Patents by Inventor Shinsuke Fujisawa

Shinsuke Fujisawa 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: 20220182170
    Abstract: Aspects of the present disclosure describe systems, methods. and structures directed to an integrated 3-way branching unit switch module suitable for undersea application.
    Type: Application
    Filed: December 6, 2021
    Publication date: June 9, 2022
    Applicant: NEC LABORATORIES AMERICA, INC
    Inventors: Fatih YAMAN, Shinsuke FUJISAWA, Hussam BATSHON, Takigawa YOSHINARI, Ryuji AIDA, Takanori INOUE, Eduardo Rodriguez, Yoshihisa INADA
  • Publication number: 20220173808
    Abstract: Aspects of the present disclosure describe systems, methods. and structures in which guided acoustic Brillouin (GAWBS) noise is measured using a homodyne measurement technique and demonstrated using a number of optical fibers, such fibers being commonly used in contemporary optical communications systems. The measurements are made with single spans and determined to be consistent with separate multi-span long-distance measurements. Additionally, a technique for preparing an optical fiber exhibiting superior GAWBS noise characteristics by reducing coherence length of the optical fiber by spinning the fiber at a high rate during the drawing process such that birefringence coherence length is reduced.
    Type: Application
    Filed: December 1, 2021
    Publication date: June 2, 2022
    Applicant: NEC LABORATORIES AMERICA, INC
    Inventors: Fatih YAMAN, Kohei NAKAMURA, Takanori INOUE, Eduardo Mateo RODRIGUEZ, Shinsuke FUJISAWA, Hussam BATSHON, Yoshihisa INADA, Takaaki OGATA
  • Publication number: 20220085896
    Abstract: Aspects of the present disclosure describe a three-way branching unit switch module having a small footprint suitable for application in an undersea application.
    Type: Application
    Filed: September 7, 2021
    Publication date: March 17, 2022
    Applicants: NEC Laboratories America, Inc., NEC Corporation
    Inventors: Fatih YAMAN, Shinsuke FUJISAWA, Hussam BATSHON, Yoshinari Takigawa, Ryu Kurahashi, Ryuji Aida, Kohei NAKAMURA, Takanori INOUE, Eduardo RODRIGUEZ, Yoshihisa INADA
  • Publication number: 20220060257
    Abstract: If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.
    Type: Application
    Filed: November 5, 2021
    Publication date: February 24, 2022
    Applicant: NEC Corporation
    Inventors: Tomoyuki HINO, Akio Tajima, Hitoshi Takeshita, Shinsuke Fujisawa
  • Publication number: 20220011195
    Abstract: Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.
    Type: Application
    Filed: June 7, 2021
    Publication date: January 13, 2022
    Applicants: NEC LABORATORIES AMERICA, INC, NEC Corporation
    Inventors: Fatih YAMAN, Eduardo Mateo RODRIGUEZ, Shinsuke FUJISAWA, Hussam BATSHON, Kohei NAKAMURA, Takanori INOUE, Yoshihisa INADA, Takaaki OGATA
  • Patent number: 11212027
    Abstract: This optical path setting device comprises: a transmission characteristic calculating means for calculating an inter-endpoint transmission characteristic that is a characteristic for transmission between endpoints of an optical path accommodating traffic in a plurality of optical communication systems; a required wavelength bandwidth determining means for determining a required wavelength bandwidth that is a wavelength bandwidth meeting an arrival performance of the optical path on the basis of the inter-endpoint transmission characteristic; and an accommodating wavelength band determining means for determining, as an accommodating wavelength band for accommodating the optical path, a common wavelength band that is a wavelength band where an optical path having the required wavelength bandwidth can be allocated, and that is common to the plurality of optical communication systems.
    Type: Grant
    Filed: November 29, 2018
    Date of Patent: December 28, 2021
    Assignee: NEC CORPORATION
    Inventors: Shinsuke Fujisawa, Hitoshi Takeshita, Shigeyuki Yanagimachi, Emmanuel Le Taillandier De Gabory
  • Patent number: 11201668
    Abstract: If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.
    Type: Grant
    Filed: June 17, 2020
    Date of Patent: December 14, 2021
    Assignee: NEC CORPORATION
    Inventors: Tomoyuki Hino, Akio Tajima, Hitoshi Takeshita, Shinsuke Fujisawa
  • Publication number: 20210356316
    Abstract: Aspects of the present disclosure are directed to alternative repeater design(s) that advantageously improve signal-to-noise of distributed acoustic sensing (DAS) systems using coherent detection of Rayleigh backscatter in multi-span links including inline amplification that may be employed—for example—in undersea submarine systems. The repeater designs incorporate Rayleigh combine units (RCU) and Rayleigh drop units (RDU) to reduce Rayleigh backscatter loss as Rayleigh signal(s) is/are routed to a link that propagates the backscatter signal in an opposite direction relative to interrogation pulse(s).
    Type: Application
    Filed: May 6, 2021
    Publication date: November 18, 2021
    Applicant: NEC LABORATORIES AMERICA, INC
    Inventors: Ezra IP, Yue-Kai HUANG, Fatih YAMAN, Shinsuke FUJISAWA
  • Publication number: 20210352386
    Abstract: It is difficult to improve the usage efficiency of an optical communication network due to the passband narrowing effect in a wavelength selection process in an optical communication network using a wavelength division multiplexing system; therefore, an optical network management apparatus according to an exemplary aspect of the present invention includes wavelength selection information generating means for generating wavelength selection information on a wavelength selection process through which an optical path accommodating an information signal goes, with respect to each optical path; and wavelength selection information notifying means for notifying an optical node device through which the optical path goes of the wavelength selection information.
    Type: Application
    Filed: July 26, 2021
    Publication date: November 11, 2021
    Applicant: NEC CORPORATION
    Inventors: Hitoshi Takeshita, Shinsuke Fujisawa, Tomoyuki Hino, Akio Tajima
  • Patent number: 11115117
    Abstract: A submarine optical communication system control device (1) according to the present invention includes: a light intensity distribution determination device (2) configured to determine an optimum distribution of signal light intensity of each optical path for each allocated frequency; a light intensity distribution measuring device (3) configured to measure a light intensity distribution of an optical path after transmission through a submarine cable transmission line; an equalization setting calculation unit (4) configured to calculate a gain equalization setting for compensating for the difference between an optimum distribution in the light intensity distribution determination device and a measured distribution in the light intensity distribution measuring device; and a variable gain equalizer (5) configured to compensate for a light intensity distribution of an optical path to the optimum distribution, based on a gain equalization setting in the equalization setting calculation unit.
    Type: Grant
    Filed: March 27, 2018
    Date of Patent: September 7, 2021
    Assignee: NEC CORPORATION
    Inventors: Shinsuke Fujisawa, Hitoshi Takeshita, Shigeyuki Yanagimachi, Emmanuel Le Taillandier De Gabory
  • Patent number: 11115318
    Abstract: An optical network control device includes: a path setting unit that sets, based on topology information including a connection relationship among a plurality of nodes and a first route selection index value of routes each connecting the plurality of nodes, a first path for a route having the first route selection index value being minimum from among route candidates linking a start point node and an end point node of a requested traffic; a topology information modification unit that calculates a second route selection index value acquired by increasing the first route selection index value of the route that accommodates the first path; and a path selection unit that selects a second path for a route having the second route selection index value being minimum from among the route candidates.
    Type: Grant
    Filed: October 4, 2017
    Date of Patent: September 7, 2021
    Assignee: NEC CORPORATION
    Inventors: Shinsuke Fujisawa, Hitoshi Takeshita, Akio Tajima
  • Patent number: 11109123
    Abstract: It is difficult to improve the usage efficiency of an optical communication network due to the passband narrowing effect in a wavelength selection process in an optical communication network using a wavelength division multiplexing system; therefore, an optical network management apparatus according to an exemplary aspect of the present invention includes wavelength selection information generating means for generating wavelength selection information on a wavelength selection process through which an optical path accommodating an information signal goes, with respect to each optical path; and wavelength selection information notifying means for notifying an optical node device through which the optical path goes of the wavelength selection information.
    Type: Grant
    Filed: July 9, 2020
    Date of Patent: August 31, 2021
    Assignee: NEC CORPORATION
    Inventors: Hitoshi Takeshita, Shinsuke Fujisawa, Tomoyuki Hino, Akio Tajima
  • Publication number: 20210256347
    Abstract: Aspects of the present disclosure describe optical transmission systems exhibiting low complexity fiber nonlinearity compensation provided by neural networks using lookup tables for multiplication operations.
    Type: Application
    Filed: January 12, 2021
    Publication date: August 19, 2021
    Applicant: NEC LABORATORIES AMERICA, INC
    Inventors: Shinsuke FUJISAWA, Fatih YAMAN, Eduardo Mateo RODRIGUEZ, Yoshihisa INADA, Kohei NAKAMURA, Takanori INOUE
  • Patent number: 10938499
    Abstract: It is difficult in the elastic optical network to achieve a balance between the improvement in the frequency utilization efficiency and the increase in the probability of opening an optical path; therefore, an optical path controller according to an exemplary aspect of the present invention includes route selection means for searching for a route candidate being a candidate for a route to accommodate an optical path, and selecting a best possible route with a minimum route selection index serving as an index for route search; use rate collecting means for collecting a use rate serving as an index to indicate a usage condition of an optical frequency band in an optical fiber transmission line included in the route candidate; and route selection index judgment means for determining the route selection index based on the use rate.
    Type: Grant
    Filed: July 6, 2017
    Date of Patent: March 2, 2021
    Assignee: NEC Corporation
    Inventors: Shinsuke Fujisawa, Akio Tajima, Hitoshi Takeshita
  • Publication number: 20210058157
    Abstract: In a multi-layer network, a control load in the upper layer network increases, and the usage efficiency and the reliability of the entire network decrease; therefore, a multi-layer network system according to an exemplary aspect of the present invention includes a first network manager configured to set a logical path in a first network layer; and a second network manager configured to set a physical path corresponding to the logical path, in a second network layer, wherein the second network manager includes a network information storage configured to store physical network information including physical route information and transmission characteristic information on the second network layer, and the first network manager sets the logical path based on the physical network information.
    Type: Application
    Filed: November 6, 2020
    Publication date: February 25, 2021
    Applicant: NEC Corporation
    Inventors: Hitoshi TAKESHITA, Shinsuke FUJISAWA, Tomoyuki HINO, Akio TAJIMA
  • Publication number: 20210013965
    Abstract: A submarine optical communication system control device (1) according to the present invention includes: a light intensity distribution determination device (2) configured to determine an optimum distribution of signal light intensity of each optical path for each allocated frequency; a light intensity distribution measuring device (3) configured to measure a light intensity distribution of an optical path after transmission through a submarine cable transmission line; an equalization setting calculation unit (4) configured to calculate a gain equalization setting for compensating for the difference between an optimum distribution in the light intensity distribution determination device and a measured distribution in the light intensity distribution measuring device; and a variable gain equalizer (5) configured to compensate for a light intensity distribution of an optical path to the optimum distribution, based on a gain equalization setting in the equalization setting calculation unit.
    Type: Application
    Filed: March 27, 2018
    Publication date: January 14, 2021
    Applicant: NEC CORPORATION
    Inventors: Shinsuke FUJISAWA, Hitoshi TAKESHITA, Shigeyuki YANAGIMACHI, Emmanuel LE TAILLANDIER DE GABORY
  • Publication number: 20200403383
    Abstract: Aspects of the present disclosure describe systems, methods and structures for providing semiconductor amplifiers exhibiting a low polarization-dependent gain.
    Type: Application
    Filed: June 17, 2020
    Publication date: December 24, 2020
    Applicant: NEC LABORATORIES AMERICA, INC
    Inventors: Fatih YAMAN, Shinsuke FUJISAWA, Eduardo Mateo RODRIGUEZ, Kohei NAKAMURA, Takanori INOUE, Yoshihisa INADA, Takaaki OGATA
  • Publication number: 20200374607
    Abstract: This optical path setting device comprises: a transmission characteristic calculating means for calculating an inter-endpoint transmission characteristic that is a characteristic for transmission between endpoints of an optical path accommodating traffic in a plurality of optical communication systems; a required wavelength bandwidth determining means for determining a required wavelength bandwidth that is a wavelength bandwidth meeting an arrival performance of the optical path on the basis of the inter-endpoint transmission characteristic; and an accommodating wavelength band determining means for determining, as an accommodating wavelength band for accommodating the optical path, a common wavelength band that is a wavelength band where an optical path having the required wavelength bandwidth can be allocated, and that is common to the plurality of optical communication systems.
    Type: Application
    Filed: November 29, 2018
    Publication date: November 26, 2020
    Applicant: NEC CORPORATION
    Inventors: Shinsuke FUJISAWA, Hitoshi TAKESHITA, Shigeyuki YANAGIMACHI, Emmanuel LE TAILLANDIER DE GABORY
  • Patent number: 10848245
    Abstract: In a multi-layer network, a control load in the upper layer network increases, and the usage efficiency and the reliability of the entire network decrease; therefore, a multi-layer network system according to an exemplary aspect of the present invention includes a first network manager configured to set a logical path in a first network layer; and a second network manager configured to set a physical path corresponding to the logical path, in a second network layer, wherein the second network manager includes a network information storage configured to store physical network information including physical route information and transmission characteristic information on the second network layer, and the first network manager sets the logical path based on the physical network information.
    Type: Grant
    Filed: December 15, 2015
    Date of Patent: November 24, 2020
    Assignee: NEC CORPORATION
    Inventors: Hitoshi Takeshita, Shinsuke Fujisawa, Tomoyuki Hino, Akio Tajima
  • Patent number: 10848262
    Abstract: In an optical communication network using the wavelength division multiplexing system, the accommodation efficiency for the optical paths decreases, and it becomes difficult to use the optical communication network efficiently, if the optical frequency slots are used concentrically in a specific optical fiber; therefore, an optical path design apparatus according to an exemplary aspect of the present invention includes route candidate selection means for searching for a route of an optical path to accommodate a communication demand and selecting a plurality of route candidates; optical path candidate selection means for selecting a plurality of optical path candidates by allocating an optical frequency band required to accommodate the optical path to each of optical fibers on the plurality of route candidates; and optical path determination means for determining the optical path from among the plurality of optical path candidates based on an optical frequency band utilization rate in the optical fibers.
    Type: Grant
    Filed: September 20, 2017
    Date of Patent: November 24, 2020
    Assignee: NEC CORPORATION
    Inventors: Hitoshi Takeshita, Shinsuke Fujisawa, Akio Tajima