Patents by Inventor Kentaro Ichii
Kentaro Ichii 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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Patent number: 10883860Abstract: An optical fiber sensor includes: a central core disposed at a center of an optical fiber; and an outer peripheral core that spirally surrounds the central core. The effective refractive index ne2 of the outer peripheral core is lower than the effective refractive index ne1 of the central core. A ratio between the effective refractive index ne2 and the effective refractive index ne1 matches a ratio between an optical path length of the central core and an optical path length of the outer peripheral core.Type: GrantFiled: December 8, 2017Date of Patent: January 5, 2021Assignee: Fujikura Ltd.Inventors: Kenichi Ohmori, Koji Omichi, Shingo Matsushita, Kentaro Ichii
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Patent number: 10670812Abstract: An optical fiber includes: a core that includes quartz glass doped with a core updopant; an inner cladding that includes quartz glass doped with a cladding updopant and a downdopant and that covers a circumferential surface of the core; and an outer cladding that includes quartz glass and that covers an outer circumferential surface of the inner cladding. A refractive index of the inner cladding is substantially equal to a refractive index of the outer cladding. The inner cladding contains the cladding updopant at a concentration such that a refractive index increase rate ascribed to the cladding updopant falls within a range of 0.25% to 0.5%.Type: GrantFiled: May 30, 2017Date of Patent: June 2, 2020Assignee: Fujikura Ltd.Inventors: Keisuke Hirakawa, Kentaro Ichii, Kazuyuki Hayashi
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Publication number: 20200041313Abstract: An optical fiber sensor includes: a central core disposed at a center of an optical fiber; and an outer peripheral core that spirally surrounds the central core. The effective refractive index ne2 of the outer peripheral core is lower than the effective refractive index ne1 of the central core. A ratio between the effective refractive index ne2 and the effective refractive index ne1 matches a ratio between an optical path length of the central core and an optical path length of the outer peripheral core.Type: ApplicationFiled: December 8, 2017Publication date: February 6, 2020Applicant: FUJIKURA LTD.Inventors: Kenichi Ohmori, Koji Omichi, Shingo Matsushita, Kentaro Ichii
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Publication number: 20200012041Abstract: A polarization maintaining fiber includes: a core; an inner cladding enclosing the core; two stress applying parts that sandwich the inner cladding therebetween; and an outer cladding enclosing the inner cladding and the two stress applying parts. Each of the two stress applying parts is depressed inward against the inner cladding, and the core has a flattened cross section having a long-axis that corresponds to a direction in which the two stress applying parts are aligned.Type: ApplicationFiled: March 22, 2018Publication date: January 9, 2020Applicant: FUJIKURA LTD.Inventors: Kentaro Ichii, Keisuke Hirakawa, Kazuyuki Hayashi
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Publication number: 20190204512Abstract: An optical fiber includes: a core that includes quartz glass doped with a core updopant; an inner cladding that includes quartz glass doped with a cladding updopant and a downdopant and that covers a circumferential surface of the core; and an outer cladding that includes quartz glass and that covers an outer circumferential surface of the inner cladding. A refractive index of the inner cladding is substantially equal to a refractive index of the outer cladding. The inner cladding contains the cladding updopant at a concentration such that a refractive index increase rate ascribed to the cladding updopant falls within a range of 0.25% to 0.5%.Type: ApplicationFiled: May 30, 2017Publication date: July 4, 2019Applicant: FUJIKURA LTD.Inventors: Keisuke Hirakawa, Kentaro Ichii, Kazuyuki Hayashi
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Patent number: 10246366Abstract: Provided is a method of manufacturing an optical fiber base material by an inside mounting method, including: a step of rotating and heating a glass tube fixed at two positions and supplying a gas into a through-hole of the glass tube, wherein in the step, the glass tube is warped so that an axis between respective fixed portions of the glass tube has a shape in which a catenary curve is reversed in the vertical direction.Type: GrantFiled: September 27, 2012Date of Patent: April 2, 2019Assignee: FUJIKURA LTD.Inventors: Nobuo Oozeki, Kentaro Ichii, Tomofumi Arai
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Patent number: 10073220Abstract: Provided is an optical coupler configured to cause an NA of light, which exits a taper fiber, to be smaller as compared with a conventional optical coupler. A taper fiber has a high refractive index part which is provided inside a core of the taper fiber and which has a refractive index smaller than a refractive index ncore of the core. An exit end surface of each GI fiber is bonded to an entrance end surface of the taper fiber so that at least a part of the exit end surface of the each GI fiber overlaps with a section of the high refractive index part. A relative refractive index difference of the taper fiber is smaller than 0.076%.Type: GrantFiled: March 6, 2017Date of Patent: September 11, 2018Assignee: FUJIKURA LTD.Inventors: Tomoyuki Fujita, Kentaro Ichii, Ken Katagiri, Kenichi Ohmori, Rintaro Kitahara, Tatsuya Kishi
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Publication number: 20170235055Abstract: Provided is an optical coupler configured to cause an NA of light, which exits a taper fiber, to be smaller as compared with a conventional optical coupler. A taper fiber has a high refractive index part which is provided inside a core of the taper fiber and which has a refractive index smaller than a refractive index ncore of the core. An exit end surface of each GI fiber is bonded to an entrance end surface of the taper fiber so that at least a part of the exit end surface of the each GI fiber overlaps with a section of the high refractive index part. A relative refractive index difference of the taper fiber is smaller than 0.076%.Type: ApplicationFiled: March 6, 2017Publication date: August 17, 2017Applicant: FUJIKURA LTD.Inventors: Tomoyuki Fujita, Kentaro Ichii, Ken Katagiri, Kenichi Ohmori, Rintaro Kitahara, Tatsuya Kishi
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Patent number: 9698557Abstract: An optical fiber for amplification includes a core having an inner core and an outer core surrounding the outer circumferential surface of the inner core. The relative refractive index difference of the inner core to a cladding is smaller than the relative refractive index difference of the outer core to the cladding. The outer core is entirely doped with erbium. The theoretical cutoff wavelength of an LP11 mode light beam is a wavelength of 1,565 nm or more. The theoretical cutoff wavelength of an LP21 mode light beam is a wavelength of 1,530 nm or less. The theoretical cutoff wavelength of the LP02 mode light beam is a wavelength of 980 nm or less.Type: GrantFiled: March 7, 2016Date of Patent: July 4, 2017Assignees: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATIONInventors: Tsukasa Hosokawa, Kentaro Ichii, Katsuhiro Takenaga, Shoichiro Matsuo, Hirotaka Ono, Makoto Yamada
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Patent number: 9673589Abstract: An amplification optical fiber operable to propagate light beams in a plurality of modes in a predetermined wavelength range through a core doped with a rare earth element, wherein Expression (1) is satisfied, where a cutoff wavelength of a propagated highest mode light beam is defined as ?max, under conditions in which the cutoff wavelength of the highest mode light beam is defined as ?c, a shortest wavelength of the wavelength range is defined as ?min, and a cutoff wavelength of a second-highest mode light beam to the highest mode light beam is ?min. ?c>0.5 ?min+0.5 ?max??(1).Type: GrantFiled: August 15, 2016Date of Patent: June 6, 2017Assignees: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATIONInventors: Tsukasa Hosokawa, Kentaro Ichii, Katsuhiro Takenaga, Shoichiro Matsuo, Hirotaka Ono, Makoto Yamada
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Publication number: 20170054266Abstract: An amplification optical fiber operable to propagate light beams in a plurality of modes in a predetermined wavelength range through a core doped with a rare earth element, wherein Expression (1) is satisfied, where a cutoff wavelength of a propagated highest mode light beam is defined as ?max, under conditions in which the cutoff wavelength of the highest mode light beam is defined as ?c, a shortest wavelength of the wavelength range is defined as ?min, and a cutoff wavelength of a second-highest mode light beam to the highest mode light beam is ?min. ?c>0.5 ?min+0.Type: ApplicationFiled: August 15, 2016Publication date: February 23, 2017Applicants: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATIONInventors: Tsukasa Hosokawa, Kentaro Ichii, Katsuhiro Takenaga, Shoichiro Matsuo, Hirotaka Ono, Makoto Yamada
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Patent number: 9515450Abstract: A plurality of cores 51 is disposed around the center axis of a first cladding 52 in a state in which an inter-core distance ? of cores adjacent to each other is equal, a refractive index n1 of the core 51 is provided higher than a refractive index n2 of the first cladding 52, and the refractive index n2 of the first cladding 52 is provided higher than a refractive index n3 of a second cladding 53. Moreover, 5.8??/MFD(2?c/(?c+?op))?8 is satisfied, where the inter-core distance is defined as ?, a mode field diameter of the core is defined as MFD, a cutoff wavelength is defined as ?c, and a wavelength of communication light incident on the core 51 is defined as ?op.Type: GrantFiled: October 31, 2013Date of Patent: December 6, 2016Assignees: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATION, NATIONAL UNIVERSITY CORPORATION SHIMANE UNIVERSITYInventors: Shoichiro Matsuo, Katsuhiro Takenaga, Kentaro Ichii, Hirotaka Ono, Kyouzou Tsujikawa, Makoto Yamada, Hiroji Masuda
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Publication number: 20160268757Abstract: An optical fiber for amplification includes a core having an inner core and an outer core surrounding the outer circumferential surface of the inner core. The relative refractive index difference of the inner core to a cladding is smaller than the relative refractive index difference of the outer core to the cladding. The outer core is entirely doped with erbium. The theoretical cutoff wavelength of an LP11 mode light beam is a wavelength of 1,565 nm or more. The theoretical cutoff wavelength of an LP21 mode light beam is a wavelength of 1,530 nm or less. The theoretical cutoff wavelength of the LP02 mode light beam is a wavelength of 980 nm or less.Type: ApplicationFiled: March 7, 2016Publication date: September 15, 2016Applicants: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATIONInventors: Tsukasa Hosokawa, Kentaro Ichii, Katsuhiro Takenaga, Shoichiro Matsuo, Hirotaka Ono, Makoto Yamada
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Patent number: 9252556Abstract: The first cladding 52 has a two-layer structure formed of a solid inner layer 62A passed through the center axis of the first cladding 52 and an outer layer 62B enclosing the inner layer 62A and the plurality of cores 51 with no gap. A refractive index n1 of the core 51 is provided higher than refractive indexes n2A and n2B of the inner layer 62A and the outer layer 62B, the refractive indexes n2A and n2B of the inner layer 62A and the outer layer 62B are provided higher than a refractive index n3 of the second cladding 53, and the refractive index n2A of the inner layer 62A is provided lower than the refractive index n2B of the outer layer 62B.Type: GrantFiled: October 31, 2013Date of Patent: February 2, 2016Assignees: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATION, NATIONAL UNIVERSITY CORPORATION SHIMANE UNIVERSITYInventors: Shoichiro Matsuo, Katsuhiro Takenaga, Kentaro Ichii, Hirotaka Ono, Kyouzou Tsujikawa, Makoto Yamada, Hiroji Masuda
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Publication number: 20150318661Abstract: The first cladding 52 has a two-layer structure formed of a solid inner layer 62A passed through the center axis of the first cladding 52 and an outer layer 62B enclosing the inner layer 62A and the plurality of cores 51 with no gap. A refractive index n1 of the core 51 is provided higher than refractive indexes n2A and n2B of the inner layer 62A and the outer layer 62B, the refractive indexes n2A and n2B of the inner layer 62A and the outer layer 62B are provided higher than a refractive index n3 of the second cladding 53, and the refractive index n2A of the inner layer 62A is provided lower than the refractive index n2B of the outer layer 62B.Type: ApplicationFiled: October 31, 2013Publication date: November 5, 2015Applicants: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATION, NATIONAL UNIVERSITY CORPORATION SHIMANE UNIVERSITYInventors: Shoichiro Matsuo, Katsuhiro Takenaga, Kentaro Ichii, Hirotaka Ono, Kyouzou Tsujikawa, Makoto Yamada, Hiroji Masuda
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Publication number: 20150318659Abstract: A plurality of cores 51 is disposed around the center axis of a first cladding 52 in a state in which an inter-core distance ? of cores adjacent to each other is equal, a refractive index n1 of the core 51 is provided higher than a refractive index n2 of the first cladding 52, and the refractive index n2 of the first cladding 52 is provided higher than a refractive index n3 of a second cladding 53. Moreover, 5.8??/MFD(2?c/(?c+?op))?8 is satisfied, where the inter-core distance is defined as ?, a mode field diameter of the core is defined as MFD, a cutoff wavelength is defined as ?c, and a wavelength of communication light incident on the core 51 is defined as ?op.Type: ApplicationFiled: October 31, 2013Publication date: November 5, 2015Applicants: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION, OSAKA PREFECTURE UNIVERSITY PUBLIC CORPORATION, NATIONAL UNIVERSITY CORPORATION SHIMANE UNIVERSITYInventors: Shoichiro Matsuo, Katsuhiro Takenaga, Kentaro Ichii, Hirotaka Ono, Kyouzou Tsujikawa, Makoto Yamada, Hiroji Masuda
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Patent number: 8941912Abstract: An ytterbium-doped optical fiber includes: a core which contains at least ytterbium, aluminum, and phosphorus; and a cladding which encircles the core, wherein an aluminum oxide equivalent concentration of the aluminum in the core is 0.2 mol % or more, a diphosphorus pentaoxide equivalent concentration of the phosphorus is higher than the aluminum oxide equivalent concentration, and the core either does not contain germanium or contains less than 1.1 mol % of germanium in a germanium dioxide equivalent concentration.Type: GrantFiled: February 3, 2011Date of Patent: January 27, 2015Assignee: Fujikura Ltd.Inventors: Shoji Tanigawa, Teruno Nakaguma, Tomofumi Arai, Kentaro Ichii
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Patent number: 8774590Abstract: Provided is an ytterbium-doped optical fiber including a core containing at least ytterbium, aluminum and phosphorous and a clad surrounding the core, wherein a molar concentration of diphosphorus pentoxide with respect to phosphorus in the core is equal to a molar concentration of aluminum oxide with respect to aluminum in the core, wherein a ratio of a molar concentration of diphosphorus pentoxide with respect to phosphorus in the core to the molar concentration of ytterbium oxide with respect to ytterbium in the core is higher than or equal to 10 and lower than or equal to 30, and wherein a relative refractive index difference between the core and the clad is higher than or equal to 0.05% and lower than or equal to 0.30%.Type: GrantFiled: April 29, 2011Date of Patent: July 8, 2014Assignee: Fujikura Ltd.Inventors: Kentaro Ichii, Shoji Tanigawa, Tomofumi Arai
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Patent number: 8693833Abstract: Provided is a manufacturing method for an optical fiber preform of which the core is doped with a rare earth element. The method includes: depositing glass particles within a silica tube by the modified chemical vapor deposition method, the glass particles mainly consisting of silicon dioxide; adding the rare earth element and aluminum to the glass particles within the silica tube by the solution doping method; heating the silica tube while flowing a phosphorous-containing gas into the silica tube to sinter the glass particles within the silica tube while adding the phosphorous; and heating and collapsing the silica tube to which the rare earth element, the aluminum, and the phosphorous are added.Type: GrantFiled: September 23, 2011Date of Patent: April 8, 2014Assignee: Fujikura Ltd.Inventors: Kentaro Ichii, Shoji Tanigawa
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Patent number: 8660396Abstract: Provided is a multi-cladding optical fiber which includes: a core with an average refractive index n1; and a cladding including an inner cladding with an average refractive index n2 formed on the periphery of the core, an intermediate cladding with an average refractive index n3 formed on the periphery of the inner cladding, and an outer cladding with an average refractive index n4 formed on the periphery of the intermediate cladding where n1>n2>n3>n4. Two or more axisymmetric modes exist in the core at a wavelength of the signal light; the two or more axisymmetric modes including a fundamental mode and at least a high-order mode. When the fiber is bent at a predetermined bending diameter, the high-order mode in the core disperses within the inner cladding due to coupling with an inner cladding mode, so that only the fundamental mode substantially propagates through the core.Type: GrantFiled: August 24, 2011Date of Patent: February 25, 2014Assignees: Fujikura Ltd., National University Corporation Hokkaido UniversityInventors: Shoji Tanigawa, Kentaro Ichii, Katsuhiro Takenaga, Kunimasa Saitoh