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).
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Publication number: 20240118564Abstract: An optical isolator for a wavelength band of 400 to 470 nm includes: a Faraday rotator having a Verdet constant equal to or greater than 750 Rad/T·m at a wavelength of 400 nm to 470 nm; and a hollow magnet provided on an outer periphery of the Faraday rotator, wherein a magnetic flux density B(T) applied to the Faraday rotator is within the range of the following formula (1), and an optical path length L(cm) over which the Faraday rotator is provided is within the range of the following formula (2): B?0.40 (1); 0.26?L?0.50 (2). Thus, a miniaturized optical isolator which is transparent at violet and blue wavelengths of 400 to 470 nm is provided.Type: ApplicationFiled: March 28, 2022Publication date: April 11, 2024Applicant: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Akira YAHAGI, Shinji MAKIKAWA
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Publication number: 20220146866Abstract: 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: ApplicationFiled: October 2, 2019Publication date: May 12, 2022Applicant: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Akira YAHAGI, Masanori IKARI, Takuto MATSUMOTO
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Patent number: 9470915Abstract: 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: GrantFiled: March 15, 2012Date of Patent: October 18, 2016Assignee: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Shinji Makikawa, Akira Yahagi, Akio Ikesue
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Patent number: 9429778Abstract: 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: GrantFiled: June 20, 2014Date of Patent: August 30, 2016Assignee: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
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Patent number: 9013792Abstract: 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: GrantFiled: March 15, 2012Date of Patent: April 21, 2015Assignee: Shin-Etsu Chemical Co., Ltd.Inventors: Akira Yahagi, Toshiaki Watanabe
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Publication number: 20150015947Abstract: 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: ApplicationFiled: June 20, 2014Publication date: January 15, 2015Applicant: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
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Publication number: 20140300963Abstract: 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: ApplicationFiled: December 7, 2012Publication date: October 9, 2014Applicant: Shin-Etsu Chemical Co., Ltd.Inventors: Akira Yahagi, Toshiaki Watanabe, Shinji Makikawa
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Publication number: 20140002900Abstract: 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: ApplicationFiled: March 15, 2012Publication date: January 2, 2014Applicant: SHIN-ETSU CHEMICAL CO., LTD.Inventors: Shinji Makikawa, Akira Yahagi, Akio Ikesue
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Publication number: 20120236409Abstract: 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: ApplicationFiled: March 15, 2012Publication date: September 20, 2012Inventors: Akira YAHAGI, Toshiaki Watanabe
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Patent number: 6950596Abstract: 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: GrantFiled: November 19, 2003Date of Patent: September 27, 2005Assignees: NEC Tokin Corporation, NEC Tokin Iwate, Ltd.Inventors: Akira Yahagi, Shigeru Kasai, Tatsumi Ide, Michikazu Kondo
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Publication number: 20040101245Abstract: 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: ApplicationFiled: November 19, 2003Publication date: May 27, 2004Applicants: NEC TOKIN Corporation, NEC TOKIN Iwate, Ltd.Inventors: Akira Yahagi, Shigeru Kasai, Tatsumi Ide, Michikazu Kondo
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Patent number: 4785034Abstract: 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: GrantFiled: March 3, 1987Date of Patent: November 15, 1988Assignees: Mitsubishi Gas Chemical Company, Inc., Dainichiseika Color & Chemicals Mfg. Co. Ltd.Inventors: Morio Gaku, Hidenori Kimbara, Akira Yahagi, Takaaki Osanai