Patents by Inventor Taketo Endo
Taketo Endo 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: 20200169324Abstract: An optical transmission apparatus includes a detecting circuit configured to detect one or more empty slots in which a data signal is not accommodated in a plurality of slots included in a frame, a frame processing circuit configured to reduce size of the frame by deleting the one or more empty slots from the frame based on a detection result of the one or more empty slots and closing up gaps between remaining slots in the plurality of slots, and an optical modulation processing circuit configured to carry out multi-level modulation of the frame at a bit rate according to size of the frame after reduction.Type: ApplicationFiled: November 22, 2019Publication date: May 28, 2020Applicant: FUJITSU LIMITEDInventors: Kunihiko YANAGIKUIDA, Shota Shinohara, Hisayuki Ojima, Toshihiro Suzuki, Taketo Endo, Hayato Furukawa
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Patent number: 10020879Abstract: An optical transmission apparatus may include a coherent detector, a photoelectric converter, an amplifier, a gain controller, and an optical power monitor. The coherent detector may perform a coherent detection on received light including a plurality of wavelengths to select light having any one of the wavelengths. The photoelectric converter may convert the light having the selected wavelength to an electrical signal. The amplifier may amplify the electrical signal. The gain controller may control a gain of the amplifier depending on an output amplitude of the amplifier. The optical power monitor may calculate an optical power level of the selected wavelength based on the gain and the output amplitude.Type: GrantFiled: October 21, 2016Date of Patent: July 10, 2018Assignee: FUJITSU LIMITEDInventors: Taku Saito, Taketo Endo, Kosuke Komaki
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Optical transmission apparatus, optical transmission system, and polarization dependent loss monitor
Patent number: 9882647Abstract: An optical transmission apparatus includes: a coherent detector configured to receive light including different polarization components from an optical transmission path, and perform coherent detection of received light including the different polarization components; an adaptive equalizer configured to adaptively equalize, by a digital filter, a complex electric signal for each of the polarization components obtained by the coherent detection, a gain value for controlling an amplitude of the complex electric signal being applied to the complex electric signal; and a polarization dependent loss monitor configured to determine a polarization dependent loss of the optical transmission path, based on a correction filter parameter obtained by correcting a filter parameter of the digital filter according to the gain value, the filter parameter being adaptively updated by an adaptive equalization of the adaptive equalizer.Type: GrantFiled: February 2, 2016Date of Patent: January 30, 2018Assignee: FUJITSU LIMITEDInventors: Taketo Endo, Kosuke Komaki, Taku Saito, Hirofumi Araki, Makoto Shimizu, Hiroshi Nishida -
Patent number: 9722704Abstract: An optical transmission apparatus includes: an optical receiver configured to receive an optical signal; a variable optical attenuator configured to adjust a power of the optical signal to be input to the optical receiver according to a variable attenuation amount; and a controller configured to control the attenuation amount of the variable optical attenuator based on an electrical signal obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver.Type: GrantFiled: February 1, 2016Date of Patent: August 1, 2017Assignee: FUJITSU LIMITEDInventors: Taku Saito, Kosuke Komaki, Taketo Endo, Shuzo Matsushita, Hirofumi Araki, Hiroshi Nishida, Makoto Shimizu
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Patent number: 9698905Abstract: An optical transmission system includes comprising: a first optical transmission apparatus to transmit wavelength-multiplexed optical signals; and a second optical transmission apparatus to receive the wavelength-multiplexed optical signals, the second optical transmission apparatus including: a receiver to perform digital coherent reception; a wavelength spacing monitor to transform a reception signal obtained by the digital coherent reception from a time domain signal to a frequency domain spectrum signal, and to monitor wavelength spacing of the spectrum signal; and a transmitter to transmit, to the first optical transmission apparatus, wavelength control information according to a monitor result obtained by the wavelength spacing monitor or the monitor result, wherein the first optical transmission apparatus includes: a receiver to receive the wavelength control information or the monitor result; and a control unit to control the wavelength spacing based on the wavelength control information or the monitoType: GrantFiled: May 14, 2015Date of Patent: July 4, 2017Assignee: FUJITSU LIMITEDInventors: Taku Saito, Kosuke Komaki, Taketo Endo
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Publication number: 20170126315Abstract: An optical transmission apparatus may include a coherent detector, a photoelectric converter, an amplifier, a gain controller, and an optical power monitor. The coherent detector may perform a coherent detection on received light including a plurality of wavelengths to select light having any one of the wavelengths. The photoelectric converter may convert the light having the selected wavelength to an electrical signal. The amplifier may amplify the electrical signal. The gain controller may control a gain of the amplifier depending on an output amplitude of the amplifier. The optical power monitor may calculate an optical power level of the selected wavelength based on the gain and the output amplitude.Type: ApplicationFiled: October 21, 2016Publication date: May 4, 2017Applicant: FUJITSU LIMITEDInventors: Taku Saito, Taketo Endo, Kosuke Komaki
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Patent number: 9479249Abstract: An optical transmission system includes a transmitting device and a receiving device, wherein the transmitting device includes a modulating unit that changes a frequency of an optical signal, and the receiving device includes a filtering unit that passes an optical signal in a predetermined frequency band; a measuring unit that measures an intensity of an optical signal that passes through the filtering unit; a detecting unit that detects a center wavelength of the optical signal in accordance with an intensity of the optical signal that is measured when a frequency of the optical signal is changed in a state of a passed band that corresponds to the optical signal; and an output unit that outputs information that indicates the detected center wavelength to the transmitting device, wherein the transmitting device controls a wavelength of the optical signal in accordance with the information from the receiving device.Type: GrantFiled: August 5, 2015Date of Patent: October 25, 2016Assignee: FUJITSU LIMITEDInventors: Taketo Endo, Tomohiro Kaneoka, Hisayuki Ojima, Shoichi Murakami
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Publication number: 20160248513Abstract: An optical transmission apparatus includes: an optical receiver configured to receive an optical signal; a variable optical attenuator configured to adjust a power of the optical signal to be input to the optical receiver according to a variable attenuation amount; and a controller configured to control the attenuation amount of the variable optical attenuator based on an electrical signal obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver.Type: ApplicationFiled: February 1, 2016Publication date: August 25, 2016Applicant: FUJITSU LIMITEDInventors: Taku Saito, Kosuke Komaki, Taketo Endo, Shuzo Matsushita, Hirofumi Araki, Hiroshi Nishida, Makoto Shimizu
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OPTICAL TRANSMISSION APPARATUS, OPTICAL TRANSMISSION SYSTEM, AND POLARIZATION DEPENDENT LOSS MONITOR
Publication number: 20160241341Abstract: An optical transmission apparatus includes: a coherent detector configured to receive light including different polarization components from an optical transmission path, and perform coherent detection of received light including the different polarization components; an adaptive equalizer configured to adaptively equalize, by a digital filter, a complex electric signal for each of the polarization components obtained by the coherent detection, a gain value for controlling an amplitude of the complex electric signal being applied to the complex electric signal; and a polarization dependent loss monitor configured to determine a polarization dependent loss of the optical transmission path, based on a correction filter parameter obtained by correcting a filter parameter of the digital filter according to the gain value, the filter parameter being adaptively updated by an adaptive equalization of the adaptive equalizer.Type: ApplicationFiled: February 2, 2016Publication date: August 18, 2016Inventors: Taketo Endo, Kosuke Komaki, Taku Saito, Hirofumi Araki, Makoto SHIMIZU, Hiroshi Nishida -
Publication number: 20160065305Abstract: An optical transmission system includes a transmitting device and a receiving device, wherein the transmitting device includes a modulating unit that changes a frequency of an optical signal, and the receiving device includes a filtering unit that passes an optical signal in a predetermined frequency band; a measuring unit that measures an intensity of an optical signal that passes through the filtering unit; a detecting unit that detects a center wavelength of the optical signal in accordance with an intensity of the optical signal that is measured when a frequency of the optical signal is changed in a state of a passed band that corresponds to the optical signal; and an output unit that outputs information that indicates the detected center wavelength to the transmitting device, wherein the transmitting device controls a wavelength of the optical signal in accordance with the information from the receiving device.Type: ApplicationFiled: August 5, 2015Publication date: March 3, 2016Applicants: FUJITSU LIMITED, FUJITSU TELECOM NETWORKS LIMITEDInventors: Taketo ENDO, Tomohiro Kaneoka, Hisayuki Ojima, Shoichi Murakami
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Publication number: 20150381276Abstract: An optical transmission system includes comprising: a first optical transmission apparatus to transmit wavelength-multiplexed optical signals; and a second optical transmission apparatus to receive the wavelength-multiplexed optical signals, the second optical transmission apparatus including: a receiver to perform digital coherent reception; a wavelength spacing monitor to transform a reception signal obtained by the digital coherent reception from a time domain signal to a frequency domain spectrum signal, and to monitor wavelength spacing of the spectrum signal; and a transmitter to transmit, to the first optical transmission apparatus, wavelength control information according to a monitor result obtained by the wavelength spacing monitor or the monitor result, wherein the first optical transmission apparatus includes: a receiver to receive the wavelength control information or the monitor result; and a control unit to control the wavelength spacing based on the wavelength control information or the monitoType: ApplicationFiled: May 14, 2015Publication date: December 31, 2015Applicant: FUJITSU LIMITEDInventors: Taku Saito, Kosuke Komaki, Taketo Endo