Patents by Inventor Youichi Akasaka

Youichi Akasaka 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).

  • Publication number: 20190075378
    Abstract: Methods and systems for intra data center optical switching of optical signals use an intra data center optical switch to optically transmit N optical wavelengths as an optical signal transmitting a data stream generated by a data center system included within N data center systems. The data center system may selectively receive one of N?1 optical wavelengths as another optical signal corresponding to one of N?1 other data center systems excluding the data center system from the intra data center optical switch. In this manner, intra data center optical switching may be performed without utilizing Ethernet and optical switches, which may result in reduced power consumption for data center communication.
    Type: Application
    Filed: September 5, 2017
    Publication date: March 7, 2019
    Applicant: Fujitsu Limited
    Inventors: Youichi Akasaka, Tadashi Ikeuchi
  • Publication number: 20180366900
    Abstract: Phase modulation of an output optical signal from a phase-sensitive amplifier may be used to perform phase adjustment for optimal phase-sensitive amplification. Specifically, when the optical pump is phase modulated to suppress SBS, a second phase modulator may be used to counter dither the first phase modulator. Both phase modulators may be controlled by a phase shifter. Intensity modulation of the output optical signal may also be performed to reduce noise. In this manner, the OSNR of the output optical signal may be increased.
    Type: Application
    Filed: June 20, 2017
    Publication date: December 20, 2018
    Inventors: Youichi Akasaka, Tadashi Ikeuchi, Daniel Bihon, Richard Colter
  • Patent number: 10050738
    Abstract: Methods and systems for implementing a low noise CDC ROADM include incorporating individual stages of an optical PSA before and after WSSs included in the CDC ROADM. The WSSs may be used to route the pump and idler signals, as well as to perform phase tuning for optimal phase-sensitive amplification.
    Type: Grant
    Filed: January 23, 2017
    Date of Patent: August 14, 2018
    Assignee: Fujitsu Limited
    Inventors: Youichi Akasaka, Takeshi Hoshida, Tadashi Ikeuchi
  • Publication number: 20180212701
    Abstract: Methods and systems for implementing a low noise CDC ROADM include incorporating individual stages of an optical PSA before and after WSSs included in the CDC ROADM. The WSSs may be used to route the pump and idler signals, as well as to perform phase tuning for optimal phase-sensitive amplification.
    Type: Application
    Filed: January 23, 2017
    Publication date: July 26, 2018
    Inventors: Youichi Akasaka, Takeshi Hoshida, Tadashi Ikeuchi
  • Patent number: 9997887
    Abstract: Fiber Bragg gratings (FBG) may be used to perform phase adjustment for optimal phase-sensitive amplification. Specifically, FBGs may be used between the idler stage and the amplification stage of an optical phase-sensitive amplifier for phase shifting or tuning. The phase shifting or tuning may be applied to at least one of an input optical signal, an idler signal, and an optical pump. A feedback control loop may be used in the phase-sensitive optical amplifier with respect to an output optical signal for optimal phase adjustment.
    Type: Grant
    Filed: February 7, 2017
    Date of Patent: June 12, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Youichi Akasaka, Tadashi Ikeuchi
  • Publication number: 20180159629
    Abstract: Methods and systems enable amplifying optical signals using a Bragg reflection waveguide (BRW) having second order optical nonlinearity to generate an optical pump by injection locking. The BRW may also be used for parametric amplification of optical signals using the optical pump. Feedback phase-power control may be performed to maximize output power.
    Type: Application
    Filed: January 19, 2018
    Publication date: June 7, 2018
    Inventors: Inwoong Kim, Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya
  • Patent number: 9923634
    Abstract: Methods and systems enable amplifying optical signals using a Bragg reflection waveguide (BRW) having second order optical nonlinearity to generate an optical pump by injection locking. The BRW may also be used for parametric amplification of optical signals using the optical pump. Feedback phase-power control may be performed to maximize output power.
    Type: Grant
    Filed: September 23, 2015
    Date of Patent: March 20, 2018
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya
  • Patent number: 9843410
    Abstract: Methods and systems for amplifying optical signals include generating idler signals for input signals using an optical pump at a first Bragg reflection waveguide (BRW) having second order optical nonlinearity. Phase and amplitude regulation is performed using the output from the first BRW. Optical power monitoring of the input signals may be used for power equalization. The phase-sensitive amplified signal is generated at a second BRW using the optical pump. Optical power monitoring of the input signals may be used for power equalization.
    Type: Grant
    Filed: November 18, 2015
    Date of Patent: December 12, 2017
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Inwoong Kim, Youichi Akasaka, Motoyoshi Sekiya
  • Patent number: 9837788
    Abstract: A method and system for amplifying optical signals includes generating idler signals for input signals using an optical pump at a first non-linear element (NLE). An intermediate stage including a Raman amplifier performs pump amplification using the output from the first NLE along a single optical path. Optical power monitoring of the input signals may be used for power equalization. The intermediate stage may include a wavelength selective switch for a certain degree of phase modulation. The phase-sensitive amplified signal is generated at a second NLE using the optical pump. Optical power monitoring of the input signals may be used for power equalization and other control functions to achieve low-noise operation.
    Type: Grant
    Filed: December 3, 2015
    Date of Patent: December 5, 2017
    Assignee: Fujitsu Limited
    Inventors: Youichi Akasaka, Motoyoshi Sekiya
  • Publication number: 20170141871
    Abstract: Methods and systems for amplifying optical signals include generating idler signals for input signals using an optical pump at a first Bragg reflection waveguide (BRW) having second order optical nonlinearity. Phase and amplitude regulation is performed using the output from the first BRW. Optical power monitoring of the input signals may be used for power equalization. The phase-sensitive amplified signal is generated at a second BRW using the optical pump. Optical power monitoring of the input signals may be used for power equalization.
    Type: Application
    Filed: November 18, 2015
    Publication date: May 18, 2017
    Inventors: Jeng-Yuan Yang, Inwoong Kim, Youichi Akasaka, Motoyoshi Sekiya
  • Publication number: 20170085322
    Abstract: Methods and systems enable amplifying optical signals using a Bragg reflection waveguide (BRW) having second order optical nonlinearity to generate an optical pump by injection locking The BRW may also be used for parametric amplification of optical signals using the optical pump. Feedback phase-power control may be performed to maximize output power.
    Type: Application
    Filed: September 23, 2015
    Publication date: March 23, 2017
    Inventors: Inwoong Kim, Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya
  • Patent number: 9515727
    Abstract: Methods and systems for in-band OSNR monitoring include a tunable optical filter to scan a passband of a desired optical channel. The optical power over the passband is measured and digitized to power waveform data. The power waveform data is processed with a digital signal processor to calculate OSNR. Additionally, various implementations accommodate dual polarization modulation formats using a parallel architecture and an alternating sequential architecture.
    Type: Grant
    Filed: March 5, 2015
    Date of Patent: December 6, 2016
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Takuji Maeda, Hiroki Ooi, Satoru Okano
  • Patent number: 9515733
    Abstract: Methods and systems for mitigating spectral offset may use a scanning optical filter to scan different frequencies (or wavelengths) in a signal bandwidth of an optical channel. The maximum optical power value for the optical channel may be accurate determined as well as an effective wavelength corresponding to the maximum optical power value.
    Type: Grant
    Filed: March 5, 2015
    Date of Patent: December 6, 2016
    Assignee: Fujitsu Limited
    Inventors: Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya, Hiroki Ooi, Satoru Okano, Takuji Maeda
  • Publication number: 20160261340
    Abstract: Methods and systems for in-band OSNR monitoring include a tunable optical filter to scan a passband of a desired optical channel. The optical power over the passband is measured and digitized to power waveform data. The power waveform data is processed with a digital signal processor to calculate OSNR. Additionally, various implementations accommodate dual polarization modulation formats using a parallel architecture and an alternating sequential architecture.
    Type: Application
    Filed: March 5, 2015
    Publication date: September 8, 2016
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Takuji Maeda, Hiroki Ooi, Satoru Okano
  • Publication number: 20160261088
    Abstract: A method and system for amplifying optical signals includes generating idler signals for input signals using an optical pump at a first non-linear element (NLE). An intermediate stage including a Raman amplifier performs pump amplification using the output from the first NLE along a single optical path. Optical power monitoring of the input signals may be used for power equalization. The intermediate stage may include a wavelength selective switch for a certain degree of phase modulation. The phase-sensitive amplified signal is generated at a second NLE using the optical pump. Optical power monitoring of the input signals may be used for power equalization and other control functions to achieve low-noise operation.
    Type: Application
    Filed: December 3, 2015
    Publication date: September 8, 2016
    Inventors: Youichi Akasaka, Motoyoshi Sekiya
  • Publication number: 20160261343
    Abstract: Methods and systems for mitigating spectral offset may use a scanning optical filter to scan different frequencies (or wavelengths) in a signal bandwidth of an optical channel. The maximum optical power value for the optical channel may be accurate determined as well as an effective wavelength corresponding to the maximum optical power value.
    Type: Application
    Filed: March 5, 2015
    Publication date: September 8, 2016
    Inventors: Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya, Hiroki Ooi, Satoru Okano, Takuji Maeda
  • Patent number: 9281654
    Abstract: A Raman amplifier using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, to output pumping lights having different central wavelengths, an interval between adjacent central wavelengths greater than 6 nm and smaller than 35 nm. An optical repeater is adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. A Raman amplification method wherein the shorter the central wavelength of the pumping light, the higher light power of the pumping light. In the Raman amplifier, a certain pumping 1 wavelength being a first channel, and second to n-th channels are arranged with an interval of about 1 THz toward a longer wavelength side, pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source.
    Type: Grant
    Filed: April 9, 2013
    Date of Patent: March 8, 2016
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki
  • Patent number: 9270369
    Abstract: The present disclosure includes a computer-implemented method of correcting a measured optical signal-to-noise ratio (OSNR) comprising receiving an optical signal and measuring OSNR of the optical signal using an interferometric OSNR monitor device. The method also includes applying a correction table to the measured OSNR to generate a corrected OSNR using a controller, the correction table comprising a correction function to counteract an artifact in the measured OSNR. The method also includes storing the corrected OSNR in a non-transitory computer-readable medium. The present disclosure also includes associated devices applying the correction table and methods of generating the correction table.
    Type: Grant
    Filed: January 13, 2014
    Date of Patent: February 23, 2016
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Takuji Maeda, Hiroki Ooi, Kentaro Nakamura, Satoru Okano
  • Patent number: 9252881
    Abstract: A method for regenerating optical signals includes determining an input including a source amplitude-modulated optical signal, regenerating the source amplitude-modulated optical signal by using successive saturation modes of amplification, and producing an output optical signal from the regeneration. The source amplitude-modulated optical signal includes input power modulation levels that each indicate information carried on the source amplitude-modulated optical signal. The output optical signal includes output power modulation levels that include information equivalent to information of the input power modulation levels.
    Type: Grant
    Filed: May 31, 2013
    Date of Patent: February 2, 2016
    Assignee: Fujitsu Limited
    Inventors: Youichi Akasaka, Jeng-Yuan Yang
  • Patent number: 9112605
    Abstract: The present disclosure includes a method of determining optical signal-to-noise ratio (OSNR) of a signal, comprising separating one polarization component from a plurality of polarization components in an optical signal, selecting one wavelength from a plurality of wavelengths in the optical signal, delaying a first portion of the one polarization component of the one wavelength of the optical signal, shifting a phase of the first portion by a first amount and the first amount plus pi radians, causing the first portion to interfere with a second portion, measuring a power of the interference of the first and second portions, receiving the power of the interference, and comparing the power of the interference when the phase is shifted by the first amount with the interference when the phase is shifted by the first amount plus pi radians to determine OSNR. The present disclosure also includes associated devices.
    Type: Grant
    Filed: June 18, 2013
    Date of Patent: August 18, 2015
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Takuji Maeda, Hiroki Ooi, Satoru Okano