Patents by Inventor Misao Sakano
Misao Sakano 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: 8494378Abstract: A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.Type: GrantFiled: July 6, 2007Date of Patent: July 23, 2013Assignees: Japan Science and Technology Agency, The Furukawa Electric Co., Ltd.Inventors: Shigehiro Takasaka, Yasuyuki Ozeki, Misao Sakano
-
Patent number: 7869014Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: GrantFiled: February 12, 2008Date of Patent: January 11, 2011Assignee: The Furukawa Electric Co., Ltd.Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Publication number: 20090208200Abstract: A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.Type: ApplicationFiled: July 6, 2007Publication date: August 20, 2009Applicants: JAPAN SCIENCE AND TECHNOLOGY AGENCY, THE FURUKAWA ELECTRIC CO., LTD.Inventors: Shigehiro Takasaka, Yasuyuki Ozeki, Misao Sakano
-
Patent number: 7567378Abstract: A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.Type: GrantFiled: February 25, 2008Date of Patent: July 28, 2009Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Fujimura, Masami Ikeda, Misao Sakano
-
Method and apparatus for controlling multiple-wavelength-pumped Raman amplifier and computer product
Patent number: 7535629Abstract: An apparatus, method and computer program product for controlling pumping light powers for a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources, by measuring gain wavelength characteristic or signal-power wavelength characteristic of the multiple-wavelength-pumped Raman amplifier using a plurality of photodetectors having different wavelength-sensitivity characteristics. The apparatus includes a determining unit that estimates a power of each of signal channels in a wavelength band for use based on values monitored by the photodetectors, and determines the pumping light powers using the power of each of the signal channels estimated. The determining unit estimates the power of each of the signal channels by performing an interpolation of the values monitored by the photodetectors.Type: GrantFiled: July 3, 2007Date of Patent: May 19, 2009Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Fujimura, Misao Sakano, Takeshi Nakajima, Shu Namiki -
Publication number: 20080225276Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: ApplicationFiled: February 12, 2008Publication date: September 18, 2008Applicant: The Furukawa Electric Co., Ltd.Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Patent number: 7424191Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: GrantFiled: October 13, 2006Date of Patent: September 9, 2008Assignee: The Furukawa Electric Co., Ltd.Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Patent number: 7408701Abstract: A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as a an inexpensive light source producing a plurality of optical frequencies.Type: GrantFiled: April 20, 2006Date of Patent: August 5, 2008Assignee: The Furukawa Electric Co., Ltd.Inventors: Osamu Aso, Shunichi Matushita, Misao Sakano, Masateru Tadakuma
-
Publication number: 20080170290Abstract: A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.Type: ApplicationFiled: February 25, 2008Publication date: July 17, 2008Applicant: THE FURUKAWA ELECTRIC CO., LTD.Inventors: Koji Fujimura, Masami Ikeda, Misao Sakano
-
Patent number: 7355786Abstract: A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.Type: GrantFiled: March 27, 2006Date of Patent: April 8, 2008Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Fujimura, Masami Ikeda, Misao Sakano
-
METHOD AND APPARATUS FOR CONTROLLING MULTIPLE-WAVELENGTH-PUMPED RAMAN AMPLIFIER AND COMPUTER PRODUCT
Publication number: 20080040057Abstract: A multiple-wavelength-pumped Raman amplifier includes a control unit that controls, based on a relational expression associating an amount of fluctuation in a current signal light power at a signal input end, an amount of fluctuation in a current pumping light power at a pumping light input end, an amount of fluctuation in the current signal power at a signal output end, and an amount of fluctuation in the current pumping light power at a pumping light output end, two fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression.Type: ApplicationFiled: July 3, 2007Publication date: February 14, 2008Applicant: The Furukawa Electric Co, Ltd.Inventors: Koji Fujimura, Misao Sakano, Takeshi Nakajima, Shu Namiki -
Method and apparatus for controlling multiple-wavelength-pumped raman amplifier and computer product
Patent number: 7262903Abstract: A multiple-wavelength-pumped Raman amplifier includes a control unit that controls, based on a relational expression associating an amount of fluctuation in a current signal light power at a signal input end, an amount of fluctuation in a current pumping light power at a pumping light input end, an amount of fluctuation in the current signal power at a signal output end, and an amount of fluctuation in the current pumping light power at a pumping light output end, two fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression.Type: GrantFiled: August 29, 2005Date of Patent: August 28, 2007Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Fujimura, Misao Sakano, Takeshi Nakajima, Shu Namiki -
Publication number: 20070035722Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: ApplicationFiled: October 13, 2006Publication date: February 15, 2007Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Patent number: 7146085Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: GrantFiled: October 13, 2005Date of Patent: December 5, 2006Assignee: The Furukawa Electric Co., Ltd.Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Publication number: 20060193034Abstract: A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.Type: ApplicationFiled: March 27, 2006Publication date: August 31, 2006Applicant: THE FURUKAWA ELECTRIC CO., LTD.Inventors: Koji Fujimura, Masami Ikeda, Misao Sakano
-
Publication number: 20060193032Abstract: A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as a an inexpensive light source producing a plurality of optical frequencies.Type: ApplicationFiled: April 20, 2006Publication date: August 31, 2006Applicant: THE FURUKAWA ELECTRIC CO., LTD.Inventors: Osamu Aso, Shunichi Matushita, Misao Sakano, Masateru Tadakuma
-
Patent number: 7057800Abstract: A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.Type: GrantFiled: April 1, 2005Date of Patent: June 6, 2006Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Fujimura, Masami Ikeda, Misao Sakano
-
Patent number: 7054057Abstract: A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as an inexpensive light source producing a plurality of optical frequencies.Type: GrantFiled: March 27, 2002Date of Patent: May 30, 2006Assignee: The Furukawa Electric Co., Ltd.Inventors: Osamu Aso, Shunichi Matushita, Misao Sakano, Masateru Tadakuma
-
Patent number: 7003202Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of thee optical fiber are simultaneously specified.Type: GrantFiled: April 27, 2004Date of Patent: February 21, 2006Assignee: The Furukawa Electric Co., Ltd.Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
-
Publication number: 20060029342Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.Type: ApplicationFiled: October 13, 2005Publication date: February 9, 2006Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi