Patents by Inventor Yoichi Akasaka

Yoichi 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).

  • Patent number: 10020878
    Abstract: An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.
    Type: Grant
    Filed: April 17, 2015
    Date of Patent: July 10, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Shoichiro Oda, Yasuhiko Aoki, Hiroki Oi, Satoru Okano, Yoichi Akasaka, Jeng-Yuan Yang
  • Publication number: 20160308611
    Abstract: An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.
    Type: Application
    Filed: April 17, 2015
    Publication date: October 20, 2016
    Applicant: Fujitsu Limited
    Inventors: Shoichiro ODA, Yasuhiko AOKI, Hiroki Oi, Satoru OKANO, Yoichi AKASAKA, Jeng-Yuan YANG
  • Patent number: 9246624
    Abstract: A method and system for amplifying optical signals includes generating idler signals for input signals using a pump signal at a first non-linear element (NLE). Phase and amplitude regulation is performed using the output from the first NLE. Optical power monitoring of the input signals may be used for power equalization. The phase regulation may use input from a feed forward phase-power monitoring of the output phase-sensitive amplified signal. After phase regulation the phase-sensitive amplified signal is generated at a second NLE using the pump signal. 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: September 5, 2014
    Date of Patent: January 26, 2016
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Yoichi Akasaka, Motoyoshi Sekiya
  • Patent number: 9030730
    Abstract: A method for amplifying optical signals includes determining a source optical signal, generating a first resultant signal including a pump signal and the source optical signal, sending the first resultant signal through a non-linear element to generate a second resultant signal including the first resultant signal and an idler signal, and sending the second resultant signal through a non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal, the pump signal, and the idler signal. The method also includes filtering the third resultant signal to remove the pump signal and the idler signal and outputting the amplified source optical signal.
    Type: Grant
    Filed: January 14, 2013
    Date of Patent: May 12, 2015
    Assignee: Fujitsu Limited
    Inventors: Jeng-Yuan Yang, Motoyoshi Sekiya, Yoichi Akasaka
  • Publication number: 20140198375
    Abstract: A method for amplifying optical signals includes determining a source optical signal, generating a first resultant signal including a pump signal and the source optical signal, sending the first resultant signal through a non-linear element to generate a second resultant signal including the first resultant signal and an idler signal, and sending the second resultant signal through a non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal, the pump signal, and the idler signal. The method also includes filtering the third resultant signal to remove the pump signal and the idler signal and outputting the amplified source optical signal.
    Type: Application
    Filed: January 14, 2013
    Publication date: July 17, 2014
    Applicant: FUJITSU LIMITED
    Inventors: Jeng-Yuan Yang, Motoyoshi Sekiya, Yoichi Akasaka
  • Patent number: 7684706
    Abstract: In accordance with the teachings of the present invention, a system and method for traffic distribution in an optical network is provided. In a particular embodiment, a traffic distribution module in a passive optical network (PON), includes a filter configured to receive downstream traffic in a first set of one or more wavelengths and a second set of one or more wavelengths from an optical line terminal (OLT), direct the traffic in the first set of wavelengths to a primary power splitter, and direct the traffic in the second set of wavelengths to a first connector. The traffic distribution module also includes a primary power splitter and a plurality of secondary power splitters. The primary power splitter is configured to receive the traffic in the first set of wavelengths and distribute the traffic in the first set to the plurality of secondary power splitters coupled to the primary power splitter such that optical network units (ONUs) in the PON receive the traffic in the first set of wavelengths.
    Type: Grant
    Filed: June 27, 2006
    Date of Patent: March 23, 2010
    Assignee: Fujitsu Limited
    Inventors: Yoichi Akasaka, Martin Bouda, Takao Naito
  • Publication number: 20070092249
    Abstract: In accordance with the teachings of the present invention, a system and method for traffic distribution in an optical network is provided. In a particular embodiment, a traffic distribution module in a passive optical network (PON), includes a filter configured to receive downstream traffic in a first set of one or more wavelengths and a second set of one or more wavelengths from an optical line terminal (OLT), direct the traffic in the first set of wavelengths to a primary power splitter, and direct the traffic in the second set of wavelengths to a first connector. The traffic distribution module also includes a primary power splitter and a plurality of secondary power splitters. The primary power splitter is configured to receive the traffic in the first set of wavelengths and distribute the traffic in the first set to the plurality of secondary power splitters coupled to the primary power splitter such that optical network units (ONUs) in the PON receive the traffic in the first set of wavelengths.
    Type: Application
    Filed: June 27, 2006
    Publication date: April 26, 2007
    Inventors: Yoichi Akasaka, Martin Bouda, Takao Naito
  • Patent number: 4948742
    Abstract: Oxygen ions or nitrogen ions are implanted into a semiconductor substrate to form a dielectric layer in the semiconductor substrate. An epitaxial semiconductor layer of at least 2 .mu.m in thickness, having excellent reproducibility and good crystallinity, is formed on a residual semiconductor layer on the dielectric layer by epitaxial growth, to serve as a region for forming semiconductor elements. Thus, a semiconductor device having high isolation breakdown voltage is impemented.Further, both oxygen ions and nitrogen ions are respectively implanted into a portions of a semiconductor substrate, which are adjacent to each other along the direction of thickness, to form two dielectric layers. Thus, a semiconductor device having higher isolation breakdown voltage is implemented.
    Type: Grant
    Filed: November 20, 1989
    Date of Patent: August 14, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tadashi Nishimura, Yoichi Akasaka
  • Patent number: 4899206
    Abstract: Described is a semiconductor device comprising a metal wiring formed on a semiconductor wiring including a device or devices, wherein impurities are injected into the metal wiring by ion implantation for suppressing the whiskers that may otherwise develop during processing of the metal wiring. Shorting among the wiring layers caused by such whiskers may be suppressed and the yield rate and operational reliability of the semiconductor device may be improved.
    Type: Grant
    Filed: April 1, 1985
    Date of Patent: February 6, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hiromi Sakurai, Yoichi Akasaka
  • Patent number: 4797723
    Abstract: A stacked semiconductor device includes a first integrated circuit formed on the principal surface of a semiconductor layer and containing active elements, and a second integrated circuit formed on the first integrated circuit through an insulation layer and containing active elements. The second integrated circuit is formed on that part of the surface of the first integrated circuit which is exclusive of selected active elements, to establish an open space for heat dissipation.
    Type: Grant
    Filed: September 8, 1987
    Date of Patent: January 10, 1989
    Assignee: Mitsubishi Denki, K.K.
    Inventors: Tadashi Nishimura, Yoichi Akasaka
  • Patent number: 4454166
    Abstract: A nitride film is formed on a main surface of a semiconductor substrate by plasma CVD process and an oxygen-containing layer is formed on the nitride film and an aluminum-containing film is further formed on the oxygen-containing layer.
    Type: Grant
    Filed: January 3, 1983
    Date of Patent: June 12, 1984
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Haruhiko Abe, Hiroshi Harada, Shigeji Kinoshita, Yoshihiro Hirata, Masahiko Denda, Yoichi Akasaka
  • Patent number: 4448632
    Abstract: A method of manufacturing a semiconductor device utilizing a monocrystalline silicon layer includes forming and irradiating a polycrystalline silicon layer to increase the grain size thereof, and forming an epitaxial layer thereover. Both layers are then irradiated to convert them into high quality monocrystalline silicon.
    Type: Grant
    Filed: May 21, 1982
    Date of Patent: May 15, 1984
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Yoichi Akasaka
  • Patent number: 4441932
    Abstract: A process for preparing a semiconductor device having a walled emitter structure covering at least one side surface with a dielectric layer for separation of devices comprises a step of forming a base by implantation of ions with a resist mask for base; a step of forming an emitter by implantation of ions from an emitter-opening part; and a step of formation an active base in a base just below said emitter by implantation of ions from said emitter-opening part.
    Type: Grant
    Filed: March 11, 1982
    Date of Patent: April 10, 1984
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yoichi Akasaka, Katsuhiro Tsukamoto