xiaoxu Li, Gilad Goldfarb, Xin Chen, Inwoong Kim, Fatih Yaman
  • Publication number: 20120148232
    Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.
    Type: Application
    Filed: December 14, 2010
    Publication date: June 14, 2012
    Inventors: Inwoong Kim, Olga I. Vassilieva
  • Publication number: 20120082458
    Abstract: According to one embodiment, a system for transmitting an optical signal comprises a traffic distribution circuit configured to distribute traffic to a plurality of wavelength division multiplexer (WDM) modules. The system further comprises a first WDM module and a second WDM module. The first and second WDM modules each comprise a plurality of tunable optical transmitters, with each transmitter associated with a different wavelength band of a plurality of wavelength bands. Each transmitter in the first and second WDM modules is also tuned to transmit optical signals in channels included within the associated wavelength band of the transmitter. The first and second WDM modules each comprise a multiplexer configured to combine the optical signals transmitted from the plurality of transmitters into optical signals. The system further comprises a cyclic multiplexer configured to combine the optical signals from the first and second WDM modules into an optical output signal.
    Type: Application
    Filed: September 30, 2010
    Publication date: April 5, 2012
    Applicant: FUJITSU LIMITED
    Inventors: Martin Bouda, Inwoong Kim, Takao Naito