Patents by Inventor Kazue Otsuka
Kazue Otsuka 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: 7142785Abstract: A light branching/inserting apparatus which can easily control light signal wavelengths, and which can branch, insert or transmit light signals having an optional wavelength and optional multiplexed number, by using a wavelength selection filter utilizing acousto-optic effects.Type: GrantFiled: January 30, 2003Date of Patent: November 28, 2006Assignee: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka, Terumi Chikama
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Patent number: 6930824Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength ?0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: May 19, 1998Date of Patent: August 16, 2005Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Publication number: 20030138254Abstract: A light branching/inserting apparatus which can easily control light signal wavelengths, and which can branch, insert or transmit light signals having an optional wavelength and optional multiplexed number, by using a wavelength selection filter utilizing acousto-optic effects.Type: ApplicationFiled: January 30, 2003Publication date: July 24, 2003Applicant: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka, Terumi Chikama
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Patent number: 6583900Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.Type: GrantFiled: December 31, 2001Date of Patent: June 24, 2003Assignee: Fujitsu LimitedInventors: Hiroshi Onaka, Hideyuki Miyata, Kazue Otsuka, Yutaka Kai, Tadao Nakazawa, Terumi Chikama
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Patent number: 6538782Abstract: A light branching/inserting apparatus which can easily control light signal wavelengths, and which can branch, insert or transmit light signals having an optional wavelength and optional multiplexed number, by using a wavelength selection filter utilizing acousto-optic effects.Type: GrantFiled: May 12, 1998Date of Patent: March 25, 2003Assignee: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka, Terumi Chikama
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Publication number: 20020101633Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.Type: ApplicationFiled: December 31, 2001Publication date: August 1, 2002Applicant: Fujitsu LimitedInventors: Hiroshi Onaka, Hideyuki Miyata, Kazue Otsuka, Yutaka Kai, Tadao Nakazawa, Terumi Chikama
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Patent number: 6351323Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.Type: GrantFiled: May 18, 1998Date of Patent: February 26, 2002Assignee: Fujitsu LimitedInventors: Hiroshi Onaka, Hideyuki Miyata, Kazue Otsuka, Yutaka Kai, Tadao Nakazawa, Terumi Chikama
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Patent number: 6275314Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength &lgr;0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: April 27, 1998Date of Patent: August 14, 2001Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 6252687Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength &lgr;0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: April 27, 1998Date of Patent: June 26, 2001Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 6243176Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength &lgr;&thgr; of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: August 25, 1997Date of Patent: June 5, 2001Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 6067187Abstract: An optical amplifier has an optical amplifying medium, a pump light source outputting pump light, and a first optical coupler for supplying the pump light to the optical amplifying medium. A probe light source outputs probe light having a wavelength included in an amplification band, a second optical coupler supplies the probe light to the optical amplifying medium, and detectors detect the powers of input signal light and the probe light, respectively. A control unit controls the power of the probe light according to outputs from the detectors. This structure makes it possible to provide an optical amplifier which can reduce the wavelength dependence of gain.Type: GrantFiled: November 22, 1996Date of Patent: May 23, 2000Assignee: Fujitsu LimitedInventors: Hiroshi Onaka, Hideyuki Miyata, Kazue Otsuka
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Patent number: 5894362Abstract: An optical communication system for transmitting wavelength division multiplexed (WDM) signal light through an optical fiber. The optical communication system includes a decoupling unit and a monitoring unit. The decoupling unit decouples a portion of the WDM signal light from the optical fiber as a monitoring signal. The monitoring unit determines the spectrum of the WDM signal light from the monitoring signal and performs control processing in accordance with the determined spectrum.Type: GrantFiled: August 19, 1996Date of Patent: April 13, 1999Assignee: Fujitsu LimitedInventors: Hiroshi Onaka, Kazue Otsuka, Hideyuki Miyata
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Patent number: 5886804Abstract: In an optical transmission system for intensively modulating an optical wavelength with a sending signal to be transmitted and optically amplifying a modulated optical signal, a wavelength dispersion characteristic of a single mode optical transmission line can be suitably compensated. The optical transmission system comprises a modulating circuit for modulating optical phases or frequencies of the optical wavelength with the sending signal to set a chirping parameter .alpha. to -0.65 to -1.3, and outputting an modulated signal; an optical transmission line having wavelength residual dispersion value of 16 to 21 ps/nm/Km for transmitting the modulated signal; and a dispersion compensating circuit for compensating wavelength dispersion value, of the optical transmission line, which is set to approximately +500 to +1200 ps/nm when an input optical power is more than -5 dBm.Type: GrantFiled: April 1, 1996Date of Patent: March 23, 1999Assignee: Fujitsu LimitedInventors: Hiroshi Onaka, Hideyuki Miyata, Kazue Otsuka
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Patent number: 5856881Abstract: An optical fiber transmission line capable of suppressing the generation efficiency of four wave mixing in transmitting wavelength multiplex signal light. The transmission line employs a single mode optical fiber in which a zero dispersion wavelength is varied in the longitudinal direction of the optical fiber more largely than manufacturing variations in manufacturing conditions of the optical fiber. The use of this optical fiber as the transmission line suppresses the generation efficiency of four wave mixing in transmitting the wavelength multiplex signal light to allow the transmission of the wavelength multiplex signal light with a reduced crosstalk.Type: GrantFiled: July 31, 1997Date of Patent: January 5, 1999Assignee: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka
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Patent number: 5841557Abstract: A method and apparatus for scrambling the polarization of signal lights combined into a wavelength division multiplexed signal light, to suppress non-linear optical effect and thereby improve transmission quality. For example, each signal light has a different polarization before being combined into a wavelength division multiplexed signal light. The polarization of the wavelength division multiplexed signal light can then be scrambled. Alternatively, the polarization of each signal light can be scrambled at a different scrambling frequency before being combined into the wavelength division multiplexed signal light.Type: GrantFiled: October 22, 1996Date of Patent: November 24, 1998Assignee: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka, Takafumi Terahara, Takao Naito
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Patent number: 5790292Abstract: An optical fiber transmission line capable of suppressing the generation efficiency of four wave mixing in transmitting wavelength multiplex signal light. The transmission line employs a single mode optical fiber in which a zero dispersion wavelength is varied in the longitudinal direction of the optical fiber more largely than manufacturing variations in manufacturing conditions of the optical fiber. The use of this optical fiber as the transmission line suppresses the generation efficiency of four wave mixing in transmitting the wavelength multiplex signal light to allow the transmission of the wavelength multiplex signal light with a reduced crosstalk.Type: GrantFiled: October 2, 1995Date of Patent: August 4, 1998Assignee: Fujitsu LimitedInventors: Kazue Otsuka, Hiroshi Onaka
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Patent number: 5696614Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength .lambda..sub.0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: January 9, 1997Date of Patent: December 9, 1997Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 5636046Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength .lambda..sub.0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.Type: GrantFiled: April 20, 1995Date of Patent: June 3, 1997Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 5612807Abstract: An optical wavelength multiplex transmission method uses a band around a zero dispersion wavelength of an optical fiber to compensate for waveform degradation, which is produced by a synergetic effect of self phase modulation and chromatic dispersion, to increase transmission distance and transmission rate in optical systems. The optical dispersion compensation method is performed in an optical system including a transmitter, a repeater and a receiver, which collectively transmit and receive optical information along the optical fiber. Light is transmitted within a transmissible band which is defined by an allowable dispersion value determined from a synergetic effect of self phase modulation and group velocity dispersion in the optical fiber. The transmissible band is set on a shorter wavelength side than a shorter wavelength end .lambda..theta.-.DELTA..lambda..theta. or on a longer wavelength side than a longer wavelength end .lambda..theta.+.DELTA..lambda..theta.Type: GrantFiled: April 20, 1995Date of Patent: March 18, 1997Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka
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Patent number: 5602666Abstract: An optical wavelength multiplex transmission method uses a band around a zero dispersion wavelength of an optical fiber to compensate for waveform degradation, which is produced by a synergetic effect of self phase modulation and chromatic dispersion, to increase transmission distance and transmission rate in optical systems. The optical dispersion compensation method is performed in an optical system including a transmitter, a repeater and a receiver, which collectively transmit and receive optical information along the optical fiber. Light is transmitted within a transmissible band which is defined by an allowable dispersion value determined from a synergetic effect of self phase modulation and group velocity dispersion in the optical fiber. The transmissible band is set on a shorter wavelength side than a shorter wavelength end .lambda..theta.-.DELTA..lambda..theta. or on a longer wavelength side than a longer wavelength end .lambda..theta.+.DELTA..lambda..theta.Type: GrantFiled: April 20, 1995Date of Patent: February 11, 1997Assignee: Fujitsu LimitedInventors: George Ishikawa, Hideyuki Miyata, Hiroshi Onaka, Motoyoshi Sekiya, Kazue Otsuka