Patents by Inventor Masateru Tadakuma

Masateru Tadakuma 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: 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: 10718658
    Abstract: An optical fiber sensor includes: a transmitting unit configured to output two lights into an optical fiber, wavelengths of the two lights being different from each other at a specific time, and at least one of the wavelengths of the two lights varying with time; and a measuring unit configured to receive back-scattered light output from the optical fiber and detect a temporal variation of an optical phase at an arbitrary interval in a longitudinal direction of the optical fiber by measuring measure an interference state of the two lights.
    Type: Grant
    Filed: January 31, 2017
    Date of Patent: July 21, 2020
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Masateru Tadakuma
  • 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: 20170138785
    Abstract: An optical fiber sensor includes: a transmitting unit configured to output two lights into an optical fiber, wavelengths of the two lights being different from each other at a specific time, and at least one of the wavelengths of the two lights varying with time; and a measuring unit configured to receive back-scattered light output from the optical fiber and detect a temporal variation of an optical phase at an arbitrary interval in a longitudinal direction of the optical fiber by measuring measure an interference state of the two lights.
    Type: Application
    Filed: January 31, 2017
    Publication date: May 18, 2017
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Masateru TADAKUMA
  • 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: 7869014
    Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.
    Type: Grant
    Filed: February 12, 2008
    Date of Patent: January 11, 2011
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
  • Patent number: 7769298
    Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.
    Type: Grant
    Filed: September 25, 2008
    Date of Patent: August 3, 2010
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
  • Patent number: 7693377
    Abstract: An optical fiber module includes an optical fiber that transmits a light and a holding unit that holds the optical fiber in a state in which the optical fiber is stretched in its longitudinal direction to change optical characteristics of the optical fiber.
    Type: Grant
    Filed: September 3, 2008
    Date of Patent: April 6, 2010
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Masanori Takahashi, Jiro Hiroishi, Masateru Tadakuma, Takeshi Yagi
  • Patent number: 7630607
    Abstract: An optical fiber device converts an input optical pulse having a predetermined center wavelength into an optical pulse having a wavelength bandwidth broader than that of the input optical pulse. The optical fiber device includes a plurality of optical fibers connected in a cascaded manner each having negative wavelength dispersion at the center wavelength. The optical fibers have different relative refractive index differences between a core region and a cladding region from each other. The optical fibers are connected such that wavelength dispersions of adjacent optical fibers at the center wavelength are different from each other.
    Type: Grant
    Filed: July 7, 2008
    Date of Patent: December 8, 2009
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Masateru Tadakuma, Masanori Takahashi
  • Patent number: 7536074
    Abstract: An optical fiber made of silica-based material includes a core and a cladding formed around the core. The core is doped with germanium dioxide, which increases refractive index and decreases acoustic-wave velocity, and aluminum oxide, which increases both refractive index and acoustic-wave velocity, satisfying—2.814+0.594×W1?W2?54.100+0.218×W1, W1+W2?60, and W2?56.63?2.04×W1, where W1 is doping amount of germanium dioxide in weight percentage, which is larger than 4.74, and W2 is doping amount of aluminum oxide in weight percentage. A nonlinear coefficient of the optical fiber is equal to or larger than 2.6×10?9W?1.
    Type: Grant
    Filed: August 25, 2008
    Date of Patent: May 19, 2009
    Assignee: The Furukawa Electric Co., Ltd.
    Inventor: Masateru Tadakuma
  • Publication number: 20090092400
    Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.
    Type: Application
    Filed: September 25, 2008
    Publication date: April 9, 2009
    Applicant: THE FURUKAWA ELECTRIC CO., LTD
    Inventors: Koji IGARASHI, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
  • Publication number: 20090060433
    Abstract: An optical fiber made of silica-based material includes a core and a cladding formed around the core. The core is doped with germanium dioxide, which increases refractive index and decreases acoustic-wave velocity, and aluminum oxide, which increases both refractive index and acoustic-wave velocity, satisfying ?2.814+0.594×W1?W2?54.100+0.218×W1, W1+W2?60, and W2?56.63?2.04×W1, where W1 is doping amount of germanium dioxide in weight percentage, which is larger than 4.74, and W2 is doping amount of aluminum oxide in weight percentage. A nonlinear coefficient of the optical fiber is equal to or larger than 2.6×10?9W?1.
    Type: Application
    Filed: August 25, 2008
    Publication date: March 5, 2009
    Applicant: THE FURUKAWA ELECTRIC CO. LTD.
    Inventor: Masateru TADAKUMA
  • Publication number: 20090028509
    Abstract: An optical fiber device converts an input optical pulse having a predetermined center wavelength into an optical pulse having a wavelength bandwidth broader than that of the input optical pulse. The optical fiber device includes a plurality of optical fibers connected in a cascaded manner each having negative wavelength dispersion at the center wavelength. The optical fibers have different relative refractive index differences between a core region and a cladding region from each other. The optical fibers are connected such that wavelength dispersions of adjacent optical fibers at the center wavelength are different from each other.
    Type: Application
    Filed: July 7, 2008
    Publication date: January 29, 2009
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Masateru TADAKUMA, Masanori TAKAHASHI
  • Publication number: 20090003786
    Abstract: An optical fiber module includes an optical fiber that transmits a light and a holding unit that holds the optical fiber in a state in which the optical fiber is stretched in its longitudinal direction to change optical characteristics of the optical fiber.
    Type: Application
    Filed: September 3, 2008
    Publication date: January 1, 2009
    Applicant: The Furukawa Electric Co., Ltd.
    Inventors: Masanori TAKAHASHI, Jiro Hiroishi, Masateru Tadakuma, Takeshi Yagi
  • Patent number: 7447444
    Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.
    Type: Grant
    Filed: May 23, 2005
    Date of Patent: November 4, 2008
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
  • Publication number: 20080225276
    Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.
    Type: Application
    Filed: February 12, 2008
    Publication date: September 18, 2008
    Applicant: The Furukawa Electric Co., Ltd.
    Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
  • Patent number: 7424191
    Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.
    Type: Grant
    Filed: October 13, 2006
    Date of Patent: September 9, 2008
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
  • Patent number: 7408701
    Abstract: A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as a an inexpensive light source producing a plurality of optical frequencies.
    Type: Grant
    Filed: April 20, 2006
    Date of Patent: August 5, 2008
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Osamu Aso, Shunichi Matushita, Misao Sakano, Masateru Tadakuma
  • Publication number: 20070216993
    Abstract: A fiber laser includes in a resonator: a normal dispersion optical fiber; an anomalous dispersion optical fiber; a rare earth-doped optical fiber as a gain medium; and a mode locking mechanism, in which at least the rare earth-doped optical fiber is included as the normal dispersion optical fiber, and a length of the rare earth-doped optical fiber is set shorter than that of the anomalous dispersion optical fiber.
    Type: Application
    Filed: March 4, 2005
    Publication date: September 20, 2007
    Applicants: The Furukawa Electric Co., Ltd, Yuichi TAKUSHIMA
    Inventors: Keiichi Aiso, Masateru Tadakuma, Yuichi Takushima
  • Publication number: 20070035722
    Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.
    Type: Application
    Filed: October 13, 2006
    Publication date: February 15, 2007
    Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi