Patents by Inventor Tomoaki Takeyama

Tomoaki Takeyama 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: 20240106560
    Abstract: A wavelength conversion device includes an optical medium that converts a first wavelength-multiplexed light including a plurality of first wavelengths belonging to a first wavelength band to a second wavelength-multiplexed light including a plurality of second wavelengths belonging to a second wavelength band, a first monitor configured to monitor power of the plurality of second wavelengths belonging to the second wavelength band, a storage unit that holds control information for adjusting a conversion characteristic of the optical medium, and a control unit configured to perform control of adjusting the conversion characteristic of the optical medium based on the control information acquired from the storage unit according to a first monitoring result by the first monitor.
    Type: Application
    Filed: September 21, 2023
    Publication date: March 28, 2024
    Applicant: Fujitsu Limited
    Inventors: Hidenobu MURANAKA, Tomoyuki KATO, Tomoaki Takeyama
  • Patent number: 11870553
    Abstract: A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.
    Type: Grant
    Filed: July 21, 2022
    Date of Patent: January 9, 2024
    Assignee: FUJITSU LIMITED
    Inventors: Makoto Hasegawa, Atsushi Kodama, Norifumi Shukunami, Tomoaki Takeyama
  • Publication number: 20230239050
    Abstract: An optical wavelength multiplexing transmission device includes: a demultiplexer configured to demultiplex a wavelength multiplexing signal for each wavelength band from a multiplexed signal that includes wavelength multiplexing signals in a plurality of the wavelength bands; a processor configured to detect an optical power value of each wavelength multiplexing signal for each wavelength band; calculate a compensation amount used to compensate a tilt of the wavelength multiplexing signal, by using the optical power value and a predetermined calculation expression; and compensate the tilt of the wavelength multiplexing signal, based on the compensation amount; and a multiplexer configured to multiplex each wavelength multiplexing signal compensated by the processor and output the wavelength multiplexing signal to a transmission line.
    Type: Application
    Filed: November 3, 2022
    Publication date: July 27, 2023
    Applicant: Fujitsu Limited
    Inventors: Shigeru ISHII, Tatsuya Tsuzuki, Takehiro Fujita, Tomoaki Takeyama
  • Publication number: 20220385373
    Abstract: A wavelength converter includes an optical waveguide substrate configured to include a plurality of optical waveguides formed with different design values, an incidence-side optical fiber from which signal light and excitation light are incident to the optical waveguide substrate, and an emission-side optical fiber to which light including converted light having a wavelength different from a wavelength of the signal light is extracted from the optical waveguide substrate, wherein the incidence-side optical fiber and the emission-side optical fiber are optically coupled to one optical waveguide among the plurality of optical waveguides.
    Type: Application
    Filed: March 3, 2022
    Publication date: December 1, 2022
    Applicant: FUJITSU LIMITED
    Inventors: Hidenobu MURANAKA, Tomoaki TAKEYAMA, Takeshi HOSHIDA
  • Patent number: 11509394
    Abstract: A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.
    Type: Grant
    Filed: June 1, 2021
    Date of Patent: November 22, 2022
    Assignee: FUJITSU LIMITED
    Inventors: Norifumi Shukunami, Tomoaki Takeyama
  • Publication number: 20220368447
    Abstract: A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in. which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based. on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.
    Type: Application
    Filed: July 21, 2022
    Publication date: November 17, 2022
    Applicant: FUJITSU LIMITED
    Inventors: Makoto HASEGAWA, Atsushi KODAMA, Norifumi SHUKUNAMI, Tomoaki TAKEYAMA
  • Patent number: 11294258
    Abstract: A transmission device includes: a first wavelength conversion circuit configured to convert a wavelength band of a wavelength multiplexed signal light based on a wavelength of a second excitation light by performing four-wave mixing on the second excitation light and the wavelength multiplexed signal light inputted to a second nonlinear medium; and a second wavelength conversion circuit configured to convert the wavelength band of the wavelength multiplexed signal light based on a difference between frequencies of a third excitation light and a fourth excitation light by performing four-wave mixing on the third excitation light and the fourth excitation light and the wavelength multiplexed signal light inputted to a third nonlinear medium.
    Type: Grant
    Filed: May 18, 2020
    Date of Patent: April 5, 2022
    Assignee: FUJITSU LIMITED
    Inventor: Tomoaki Takeyama
  • Publication number: 20220045755
    Abstract: A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.
    Type: Application
    Filed: June 1, 2021
    Publication date: February 10, 2022
    Applicant: FUJITSU LIMITED
    Inventors: Norifumi Shukunami, Tomoaki Takeyama
  • Patent number: 11153014
    Abstract: A transmitting apparatus includes: a first processor circuit; a second processor circuit; a modulation circuit; and a switch circuit, wherein the first processor circuit is configured to execute a generating process that includes mapping each of a plurality of bit strings to a symbol in predetermined order for each number of bits according to a multivalued degree of a multilevel modulation method, and generating a symbol information piece according to the symbol, wherein the modulation circuit is configured to modulate light in accordance with the symbol information piece based on the multilevel modulation method; wherein the second processor circuit is configured to execute a detecting process that includes detecting each of inputs of a plurality of data signals, wherein the switch circuit is configured to select the plurality of bit strings based on a detection result of inputs of the plurality of data signals.
    Type: Grant
    Filed: June 17, 2020
    Date of Patent: October 19, 2021
    Assignee: FUJITSU LIMITED
    Inventors: Masamichi Sugamoto, Ryo Murakami, Yuichiro Tanaka, Junichi Sugiyama, Kenichi Miyama, Tomoaki Takeyama
  • Patent number: 11063684
    Abstract: An optical transmission apparatus includes a first transmitter configured to output an optical signal having a wavelength belonging to a first wavelength band, a switch configured to output the optical signal outputted to the first transmitter toward a first transmission line or a second transmission line, a wavelength converter configured to convert the optical signal outputted from the switch toward the first transmission line into an optical signal having a wavelength belonging to a second wavelength band other than the first wavelength band, a second transmitter configured to output an optical signal having a wavelength belonging to the first wavelength band, and a first multiplexer configured to multiplex the optical signal outputted from the first wavelength converter and the optical signal outputted from the second transmitter, and output a multiplexed optical signal to the first transmission line.
    Type: Grant
    Filed: January 16, 2019
    Date of Patent: July 13, 2021
    Assignee: FUJITSU LIMITED
    Inventors: Ryo Karube, Tomoaki Takeyama, Shinichirou Muro, Yoshio Shimano
  • Patent number: 11018763
    Abstract: A network system includes a plurality of transmission devices, each of which being provided with a wavelength selective switch including a wavelength filter, configured to transmit an optical signal for each channel; and a management device configured to manage the plurality of transmission devices. The wavelength selective switch configured to enable band setting that widens a transmission band of an optical signal of a predetermined channel to the wavelength filter of an adjacent channel. The management device is further configured to calculate an OSNR of the optical signal based on power loss, calculate a bandwidth of the optical signal according to narrowing due to the wavelength filter, determine whether or not the OSNR and the bandwidth respectively satisfies a condition of transmission quality of the optical signal, and decide whether or not to cause the wavelength selective switch to perform the band setting based on a result of the determination.
    Type: Grant
    Filed: August 26, 2020
    Date of Patent: May 25, 2021
    Assignee: FUJITSU LIMITED
    Inventors: Tatsuya Tsuzuki, Shinji Komiya, Tomoaki Takeyama
  • Patent number: 10972188
    Abstract: A transmission apparatus includes a first multiplexer configured to multiplex light of wavelengths of a first wavelength band to output first wavelength multiplex light, a first wavelength converter configured to convert the first wavelength multiplex light into wavelengths of a second wavelength band which is different from the first wavelength band, by using first excitation light, a second multiplexer configured to multiplex light of wavelengths of the first wavelength band which are different from the wavelengths of the first wavelength multiplex light to output second wavelength multiplex light, a second wavelength converter configured to convert the second wavelength multiplex light into wavelengths of the second wavelength band, by using second excitation light, a third multiplexer configured to multiplex the first wavelength multiplex light converted into the wavelengths of the second wavelength band, and the second wavelength multiplex light converted into the wavelengths of the second wavelength ban
    Type: Grant
    Filed: March 21, 2019
    Date of Patent: April 6, 2021
    Assignee: FUJITSU LIMITED
    Inventors: Tomoyuki Kato, Shota Mori, Tomoaki Takeyama
  • Publication number: 20210067245
    Abstract: A network system includes a plurality of transmission devices, each of which being provided with a wavelength selective switch including a wavelength filter, configured to transmit an optical signal for each channel; and a management device configured to manage the plurality of transmission devices. The wavelength selective switch configured to enable band setting that widens a transmission band of an optical signal of a predetermined channel to the wavelength filter of an adjacent channel. The management device is further configured to calculate an OSNR of the optical signal based on power loss, calculate a bandwidth of the optical signal according to narrowing due to the wavelength filter, determine whether or not the OSNR and the bandwidth respectively satisfies a condition of transmission quality of the optical signal, and decide whether or not to cause the wavelength selective switch to perform the band setting based on a result of the determination.
    Type: Application
    Filed: August 26, 2020
    Publication date: March 4, 2021
    Applicant: FUJITSU LIMITED
    Inventors: Tatsuya Tsuzuki, Shinji KOMIYA, Tomoaki Takeyama
  • Publication number: 20200403707
    Abstract: A transmitting apparatus includes: a first processor circuit; a second processor circuit; a modulation circuit; and a switch circuit, wherein the first processor circuit is configured to execute a generating process that includes mapping each of a plurality of bit strings to a symbol in predetermined order for each number of bits according to a multivalued degree of a multilevel modulation method, and generating a symbol information piece according to the symbol, wherein the modulation circuit is configured to modulate light in accordance with the symbol information piece based on the multilevel modulation method; wherein the second processor circuit is configured to execute a detecting process that includes detecting each of inputs of a plurality of data signals, wherein the switch circuit is configured to select the plurality of bit strings based on a detection result of inputs of the plurality of data signals,
    Type: Application
    Filed: June 17, 2020
    Publication date: December 24, 2020
    Applicant: FUJITSU LIMITED
    Inventors: Masamichi Sugamoto, Ryo Murakami, YUICHIRO TANAKA, Junichi Sugiyama, Kenichi Miyama, Tomoaki Takeyama
  • Publication number: 20200371292
    Abstract: A transmission device includes: a first wavelength conversion circuit configured to convert a wavelength band of a wavelength multiplexed signal light based on a wavelength of a second excitation light by performing four-wave mixing on the second excitation light and the wavelength multiplexed signal light inputted to a second nonlinear medium; and a second wavelength conversion circuit configured to convert the wavelength band of the wavelength multiplexed signal light based on a difference between frequencies of a third excitation light and a fourth excitation light by performing four-wave mixing on the third excitation light and the fourth excitation light and the wavelength multiplexed signal light inputted to a third nonlinear medium.
    Type: Application
    Filed: May 18, 2020
    Publication date: November 26, 2020
    Applicant: FUJITSU LIMITED
    Inventor: Tomoaki Takeyama
  • Patent number: 10782589
    Abstract: A wavelength conversion apparatus includes a multiplexer-demultiplexer configured to include a first port, a second port, and a third port, a looped non-linear optical medium including one end that is optically connected to the second port of the multiplexer-demultiplexer, another end that is optically connected to the third port of the multiplexer-demultiplexer, and a main axis that rotates by 90 degrees between the second port and the third port, a first filter configured to be inserted into the non-linear optical medium, and remove stimulated Brillouin backscattered light that is bidirectionally generated in the non-linear optical medium, and a second filter configured to take out, from output light that is multiplexed in the multiplexer-demultiplexer after propagating through the non-linear optical medium and is outputted from the first port, conversion light having a third frequency different from the frequencies of a signal light and an excitation light.
    Type: Grant
    Filed: March 29, 2019
    Date of Patent: September 22, 2020
    Assignee: FUJITSU LIMITED
    Inventors: Tomoaki Takeyama, Ichiro Nakajima, Yoshitaka Yamanaka
  • Patent number: 10754224
    Abstract: A wavelength conversion device includes a light source configured to output an excitation light beam, a modulator configured to phase-modulate the excitation light beam, a polarization adjustor configured to adjust a polarization angle of the excitation light beam to 45 degrees or 135 degrees with respect to a polarization angle of a signal light beam, and a nonlinear medium configured to generate four-wave mixing of the excitation light beam whose polarization angle is adjusted and the signal light beam to generate an idler light beam having a frequency corresponding to a difference between frequencies of the signal light beam and the excitation light beam from the signal light beam.
    Type: Grant
    Filed: April 19, 2019
    Date of Patent: August 25, 2020
    Assignee: FUJITSU LIMITED
    Inventor: Tomoaki Takeyama
  • Patent number: 10644823
    Abstract: An optical transfer method of an optical transfer system including a transmitter, a first wavelength converter configured to use first excitation light to perform wavelength-conversion of first signal light which is the transmission light into second signal light in a different wavelength band, a second wavelength converter configured to use second excitation light to perform wavelength-conversion of the second signal light into third signal light in a different wavelength band, and a receiver configured to receive the third signal light, the method includes acquiring a wavelength of the transmission light, a wavelength of the first excitation light, and a wavelength of the second excitation light; and deciding local emission light of the receiver based on a wavelength of reception light of the receiver obtained from the wavelength of the transmission light, the wavelength of the first excitation light, and the wavelength of the second excitation light.
    Type: Grant
    Filed: June 10, 2019
    Date of Patent: May 5, 2020
    Assignee: FUJITSU LIMITED
    Inventors: Masahiro Yuki, Tomoaki Takeyama, Kazuo Takatsu
  • Patent number: 10634974
    Abstract: A converter includes a combiner configured to polarization-combine a first pump light and a second pump light, a nonlinear medium configured to wavelength-convert first signal light into second signal light to output the second signal light after wavelength conversion from a second port, and to wavelength-convert the second signal light into first signal light to output the first signal light after wavelength conversion from the first port, a first circulator configured to input the first signal light from the first port into the nonlinear medium, and output the first signal light after wavelength conversion in the nonlinear medium from the first port, and a second circulator configured to input the second signal light from the second port into the nonlinear medium, and output the second signal light after wavelength conversion in the nonlinear medium from the second port.
    Type: Grant
    Filed: May 3, 2019
    Date of Patent: April 28, 2020
    Assignee: FUJITSU LIMITED
    Inventors: Norifumi Shukunami, Tomoaki Takeyama
  • Publication number: 20200059313
    Abstract: A transmission device that transmits wavelength multiplexed light to a transmission line, the transmission device includes a first multiplexer configured to multiplex light of a wavelength of a first wavelength band and output first multiplexed light, a second multiplexer configured to multiplex the light of the wavelength of the first wavelength band and output second multiplexed light, a wavelength converter configured to convert the second multiplexed light into light of a wavelength of a second wavelength band different from the first wavelength band, and a third multiplexer configured to multiplex the second multiplexed light converted to the light of the wavelength of the second wavelength band and the first multiplexed light and output the wavelength multiplexed light.
    Type: Application
    Filed: October 23, 2019
    Publication date: February 20, 2020
    Applicant: FUJITSU LIMITED
    Inventors: Tomoyuki Kato, Takeshi Hoshida, Tomoaki Takeyama