Patents by Inventor Kenichi Kaburagi
Kenichi Kaburagi 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: 9124382Abstract: A transmission device includes: a wavelength detector configured to detect a first wavelength of a first optical signal; a wavelength selective switch to which the first optical signal is input; and a controller configured to detect a direction toward which a central wavelength of a passband of the wavelength selective switch is shifted from the first wavelength detected by the wavelength detector and to control the wavelength selective switch so as to increase a width of the passband toward an opposite direction of the direction toward which the central wavelength of the passband is shifted from the first wavelength.Type: GrantFiled: October 4, 2013Date of Patent: September 1, 2015Assignee: FUJITSU LIMITEDInventors: Kenichi Kaburagi, Hiroaki Tomofuji
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Publication number: 20140161448Abstract: A transmission device includes: a wavelength detector configured to detect a first wavelength of a first optical signal; a wavelength selective switch to which the first optical signal is input; and a controller configured to detect a direction toward which a central wavelength of a passband of the wavelength selective switch is shifted from the first wavelength detected by the wavelength detector and to control the wavelength selective switch so as to increase a width of the passband toward an opposite direction of the direction toward which the central wavelength of the passband is shifted from the first wavelength.Type: ApplicationFiled: October 4, 2013Publication date: June 12, 2014Applicant: FUJITSU LIMITEDInventors: Kenichi Kaburagi, Hiroaki Tomofuji
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Patent number: 8538265Abstract: An optical communication device comprises a variable dispersion compensator, a photoelectric converter, and a processor. The variable dispersion compensator compensates an amount of wavelength dispersion of an optical signal received from an optical transmission line. The photoelectric converter converts the compensated optical signal into an electrical signal. The processor is operative to extract a frequency of the converted electrical signal, and to discriminate bit information of the electrical signal based on the frequency extracted using a decision phase and a decision threshold. The processor is operative to detect bit error information that is information related to an error of the discriminated bit information, and to control the amount of wavelength dispersion based on the detected bit error information.Type: GrantFiled: September 28, 2011Date of Patent: September 17, 2013Assignee: Fujitsu LimitedInventors: Kenichi Kaburagi, Noriaki Mizuguchi
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Publication number: 20120020661Abstract: An optical communication device comprises a variable dispersion compensator, a photoelectric converter, and a processor. The variable dispersion compensator compensates an amount of wavelength dispersion of an optical signal received from an optical transmission line. The photoelectric converter converts the compensated optical signal into an electrical signal. The processor is operative to extract a frequency of the converted electrical signal, and to discriminate bit information of the electrical signal based on the frequency extracted using a decision phase and a decision threshold. The processor is operative to detect bit error information that is information related to an error of the discriminated bit information, and to control the amount of wavelength dispersion based on the detected bit error information.Type: ApplicationFiled: September 28, 2011Publication date: January 26, 2012Applicant: FUJITSU LIMITEDInventors: Kenichi Kaburagi, Noriaki Mizuguchi
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Patent number: 7991301Abstract: An optical apparatus comprising: a branching unit branching an input light modulated by DQSPK format and thereby outputting a first branched light and a second branched light; a first branch and a second branch inputting the first branched light and the second branched light, respectively, the first branch and the second branch having an interferometer, a photo detector, and discriminator and demodulating I-signal and Q-signal, respectively; and an abnormality detection unit detecting an abnormality of the input light based on a synchronized detection of a first demodulated signal output from the photo detector in the first branch and a first recovered signal output from the discriminator in the first branch, and a synchronized detection of a second demodulated signal output from the photo detector in the second branch and a second recovered signal output from the discriminator in the second branch.Type: GrantFiled: March 28, 2008Date of Patent: August 2, 2011Assignee: Fujitsu LimitedInventors: Noriaki Mizuguchi, Takashi Toyomaki, Yoshikazu Terayama, Kenichi Kaburagi
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Patent number: 7684713Abstract: A calculation processing unit controls temperature of a Peltier device based on a slope of a waveform obtained by subtracting a waveform of a B-arm monitoring signal from a waveform of an A-arm monitoring signal and a value obtained by subtracting a value B of the B-arm monitoring signal from a value A of the A-arm monitoring signal. Similarly, the calculation processing unit controls a phase of the A-arm and a phase of the B-arm. An A-arm side micro-controller controls temperature of an A-arm side heater 22 based on the value of the A-arm monitoring signal, and controls the phase of the A-arm. A B-arm side micro-controller controls temperature of a B-arm side heater based on the value B of the B-arm monitoring signal, and controls the phase of the B-arm.Type: GrantFiled: November 7, 2006Date of Patent: March 23, 2010Assignee: Fujitsu LimitedInventors: Yoshikazu Terayama, Noriaki Mizuguchi, Eiji Ishikawa, Takashi Toyomaki, Kenichi Kaburagi, Takeshi Hoshida, Jens Rasmussen, Akihiko Isomura
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Patent number: 7676162Abstract: Branches are grouped into a group 1 including first and second branches, and a group 2 including third and fourth branches. The signal after being passed through a dual pin photodiode in one branch included in the group 1 and being at the earlier stage of a CDR circuit is obtained. Also, from the later stage of the CDR circuit in the other branch in the group 1 is obtained. The obtained signals are passed through low pass filters, and an average value over a plurality of symbols is obtained. The signal from the earlier stage of the CDR circuit is multiplied by the signal from the later stage, and they are averaged. The obtained value reflects the phase difference of the two delay interferometers in the group 1. The group 2 is monitored by using the same method.Type: GrantFiled: November 29, 2006Date of Patent: March 9, 2010Assignee: Fujitsu LimitedInventors: Akihiko Isomura, Jens C. Rasmussen, Zhenning Tao, Noriaki Mizuguchi, Kenichi Kaburagi
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Publication number: 20090214226Abstract: First and second delay interferometers respectively have a phase-shift element. First and second photo detectors respectively detect optical signals output from the first and second delay interferometers. First and second data recovery circuits recover data from signals detected by the first and second photo detectors, respectively. A common adjustment unit adjusts the phase-shift elements of both first and second delay interferometers in accordance with an output signal from the first photo detector and an output signal from the second data recovery circuit. An individual adjustment unit adjusts the phase-shift element of the second delay interferometer in accordance with the output signal from the first photo detector and an output signal from the second photo detector.Type: ApplicationFiled: September 30, 2008Publication date: August 27, 2009Applicant: Fujitsu LimitedInventors: Noriaki MIZUGUCHI, Yoshikazu Terayama, Kenichi Kaburagi
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Publication number: 20080253761Abstract: An optical apparatus comprising: a branching unit branching an input light modulated by DQSPK format and thereby outputting a first branched light and a second branched light; a first branch and a second branch inputting the first branched light and the second branched light, respectively, the first branch and the second branch having an interferometer, a photo detector, and discriminator and demodulating I-signal and Q-signal, respectively; and an abnormality detection unit detecting an abnormality of the input light based on a synchronized detection of a first demodulated signal output from the photo detector in the first branch and a first recovered signal output from the discriminator in the first branch, and a synchronized detection of a second demodulated signal output from the photo detector in the second branch and a second recovered signal output from the discriminator in the second branch.Type: ApplicationFiled: March 28, 2008Publication date: October 16, 2008Applicant: FUJITSU LIMITEDInventors: Noriaki MIZUGUCHI, Takashi Toyomaki, Yoshikazu Terayama, Kenichi Kaburagi
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Publication number: 20080056733Abstract: Branches are grouped into a group 1 including first and second branches, and a group 2 including third and fourth branches. The signal after being passed through a dual pin photodiode in one branch included in the group 1 and being at the earlier stage of a CDR circuit is obtained. Also, from the later stage of the CDR circuit in the other branch in the group 1 is obtained. The obtained signals are passed through low pass filters, and an average value over a plurality of symbols is obtained. The signal from the earlier stage of the CDR circuit is multiplied by the signal from the later stage, and they are averaged. The obtained value reflects the phase difference of the two delay interferometers in the group 1. The group 2 is monitored by using the same method.Type: ApplicationFiled: November 29, 2006Publication date: March 6, 2008Inventors: Akihiko Isomura, Jens C. Rasmussen, Zhenning Tao, Noriaki Mizuguchi, Kenichi Kaburagi
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Publication number: 20070292140Abstract: A calculation processing unit controls temperature of a Peltier device based on a slope of a waveform obtained by subtracting a waveform of a B-arm monitoring signal from a waveform of an A-arm monitoring signal and a value obtained by subtracting a value B of the B-arm monitoring signal from a value A of the A-arm monitoring signal. Similarly, the calculation processing unit controls a phase of the A-arm and a phase of the B-arm. An A-arm side micro-controller controls temperature of an A-arm side heater 22 based on the value of the A-arm monitoring signal, and controls the phase of the A-arm. A B-arm side micro-controller controls temperature of a B-arm side heater based on the value B of the B-arm monitoring signal, and controls the phase of the B-arm.Type: ApplicationFiled: November 7, 2006Publication date: December 20, 2007Applicant: FUJITSU LIMITEDInventors: Yoshikazu Terayama, Noriaki Mizuguchi, Eiji Ishikawa, Takashi Toyomaki, Kenichi Kaburagi, Takeshi Hoshida, Jens Rasmussen, Akihiko Isomura