Patents by Inventor Akira Yahagi

Akira Yahagi 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: 20220146866
    Abstract: An optical isolator includes a Faraday rotator including a trivalent ion exchange TAG (terbium-aluminum garnet), and arranged around the Faraday rotator, a central hollow magnet and a first and a second hollow magnet units arranged to sandwich the central hollow magnet in an optical axis direction. A magnetic flux density B [T] in the Faraday rotator and an optical path length L [mm] where the Faraday rotator is arranged satisfy 0<B??(1) and 14.0?L?24.0??(2). The optical isolator, compared with a conventional Faraday rotator such as a terbium-gallium garnet (TGG) crystal, contributes to reduction of a thermal lensing effect, being a pending problem, in a high-output fiber laser.
    Type: Application
    Filed: October 2, 2019
    Publication date: May 12, 2022
    Applicant: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Akira YAHAGI, Masanori IKARI, Takuto MATSUMOTO
  • Patent number: 9470915
    Abstract: A transparent ceramic having terbium oxide (Tb2O3) in a molar ratio of at least 40%; and at least one oxide selected among an yttrium oxide, a scandium oxide, and a lanthanide rare earth oxide, wherein (1) the crystal structure of the terbium-oxide-based ceramic does not contain a non-cubic-crystal phase, (2) the mean crystal particle diameter is in a range of 0.5 to 100 ?m, and (3) the ceramic comprises a sintering auxiliary having no incidence of deposition of a non-cubic-crystal phase in the crystal structure of the terbium-oxide-based ceramic. This transparent ceramic makes a magneto-optical element that performs at least as well as terbium gallium garnet or other existing monocrystal materials. It also makes a functional element for an optical isolator in the infrared region between 500 nm and 1.5 ?m having very little scattering and very few birefringence components.
    Type: Grant
    Filed: March 15, 2012
    Date of Patent: October 18, 2016
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Shinji Makikawa, Akira Yahagi, Akio Ikesue
  • Patent number: 9429778
    Abstract: An optical isolator for use with a wavelength band of 600-800 nm is improved in that it has a Faraday rotator made of an oxide material in which said oxide material contains (TbxR1-x)2O3 such that 0.5?x?1.0, and R is scandium, yttrium or any lanthanoid but Tb.
    Type: Grant
    Filed: June 20, 2014
    Date of Patent: August 30, 2016
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
  • Patent number: 9013792
    Abstract: An optical module is provided that includes a Faraday rotator having a Verdet constant at a wavelength of 1.06 ?m of at least 0.27 min/(Oe·cm), a first hollow magnet disposed on the outer periphery of the Faraday rotator, and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis. The second and third hollow magnet units include 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis. A magnetic flux density B (Oe) applied to the Faraday rotator is in the range of 0.5×104?B?1.5×104. The Faraday rotator is disposed on a sample length L (cm) in the range of 0.70?L?1.10, and has an external diameter D (cm) in the range of 0.20?D?0.60.
    Type: Grant
    Filed: March 15, 2012
    Date of Patent: April 21, 2015
    Assignee: Shin-Etsu Chemical Co., Ltd.
    Inventors: Akira Yahagi, Toshiaki Watanabe
  • Publication number: 20150015947
    Abstract: An optical isolator for use with a wavelength band of 600-800 nm is improved in that it has a Faraday rotator made of an oxide material in which said oxide material contains (TbxR1-x)2O3 such that 0.5?x?1.0, and R is scandium, yttrium or any lanthanoid but Tb.
    Type: Application
    Filed: June 20, 2014
    Publication date: January 15, 2015
    Applicant: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
  • Publication number: 20140300963
    Abstract: It is an object to provide a small-sized optical isolator that is suitable as an optical isolator used in a semiconductor laser used in applications such as medical treatment or optical measurement The optical isolator for a wavelength band of 320 to 633 nm of the present invention comprises a Faraday device having a Verdet constant at a wavelength of 405 nm of at least 0.70 min/(Oe·cm), and a first hollow magnet disposed on the outer periphery of the Faraday device and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis, the second and third hollow magnet units comprising 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis, the Faraday device having applied thereto a magnetic flux density B (Oe) within the range of Expression (1) below, and a sample length L (cm) on which the Faraday device is disposed being within the range of Expression (2) below. 0.8×104?B?1.5×104??(1) 0.25?L?0.
    Type: Application
    Filed: December 7, 2012
    Publication date: October 9, 2014
    Applicant: Shin-Etsu Chemical Co., Ltd.
    Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
  • Publication number: 20140002900
    Abstract: A transparent ceramic having terbium oxide (Tb2O3) in a molar ratio of at least 40%; and at least one oxide selected among an yttrium oxide, a scandium oxide, and a lanthanide rare earth oxide, wherein (1) the crystal structure of the terbium-oxide-based ceramic does not contain a non-cubic-crystal phase, (2) the mean crystal particle diameter is in a range of 0.5 to 100 ?m, and (3) the ceramic comprises a sintering auxiliary having no incidence of deposition of a non-cubic-crystal phase in the crystal structure of the terbium-oxide-based ceramic. This transparent ceramic makes a magneto-optical element that performs at least as well as terbium gallium garnet or other existing monocrystal materials. It also makes a functional element for an optical isolator in the infrared region between 500 nm and 1.5 ?m having very little scattering and very few birefringence components.
    Type: Application
    Filed: March 15, 2012
    Publication date: January 2, 2014
    Applicant: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Shinji Makikawa, Akira Yahagi, Akio Ikesue
  • Publication number: 20120236409
    Abstract: An optical module is provided that includes a Faraday rotator having a Verdet constant at a wavelength of 1.06 ?m of at least 0.27 min/(Oe·cm), a first hollow magnet disposed on the outer periphery of the Faraday rotator, and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis. The second and third hollow magnet units include 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis. A magnetic flux density B (Oe) applied to the Faraday rotator is in the range of 0.5×104?B?1.5×104. The Faraday rotator is disposed on a sample length L (cm) in the range of 0.70?L?1.10, and has an external diameter D (cm) in the range of 0.20?D?0.60.
    Type: Application
    Filed: March 15, 2012
    Publication date: September 20, 2012
    Inventors: Akira YAHAGI, Toshiaki Watanabe
  • Patent number: 6950596
    Abstract: A variable optical attenuator comprises an incoming fiber for propagating an incoming light beam, a mirror for reflecting the incoming light beam as a reflected light beam and an outgoing fiber for propagating as an outgoing light beam at least one part of the reflected light beam. The light intensity of the outgoing light beam is determined by the angle of reflection at the mirror. The angle of reflection at the mirror is adjusted by an actuator for rotating the mirror. The actuator comprises a plate, a coil, a housing and permanents magnets. The mirror and the coil are fixed on the plate. The housing supports the plate so that the plate is able to rotate around a rotation axis, which is included on a predetermined plane. The permanent magnets are fixed on the housing and generate predetermined magnetic flux density along the predetermined plane. When a driving current is supplied to the coil under the predetermined magnetic flux density, a Lorentz force occurs at the coil so as to rotate the coil.
    Type: Grant
    Filed: November 19, 2003
    Date of Patent: September 27, 2005
    Assignees: NEC Tokin Corporation, NEC Tokin Iwate, Ltd.
    Inventors: Akira Yahagi, Shigeru Kasai, Tatsumi Ide, Michikazu Kondo
  • Publication number: 20040101245
    Abstract: A variable optical attenuator comprises an incoming fiber for propagating an incoming light beam, a mirror for reflecting the incoming light beam as a reflected light beam and an outgoing fiber for propagating as an outgoing light beam at least one part of the reflected light beam. The light intensity of the outgoing light beam is determined by the angle of reflection at the mirror. The angle of reflection at the mirror is adjusted by an actuator for rotating the mirror. The actuator comprises a plate, a coil, a housing and permanents magnets. The mirror and the coil are fixed on the plate. The housing supports the plate so that the plate is able to rotate around a rotation axis, which is included on a predetermined plane. The permanent magnets are fixed on the housing and generate predetermined magnetic flux density along the predetermined plane. When a driving current is supplied to the coil under the predetermined magnetic flux density, a Lorentz force occurs at the coil so as to rotate the coil.
    Type: Application
    Filed: November 19, 2003
    Publication date: May 27, 2004
    Applicants: NEC TOKIN Corporation, NEC TOKIN Iwate, Ltd.
    Inventors: Akira Yahagi, Shigeru Kasai, Tatsumi Ide, Michikazu Kondo
  • Patent number: 4785034
    Abstract: A stabilized polyolefin resin composition in which (a) 0.005-5% by weight of at least one monofunctional or polyfunctional cyanate ester compound having at least one cyanato group in its molecule, (b) 0.01-5% by weight of at least one hindered amine ultraviolet absorber and (c) 0.005-2% by weight of at least one hindered phenolic antioxidant are incorporated into a polyolefin resin is disclosed. The resin composition has excellent heat stability and resistance to weathering.
    Type: Grant
    Filed: March 3, 1987
    Date of Patent: November 15, 1988
    Assignees: Mitsubishi Gas Chemical Company, Inc., Dainichiseika Color & Chemicals Mfg. Co. Ltd.
    Inventors: Morio Gaku, Hidenori Kimbara, Akira Yahagi, Takaaki Osanai