Patents by Inventor Mitsuhiro Teshima
Mitsuhiro Teshima 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: 20050220457Abstract: To generate light with the degree of polarization zeroed and the spread of an optical spectrum suppressed even with temporal overlapping between optical pulses each of which is polarized orthogonally to the succeeding pulse, a polarization scrambler includes an optical pulse generator that generates optical pulses with an intensity waveform repetiton period T/2 and an electrical field repetition period T in which the same intensity waveform is repeated every repetition period T/2 and in which phase is inverted every repetition period T/2, and an orthogonal polarization delay unit which receives each of the optical pulses, separates the optical pulse into two optical pulses with ortogonal states of polarization, and relatively shifts the temporal position of one of the two optical pulses from that of the other optical pulse by (2n?1)T/4 (n is a natural number) to generate light in which each pulse is polarized orthogonally to a succeeding pulse.Type: ApplicationFiled: May 20, 2005Publication date: October 6, 2005Inventors: Masamichi Fujiwara, Mitsuhiro Teshima, Noboru Takachio, Katsumi Iwatsuki
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Publication number: 20050213991Abstract: To generate light with the degree of polarization zeroed and the spread of an optical spectrum suppressed even with temporal overlapping between optical pulses each of which is polarized orthogonally to the succeeding pulse, a polarization scrambler includes an optical pulse generator that generates optical pulses with an intensity waveform repetition T/2 and an electrical field repetition period T in which the same intensity waveform is repeated every repetition period T/2 and in which phase is inverted every repetition period T/2, and an orthogonal polarization delay unit which receives each of the optical pulses, separates the optical pulse into two optical pulses with orthogonal states of polarization, and relatively shifts the temporal position of one of the two optical pulses from that of the other optical pulse by (2n?1)T/4 (n is a natural number) to generate light in which each pulse is polarized orthogonally to a succeeding pulse.Type: ApplicationFiled: May 19, 2005Publication date: September 29, 2005Inventors: Masamichi Fujiwara, Mitsuhiro Teshima, Noboru Takachio, Katsumi Iwatsuki
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Patent number: 6924924Abstract: A multi-wavelength generating apparatus generates a wavelength division multiplexing (WDM) signal by modulating light with a single central frequency and with an electric signal having a particular pulse repetition frequency. The resulting optical spectrum configuration is controllable so that a Relative Intensity Noise (RIN) or Signal to Noise Ratio (SNR) requirement may be achieved. A modulated or pulsed light source is used to obtain a discrete spectrum with particular mode spacing, which is then modulated to permit dynamic power control for specific modes of the discrete spectrum.Type: GrantFiled: September 4, 2003Date of Patent: August 2, 2005Assignee: Nippon Telegraph and Telephone CorporationInventors: Masamichi Fujiwara, Katsuhiro Araya, Mitsuhiro Teshima, Junichi Kani, Kenichi Suzuki
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Publication number: 20050008373Abstract: With respect to the relative intensity noise (RIN) for inputs to an optical modulator or the signal-to-noise ratio (SNR) for outputs therefrom, the optical modulator modulating coherent lights of different wavelengths obtained by slicing a spectrum of the multi-wavelength light, the shape of a spectrum of a multi-wavelength light is controlled so that predetermined RIN and SNR can be obtained in accordance with transmission system parameters (the type and distance of optical fibers, the number of repeaters), thus enabling design meeting a performance specification for a conventional transmission section using semiconductor lasers.Type: ApplicationFiled: April 16, 2004Publication date: January 13, 2005Inventors: Masamichi Fujiwara, Katsuhiro Araya, Mitsuhiro Teshima, Junichi Kani, Kenichi Suzuki
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Patent number: 6831774Abstract: Amulti-wavelength generating apparatus generates a wavelength division multiplexing (WDM) signal by modulating light with a single central frequency and an electric signal having a particular pulse repetition frequency. The resulting optical spectrum configuration is conntrollable so that a Relative Intensity Noise (RIN) or Signal to Noise Ratio (SNR) requirement may be achieved. A modulated or pulsed light source in used to obtain a descrete spectrum with particular mode spacing, which is then modulated to permit dynamic power control for specific modes of the discrete spectrum.Type: GrantFiled: July 6, 2001Date of Patent: December 14, 2004Assignee: Nippon Telegraph and Telephone CorporationInventors: Masamichi Fujiwara, Katsuhiro Araya, Mitsuhiro Teshima, Junichi Kani, Kenichi Suzuki
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Patent number: 6744546Abstract: A multilevel light-intensity modulating circuit for suppressing the amplitude distortion regarding intermediate levels, caused by the conversion from a multilevel electric signal to a multilevel modulated optical signal. The circuit comprises a section for distributing an input optical carrier into n-channel optical carriers; n light-intensity modulators for modulating intensities of the optical carriers by using input two-level electric signals; a control section for producing a phase difference between the n-channel two-level modulated optical signals; a control section for assigning a different light intensity to each of the n-channel two-level modulated optical signals; and a section for combining the n-channel two-level modulated optical signals obtained via the control sections, and outputting a 2n-level modulated optical signal. The phase difference and the different light intensity are defined in advance so as to produce the 2n-level modulated optical signal.Type: GrantFiled: December 17, 2002Date of Patent: June 1, 2004Assignee: Nippon Telegraph and Telephone CorporationInventors: Takuya Nakamura, Jun-ichi Kani, Mitsuhiro Teshima, Noboru Takachio
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Publication number: 20040100682Abstract: With respect to the relative intensity noise (RIN) for inputs to an optical modulator or the signal-to-noise ratio (SNR) for outputs therefrom, the optical modulator modulating coherent lights of different wavelengths obtained by slicing a spectrum of the multi-wavelength light, the shape of a spectrum of a multi-wavelength light is controlled so that predetermined RIN and SNR can be obtained in accordance with transmission system parameters (the type and distance of optical fibers, the number of repeaters), thus enabling design meeting a performance specification for a conventional transmission section using semiconductor lasers.Type: ApplicationFiled: September 4, 2003Publication date: May 27, 2004Applicants: Nippon Telegraph and Telephone Corp., International Rectifier CorporationInventors: Masamichi Fujiwara, Katsuhiro Araya, Mitsuhiro Teshima, Junichi Kani, Kenichi Suzuki
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Publication number: 20030161638Abstract: To generate light with the degree of polarization zeroed and the spread of an optical spectrum suppressed even with temporal overlapping between optical pulses each of which is polarized orthogonally to the succeeding pulse, a polarization scrambler includes an optical pulse generator that generates optical pulses with an intensity waveform repetition period T/2 and an electrical field repetition period T in which the same intensity waveform is repeated every repetition period T/2 and in which phase is inverted every repetition period T/2, and an orthogonal polarization delay unit which receives each of the optical pulses, separates the optical pulse into two optical pulses with orthogonal states of polarization, and relatively shifts the temporal position of one of the two optical pulses from that of the other optical pulse by (2n−1)T/4 (n is a natural number) to generate light in which each pulse is polarized orthogonally to a succeeding pulse.Type: ApplicationFiled: February 20, 2003Publication date: August 28, 2003Applicant: Nippon Telegraph and Telephone CorporationInventors: Masamichi Fujiwara, Mitsuhiro Teshima, Noboru Takachio, Katsumi Iwatsuki
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Publication number: 20030123122Abstract: A multilevel light-intensity modulating circuit for suppressing the amplitude distortion regarding intermediate levels, caused by the conversion from a multilevel electric signal to a multilevel modulated optical signal. The circuit comprises a section for distributing an input optical carrier into n-channel optical carriers; n light-intensity modulators for modulating intensities of the optical carriers by using input two-level electric signals; a control section for producing a phase difference between the n-channel two-level modulated optical signals; a control section for assigning a different light intensity to each of the n-channel two-level modulated optical signals; and a section for combining the n-channel two-level modulated optical signals obtained via the control sections, and outputting a 2n-level modulated optical signal. The phase difference and the different light intensity are defined in advance so as to produce the 2n-level modulated optical signal.Type: ApplicationFiled: December 17, 2002Publication date: July 3, 2003Inventors: Takuya Nakamura, Jun-ichi Kani, Mitsuhiro Teshima, Noboru Takachio
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Publication number: 20030067649Abstract: A first optical fiber transmission path is used to transmit continuous-wave light for upstream signal light from the center node to each of the remote nodes, while a second optical fiber transmission path is used to transmit downstream signal light from the center node to each remote node and to transmit upstream signal light (obtained by modulating continuous-wave light) from each remote node to the center node. In this network, specific wavelength bandwidths are allocated to each remote node for the continuous-wave lights (for upstream signal lights) and the downstream signal lights, and the wavelength bandwidths for the continuous-wave lights (for upstream signal lights) and the downstream signal lights are alternately set.Type: ApplicationFiled: October 8, 2002Publication date: April 10, 2003Applicant: Nippon Telegraph and Telephone CorporationInventors: Hiroo Suzuki, Masamichi Fujiwara, Mitsuhiro Teshima, Koji Akimoto, Shingo Kawai, Jun-ichi Kani, Noboru Takachio, Katsumi Iwatsuki
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Publication number: 20030039010Abstract: Cost-reduction in an optical communication unit is achieved by using spectrum-sliced modulated broadband light for transmitting upstream signals, instead of using laser light. An optical communication system includes at least one pair of optical communication units that each has a bi-directional network interface in which physical bit rates of transmission signals and reception signals are identical, an optical transmitter, and an optical receiver, and that performs bi-directional transmissions via at least one optical fiber. One optical communication unit includes a physical bit rate down-converter that lowers the physical bit rate of transmission signals from the bi-directional network interface and outputs to the optical transmitter, and the other optical communication unit includes a physical bit rate up-converter that raises the physical bit rate of signals received by the optical receiver and outputs to the bi-directional network interface.Type: ApplicationFiled: August 14, 2002Publication date: February 27, 2003Applicant: Nippon Telegraph and Telephone CorporationInventors: Koji Akimoto, Jun-ichi Kani, Mitsuhiro Teshima, Katsumi Iwatsuki, Masaki Fukui
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Publication number: 20030030877Abstract: This invention discloses an optical burst transmission system in which an optical generator generates Type 1 lightwaves having different wavelengths corresponding to transmission lines and having undergone intensity modulation with obtained data; a broad spectrum optical generator generates, by incorporating Type 2 lightwaves, a Type 3 lightwave using a fewer light emitting devices than the number of the Type 1 lightwaves, each Type 2 lightwaves having a corresponding wavelength apart from Type 1 lightwave's wavelength with an FSR interval and having undergone the intensity modulation with clock signals; an optical multiplexer multiplexes the Type 1 and Type 3 lightwaves to output the combination to each transmission line; and an optical routing unit extracts, from the combination, pairs of one Type 1 lightwave and one Type 2 lightwave having the corresponding wavelength, and guides pairs to each transmission line corresponding to the Type 1 lightwave's wavelength in each pair.Type: ApplicationFiled: August 5, 2002Publication date: February 13, 2003Inventors: Masaru Fuse, Toru Shiozaki, Yoshikazu Ishii, Hiroaki Asano, Kuniaki Utsumi, Katsumi Iwatsuki, Hitoshi Uematsu, Shigeru Kuwano, Mitsuhiro Teshima
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Publication number: 20020191904Abstract: Multi-wavelength light having a frequency band equal to or greater than the FSR of an AWG is demultiplexed into individual wavelength channels, and power level deviations between wavelength channels are suppressed. An optical demultiplexer includes a wavelength-group demultiplexer that demultiplexes multi-wavelength light into wavelength groups formed from wavelength channels, and channel demultiplexers that demultiplex each wavelength group into wavelength channels light. An optical multiplexer includes channel multiplexers that multiplex modulated signal light of each wavelength channel for each wavelength group, and a wavelength-group multiplexer that multiplexes, for each wavelength group, WDM signal light output from the channel multiplexers. The FSR of the wavelength-group multiplexer/demultiplexer is set to be equal to or greater than the frequency band of the multi-wavelength light.Type: ApplicationFiled: June 5, 2002Publication date: December 19, 2002Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Jun-Ichi Kani, Katsuhiro Araya, Noboru Takachio, Koji Akimoto, Mitsuhiro Teshima, Masamichi Fujiwara, Hiroo Suzuki, Shingo Kawai, Katsumi Iwatsuki
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Publication number: 20020015212Abstract: With respect to the relative intensity noise (RIN) for inputs to an optical modulator or the signal-to-noise ratio (SNR) for outputs therefrom, the optical modulator modulating coherent lights of different wavelengths obtained by slicing a spectrum of the multi-wavelength light, the shape of a spectrum of a multi-wavelength light is controlled so that predetermined RIN and SNR can be obtained in accordance with transmission system parameters (the type and distance of optical fibers, the number of repeaters), thus enabling design meeting a performance specification for a conventional transmission section using semiconductor lasers.Type: ApplicationFiled: July 6, 2001Publication date: February 7, 2002Inventors: Masamichi Fujiwara, Katsuhiro Araya, Mitsuhiro Teshima, Junichi Kani, Kenichi Suzuki
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Patent number: 5617234Abstract: A multiwavelength simultaneous monitoring circuit capable of precise discrimination of wavelengths of a WDM (Wavelength Division Multiplexed) signal including multiplexed wavelength waves, and suitable for optical integrated circuits having large resistance to vibration.Type: GrantFiled: September 21, 1995Date of Patent: April 1, 1997Assignee: Nippon Telegraph & Telephone CorporationInventors: Masafumi Koga, Mitsuhiro Teshima, Hitoshi Obara, Ken'ichi Sato