Patents by Inventor Keiko Sasaki

Keiko Sasaki 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: 7330303
    Abstract: A wavelength division multiplexed optical amplifier, enabling elimination of the problems of oscillation and fluctuation in output due to ASE at the time of a rapid change in the number of input wavelengths, provided with a first-stage optical amplifying unit, second-stage optical amplifying unit, a common AGC circuit for common AGC of the first and second optical amplifying units, and a pumping light distribution means for applying pumping light to the first and second-stage optical amplifying units with a predetermined distribution ratio.
    Type: Grant
    Filed: March 19, 2004
    Date of Patent: February 12, 2008
    Assignee: Fujitsu Limited
    Inventors: Takashi Sato, Kazunari Tsubaki, Tomoaki Takeyama, Keiko Sasaki, Shinya Inagaki
  • Publication number: 20070274725
    Abstract: In an optical transmission apparatus, optical power of each of wavelength contained in a wavelength multiplexing signal is measured, a measured value of the optical power of each wavelength is compared with a predetermined threshold value, a total value of the measured values of the optical power, which are equal to or larger than the threshold value, is calculated as a total value of signal beam power, and a total value of the measured values of the optical power, which are less then the threshold value, is calculated as a total value of ASE power. The number of the measured values of the optical power, which are equal to or larger than the threshold value, is calculated as a wavelength count of the signal beams contained in the wavelength multiplexing signal. A signal-to-ASE ratio is calculated from the total value of the signal beam power and the total value of the ASE power.
    Type: Application
    Filed: February 23, 2007
    Publication date: November 29, 2007
    Applicant: Fujitsu Limited
    Inventors: Tomoaki Takeyama, Keiko Sasaki, Shinichirou Muro, Etsuko Hayashi
  • Patent number: 7296940
    Abstract: An optical apparatus of the invention has a fusion splice portion where respective ends of two optical fibers each having a core, a cladding, and a UV coat portion provided on the outside of the cladding are fusion spliced, and a re-coat portion which re-coats a portion where the UV coat portion is removed in the vicinity of the fusion splice portion is formed using a material capable of absorbing light radiated from the fusion splice portion. As a result light which is radiated from the fusion splice portion can be reliably prevented from coupling into another optical fiber adjacent to an outside of the re-coat portion.
    Type: Grant
    Filed: October 19, 2006
    Date of Patent: November 20, 2007
    Assignee: Fujitsu Limited
    Inventors: Norifumi Shukunami, Hiroyuki Furukawa, Keiko Sasaki
  • Publication number: 20070229941
    Abstract: An optical amplifier of the present invention comprises: first and second optical amplifying sections connected in series to each other between an input port and an output port; a first variable optical attenuator arranged on a former stage of the first optical amplifying section; a second variable optical attenuator arranged between the first and second optical amplifying sections; an optical amplification control section that controls the first and second optical amplifying sections; and an optical attenuation control section that controls the first and second variable optical attenuators.
    Type: Application
    Filed: November 13, 2006
    Publication date: October 4, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Tomoaki Takeyama, Keiko Sasaki, Shinichirou Muro
  • Patent number: 7236294
    Abstract: A contrivance, if a WDM signal state changes, is to improve an optical transmission quality by compensating gain flatness. A first excitation control unit sets a first optical pumping light source unit to emit excitation power needed to get the same amplifying operating level of a first amplifying medium as at the time of a maximum wavelength count when allocating wavelengths after a change in wavelength count at an equal interval in a wavelength range. A wavelength allocation bias estimation unit compares a present monitor value of optical power after outputting of a gain equalizer 13 with wavelength equi-allocation power associated with the recognized wavelength count, and thus estimates a wavelength allocation bias occurred as a concomitant of the change in the wavelength count. A primary gradient calculation unit obtains a primary gradient quantity defines as a gain deviation from the wavelength allocation bias.
    Type: Grant
    Filed: March 2, 2005
    Date of Patent: June 26, 2007
    Assignee: Fujitsu Limited
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Yoshihito Onoda, Takashi Shimizu, Keiko Sasaki
  • Publication number: 20070087429
    Abstract: [Problem]A reaction disk capable of compact and inexpensive design of an automatic analyzer is provided so that the constituents in suspension such as blood sampled from a patient at a sick room or other place in a hospital can be analyzed immediately and quantitatively. [Means of Solution]A separation cell and a determination cell are formed in a same reaction disk so as to keep their upright position even during rotation of the both cells, the separation cell being formed to prevent poured suspension therein from flowing out during centrifugal separation, and a supernatant separated by centrifugation from the suspension contained in the separation cell being dispensed to the determination cell to analyze a target substance in the supernatant. [Selected Drawing] FIG.
    Type: Application
    Filed: December 7, 2004
    Publication date: April 19, 2007
    Inventors: Kazuhito Tanimoto, Keiko Sasaki, Masayoshi Hayashi, Hishiri Komiyama
  • Publication number: 20070041084
    Abstract: The present invention has an object to provide an optical amplifier capable of realizing a good response characteristic in a wide frequency band, even when a population inversion state is formed by a pumping light supplied to an optical amplification medium and an ASE light generated in the optical amplification medium. To this end, in the optical amplifier according to the present invention, a delayed phase matching fiber in which a first fiber whose response speed is relatively low is arranged on the input side and a second fiber whose response speed is relatively high is arranged on the output side, is used as the optical amplification medium doped with a rare-earth element.
    Type: Application
    Filed: October 26, 2006
    Publication date: February 22, 2007
    Applicant: Fujitsu Limited
    Inventors: Takashi Shimizu, Shinya Inagaki, Tomoaki Takeyama, Keiko Sasaki
  • Publication number: 20070036499
    Abstract: An optical apparatus of the invention has a fusion splice portion where respective ends of two optical fibers each having a core, a cladding, and a UV coat portion provided on the outside of the cladding are fusion spliced, and a re-coat portion which re-coats a portion where the UV coat portion is removed in the vicinity of the fusion splice portion is formed using a material capable of absorbing light radiated from the fusion splice portion. As a result light which is radiated from the fusion splice portion can be reliably prevented from coupling into another optical fiber adjacent to an outside of the re-coat portion.
    Type: Application
    Filed: October 19, 2006
    Publication date: February 15, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Norifumi Shukunami, Hiroyuki Furukawa, Keiko Sasaki
  • Patent number: 7139453
    Abstract: A dispersion compensator and method of dispersion compensation in which an input light is converted to a selected second wavelength, the converted light beam having the second wavelength is dispersion compensated in an amount dependent upon the second wavelength, and the compensated light beam having the second wavelength is converted to the first wavelength.
    Type: Grant
    Filed: June 22, 2004
    Date of Patent: November 21, 2006
    Assignee: Fujitsu Limited
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Keiko Sasaki
  • Patent number: 7136219
    Abstract: The present invention has an object to provide an optical amplifier capable of realizing a good response characteristic in a wide frequency band, even when a population inversion state is formed by a pumping light supplied to an optical amplification medium and an ASE light generated in the optical amplification medium. To this end, in the optical amplifier according to the present invention, a delayed phase matching fiber in which a first fiber whose response speed is relatively low is arranged on the input side and a second fiber whose response speed is relatively high is arranged on the output side, is used as the optical amplification medium doped with a rare-earth element.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: November 14, 2006
    Assignee: Fujitsu Limited
    Inventors: Takashi Shimizu, Shinya Inagaki, Tomoaki Takeyama, Keiko Sasaki
  • Patent number: 7085043
    Abstract: An optical amplifier of the invention comprises first and second optical amplification sections connected in a cascade manner between an input terminal and an output terminal. Optical isolators which block C-band ASE travelling in an opposite direction to L-band signal light, are inserted on the amplification medium of each of the optical amplification sections. A constant gain control section calculates the number of wavelengths based on the input power of signal light, and controls the pumping light power of each optical amplification section at a constant slope with respect to the number of wavelengths, so that the respective gains in the optical amplification sections corresponding to the number of wavelengths each become constant. As a result, it is possible to maintain flat gain wavelength characteristics even when receiving input of WDM light where the number of wavelengths varies rapidly over a wide range.
    Type: Grant
    Filed: January 31, 2005
    Date of Patent: August 1, 2006
    Assignee: Fujitsu Limited
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Keiko Sasaki
  • Publication number: 20060087723
    Abstract: An optical amplifier of the invention comprises first and second optical amplification sections connected in a cascade manner between an input terminal and an output terminal. Optical isolators which block C-band ASE travelling in an opposite direction to L-band signal light, are inserted on the amplification medium of each of the optical amplification sections. A constant gain control section calculates the number of wavelengths based on the input power of signal light, and controls the pumping light power of each optical amplification section at a constant slope with respect to the number of wavelengths, so that the respective gains in the optical amplification sections corresponding to the number of wavelengths each become constant. As a result, it is possible to maintain flat gain wavelength characteristics even when receiving input of WDM light where the number of wavelengths varies rapidly over a wide range.
    Type: Application
    Filed: January 31, 2005
    Publication date: April 27, 2006
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Keiko Sasaki
  • Publication number: 20050179992
    Abstract: The present invention has an object to provide an optical amplifier capable of realizing a good response characteristic in a wide frequency band, even when a population inversion state is formed by a pumping light supplied to an optical amplification medium and an ASE light generated in the optical amplification medium. To this end, in the optical amplifier according to the present invention, a delayed phase matching fiber in which a first fiber whose response speed is relatively low is arranged on the input side and a second fiber whose response speed is relatively high is arranged on the output side, is used as the optical amplification medium doped with a rare-earth element.
    Type: Application
    Filed: March 31, 2005
    Publication date: August 18, 2005
    Applicant: Fujitsu Limited
    Inventors: Takashi Shimizu, Shinya Inagaki, Tomoaki Takeyama, Keiko Sasaki
  • Publication number: 20050146782
    Abstract: A contrivance, if a WDM signal state changes, is to improve an optical transmission quality by compensating gain flatness. A first excitation control unit sets a first optical pumping light source unit to emit excitation power needed to get the same amplifying operating level of a first amplifying medium as at the time of a maximum wavelength count when allocating wavelengths after a change in wavelength count at an equal interval in a wavelength range. A wavelength allocation bias estimation unit compares a present monitor value of optical power after outputting of a gain equalizer 13 with wavelength equi-allocation power associated with the recognized wavelength count, and thus estimates a wavelength allocation bias occurred as a concomitant of the change in the wavelength count. A primary gradient calculation unit obtains a primary gradient quantity defines as a gain deviation from the wavelength allocation bias.
    Type: Application
    Filed: March 2, 2005
    Publication date: July 7, 2005
    Applicant: Fujitsu Limited
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Yoshihito Onoda, Takashi Shimizu, Keiko Sasaki
  • Publication number: 20050078358
    Abstract: A wavelength division multiplexed optical amplifier, enabling elimination of the problems of oscillation and fluctuation in output due to ASE at the time of a rapid change in the number of input wavelengths, provided with a first-stage optical amplifying unit, second-stage optical amplifying unit, a common AGC circuit for common AGC of the first and second optical amplifying units, and a pumping light distribution means for applying pumping light to the first and second-stage optical amplifying units with a predetermined distribution ratio.
    Type: Application
    Filed: March 19, 2004
    Publication date: April 14, 2005
    Applicant: FUJITSU LIMITED
    Inventors: Takashi Sato, Kazunari Tsubaki, Tomoaki Takeyama, Keiko Sasaki, Shinya Inagaki
  • Patent number: 6863829
    Abstract: For providing an anti-bacteria which is made from a natural material, therefore harmless if it is absorbed in the human body, can be produced in mass production with low cost, and shows a high anti-bacteria effect, the anti-bacteria agent is obtained by heating a shell in an atmosphere of inactive gas and burning the shell under the temperature which finally reaches 700° C.-2,500° C.
    Type: Grant
    Filed: August 12, 2002
    Date of Patent: March 8, 2005
    Assignee: Surfcera Co., Ltd.
    Inventors: Keiko Sasaki, Manabu Sasaki, Yukio Funai, Kasumi Koyama
  • Publication number: 20040258352
    Abstract: A dispersion compensator and method of dispersion compensation in which an input light is converted to a selected second wavelength, the converted light beam having the second wavelength is dispersion compensated in an amount dependent upon the second wavelength, and the compensated light beam having the second wavelength is converted to the first wavelength.
    Type: Application
    Filed: June 22, 2004
    Publication date: December 23, 2004
    Inventors: Tomoaki Takeyama, Shinya Inagaki, Keiko Sasaki
  • Patent number: 6738184
    Abstract: Optical signals (multi-wavelength light) are guided to an EDF. The EDF is supplied with pump light generated by a first and a second pump light sources. Dummy light is generated by a dummy light source and supplied to the EDF. The wavelength of the dummy light is shorter than a wavelength range in which the optical signals are allocated.
    Type: Grant
    Filed: September 12, 2001
    Date of Patent: May 18, 2004
    Assignee: Fujitsu Limited
    Inventors: Etsuko Hayashi, Yasushi Sugaya, Yoshihito Onoda, Keiko Sasaki
  • Patent number: 6738182
    Abstract: A signal light passes through an isolator, and is coupled by a coupler with a pump light from a pump light source. Then, the signal light passes through an ASE reflection filter, is amplified by an EDF, and is transmitted from an isolator. At this time, an ASE light having a predetermined wavelength among ASE lights that occur within the EDF and proceed to the ASE reflection filter is reflected and again input to the EDF. By setting the predetermined wavelength to a wavelength on the short wavelength side of an amplification band of the EDF, gain deviation occurring on the long wavelength side of the amplification band can be cancelled.
    Type: Grant
    Filed: July 13, 2001
    Date of Patent: May 18, 2004
    Assignee: Fujitsu Limited
    Inventors: Shinya Inagaki, Norifumi Shukunami, Manabu Watanabe, Hisashi Takamatsu, Keiko Sasaki, Tomoaki Takeyama, Yasushi Sugaya, Kaoru Moriya, Takashi Satou
  • Publication number: 20030039700
    Abstract: For providing an anti-bacteria which is made from a natural material, therefore harmless if it is absorbed in the human body, can be produced in mass production with low cost, and shows a high anti-bacteria effect, the anti-bacteria agent is obtained by heating a shell in an atmosphere of inactive gas and burning the shell under the temperature which finally reaches 700° C.-2,500° C.
    Type: Application
    Filed: August 12, 2002
    Publication date: February 27, 2003
    Applicant: ION CORPORATION CO., LTD.
    Inventors: Keiko Sasaki, Manabu Sasaki, Yukio Funai, Kasumi Koyama