Patents by Inventor Kaoru Higuma
Kaoru Higuma 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: 20070195396Abstract: An optical modulator is provided which includes: an optical splitting part that splits an input light wave into two light waves; two optical waveguides that propagate the two light waves into which the input light wave is split, respectively; a first SSB modulating part that is provided in one of the two optical waveguides and modulates a light wave, which propagates into the first SSB modulating part, with a carrier frequency so that the light wave is converted into a different light wave having a single side band; a second SSB modulating part that is provided in the other of the two optical waveguides and modulates a light wave, which propagates into the second SSB modulating part, with a data signal in order to generate a signal light wave having a different single side band; and an optical combining part that combines the light wave modulated by the first SSB modulating part with the signal light wave generated by the second SSB modulating part.Type: ApplicationFiled: January 19, 2007Publication date: August 23, 2007Inventors: Yoshihiro HASHIMOTO, Shingo MORI, Norikazu MIYAZAKI, Kaoru HIGUMA, Toshio SAKANE
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Patent number: 7239763Abstract: An optical SSB modulator capable of appropriately adjusting a phase difference of light in the MZ waveguides and automatically adjusting a voltage impressed to the bias adjustment electrodes is provided. The above-mentioned object is achieved by an optical SSB modulator (1) provided with a first sub Mach-Zehnder waveguide (MZA) (2), a second sub Mach-Zehnder waveguide (MZB) (3), a main Mach-Zehnder waveguide (MZC) (4), a first bias adjustment electrode (DCA electrode) (5), a second bias adjustment electrode (DCB electrode) (6), a first modulation electrode (RFA electrode) (7), a second modulation electrode (RFB electrode) (8) and a third bias adjustment electrode (DCC electrode) (9), wherein either one of or both of output portions (10, 11) of the MZA and the MZB have an X-branching form, and specifically having one of light paths of the X-branching connected to a photodetector.Type: GrantFiled: March 22, 2005Date of Patent: July 3, 2007Assignees: National Institute of Information and Communications Technology, Incorporated Administrative Agency, Sumitomo Osaka Cement Co., LtdInventors: Tetsuya Kawanishi, Masayuki Izutsu, Kaoru Higuma, Shingo Mori
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Publication number: 20070019968Abstract: A method and device for adequately controlling the DC bias of each of the optical modulating sections of an optical modulator even while the optical modulator is operating in normal mode and even with a simple structure.Type: ApplicationFiled: March 26, 2004Publication date: January 25, 2007Inventors: Yoshihiro Hashimoto, Junichiro Ichikawa, Kaoru Higuma, Takahisa Fujita
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Publication number: 20060285787Abstract: An optical modulator which magnifies a modulation index and reduces affection of SBS by suppressing a light source carrier component in an equivalent light source spectral width and performs more long-distance transmission by suppressing one of sideband spectrums generated by a modulation signal to reduce affection of fiber dispersion, having a light branch means that branches input light having a carrier component into two light waves; a SSB modulation means that modulates one branched wave and generates a wave having the carrier component and one sideband spectrum; an intensity adjustment means that adjusts intensity of the carrier component of the other wave; a phase adjustment means that adjusts the phase of the carrier component with respect to at least one of the two waves; and a multiplexing means that multiplexes the two waves passing through the modulation means, and the intensity and phase adjustment means, and emits output light.Type: ApplicationFiled: December 22, 2005Publication date: December 21, 2006Applicant: Sumitomo Osaka Cement Co., Ltd.Inventors: Toshio Sakane, Norikazu Miyazaki, Kaoru Higuma, Shingo Mori
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Publication number: 20050220385Abstract: An optical SSB modulator capable of appropriately adjusting a phase difference of light in the MZ waveguides and automatically adjusting a voltage impressed to the bias adjustment electrodes is provided. The above-mentioned object is achieved by an optical SSB modulator (1) provided with a first sub Mach-Zehnder waveguide (MZA) (2), a second sub Mach-Zehnder waveguide (MZB) (3), a main Mach-Zehnder waveguide (MZC) (4), a first bias adjustment electrode (DCA electrode) (5), a second bias adjustment electrode (DCB electrode) (6), a first modulation electrode (RFA electrode) (7), a second modulation electrode (RFB electrode) (8) and a third bias adjustment electrode (DCC electrode) (9), wherein either one of or both of output portions (10, 11) of the MZA and the MZB have an X-branching form, and specifically having one of light paths of the X-branching connected to a photodetector.Type: ApplicationFiled: March 22, 2005Publication date: October 6, 2005Applicants: NATIONAL INSTITUTE OF INFORMATION & COMMUNICATIONS TECHNOLOGY, INCORPORATED ADMINISTRATIVE AGENCY, SUMITOMO OSAKA CEMENT CO., LTD.Inventors: Tetsuya Kawanishi, Masayuki Izutsu, Kaoru Higuma, Shingo Mori
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Patent number: 6788832Abstract: An optical modulation apparatus includes an optical signal input section, an optical signal propagation path, an optical modulator that modulates the phase of optical signals in at least two of a plurality of optical paths, and a wavelength selective filter that selectively reflects and transmits. Optical signals input via the input section are divided into a plurality of optical paths at a branching point and phase modulated by the phase modulator, that divides the optical path into a plurality of optical paths. Light transmitted by the filter is output via the output section, while light reflected by the filter travels back along the optical path and is again phase modulated by the phase modulator combined at the branching point and output from the input section as an intensity modulated optical signal.Type: GrantFiled: December 27, 2002Date of Patent: September 7, 2004Assignee: Communications Research Laboratory, Independent Administrative InstitutionInventors: Tetsuya Kawanishi, Masayuki Izutsu, Satoshi Oikawa, Kaoru Higuma
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Publication number: 20030128417Abstract: An optical modulation apparatus includes an optical signal input section, an optical signal propagation path, an optical modulator that modulates the phase of optical signals in at least two of a plurality of optical paths, and a wavelength selective filter that selectively reflects and transmits. Optical signals input via the input section are divided into a plurality of optical paths at a branching point and phase modulated by the phase modulator, that divides the optical path into a plurality of optical paths. Light transmitted by the filter is output via the output section, while light reflected by the filter travels back along the optical path and is again phase modulated by the phase modulator combined at the branching point and output from the input section as an intensity modulated optical signal.Type: ApplicationFiled: December 27, 2002Publication date: July 10, 2003Applicant: Communications Res. Lab., Ind. Admin. Inst.Inventors: Tetsuya Kawanishi, Masayuki Izutsu, Satoshi Oikawa, Kaoru Higuma
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Patent number: 6539153Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: GrantFiled: March 26, 2001Date of Patent: March 25, 2003Assignee: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Publication number: 20010012431Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: ApplicationFiled: March 26, 2001Publication date: August 9, 2001Applicant: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Kaoru Higuma, Junichiro Ichikawa
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Patent number: 6233385Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: GrantFiled: January 28, 1999Date of Patent: May 15, 2001Assignee: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Patent number: 6218658Abstract: The optical fuse of the present invention comprises: at least one light heatable portion for receiving an incident beam, and at least one thermally sensitive degradable portion with transparency and reflectivity, positioned in contact with the light heatable portion. The light heatable portion contains a light heatable material which generates heat depending on a specified light intensity of the incident beam. The thermally sensitive degradable portion contains a thermally sensitive degradable material which loses or reduces its transparency and reflectivity, depending on the heat generated by the light heatable portion when the light intensity of the incident beam exceeds a threshold value.Type: GrantFiled: March 17, 1999Date of Patent: April 17, 2001Assignees: NEC Corporation, Sumitomo Osaka Cement Co., Ltd.Inventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Patent number: 6134372Abstract: A light intensity attenuator and attenuating method is provided, by which a pulse-shaped optical surge can be attenuated and an optical signal component using desired light intensity can be output by using a simpler structural arrangement, and without using many optical components and circuits. In this method, an optical signal including a pulse-shaped optical surge component is received, and the optical signal is again output after the light intensity of the surge component is attenuated by a desired amount.Type: GrantFiled: June 1, 1999Date of Patent: October 17, 2000Assignees: Sumitomo Osaka Cement Co., Ltd., NEC CorporationInventors: Junichiro Ichikawa, Hirotoshi Nagata, Kaoru Higuma, Junichiro Minowa, Takaaki Ogata, Yasuhisa Taneda