Patents by Inventor Katsuyoshi Kawaguchi
Katsuyoshi Kawaguchi 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: 7768698Abstract: A Raman amplifier includes a pumping light source, an optical coupler, and a Raman amplifier medium. The pumping light source outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz. The optical coupler couples the pumping light with a carrier light. The Raman amplification medium is pumped by the pumping light to amplify the carrier light. The Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.Type: GrantFiled: August 30, 2004Date of Patent: August 3, 2010Assignees: Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Mitsubishi Electric CorporationInventors: Toshiyuki Tokura, Katsuhiro Shimizu, Tasuku Fujieda, Ken'ichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Patent number: 7539413Abstract: The present invention discloses a submarine observation system in which a plurality of carrier lights assigned to each submarine observation equipment is transmitted from a land terminal apparatus to an optical submarine cable (down-going) by using a WDM transmission. In the submarine observation equipment, only a prescribed carrier light is demultiplexed by an optical demultiplexer, an observation signal indicating an observation result is generated by an observation device, intensity of the carrier light demultiplexed by the optical demultiplexer is modulated by an optical amplifier based on an observation signal, and the modulated carrier light is multiplexed by an optical multiplexer. The multiplexed carrier light is output to the optical submarine cable (up-going) to be returned to the land terminal apparatus being the transmission station.Type: GrantFiled: March 14, 2005Date of Patent: May 26, 2009Assignees: Mitsubishi Denki Kabushiki Kaisha, Independent Administrative Institution, Japan Agency for Marine-Earth Science and TechnologyInventors: Hiroaki Munehira, Junichi Nakagawa, Toshiyuki Tokura, Kenichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Patent number: 7437070Abstract: In each of a plurality of submarine observation apparatus (1 to n), a branching unit (63) branches fixed-wavelength light (?1) from an incoming wavelength-multiplexed light signal. An observation signal modulating unit (64) modulates the intensity of the branched fixed-wavelength light (?1) with observation information multiplexed by an observation signal multiplex unit (61). A combining unit (65) combines light signals (?2) to (?n) passing through the branching unit (63) and the fixed-wavelength light (?1a) modulated by the observation signal modulating unit (64) into a composite light signal, and outputs it to an optical fiber (12a). Therefore, in each of the plurality of submarine observation apparatus (1 to n), there is no necessity for providing a wavelength-division-multiplexing-transmission optical transmitter which requires high wavelength stability.Type: GrantFiled: February 18, 2005Date of Patent: October 14, 2008Assignees: Mitsubishi Denki Kabushiki Kaisha, Japan Agency for Marine-Earth Science and TechnologyInventors: Tasuku Fujieda, Hideki Goto, Kenichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Publication number: 20080013161Abstract: A Raman amplifier includes a pumping light source, an optical coupler, and a Raman amplifier medium. The pumping light source outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz. The optical coupler couples the pumping light with a carrier light. The Raman amplification medium is pumped by the pumping light to amplify the carrier light. The Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.Type: ApplicationFiled: August 30, 2004Publication date: January 17, 2008Applicants: INDEPENDENT ADMINISTRATIVE INSTITUTION, JAPAN AGENCY FOR MARINE-EARTH SCIENCE AND TECHNOLOGY, MITSUBISHI ELECTRIC CORPORATIONInventors: Toshiyuki Tokura, Katsuhiro Shimizu, Tasuku Fujieda, Ken'ichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Patent number: 7276811Abstract: A submarine power feeding branching device comprises a constant current-constant current converter which isolates an input side for a trunk submarine cable from an output side for a branch submarine cable. The converter receives a first constant current and produces a second constant current by using the first constant current. The second constant current is supplied to the output side while the first constant current is returned to the input side. Because the input side and the output side are isolated, it is easy to add/remove the device to/from a submarine power feeding system. Intensity of the second constant current can be controlled by controlling duty ratios of switches included in the converter. Thus, it is possible that the intensity of the second constant current is equal to that of the first constant current. Therefore, a submarine repeater can be provided along either the trunk cable or the branch cable.Type: GrantFiled: November 29, 2006Date of Patent: October 2, 2007Assignees: NEC Corporation, Independent Administrative Intitiution, Japan Agency for Marine-Earth Science and TechnologyInventors: Jun Muramatsu, Kenichi Asakawa, Katsuyoshi Kawaguchi
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Publication number: 20070069588Abstract: A submarine power feeding branching device comprises a constant current-constant current converter which isolates an input side for a trunk submarine cable from an output side for a branch submarine cable. The converter receives a first constant current and produces a second constant current by using the first constant current. The second constant current is supplied to the output side while the first constant current is returned to the input side. Because the input side and the output side are isolated, it is easy to add/remove the device to/from a submarine power feeding system. Intensity of the second constant current can be controlled by controlling duty ratios of switches included in the converter. Thus, it is possible that the intensity of the second constant current is equal to that of the first constant current. Therefore, a submarine repeater can be provided along either the trunk cable or the branch cable.Type: ApplicationFiled: November 29, 2006Publication date: March 29, 2007Inventors: Jun Muramatsu, Kenichi Asakawa, Katsuyoshi Kawaguchi
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Patent number: 7166933Abstract: A submarine power feeding branching device comprises a constant current-constant current converter which isolates an input side for a trunk submarine cable from an output side for a branch submarine cable. The converter receives a first constant current and produces a second constant current by using the first constant current. The second constant current is supplied to the output side while the first constant current is returned to the input side. Because the input side and the output side are isolated, it is easy to add/remove the device to/from a submarine power feeding system. Intensity of the second constant current can be controlled by controlling duty ratios of switches included in the converter. Thus, it is possible that the intensity of the second constant current is equal to that of the first constant current. Therefore, a submarine repeater can be provided along either the trunk cable or the branch cable.Type: GrantFiled: October 20, 2003Date of Patent: January 23, 2007Assignees: NEC Corporation, Independent Administrative Institution Japan Agency for Marine-Earth Science and TechnologyInventors: Jun Muramatsu, Kenichi Asakawa, Katsuyoshi Kawaguchi
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Patent number: 7102257Abstract: A submarine cable power feeding system includes N (N is an integer of 2 or larger) main submarine cables extending from the land in the offshore direction, N-stage (N is an integer of 2 or larger) submarine feed branching devices, and first to Nth (N is an integer of 2 or larger) sub submarine cables. Each submarine feed branching device is connected to the main submarine cable to receive constant-voltage power from a constant-voltage feed unit. Each sub submarine cable connects the Nth-stage submarine feed branching device, connected to the Nth main submarine cable, to the adjacent submarine feed branching device through submarine repeaters, thereby receiving power from a constant-current feed unit. Each constant-current feed unit is built in the submarine feed branching device. The submarine feed branching devices and the submarine repeaters are arranged in a matrix on a plane.Type: GrantFiled: February 13, 2003Date of Patent: September 5, 2006Assignees: NEC Corporation, Japan Marine Science and Technology CenterInventors: Jun Muramatsu, Katsuyoshi Kawaguchi, Kenichi Asakawa
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Publication number: 20050259998Abstract: In each of a plurality of submarine observation apparatus (1 to n), a branching unit (63) branches fixed-wavelength light (?1) from an incoming wavelength-multiplexed light signal. An observation signal modulating unit (64) modulates the intensity of the branched fixed-wavelength light (?1) with observation information multiplexed by an observation signal multiplex unit (61). A combiningunit (65) combines lightsignals (?2) to (?n) passing through the branching unit (63) and the fixed-wavelength light (?1a) modulated by the observation signal modulating unit (64) into a composite light signal, and outputs it to an optical fiber (12a). Therefore, in each of the plurality of submarine observation apparatus (1 to n), there is no necessity for providing a wavelength-division-multiplexing-transmission optical transmitter which requires high wavelength stability.Type: ApplicationFiled: February 18, 2005Publication date: November 24, 2005Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA, Japan Agency for Marine-Earth Science and Tech.Inventors: Tasuku Fujieda, Hideki Goto, Kenichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Publication number: 20050259264Abstract: The present invention discloses a submarine observation system in which a plurality of carrier lights assigned to each submarine observation equipment is transmitted from a land terminal apparatus to an optical submarine cable (down-going) by using a WDM transmission. In the submarine observation equipment, only a prescribed carrier light is demultiplexed by an optical demultiplexer, an observation signal indicating an observation result is generated by an observation device, intensity of the carrier light demultiplexed by the optical demultiplexer is modulated by an optical amplifier based on an observation signal, and the modulated carrier light is multiplexed by an optical multiplexer. The multiplexed carrier light is output to the optical submarine cable (up-going) to be returned to the land terminal apparatus being the transmission station.Type: ApplicationFiled: March 14, 2005Publication date: November 24, 2005Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA, Japan Agency for Marine-Earth Science and Tech.Inventors: Hiroaki Munehira, Junichi Nakagawa, Toshiyuki Tokura, Kenichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
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Publication number: 20040130215Abstract: A submarine power feeding branching device comprises a constant current-constant current converter which isolates an input side for a trunk submarine cable from an output side for a branch submarine cable. The converter receives a first constant current and produces a second constant current by using the first constant current. The second constant current is supplied to the output side while the first constant current is returned to the input side. Because the input side and the output side are isolated, it is easy to add/remove the device to/from a submarine power feeding system. Intensity of the second constant current can be controlled by controlling duty ratios of switches included in the converter. Thus, it is possible that the intensity of the second constant current is equal to that of the first constant current. Therefore, a submarine repeater can be provided along either the trunk cable or the branch cable.Type: ApplicationFiled: October 20, 2003Publication date: July 8, 2004Applicant: NEC CORPORATION and JAPAN MARINE SCIENCE AND TECHNOLOGY CENTERInventors: Jun Muramatsu, Kenichi Asakawa, Katsuyoshi Kawaguchi
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Publication number: 20030230936Abstract: A submarine cable power feeding system includes N (N is an integer of 2 or larger) main submarine cables extending from the land in the offshore direction, N-stage (N is an integer of 2 or larger) submarine feed branching devices, and first to Nth (N is an integer of 2 or larger) sub submarine cables. Each submarine feed branching device is connected to the main submarine cable to receive constant-voltage power from a constant-voltage feed unit. Each sub submarine cable connects the Nth-stage submarine feed branching device, connected to the Nth main submarine cable, to the adjacent submarine feed branching device through submarine repeaters, thereby receiving power from a constant-current feed unit. Each constant-current feed unit is built in the submarine feed branching device. The submarine feed branching devices and the submarine repeaters are arranged in a matrix on a plane.Type: ApplicationFiled: February 13, 2003Publication date: December 18, 2003Applicants: NEC CORPORATION, JAPAN MARINE SCIENCE AND TECHNOLOGY CENTERInventors: Jun Muramatsu, Katsuyoshi Kawaguchi, Kenichi Asakawa