Patents by Inventor Kosuke Komaki

Kosuke Komaki 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: 20070109630
    Abstract: Optical amplifier which can eliminate the need for an optical detection section before an external attenuating medium, can prevent SN degradation, and can reduce power required for pumping light. An attenuation amount detection section detects an amount of signal light attenuation caused by a variable optical attenuator and the external attenuating medium connected in series, by means of a front optical detection section provided before the variable optical attenuator and the external attenuating medium and a back optical detection section provided thereafter. An attenuation amount control section controls the variable optical attenuator such that the amount of signal light attenuation detected by the attenuation amount detection section is kept constant. A connection detection section detects a connection or disconnection of the external attenuating medium in accordance with the amount of signal light attenuation obtained when the amount of attenuation caused by the variable optical attenuator is minimized.
    Type: Application
    Filed: April 4, 2006
    Publication date: May 17, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Kosuke Komaki, Hiroyuki Itoh
  • Patent number: 7215464
    Abstract: Optical amplifier which can eliminate the need for an optical detection section before an external attenuating medium, can prevent SN degradation, and can reduce power required for pumping light. An attenuation amount detection section detects an amount of signal light attenuation caused by a variable optical attenuator and the external attenuating medium connected in series, by means of a front optical detection section provided before the variable optical attenuator and the external attenuating medium and a back optical detection section provided thereafter. An attenuation amount control section controls the variable optical attenuator such that the amount of signal light attenuation detected by the attenuation amount detection section is kept constant. A connection detection section detects a connection or disconnection of the external attenuating medium in accordance with the amount of signal light attenuation obtained when the amount of attenuation caused by the variable optical attenuator is minimized.
    Type: Grant
    Filed: April 4, 2006
    Date of Patent: May 8, 2007
    Assignee: Fujitsu Limited
    Inventors: Kosuke Komaki, Hiroyuki Itoh
  • Patent number: 7202997
    Abstract: An optical amplifier includes first and second optical amplifier units, a variable optical attenuator optically coupled between the first and second optical amplifier units, a first control unit to control gains of the first and second optical amplifier units based on an input of the first optical amplifier unit and an output of the second optical amplifier unit, and a second control unit to control an attenuation quantity of the variable optical attenuator based on the input and an output of the first optical amplifier unit and an input and the output of the second optical amplifier unit.
    Type: Grant
    Filed: November 17, 2003
    Date of Patent: April 10, 2007
    Assignee: Fujitsu Limited
    Inventors: Hiroshi Iizuka, Kosuke Komaki, Hiroyuki Itou
  • Patent number: 7145717
    Abstract: An optical amplifier that improves transmission quality by driving an excitation light source according to a change in the level of an input optical signal and by compensating for a change in the characteristics of the excitation light source. An optical amplification section includes an amplification medium doped with an active substance for optical amplification and an excitation light source for emitting excitation light. A constant-gain control section finds out target excitation light power to be set according to a change in the level of an input optical signal on the basis of a correlation between a gain and excitation light power to obtain a target gain, finds out a target drive signal for making the excitation light source emit the target excitation light power on the basis of a correlation between a drive signal for driving the excitation light source and excitation light power, and exercises constant-gain control over the optical amplification section by a feedforward control system.
    Type: Grant
    Filed: March 5, 2004
    Date of Patent: December 5, 2006
    Assignee: Fujitsu Limited
    Inventors: Masao Nakata, Kosuke Komaki, Yoshio Shimano
  • Patent number: 7038769
    Abstract: A monitoring method is realized which is capable of detecting the optical power characteristic of a pumping light source with high accuracy at the operation time of an optical amplifier, wherein the optical amplifier is capable of performing a pumping light control without affecting a signal light in the operation even when the number of signal light wavelengths is abruptly changed. To this end, a drive signal for the pumping light source is modulated at a frequency higher than a cut-off frequency of an EDF, and the power of a pumping light output form the pumping light source driven by the drive signal is measured so as to correspond to a drive condition of the pumping light source, to calculate a slope of an I-L characteristic of the pumping light source, which is used to correct a proportional factor of an AGC circuit.
    Type: Grant
    Filed: May 25, 2004
    Date of Patent: May 2, 2006
    Assignee: Fujitsu Limited
    Inventor: Kosuke Komaki
  • Patent number: 6977770
    Abstract: The optical amplifier according to the present invention includes a first optical amplifying unit, a second optical amplifying unit, a variable optical attenuator optically connected between the first and second optical amplifying units and a first control unit for controlling the gains of the first and second optical amplifying units according to an input to the first optical amplifying unit and an output from the second optical amplifying unit, and a second control unit for controlling the attenuation of the variable optical attenuator according to an input to and an output from the first optical amplifying unit and an input to and an output from the second optical amplifying unit.
    Type: Grant
    Filed: December 11, 2002
    Date of Patent: December 20, 2005
    Assignee: Fujitsu Limited
    Inventors: Kosuke Komaki, Hiroyuki Itou, Hiroshi Iizuka
  • Publication number: 20050128467
    Abstract: The present invention aims at realizing a monitoring method capable of detecting the optical power characteristic of a pumping light source with high accuracy at the operation time of an optical amplifier, and also providing an optical amplifier capable of performing a pumping light control without affecting a signal light in the operation even when the number of signal light wavelengths is abruptly changed. To this end, in the present optical amplifier, a drive signal for the pumping light source is modulated at a frequency higher than a cut-off frequency of an EDF, and the power of a pumping light output from the pumping light source driven by the drive signal is measured so as to correspond to a drive condition of the pumping light source, to calculate a slope of an I-L characteristic of the pumping light source without affecting the signal light to be amplified by the EDF.
    Type: Application
    Filed: May 25, 2004
    Publication date: June 16, 2005
    Applicant: Fujitsu Limited
    Inventor: Kosuke Komaki
  • Publication number: 20040174586
    Abstract: An optical amplifier that improves transmission quality by driving an excitation light source according to a change in the level of an input optical signal and by compensating for a change in the characteristics of the excitation light source. An optical amplification section includes an amplification medium doped with an active substance for optical amplification and an excitation light source for emitting excitation light. A constant-gain control section finds out target excitation light power to be set according to a change in the level of an input optical signal on the basis of a correlation between a gain and excitation light power to obtain a target gain, finds out a target drive signal for making the excitation light source emit the target excitation light power on the basis of a correlation between a drive signal for driving the excitation light source and excitation light power, and exercises constant-gain control over the optical amplification section by a feedforward control system.
    Type: Application
    Filed: March 5, 2004
    Publication date: September 9, 2004
    Applicant: Fujitsu Limited
    Inventors: Masao Nakata, Kosuke Komaki, Yoshio Shimano
  • Publication number: 20040100688
    Abstract: An optical amplifier includes first and second optical amplifier units, a variable optical attenuator optically coupled between the first and second optical amplifier units, a first control unit to control gains of the first and second optical amplifier units based on an input of the first optical amplifier unit and an output of the second optical amplifier unit, and a second control unit to control an attenuation quantity of the variable optical attenuator based on the input and an output of the first optical amplifier unit and an input and the output of the second optical amplifier unit.
    Type: Application
    Filed: November 17, 2003
    Publication date: May 27, 2004
    Inventors: Hiroshi Iizuka, Kosuke Komaki, Hiroyuki Itou
  • Publication number: 20030231379
    Abstract: The optical amplifier according to the present invention includes a first optical amplifying unit, a second optical amplifying unit, a variable optical attenuator optically connected between the first and second optical amplifying units and a first control unit for controlling the gains of the first and second optical amplifying units according to an input to the first optical amplifying unit and an output from the second optical amplifying unit, and a second control unit for controlling the attenuation of the variable optical attenuator according to an input to and an output from the first optical amplifying unit and an input to and an output from the second optical amplifying unit.
    Type: Application
    Filed: December 11, 2002
    Publication date: December 18, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Kosuke Komaki, Hiroyuki Itou, Hiroshi Iizuka