Patents by Inventor Kunimasa Saitoh
Kunimasa Saitoh 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: 20230275399Abstract: A semiconductor optical device includes a substrate formed of silicon and having a first optical waveguide and a semiconductor element formed of a III-V compound semiconductor and having a second optical waveguide, the semiconductor element being bonded to an upper surface of the substrate. The first optical waveguide and the second optical waveguide form a directional coupler.Type: ApplicationFiled: February 6, 2023Publication date: August 31, 2023Applicants: Sumitomo Electric Industries, Ltd., National University Corporation Hokkaido UniversityInventors: Naoya KONO, Naoki FUJIWARA, Kunimasa SAITOH, Takeshi FUJISAWA, Takanori SATO
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Publication number: 20230089696Abstract: An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, a second waveguide optically coupled to the first loop mirror and the second loop mirror, a first access waveguide optically coupled to the first waveguide, a second access waveguide optically coupled to the second waveguide, and an output section, wherein the first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer, the second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer, the output section includes a third loop waveguide, a third multiplexer/demultiplexer, a third waveguide, and a fourth waveguide, the third loop waveguide optically coupled to the second loop waveguide and the third multiplexer/demultiplexer, the third waveguide and the fourth waveguide optically coupled to the third multiplexer/demultiplexer, and the output section.Type: ApplicationFiled: September 12, 2022Publication date: March 23, 2023Applicants: Sumitomo Electric Industries, Ltd., National University Corporation Hokkaido UniversityInventors: Takuo HIRATANI, Naoki FUJIWARA, Kunimasa SAITOH, Takeshi FUJISAWA, Takanori SATO
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Publication number: 20230040798Abstract: An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, and a first access waveguide. The first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer. The second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer. The first loop waveguide is optically coupled to the first multiplexer/demultiplexer. The second loop waveguide is optically coupled to the second multiplexer/demultiplexer. The first waveguide is optically coupled to the first multiplexer/demultiplexer and the second multiplexer/demultiplexer. The first access waveguide is optically coupled to the first waveguide.Type: ApplicationFiled: July 8, 2022Publication date: February 9, 2023Applicants: SUMITOMO ELECTRIC INDUSTRIES, LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Naoya KONO, Naoki FUJIWARA, Kunimasa SAITOH, Takeshi FUJISAWA, Takanori SATO
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Publication number: 20220276430Abstract: An object of the present invention is to provide a multi-core optical fiber that can prevent an increase in bending loss even when a distance between a peripheral core and a cladding boundary is decreased, and can improve a bending loss characteristic in a state where an influence on a cutoff wavelength and a mode field diameter is small, and a design method thereof.Type: ApplicationFiled: July 21, 2020Publication date: September 1, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Taiji SAKAMOTO, Kazuhide NAKAJIMA, Takashi MATSUI, Kyozo TSUJIKAWA, Kunimasa SAITOH, Takeshi FUJISAWA
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Patent number: 10690843Abstract: A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.Type: GrantFiled: March 2, 2017Date of Patent: June 23, 2020Assignees: Fujikura Ltd., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY, Technical University of DenmarkInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh, Toshio Morioka
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Patent number: 10663653Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.Type: GrantFiled: October 30, 2018Date of Patent: May 26, 2020Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
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Patent number: 10365429Abstract: A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.Type: GrantFiled: July 6, 2016Date of Patent: July 30, 2019Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSTIYInventors: Shota Saito, Katsuhiro Takenaga, Kunimasa Saitoh, Takeshi Fujisawa
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Patent number: 10310176Abstract: A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.Type: GrantFiled: May 20, 2016Date of Patent: June 4, 2019Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
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Publication number: 20190072712Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12;a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.Type: ApplicationFiled: October 30, 2018Publication date: March 7, 2019Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
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Patent number: 10215913Abstract: A multicore fiber includes: a first core configured to propagate an LP01 mode, an LP11 mode, and an LP21 mode light beam; and a second core configured to propagate an LP01 mode light beam, wherein a different mode interaction section is provided in which a propagation constant of the LP21 mode light beam propagated through the first core is matched with a propagation constant of the LP01 mode light beam propagated through the second core, a different mode non-interaction section is provided in which propagation constants of the LP mode light beams propagated through the first core are not matched with propagation constants of the LP mode light beams propagated through the second core, and the first core includes an inner core and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core.Type: GrantFiled: February 2, 2017Date of Patent: February 26, 2019Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Hitoshi Uemura, Kunimasa Saitoh, Takeshi Fujisawa
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Publication number: 20190033513Abstract: A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.Type: ApplicationFiled: March 2, 2017Publication date: January 31, 2019Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY, Technical University of DenmarkInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh, Toshio Morioka
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Patent number: 10156674Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.Type: GrantFiled: April 29, 2016Date of Patent: December 18, 2018Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
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Patent number: 10101526Abstract: A multicore fiber communicates using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multicore fiber includes: a plurality of cores; a clad that surrounds the plurality of cores and has a refractive index lower than refractive indexes of the plurality of cores; and a cover layer that covers the clad and has a refractive index higher than the refractive index of the clad. Each of the plurality of cores propagates light up to an (x+1)th-order LP mode. A core pitch is set to a distance where crosstalk of the light up to the xth-order LP mode becomes less than or equal to ?40 dB/km and crosstalk of light of the (x+1)th-order LP mode becomes greater than or equal to ?30 dB/km.Type: GrantFiled: April 26, 2016Date of Patent: October 16, 2018Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
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Patent number: 10094972Abstract: A multicore fiber includes: a center core that propagates four LP mode light beams including an LP02 mode light beam; and a first to a fifth cores disposed on a first line to a fifth line segments extend from the center of the center core in the radial direction at predetermined angles. The multicore fiber includes a different mode interaction section in which the propagation constants of each mode light beam propagated through the center core are matched with the propagation constants of LP01 mode light beams propagated through the first to fifth cores.Type: GrantFiled: February 3, 2017Date of Patent: October 9, 2018Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Hitoshi Uemura, Kunimasa Saitoh, Takeshi Fujisawa
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Publication number: 20180246275Abstract: A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.Type: ApplicationFiled: July 6, 2016Publication date: August 30, 2018Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Shota Saito, Katsuhiro Takenaga, Kunimasa Saitoh, Takeshi Fujisawa
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Patent number: 10042114Abstract: A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 ?m, distances between centers of the mutually neighboring cores 11a and 11b are 30 ?m or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 ?m or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 ?m to 13 ?m.Type: GrantFiled: April 29, 2016Date of Patent: August 7, 2018Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Katsuhiro Takenaga, Shoichiro Matsuo, Yusuke Sasaki, Kunimasa Saitoh
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Publication number: 20180120502Abstract: A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.Type: ApplicationFiled: May 20, 2016Publication date: May 3, 2018Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
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Publication number: 20180120501Abstract: A multicore fiber communicates using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multicore fiber includes: a plurality of cores; a clad that surrounds the plurality of cores and has a refractive index lower than refractive indexes of the plurality of cores; and a cover layer that covers the clad and has a refractive index higher than the refractive index of the clad. Each of the plurality of cores propagates light up to an (x+1)th-order LP mode. A core pitch is set to a distance where crosstalk of the light up to the xth-order LP mode becomes less than or equal to ?40 dB/km and crosstalk of light of the (x+1)th-order LP mode becomes greater than or equal to ?30 dB/km.Type: ApplicationFiled: April 26, 2016Publication date: May 3, 2018Applicants: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yusuke Sasaki, Katsuhiro Takenaga, Kunimasa Saitoh
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Patent number: 9891377Abstract: A multicore fiber including two or more cores each capable of single mode transmission, a cladding covering around the two or more cores in common, and a low refractive index portion having a refractive index lower than a refractive index of the cladding, wherein a cross-section perpendicular to a longitudinal direction includes a region where two or more cores of a part or all of the two or more cores are arranged in a circular shape and at least a part of the low refractive index portion is arranged inside an inscribed circle of the cores included in the region.Type: GrantFiled: February 8, 2016Date of Patent: February 13, 2018Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Shota Saito, Katsuhiro Takenaga, Kunimasa Saitoh, Takeshi Fujisawa
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Patent number: 9817183Abstract: No core is disposed at the lattice point of a triangular lattice of a first layer LY1. First cores 11a and 11b of the core elements 10a and 10b are disposed at the lattice points of a second layer LY2. A first core 11c of the core element 10c and the second core 21 are alternately disposed at the lattice points of a third layer LY3. In a fourth layer LY4, no core is disposed at six lattice points, and the first cores 11a and 11b of the core elements 10a and 10b are disposed at the other lattice points. The second cores 21 are adjacent to the lattice points of the fourth layer LY4, at which no core is disposed. The effective refractive indexes of the core elements adjacent to each other are different from each other.Type: GrantFiled: February 10, 2016Date of Patent: November 14, 2017Assignees: FUJIKURA LTD., NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITYInventors: Yoshimichi Amma, Katsuhiro Takenaga, Yusuke Sasaki, Kunimasa Saitoh