Patents by Inventor Shigehiro Takasaka

Shigehiro Takasaka 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: 11073656
    Abstract: An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier.
    Type: Grant
    Filed: June 5, 2020
    Date of Patent: July 27, 2021
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Shigehiro Takasaka, Koichi Maeda
  • Publication number: 20210186612
    Abstract: To provide an optical probe capable of changing a traveling direction of an output beam to a sideward direction. The optical probe includes an optical fiber that outputs a beam from a distal end thereof, and a traveling direction changing unit that changes a traveling direction of the output beam to a sideward direction with respect to the optical fiber. The optical probe includes a holder member that is mounted on a distal end side of the optical fiber and holds the optical fiber, and the traveling direction changing unit may be a reflector that is arranged on the holder member and that reflects output beam.
    Type: Application
    Filed: March 9, 2021
    Publication date: June 24, 2021
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Kengo WATANABE, Shunichi MATSUSHITA, Yoshiki NOMURA, Shigehiro TAKASAKA, Masaki IWAMA
  • Publication number: 20210116265
    Abstract: A cable comprising: a plurality of optical fiber cores; and one or more optical fiber core wires including one or more of the optical fiber cores. Further, at least one of the optical fiber core wire is fixed at a plurality of positions in a longitudinal direction of the cable so as to achieve substantially no displacement in a cable radial direction, at least a pair of the optical fiber core wires are fixed in a plane perpendicular to the longitudinal direction of the cable so as to achieve substantially no displacement relative to each other, and sensing of a strain profile in the longitudinal direction of at least the pair of the optical fiber core wires leads to achievement of sensing of a shape of the cable in the longitudinal direction.
    Type: Application
    Filed: December 29, 2020
    Publication date: April 22, 2021
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Masateru TADAKUMA, Shigehiro TAKASAKA, Ryuichi SUGIZAKI
  • Patent number: 10816873
    Abstract: An optical amplifier includes: a pump-light source unit outputting pump light beams having respective phases modulated; a polarization multiplexer/demultiplexer having first, second, and third ports, demultiplexing a light beam, input from the first port, into polarization components and outputting the demultiplexed light components from the second port and the third port; a first polarization-sensitive optical amplifying fiber unit connected to the second port of the polarization multiplexer/demultiplexer; a second polarization-sensitive optical amplifying fiber unit connected to the third port of the polarization multiplexer/demultiplexer; optical multiplexers/demultiplexers connected to the first polarization-sensitive optical amplifying fiber unit and the second polarization-sensitive optical amplifying fiber unit, respectively; an optical discharge unit, connected between the first polarization-sensitive optical amplifying fiber unit and the second polarization-sensitive optical amplifying fiber unit, di
    Type: Grant
    Filed: April 13, 2018
    Date of Patent: October 27, 2020
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Shigehiro Takasaka
  • Publication number: 20200301066
    Abstract: An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier.
    Type: Application
    Filed: June 5, 2020
    Publication date: September 24, 2020
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Shigehiro TAKASAKA, Koichi MAEDA
  • Publication number: 20180231870
    Abstract: An optical amplifier includes: a pump-light source unit outputting pump light beams having respective phases modulated; a polarization multiplexer/demultiplexer having first, second, and third ports, demultiplexing a light beam, input from the first port, into polarization components and outputting the demultiplexed light components from the second port and the third port; a first polarization-sensitive optical amplifying fiber unit connected to the second port of the polarization multiplexer/demultiplexer; a second polarization-sensitive optical amplifying fiber unit connected to the third port of the polarization multiplexer/demultiplexer; optical multiplexers/demultiplexers connected to the first polarization-sensitive optical amplifying fiber unit and the second polarization-sensitive optical amplifying fiber unit, respectively; an optical discharge unit, connected between the first polarization-sensitive optical amplifying fiber unit and the second polarization-sensitive optical amplifying fiber unit, di
    Type: Application
    Filed: April 13, 2018
    Publication date: August 16, 2018
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Shigehiro Takasaka
  • Patent number: 9948057
    Abstract: An optical amplifier includes: an optical amplifying fiber; and a pump light source that supplies pump light to the optical amplifying fiber, the pump light being used for parametrically amplifying signal light input to the optical amplifying fiber by using a non-linear optical effect of the optical amplifying fiber. The fluctuation of the zero-dispersion wavelength of the optical amplifying fiber in the longitudinal direction is within the limit of 0.5 nm/100 m.
    Type: Grant
    Filed: February 24, 2016
    Date of Patent: April 17, 2018
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Shigehiro Takasaka
  • Patent number: 9722388
    Abstract: A multi-core optical amplifying fiber device includes a plurality of multi-core optical amplifying fibers including a plurality of core portions doped with amplification medium and a cladding portion formed at outer peripheries of the plurality of core portions; and a connection portion connecting the core portions of the plurality of multi-core optical amplifying fibers to one another. The connection portion connects the core portions to restrain deviation, between every connected core portions, of amplification gain for a total length of the core portions connected one another.
    Type: Grant
    Filed: December 21, 2015
    Date of Patent: August 1, 2017
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Masateru Tadakuma, Koichi Maeda, Yukihiro Tsuchida, Shigehiro Takasaka, Ryuichi Sugizaki
  • Publication number: 20160172818
    Abstract: An optical amplifier includes: an optical amplifying fiber; and a pump light source that supplies pump light to the optical amplifying fiber, the pump light being used for parametrically amplifying signal light input to the optical amplifying fiber by using a non-linear optical effect of the optical amplifying fiber. The fluctuation of the zero-dispersion wavelength of the optical amplifying fiber in the longitudinal direction is within the limit of 0.5 nm/100 m.
    Type: Application
    Filed: February 24, 2016
    Publication date: June 16, 2016
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Shigehiro TAKASAKA
  • Publication number: 20160118762
    Abstract: A multi-core optical amplifying fiber device includes a plurality of multi-core optical amplifying fibers including a plurality of core portions doped with amplification medium and a cladding portion formed at outer peripheries of the plurality of core portions; and a connection portion connecting the core portions of the plurality of multi-core optical amplifying fibers to one another. The connection portion connects the core portions to restrain deviation, between every connected core portions, of amplification gain for a total length of the core portions connected one another.
    Type: Application
    Filed: December 21, 2015
    Publication date: April 28, 2016
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Masateru TADAKUMA, Koichi MAEDA, Yukihiro TSUCHIDA, Shigehiro TAKASAKA, Ryuichi SUGIZAKI
  • Patent number: 9270076
    Abstract: An optical amplifier includes an optical gain fiber into which signal light and pump light are input and at least one relative phase shifter is inserted. Preferably, the relative phase shifter is inserted so that the relative phase in the lengthwise direction of the optical gain fiber falls within a predetermined range containing 0.5?. Preferably, the optical gain fiber is a highly non-linear optical fiber having a non-linearity constant of at least 10/W/km. Preferably, the dispersion of the optical gain fiber is within the range from ?1 ps/nm/km to 1 ps/nm/km in an amplification band. Preferably, the absolute value of the dispersion slope of the optical gain fiber at a zero dispersion wavelength is no greater than 0.05 ps/nm2/km.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: February 23, 2016
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Shigehiro Takasaka, Yu Mimura
  • Patent number: 8873898
    Abstract: A polarization independent wavelength converter includes a polarization maintaining optical fiber which includes a first and a second ends and has a first polarization axis and a second polarization axis, the first and the second polarization axes being orthogonal to each other and propagating light at different velocities, and a group velocity difference cancellation unit that receives a signal light having a certain polarization state and a pump light including a polarization component parallel to the first polarization axis and a polarization component parallel to the second polarization axis and that causes the signal light and a wavelength-converted light generated in the polarization maintaining optical fiber by the signal and the pump lights to pass through the polarization maintaining optical fiber in a manner not to be influenced by a group velocity difference of each of the signal and the wavelength-converted lights between the first and the second polarization axes.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: October 28, 2014
    Assignee: Furukawa Electric Co., Ltd.
    Inventor: Shigehiro Takasaka
  • Publication number: 20140043674
    Abstract: An optical amplifier includes an optical gain fiber into which signal light and pump light are input and at least one relative phase shifter is inserted. Preferably, the relative phase shifter is inserted so that the relative phase in the lengthwise direction of the optical gain fiber falls within a predetermined range containing 0.5 ?. Preferably, the optical gain fiber is a highly non-linear optical fiber having a non-linearity constant of at least 10/W/km. Preferably, the dispersion of the optical gain fiber is within the range from ?1 ps/nm/km to 1 ps/nm/km in an amplification band. Preferably, the absolute value of the dispersion slope of the optical gain fiber at a zero dispersion wavelength is no greater than 0.05 ps/nm2/km.
    Type: Application
    Filed: September 4, 2013
    Publication date: February 13, 2014
    Applicant: Furukawa Electric Co., Ltd.
    Inventors: Shigehiro TAKASAKA, Yu Mimura
  • Patent number: 8494378
    Abstract: A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.
    Type: Grant
    Filed: July 6, 2007
    Date of Patent: July 23, 2013
    Assignees: Japan Science and Technology Agency, The Furukawa Electric Co., Ltd.
    Inventors: Shigehiro Takasaka, Yasuyuki Ozeki, Misao Sakano
  • Publication number: 20130101248
    Abstract: A polarization independent wavelength converter includes a polarization maintaining optical fiber which includes a first and a second ends and has a first polarization axis and a second polarization axis, the first and the second polarization axes being orthogonal to each other and propagating light at different velocities, and a group velocity difference cancellation unit that receives a signal light having a certain polarization state and a pump light including a polarization component parallel to the first polarization axis and a polarization component parallel to the second polarization axis and that causes the signal light and a wavelength-converted light generated in the polarization maintaining optical fiber by the signal and the pump lights to pass through the polarization maintaining optical fiber in a manner not to be influenced by a group velocity difference of each of the signal and the wavelength-converted lights between the first and the second polarization axes.
    Type: Application
    Filed: September 14, 2012
    Publication date: April 25, 2013
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Shigehiro TAKASAKA
  • Publication number: 20120027343
    Abstract: An optical regeneration system for regenerating a degenerated signal light, comprising a regeneration device having at least one of a soliton converter, a pulse roller, a Kerr-shutter and a soliton purifier. The solilton converter uses an anomalaous-dispersion fiber (ADF) having a fiber length up to three times the soliton frequency, and the pulse roller is provided with a pulse roller fiber having high non-linear characteristics. The Kerr-shutter comprises an optical LO (local oscillation) generator for generating an optical LO on an OPLL (optical phase locked loop), a phase comparator for detecting the phase difference between an externally-input signal light and an optical LO, and a control unit for regulating the repeated frequency of an optical LO based on the phase difference. The soliton purifier has a soliton fiber disposed between two optical fibers.
    Type: Application
    Filed: October 10, 2011
    Publication date: February 2, 2012
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Koji IGARASHI, Shunichi Matsushita, Shu Namiki, Shigehiro Takasaka, Takashi Inoue, Hideaki Tobioka, Jiro Hiroishi
  • Patent number: 8059966
    Abstract: An optical regeneration system for regenerating a degenerated signal light, comprising a regeneration device having at least one of a soliton converter, a pulse roller, a Kerr-shutter and a soliton purifier. The solilton converter uses an anomalous-dispersion fiber (ADF) having a fiber length up to three times the soliton frequency, and the pulse roller is provided with a pulse roller fiber having high non-linear characteristics. The Kerr-shutter comprises an optical LO (local oscillation) generator for generating an optical LO on an OPLL (optical phase locked loop), a phase comparator for detecting the phase difference between an externally-input signal light and an optical LO, and a control unit for regulating the repeated frequency of an optical LO based on the phase difference. The soliton purifier has a soliton fiber disposed between two optical fibers.
    Type: Grant
    Filed: June 11, 2003
    Date of Patent: November 15, 2011
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Koji Igarashi, Shunichi Matsushita, Shu Namiki, Shigehiro Takasaka, Takashi Inoue, Hideaki Tobioka, Jiro Hiroishi
  • Patent number: 7715725
    Abstract: A lock detection apparatus detecting lock of an optical phase-locked loop apparatus including a first phase detector comparing phases of an input light signal and a beat light signal to output a first phase comparison signal, a loop filter forming the first phase comparison signal, and an optical voltage controlled oscillator outputting the beat light signal based on the formed first phase comparison signal. The lock detection apparatus includes: a phase shifter shifting the phase of the beat light signal; and a second phase detector comparing the phases of the input light signal and the phase-shifted beat light signal to output a second phase comparison signal, wherein the phase shifter shifts a quantity of the phase so that the phase comparison signal may not be 0 when the phases of the two light signals compared by the second phase detector synchronize with each other to the beat light signal.
    Type: Grant
    Filed: October 12, 2005
    Date of Patent: May 11, 2010
    Assignees: Japan Science and Technology Agency, The Furukawa Electric Co., Ltd.
    Inventors: Shigehiro Takasaka, Yasuyuki Ozeki
  • Publication number: 20090208200
    Abstract: A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.
    Type: Application
    Filed: July 6, 2007
    Publication date: August 20, 2009
    Applicants: JAPAN SCIENCE AND TECHNOLOGY AGENCY, THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Shigehiro Takasaka, Yasuyuki Ozeki, Misao Sakano
  • Publication number: 20080272850
    Abstract: A lock detection apparatus detecting lock of an optical phase-locked loop apparatus including a first phase detector comparing phases of an input light signal and a beat light signal to output a first phase comparison signal, a loop filter forming the first phase comparison signal, and an optical voltage controlled oscillator outputting the beat light signal based on the formed first phase comparison signal. The lock detection apparatus includes: a phase shifter shifting the phase of the beat light signal; and a second phase detector comparing the phases of the input light signal and the phase-shifted beat light signal to output a second phase comparison signal, wherein the phase shifter shifts a quantity of the phase so that the phase comparison signal may not be 0 when the phases of the two light signals compared by the second phase detector synchronize with each other to the beat light signal.
    Type: Application
    Filed: October 12, 2005
    Publication date: November 6, 2008
    Applicants: JAPAN SCIENCE AND TECHNOLOGY AGENCY, THE FURUKAWA ELECTRIC CO, LTD.
    Inventors: Shigehiro Takasaka, Yasuyuki Ozeki