Patents by Inventor Katsuhiro Takenaga

Katsuhiro Takenaga 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).

  • Patent number: 10488297
    Abstract: A characteristic-measuring apparatus for a multi-core fiber includes: a coupling device that couples, at a first end of the multi-core fiber, light to a plurality of cores in the multi-core fiber; an imaging device that takes an image, at a second end of the multi-core fiber, of emission light emitted from the plurality of cores, where the plurality of cores are imaged at the same time; and a calculating device that determines a characteristic of the multi-core fiber based on images obtained by the imaging device.
    Type: Grant
    Filed: January 26, 2018
    Date of Patent: November 26, 2019
    Assignee: Fujikura Ltd.
    Inventors: Shota Saito, Katsuhiro Takenaga
  • Patent number: 10444113
    Abstract: A method of measuring crosstalk of a multicore fiber, the method including capturing an emitted light pattern at an end portion of a dummy fiber and obtaining a correlation data between a power of the light incident on the dummy fiber and the emitted light pattern, irradiating one core of the multicore fiber with a light through the dummy fiber, and measuring a power of a reference light emitted from the core, capturing a crosstalk light emitted from a different core different from the core on which the light is incident under a state where the reference light is masked, and estimating a power of the crosstalk light from a captured data of the crosstalk light and the correlation data, and calculating the crosstalk from the power of the reference light and the power of the crosstalk light.
    Type: Grant
    Filed: January 26, 2017
    Date of Patent: October 15, 2019
    Assignee: FUJIKURA LTD.
    Inventors: Shota Saito, Katsuhiro Takenaga
  • Patent number: 10365429
    Abstract: A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.
    Type: Grant
    Filed: July 6, 2016
    Date of Patent: July 30, 2019
    Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSTIY
    Inventors: Shota Saito, Katsuhiro Takenaga, Kunimasa Saitoh, Takeshi Fujisawa
  • Patent number: 10310176
    Abstract: A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.
    Type: Grant
    Filed: May 20, 2016
    Date of Patent: June 4, 2019
    Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
  • Patent number: 10295736
    Abstract: A multicore fiber includes a plurality of cores including a first core and a cladding surrounding the plurality of cores. The first core includes: an inner core; and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core and a refractive index of the cladding. The core is not doped with any rare earth element. At least two LP mode light beams at a predetermined wavelength propagate through the first core at an attenuation of 0.3 dB/km or less.
    Type: Grant
    Filed: October 25, 2016
    Date of Patent: May 21, 2019
    Assignee: FUJIKURA LTD.
    Inventors: Yoshimichi Amma, Katsuhiro Takenaga, Shota Saito
  • Publication number: 20190072712
    Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12;a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.
    Type: Application
    Filed: October 30, 2018
    Publication date: March 7, 2019
    Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
  • Publication number: 20190049658
    Abstract: An optical fiber that communicates in a predetermined communication band includes: a signal light propagation core that propagates light beams of up to (x+1)-th order LP mode, where x is an integer of two or more; and a coupler that propagates a light beam that is: coupled with a light beam of the (x+1)-th order LP mode propagating through the signal light propagation core, and suppressed from being coupled with light beams of up to the x-th order LP mode propagating through the signal light propagation core, wherein, mode coupling of the light beams of up to the x-th order LP mode propagating through the signal light propagation core is performed, and mode coupling between the light beam of the x-th order LP mode and the light beam of (x+1)-th order LP mode is suppressed.
    Type: Application
    Filed: December 5, 2016
    Publication date: February 14, 2019
    Applicant: FUJIKURA LTD.
    Inventors: Shota Saito, Katsuhiro Takenaga
  • Publication number: 20190033512
    Abstract: An optical device includes a plurality of cores and a clad that surrounds outer circumferential surfaces of the cores and has a lower refractive index than the cores. Each of the cores has a large diameter portion, a tapered portion, and a reduced diameter portion formed along a longitudinal direction and has a refractive index gradually increasing from outer circumference to a center. In each of the cores, a radial-direction distance r (?m) from the center, a refractive index n(r) at the distance r, a relative refractive index difference ?[%] of the center with respect to the clad, a radius r0 [?m], and a constant ? satisfy predetermined formulas and a wavelength ? [nm] of light propagating through the cores and a diameter R of each core before the diameter reduction with respect to a diameter of each core after the diameter reduction satisfy predetermined formulas.
    Type: Application
    Filed: February 25, 2016
    Publication date: January 31, 2019
    Applicant: Fujikura Ltd.
    Inventors: Hitoshi Uemura, Katsuhiro Takenaga
  • Publication number: 20190033513
    Abstract: A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.
    Type: Application
    Filed: March 2, 2017
    Publication date: January 31, 2019
    Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY, Technical University of Denmark
    Inventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh, Toshio Morioka
  • Patent number: 10162136
    Abstract: An optical transmission device includes a plurality of transmitting/receiving units provided on a substrate, each transmitting/receiving unit includes: an optical transmitter; an optical receiver; a polarization combiner/splitter; and a connection portion. In the connection portions which are arranged at the positions symmetrical to each other, a direction opposite, with respect to a virtual symmetry axis, to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from one of the connection portions to an outside is substantially orthogonal to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from the other of the connection portions to an outside.
    Type: Grant
    Filed: February 6, 2018
    Date of Patent: December 25, 2018
    Assignee: FUJIKURA LTD.
    Inventors: Kazuhiro Goi, Katsuhiro Takenaga
  • Patent number: 10156674
    Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.
    Type: Grant
    Filed: April 29, 2016
    Date of Patent: December 18, 2018
    Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
  • Publication number: 20180356590
    Abstract: A multicore fiber includes a plurality of cores including a first core and a cladding surrounding the plurality of cores. The first core includes: an inner core; and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core and a refractive index of the cladding. The core is not doped with any rare earth element. At least two LP mode light beams at a predetermined wavelength propagate through the first core at an attenuation of 0.3 dB/km or less.
    Type: Application
    Filed: October 25, 2016
    Publication date: December 13, 2018
    Applicant: FUJIKURA LTD.
    Inventors: Yoshimichi Amma, Katsuhiro Takenaga, Shota Saito
  • Patent number: 10101526
    Abstract: A multicore fiber communicates using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multicore fiber includes: a plurality of cores; a clad that surrounds the plurality of cores and has a refractive index lower than refractive indexes of the plurality of cores; and a cover layer that covers the clad and has a refractive index higher than the refractive index of the clad. Each of the plurality of cores propagates light up to an (x+1)th-order LP mode. A core pitch is set to a distance where crosstalk of the light up to the xth-order LP mode becomes less than or equal to ?40 dB/km and crosstalk of light of the (x+1)th-order LP mode becomes greater than or equal to ?30 dB/km.
    Type: Grant
    Filed: April 26, 2016
    Date of Patent: October 16, 2018
    Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
  • Publication number: 20180246275
    Abstract: A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.
    Type: Application
    Filed: July 6, 2016
    Publication date: August 30, 2018
    Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Shota Saito, Katsuhiro Takenaga, Kunimasa Saitoh, Takeshi Fujisawa
  • Publication number: 20180246007
    Abstract: A method of measuring crosstalk of a multicore fiber, the method including capturing an emitted light pattern at an end portion of a dummy fiber and obtaining a correlation data between a power of the light incident on the dummy fiber and the emitted light pattern, irradiating one core of the multicore fiber with a light through the dummy fiber, and measuring a power of a reference light emitted from the core, capturing a crosstalk light emitted from a different core different from the core on which the light is incident under a state where the reference light is masked, and estimating a power of the crosstalk light from a captured data of the crosstalk light and the correlation data, and calculating the crosstalk from the power of the reference light and the power of the crosstalk light.
    Type: Application
    Filed: January 26, 2017
    Publication date: August 30, 2018
    Applicant: FUJIKURA LTD.
    Inventors: Shota Saito, Katsuhiro Takenaga
  • Publication number: 20180246008
    Abstract: A characteristic-measuring apparatus for a multi-core fiber includes: a coupling device that couples, at a first end of the multi-core fiber, light to a plurality of cores in the multi-core fiber; an imaging device that takes an image, at a second end of the multi-core fiber, of emission light emitted from the plurality of cores, where the plurality of cores are imaged at the same time; and a calculating device that determines a characteristic of the multi-core fiber based on images obtained by the imaging device.
    Type: Application
    Filed: January 26, 2018
    Publication date: August 30, 2018
    Applicant: FUJIKURA LTD.
    Inventors: Shota Saito, Katsuhiro Takenaga
  • Publication number: 20180224613
    Abstract: An optical transmission device includes a plurality of transmitting/receiving units provided on a substrate, each transmitting/receiving unit includes: an optical transmitter; an optical receiver; a polarization combiner/splitter; and a connection portion. In the connection portions which are arranged at the positions symmetrical to each other, a direction opposite, with respect to a virtual symmetry axis, to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from one of the connection portions to an outside is substantially orthogonal to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from the other of the connection portions to an outside.
    Type: Application
    Filed: February 6, 2018
    Publication date: August 9, 2018
    Applicant: FUJIKURA LTD.
    Inventors: Kazuhiro Goi, Katsuhiro Takenaga
  • Patent number: 10042114
    Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.
    Type: Grant
    Filed: April 29, 2016
    Date of Patent: August 7, 2018
    Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
  • Publication number: 20180120502
    Abstract: A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.
    Type: Application
    Filed: May 20, 2016
    Publication date: May 3, 2018
    Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
  • Publication number: 20180120501
    Abstract: A multicore fiber communicates using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multicore fiber includes: a plurality of cores; a clad that surrounds the plurality of cores and has a refractive index lower than refractive indexes of the plurality of cores; and a cover layer that covers the clad and has a refractive index higher than the refractive index of the clad. Each of the plurality of cores propagates light up to an (x+1)th-order LP mode. A core pitch is set to a distance where crosstalk of the light up to the xth-order LP mode becomes less than or equal to ?40 dB/km and crosstalk of light of the (x+1)th-order LP mode becomes greater than or equal to ?30 dB/km.
    Type: Application
    Filed: April 26, 2016
    Publication date: May 3, 2018
    Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
    Inventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh