Patents by Inventor Kazuo Hironishi
Kazuo Hironishi 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: 9768907Abstract: An optical transmission apparatus, includes: a reference-wavelength light source configured to generate reference light; a reference wavemeter configured to be calibrated by using the reference light; a receiver configured to receive measurement light transmitted from another optical transmission apparatus and wavelength information about the measurement light; and a controller, wherein the controller configured to: detect error between a first wavelength of the measurement light detected by using the reference wavemeter, and a second wavelength included in the wavelength information; and send error information that represents the error to the another optical transmission apparatus.Type: GrantFiled: September 30, 2015Date of Patent: September 19, 2017Assignee: FUJITSU LIMITEDInventor: Kazuo Hironishi
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Patent number: 9549233Abstract: A transmission device includes: a wavelength-variable light source; a wavelength stabilized light source: a wavelength measuring device; a control circuit that controls the wavelength-variable light source; and a reception circuit that receives second reference wavelength light generated based on first reference wavelength light output from the wavelength stabilized light source whose wavelength stability is higher than that of the wavelength-variable light source, the control circuit calibrating the wavelength measuring device by using the second reference wavelength light, the control circuit calibrating the wavelength-variable light source by using the calibrated wavelength measuring device.Type: GrantFiled: July 13, 2015Date of Patent: January 17, 2017Assignee: FUJITSU LIMITEDInventor: Kazuo Hironishi
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Patent number: 9503211Abstract: A signal detection circuit includes: a first optical filter configured to filter an optical signal carrying a frequency modulated signal with a first transmission band; a second optical filter configured to filter the optical signal with a second transmission band; a first photo detector configured to convert the output light of the first optical filter into a first electrical signal; a second photo detector configured to convert the output light of the second optical filter into a second electrical signal; a difference circuit configured to output a signal representing a difference between the first electrical signal and the second electrical signal; and a detector configured to detect the frequency modulated signal based on the output signal of the difference circuit.Type: GrantFiled: January 26, 2016Date of Patent: November 22, 2016Assignee: FUJITSU LIMITEDInventors: Kazuo Hironishi, Shoichiro Oda, Takeshi Hoshida
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Publication number: 20160149647Abstract: An optical transmission apparatus, includes: a reference-wavelength light source configured to generate reference light; a reference wavemeter configured to be calibrated by using the reference light; a receiver configured to receive measurement light transmitted from another optical transmission apparatus and wavelength information about the measurement light; and a controller, wherein the controller configured to: detect error between a first wavelength of the measurement light detected by using the reference wavemeter, and a second wavelength included in the wavelength information; and send error information that represents the error to the another optical transmission apparatus.Type: ApplicationFiled: September 30, 2015Publication date: May 26, 2016Inventor: Kazuo Hironishi
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Publication number: 20160142171Abstract: A signal detection circuit includes: a first optical filter configured to filter an optical signal carrying a frequency modulated signal with a first transmission band; a second optical filter configured to filter the optical signal with a second transmission band; a first photo detector configured to convert the output light of the first optical filter into a first electrical signal; a second photo detector configured to convert the output light of the second optical filter into a second electrical signal; a difference circuit configured to output a signal representing a difference between the first electrical signal and the second electrical signal; and a detector configured to detect the frequency modulated signal based on the output signal of the difference circuit.Type: ApplicationFiled: January 26, 2016Publication date: May 19, 2016Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Shoichiro Oda, Takeshi Hoshida
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Patent number: 9281913Abstract: A signal detection circuit includes: a first optical filter configured to filter an optical signal carrying a frequency modulated signal with a first transmission band; a second optical filter configured to filter the optical signal with a second transmission band; a first photo detector configured to convert the output light of the first optical filter into a first electrical signal; a second photo detector configured to convert the output light of the second optical filter into a second electrical signal; a difference circuit configured to output a signal representing a difference between the first electrical signal and the second electrical signal; and a detector configured to detect the frequency modulated signal based on the output signal of the difference circuit.Type: GrantFiled: December 16, 2013Date of Patent: March 8, 2016Assignee: FUJITSU LIMITEDInventors: Kazuo Hironishi, Shoichiro Oda, Takeshi Hoshida
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Publication number: 20160037241Abstract: A transmission device includes: a wavelength-variable light source; a wavelength stabilized light source: a wavelength measuring device; a control circuit that controls the wavelength-variable light source; and a reception circuit that receives second reference wavelength light generated based on first reference wavelength light output from the wavelength stabilized light source whose wavelength stability is higher than that of the wavelength-variable light source, the control circuit calibrating the wavelength measuring device by using the second reference wavelength light, the control circuit calibrating the wavelength-variable light source by using the calibrated wavelength measuring device.Type: ApplicationFiled: July 13, 2015Publication date: February 4, 2016Applicant: Fujitsu LimitedInventor: Kazuo Hironishi
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Patent number: 9154233Abstract: A frequency modulation signal demodulator includes: an optical signal that has a wavelength, a frequency modulation signal being superimposed onto the optical signal; an optical filter that inputs the optical signal and has a central wavelength of a pass band at a wavelength that is shifted from a central wavelength of a spectrum of the optical signal and that is set to allow the pass band to be located at one portion of the spectrum; and an asymmetry optical interferometer that demodulates the frequency modulation signal by splitting light which has passed through the optical filter, delaying different time between split lights, and interfering the split lights.Type: GrantFiled: August 5, 2014Date of Patent: October 6, 2015Assignee: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 9054814Abstract: A front end device includes: an optical filter configured to receive a WDM optical signal including a plurality of optical signals each having a superposing signal superposed thereon by frequency shift keying, with a transmittance being periodically changed with respect to a wavelength and a wavelength with which a peak of the transmittance appears being shifted according to an incident angle; an optical structure configured to guide the WDM optical signal to the optical filter so that the WDM optical signal enters the optical filter at a plurality of different angles; and an optical detector configured to convert an optical signal output from the optical filter to an electrical signal.Type: GrantFiled: February 1, 2013Date of Patent: June 9, 2015Assignee: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 8965221Abstract: A receiver includes: an extraction circuit to extract a phase fluctuation component common to phase data of two polarization components that are separated in a coherent reception of a polarization multiplexing phase modulation optical signal; and a correction circuit to correct the phase data of the two polarization components in accordance with the phase fluctuation component.Type: GrantFiled: May 31, 2012Date of Patent: February 24, 2015Assignee: Fujitsu LimitedInventors: Kazuo Hironishi, Takeshi Hoshida
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Publication number: 20150050018Abstract: A frequency modulation signal demodulator includes: an optical signal that has a wavelength, a frequency modulation signal being superimposed onto the optical signal; an optical filter that inputs the optical signal and has a central wavelength of a pass band at a wavelength that is shifted from a central wavelength of a spectrum of the optical signal and that is set to allow the pass band to be located at one portion of the spectrum; and an asymmetry optical interferometer that demodulates the frequency modulation signal by splitting light which has passed through the optical filter, delaying different time between split lights, and interfering the split lights.Type: ApplicationFiled: August 5, 2014Publication date: February 19, 2015Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 8886057Abstract: An optical receiver includes a splitter that splits a local oscillator lightwave into a first local oscillator lightwave and a second local oscillator lightwave; a measurement unit that measures phase variation of the first local oscillator lightwave; a receiving unit that receives a signal lightwave and the second local oscillator lightwave and mixes these lightwaves and converts the mixed lightwaves into digital signal; a dispersion compensator that reduces chromatic dispersion of the digital signal; a phase processing unit that rotates phase of the dispersion-reduced signal based on the phase variation; and a discriminating unit that discriminates the phase-rotated signal.Type: GrantFiled: December 14, 2011Date of Patent: November 11, 2014Assignee: Fujitsu LimitedInventors: Kazuo Hironishi, Takeshi Hoshida
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Publication number: 20140219662Abstract: A signal detection circuit includes: a first optical filter configured to filter an optical signal carrying a frequency modulated signal with a first transmission band; a second optical filter configured to filter the optical signal with a second transmission band; a first photo detector configured to convert the output light of the first optical filter into a first electrical signal; a second photo detector configured to convert the output light of the second optical filter into a second electrical signal; a difference circuit configured to output a signal representing a difference between the first electrical signal and the second electrical signal; and a detector configured to detect the frequency modulated signal based on the output signal of the difference circuit.Type: ApplicationFiled: December 16, 2013Publication date: August 7, 2014Applicant: FUJITSU LIMITEDInventors: Kazuo HIRONISHI, Shoichiro ODA, Takeshi HOSHIDA
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Publication number: 20130243430Abstract: A front end device includes: an optical filter configured to receive a WDM optical signal including a plurality of optical signals each having a superposing signal superposed thereon by frequency shift keying, with a transmittance being periodically changed with respect to a wavelength and a wavelength with which a peak of the transmittance appears being shifted according to an incident angle; an optical structure configured to guide the WDM optical signal to the optical filter so that the WDM optical signal enters the optical filter at a plurality of different angles; and an optical detector configured to convert an optical signal output from the optical filter to an electrical signal.Type: ApplicationFiled: February 1, 2013Publication date: September 19, 2013Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 8509628Abstract: A first optical splitter splits an input optical signal and outputs it to first and second optical paths. A second optical splitter outputs the optical signal from the first optical path to third and fourth optical paths. A third optical splitter outputs the optical signal from the second optical path to fifth and sixth optical paths. In the second optical path, 1-symbol delay element and ?/4 phase shifter element are configured. In the fourth optical path, ?/2 phase shifter element is configured. First and second adjuster circuits adjust the optical path length of the second and the fourth optical paths, respectively, by temperature control. A first optical coupler couples optical signals transmitted via the third and the fifth optical paths. A second optical coupler couples optical signals transmitted via the fourth and the sixth optical paths. Photodetectors convert the optical signals from the optical couplers into electrical signals.Type: GrantFiled: September 24, 2009Date of Patent: August 13, 2013Assignee: Fujitsu LimitedInventors: Kazuo Hironishi, Takeshi Hoshida
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Publication number: 20120308233Abstract: A receiver includes: an extraction circuit to extract a phase fluctuation component common to phase data of two polarization components that are separated in a coherent reception of a polarization multiplexing phase modulation optical signal; and a correction circuit to correct the phase data of the two polarization components in accordance with the phase fluctuation component.Type: ApplicationFiled: May 31, 2012Publication date: December 6, 2012Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Publication number: 20120213532Abstract: An optical receiver includes a splitter that splits a local oscillator lightwave into a first local oscillator lightwave and a second local oscillator lightwave; a measurement unit that measures phase variation of the first local oscillator lightwave; a receiving unit that receives a signal lightwave and the second local oscillator lightwave and mixes these lightwaves and converts the mixed lightwaves into digital signal; a dispersion compensator that reduces chromatic dispersion of the digital signal; a phase processing unit that rotates phase of the dispersion-reduced signal based on the phase variation; and a discriminating unit that discriminates the phase-rotated signal.Type: ApplicationFiled: December 14, 2011Publication date: August 23, 2012Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 7751721Abstract: A first interferometer comprises a first delay element and a first phase shift element, and a second interferometer comprises a second delay element and a second phase shift element. The amounts of phase shift in the first and second phase shift element are zero and ?/2, respectively. A first photo detector comprises first and second photodiodes connected in parallel, and a second photo detector comprises third and fourth photodiodes connected in series. The first photodiode is provided with a first optical output of the first interferometer, the second photodiode is provided with a first optical output of the second interferometer, the third photodiode is provided with a second optical output of the first interferometer, and the fourth photodiode is provided with a second optical output of the second interferometer. A signal process circuit recovers transmitted data based on output signals of the first and second photo detectors.Type: GrantFiled: March 30, 2006Date of Patent: July 6, 2010Assignee: Fujitsu LimitedInventors: Takeshi Hoshida, Kazuo Hironishi
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Patent number: 7706695Abstract: An interferometer comprises a delay element and a phase shift element. The delay element delays an optical DQPSK signal by one-symbol time. The phase shift element shifts the optical DQPSK signal by ?/8. A pair of photodiodes converts each of a pair of optical signals output from the interferometer into an electric signal. A photodetector circuit converts differential current obtained by a pair of the photodiodes into voltage and outputs as a detection signal. A first decision circuit outputs one-bit information based on the voltage of the detection signal. A second decision circuit outputs one-bit information based on a squared value of the voltage of the detection signal.Type: GrantFiled: June 28, 2006Date of Patent: April 27, 2010Assignee: Fujitsu LimitedInventors: Kazuo Hironishi, Takeshi Hoshida
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Publication number: 20100040383Abstract: A first optical splitter splits an input optical signal and outputs it to first and second optical paths. A second optical splitter outputs the optical signal from the first optical path to third and fourth optical paths. A third optical splitter outputs the optical signal from the second optical path to fifth and sixth optical paths. In the second optical path, 1-symbol delay element and ?/4 phase shifter element are configured. In the fourth optical path, ?/2 phase shifter element is configured. First and second adjuster circuits adjust the optical path length of the second and the fourth optical paths, respectively, by temperature control. A first optical coupler couples optical signals transmitted via the third and the fifth optical paths. A second optical coupler couples optical signals transmitted via the fourth and the sixth optical paths. Photodetectors convert the optical signals from the optical couplers into electrical signals.Type: ApplicationFiled: September 24, 2009Publication date: February 18, 2010Applicant: FUJITSU LIMITEDInventors: Kazuo Hironishi, Takeshi Hoshida