Patents by Inventor Shu Yamamoto
Shu Yamamoto 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: 6504638Abstract: To increase the number of multiplexed wavelengths and to improve transmission characteristics in a wavelength-division-multiplexed transmission, a bandwidth compressor for bandwidth-compressing the wavelength-division-multiplexed signal light is disposed at a front part of respective optical amplifiers and a bandwidth expander for bandwidth-expanding the wavelength-division-multiplexed signal light output from said optical amplifiers is disposed at a rear part of said optical amplifiers.Type: GrantFiled: December 7, 1998Date of Patent: January 7, 2003Assignee: KDD CorporationInventors: Keiji Tanaka, Noboru Edagawa, Hidenori Taga, Shu Yamamoto
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Patent number: 6459518Abstract: A laser diode continuously laser-oscillates and its output light is applied to an optical modulator. A pulse driver drives the optical modulator according to a data to be transmitted. A phase modulator is driven by a phase modulator driver and phase-modulates the output from the optical modulator. The polarization direction of the incident light of the phase modulator is set so that the modulation efficiency of the phase modulator becomes the maximum. The output light of the phase modulator inputs a birefringent medium and applies to an optical transmission line after transmitting the birefringent medium. The principal axis of the birefringent medium is disposed so as to be at an angle of 45° to the polarization direction of the output light from the phase modulator.Type: GrantFiled: June 11, 1999Date of Patent: October 1, 2002Assignees: KDD Corporation, KDD Submarine Cable Systems, Inc.Inventors: Masatoshi Suzuki, Noboru Edagawa, Hidenori Taga, Shu Yamamoto
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Optical pulse position detecting circuit and an optical pulse generating apparatus and their methods
Patent number: 6445478Abstract: Detection of an optical pulse position uses an optical pulse string with a determined repetitive ratio and an electric clock signal with a same frequency as the repetitive ratio of the optical pulse string. A phase of the electric clock signal oscillator is shifted and supplied to an optical modulator. The optical modulator modulates the optical pulse string based on the electric clock signal and outputs a modulated optical signal. A photo detector converts the modulated optical signal output from the optical modulator to an electric signal. The phase shift amount of the electric clock signal is controlled to maximize an output from the photo detector. Additionally, a dither signal may be used in the control of the phase shift, more than the optical modulator may be employed, and/or more than color light source may be employed. The use of at least one of feed forward and feedback control provided by maximizing an output of the photo detector allows an optical pulse having a short width to be realized.Type: GrantFiled: January 19, 2001Date of Patent: September 3, 2002Assignees: Mitsubishi Denki Kabushiki Kaisha, Kokusai Denshin Denwa Co., Ltd.Inventors: Katsuhiro Shimizu, Takashi Mizuochi, Takeshi Komiya, Kiwami Matsushita, Tadayoshi Kitayama, Masatoshi Suzuki, Hidenori Taga, Shu Yamamoto, Noboru Edagawa, Itsuro Morita -
Patent number: 6434288Abstract: An optical switching system is implemented by providing a transmitting section with a preparatory transmitted optical signal selector and a working transmitted optical signal splitter, which are each implemented by a 1×2 optical space switch, and by providing a receiving section with a receiving optical switch which is implemented by a 2×2 optical space switch, and with a preparatory receiving optical gate which is implemented by a 1×2 optical space switch. This makes it possible to switch between the working system and preparatory system without employing any 4×4 optical space switch, thereby implementing a practical optical switching system without causing such problems as communication interruption during maintenance or impairment of transmission path working efficiency.Type: GrantFiled: June 13, 2000Date of Patent: August 13, 2002Assignees: KDD Corporation, Mitsubishi Denki Kabushiki KaishaInventors: Aritomo Uemura, Hiroshi Ichibangase, Takashi Mizuochi, Tadayoshi Kitayama, Shu Yamamoto, Tetsuya Miyazaki, Takatomi Kabashima, Naoki Kobayashi
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Publication number: 20020075535Abstract: A four fiber ring network optical switching circuit capable of realizing the bridge function at times of the span switching and the ring switching economically by a very compact structure is disclosed. A four fiber ring network optical switching circuit is formed by a 10×8 optical matrix switch having ten input ports and eight output ports, and two branching elements adapted to branch each one of two optical signals among eight optical signals that are inputs of the four fiber ring network optical switching circuit, into two identical optical signals, and to enter the two identical optical signals into two input ports of the 10×8 optical matrix switch such that the eight optical signals are entered into the ten input ports of the 10×8 optical matrix switch as ten optical signals.Type: ApplicationFiled: December 7, 2000Publication date: June 20, 2002Inventors: Shu Yamamoto, Tetsuya Miyazaki, Yasuyuki Nagao, Tomohiro Otani
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Publication number: 20020063925Abstract: A network system capable of delivering a large amount of data such as video data freely according to the intentions of the sender and the receiver alone is realized by a plurality of stations provided on at least one loop shaped optical network in which any one of the plurality of stations is capable of carrying out unidirectional communications with respect to any other one of the plurality of stations, where at least one wavelength is allocated to each station such that each station can transmit data by using a wavelength allocated to each station, receive data of any wavelengths transmitted from any other stations, and select only necessary wavelengths so as to select correspondent stations from which data are to be received.Type: ApplicationFiled: June 8, 2001Publication date: May 30, 2002Inventors: Tomohiro Otani, Yukio Horiuchi, Shu Yamamoto, Keizou Kitahara, Atsushi Arai, Mikio Yokoyama
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Patent number: 6377375Abstract: An optical wavelength division multiplexed signal amplifying repeater capable of doubling the number of wavelength division multiplexed signals that can be transmitted is disclosed. Optical signals of both 1.3 &mgr;m band and 1.55 &mgr;m band in the entered optical wavelength division multiplexed signals are amplified, while pumping lights capable of causing Raman amplification in the 1.3 &mgr;m band are coupled with the optical wavelength division multiplexed signals so as to cause the Raman amplification for the optical signals of the 1.3 &mgr;m band, such that a difference between the loss in the 1.3 &mgr;m band and the loss in the 1.55 &mgr;m band due to the optical fibers are compensated. An optical communication transmission line using such repeaters is also disclosed.Type: GrantFiled: January 14, 1999Date of Patent: April 23, 2002Assignee: KDD CorporationInventors: Hidenori Taga, Shu Yamamoto
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Publication number: 20010055136Abstract: This invention discloses a method to easily extract a header from an optical packet. An optical data transmission method to transmit an optical packet composed of a header and data containing steps of generating a second clock which has a frequency equal to one integer of that of a first clock carrying the data and synchronizes with the first clock, and carrying the header information on the second clock.Type: ApplicationFiled: June 19, 2001Publication date: December 27, 2001Inventors: Yukio Horiuchi, Shu Yamamoto
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Patent number: 6331907Abstract: In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths &lgr;1 through &lgr;32. Optical amplifiers 14-1 through 14-32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths &lgr;1 through &lgr;32.Type: GrantFiled: July 26, 2000Date of Patent: December 18, 2001Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Tetsuya Miyazaki, Noboru Edagawa, Shu Yamamoto
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Patent number: 6317534Abstract: An optical wavelength routing device comprises an arrayed waveguide comprising a plurality of channel waveguides formed on a substrate, a plurality of input waveguides having 12 input ports located on an input side of the arrayed waveguide, a plurality of output waveguides having 16 input ports located on an output side of the arrayed waveguide, an input slab waveguide for coupling the plurality of input waveguides to the arrayed waveguide to provide a first coupling portion on the side of the input waveguide, and an output slab waveguide for coupling the arrayed waveguide to the plurality of output waveguides to provide a second coupling portion on the side of the output waveguide, in which central wavelengths of lights input to the input ports and output from the output ports are controlled such that a difference between a predetermined wavelength and a central wavelength is suppressed within the range of +&dgr;&lgr;/4.Type: GrantFiled: December 18, 1998Date of Patent: November 13, 2001Assignees: Kokusai Denshin Denwa Co., Ltd., Hitachi Cable Ltd.Inventors: Tetsuya Miyazaki, Shu Yamamoto, Koichi Maru, Hisato Uetsuka
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Publication number: 20010021046Abstract: In a signal demultiplexing device formed by a probe light source, a wavelength converter, and a wavelength demultiplexer, the probe light source is formed by a plurality of sub-probe light sources configured to respectively generate the sub-probe lights with the prescribed different wavelengths for respective time-slots, a multiplexer configured to multiplex the sub-probe lights generated by the plurality of sub-probe light sources, and a phase different giving unit configured to give phase differences corresponding to time-slot positions to the sub-probe lights multiplexed by the multiplexer, and to sequentially output the sub-probe lights with the phase differences in correspondence to respective time-slots.Type: ApplicationFiled: February 15, 2001Publication date: September 13, 2001Inventors: Tomohiro Otani, Tetsuya Miyazaki, Shu Yamamoto
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Patent number: 6285477Abstract: In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths &lgr;1 through &lgr;32. Optical amplifiers 14-1 through 14-32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths &lgr;1 through &lgr;32.Type: GrantFiled: December 21, 1999Date of Patent: September 4, 2001Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Tetsuya Miyazaki, Noboru Edagawa, Shu Yamamoto
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Publication number: 20010012144Abstract: In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths &lgr;1 through &lgr;32. Optical amplifiers 14-1 through 14-32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths &lgr;1 through &lgr;32.Type: ApplicationFiled: September 17, 1997Publication date: August 9, 2001Inventors: TETSUYA MIYAZAKI, NOBORU EDAGAWA, SHU YAMAMOTO
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Optical pulse position detecting circuit and an optical pulse generating apparatus and their methods
Publication number: 20010009469Abstract: Detection of an optical pulse position uses an optical pulse string with a determined repetitive ratio and an electric clock signal with a same frequency as the repetitive ratio of the optical pulse string. A phase of the electric clock signal oscillator is shifted and supplied to an optical modulator. The optical modulator modulates the optical pulse string based on the electric clock signal and outputs a modulated optical signal. A photo detector converts the modulated optical signal output from the optical modulator to an electric signal. The phase shift amount of the electric clock signal is controlled to maximize an output from the photo detector. Additionally, a dither signal may be used in the control of the phase shift, more than the optical modulator may be employed, and/or more than color light source may be employed. The use of at least one of feed forward and feedback control provided by maximizing an output of the photo detector allows an optical pulse having a short width to be realized.Type: ApplicationFiled: January 19, 2001Publication date: July 26, 2001Applicant: Mitsubishi Denki Kabushiki KaishaInventors: Katsuhiro Shimizu, Takashi Mizuochi, Takeshi Komiya, Kiwami Matsushita, Tadayoshi Kitayama, Masatoshi Suzuki, Hidenori Taga, Shu Yamamoto, Noboru Edagawa, Itsuro Morita -
Optical pulse position detecting circuit and an optical pulse generating apparatus and their methods
Patent number: 6236488Abstract: Detection of an optical pulse position uses an optical pulse string with a determined repetitive ratio and an electric clock signal with a same frequency as the repetitive ratio of the optical pulse string. A phase of the electric clock signal oscillator is shifted and supplied to an optical modulator. The optical modulator modulates the optical pulse string based on the electric clock signal and outputs a modulated optical signal. A photo detector converts the modulated optical signal output from the optical modulator to an electric signal. The phase shift amount of the electric clock signal is controlled to maximize an output from the photo detector. Additionally, a dither signal may be used in the control of the phase shift, more than the optical modulator may be employed, and/or more than color light source may be employed. The use of at least one of feed forward and feedback control provided by maximizing an output of the photo detector allows an optical pulse having a short width to be realized.Type: GrantFiled: March 31, 1998Date of Patent: May 22, 2001Assignees: Mitsubishi Denki Kabushiki Kaisha, Kokusai Denshin Denwa Co., LtdInventors: Katsuhiro Shimizu, Takashi Mizuochi, Takeshi Komiya, Kiwami Matsushita, Tadayoshi Kitayama, Masatoshi Suzuki, Hidenori Taga, Shu Yamamoto, Noboru Edagawa, Itsuro Morita -
Patent number: 6219163Abstract: In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths &lgr;1 through &lgr;32. optical amplifiers 14-1 through 14-32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths &lgr;1 through &lgr;32.Type: GrantFiled: July 26, 2000Date of Patent: April 17, 2001Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Tetsuya Miyazaki, Noboru Edagawa, Shu Yamamoto
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Patent number: 6215566Abstract: In a light source for generating light containing multiple wavelengths substantially uniform in intensity, a wavelength demultiplexing element 10 (for example, waveguide-type wavelength selecting filter) demultiplexes input light into a plurality of wavelengths &lgr;1 through &lgr;32. Optical amplifiers 14-1 through 14-32 amplify outputs of the element 10 and applies them to input ports of a wavelength multiplexing element 12. The wavelength multiplexing element 12 wavelength-multiplexes their input. Output of the wavelength multiplexing element 12 is applied to a fiber coupler 16 which, in turn, applies one of its outputs to the wavelength demultiplexing element 10. The optical amplifiers 14 have a gain larger by approximately 10 dB than the loss in the optical loop made of the element 10, optical amplifier 14, element 12 and fiber coupler 16. The other output of the fiber coupler 16 is wavelength-multiplex light containing wavelengths &lgr;1 through &lgr;32.Type: GrantFiled: July 26, 2000Date of Patent: April 10, 2001Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Tetsuya Miyazaki, Noboru Edagawa, Shu Yamamoto
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Patent number: 6188510Abstract: An optical amplifying transmission system comprising a first optical amplifying transmission line including a first optical amplifier, a second optical amplifying transmission line including a second optical amplifier, a pumping light generator for generating pumping lights to be supplied to said first and second amplifiers, the powers of the pumping lights being variable, and first and second terminal stations which connect respectively to both ends of said first and second optical amplifying transmission lines.Type: GrantFiled: February 10, 1999Date of Patent: February 13, 2001Assignee: KDD CorporationInventors: Noboru Edagawa, Shu Yamamoto, Shigeyuki Akiba
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Patent number: 6188508Abstract: A control signal superimposer for superimposing a control signal on a signal light, comprising a pumping light source for generating a pumping light with intensity fluctuation in accordance with the control signal; a Raman amplification medium pumped by the pumping light from the pumping light source for Raman-amplifying the signal light; a combiner for combining the pumping light output from the pumping light source and the signal light to be Raman-amplified and then supplying them to the Raman amplification medium; and an optical filter for extracting the signal light component from the output light of the Raman amplification medium and terminating the pumping light component.Type: GrantFiled: June 3, 1999Date of Patent: February 13, 2001Assignees: KDD Corporation, KDD Submarine Cable Systems, Inc.Inventors: Yukio Horiuchi, Masatoshi Suzuki, Shu Yamamoto, Shigeyuki Akiba
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Patent number: 6181449Abstract: A wavelength division multiplexed optical processing device and an optical communication transmission path which are capable of significantly improving the transmission characteristic of wavelength division multiplexed optical signals. A wavelength division multiplexed optical processing device is formed by a first arrayed optical waveguide for demultiplexing entered wavelength division multiplexed optical signals, and outputting demultiplexed optical signals; a plurality of correction units for correcting respective optical signals demultiplexed by the first arrayed optical waveguide; and a second arrayed optical waveguide for multiplexing optical signals corrected by the correction unit, and outputting multiplexed optical signals.Type: GrantFiled: February 27, 1998Date of Patent: January 30, 2001Assignee: Kokusai Denshin Denwa Kabushiki-KaishaInventors: Hidenori Taga, Kaoru Imai, Masatoshi Suzuki, Shu Yamamoto, Shigeyuki Akiba