Patents by Inventor Osamu Aso
Osamu Aso 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).
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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
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Patent number: 7769298Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.Type: GrantFiled: September 25, 2008Date of Patent: August 3, 2010Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
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Publication number: 20090092400Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.Type: ApplicationFiled: September 25, 2008Publication date: April 9, 2009Applicant: THE FURUKAWA ELECTRIC CO., LTDInventors: Koji IGARASHI, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
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Patent number: 7447444Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.Type: GrantFiled: May 23, 2005Date of Patent: November 4, 2008Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
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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
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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
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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
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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
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Patent number: 7155095Abstract: The present invention provides a method for generating four-wave mixing to obtain idler light with high efficiency, in which the range of lengths of an optical fiber is appropriately set, and probe light and pumping light, having different frequencies, are launched into the optical fiber. When the nonlinear coefficient of the optical fiber, the loss per unit distance, and the wavelength and intensity of the probe light and pumping light are set to certain values, the idler light conversion efficiency at the output end of the optical fiber is a periodic function of an optical fiber having a maximal value and a minimal value. The maximum length of the optical fiber to be used to obtain four-wave mixing is set to be equal to or less than the length Lmax (Lmax=Lm+?L) which is given by adding the length of the optical fiber Lm, at which the idler light conversion efficiency takes on the first maximal value in the aforementioned periodic function and distance ?L or 10% of L.Type: GrantFiled: December 31, 2002Date of Patent: December 26, 2006Assignee: Furukawa Electric Co., Ltd.Inventors: Osamu Aso, Masateru Tadakuma, Shu Namiki
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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
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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
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Patent number: 7061664Abstract: A wavelength converter using difference frequency generation (DFG) is disclosed. In one embodiment, the wavelength converter comprises (a) a first optical filter configured to filter out one or more lightwaves requiring wavelength conversion from wavelength-division multiplexed (WDM) lightwaves, and (b) a broadband multi-channel simultaneous wavelength conversion portion comprising a pump source that generates pump light for use in the process of the DFG, a first optical combiner for combining said pump light with said filtered lightwaves, a high non-linear medium configured to generate wavelength converted lightwaves from said filtered lightwaves using the DFG, and a second optical filter for filtering said wavelength converted from said filtered lightwaves.Type: GrantFiled: October 17, 2003Date of Patent: June 13, 2006Assignee: The Furukawa Electric Co., Ltd.Inventors: Osamu Aso, Shu Namiki, Kouki Sato, Hijiri Nimura
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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
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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
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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
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Publication number: 20060002715Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.Type: ApplicationFiled: May 23, 2005Publication date: January 5, 2006Applicant: THE FURUKAWA ELECTRIC CO., LTD.Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
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Patent number: 6920263Abstract: An optical pulse generator comprises a comb-like dispersion profiled fiber formed into an optical loop mirror. The fiber may comprise three or more segments of fiber having alternating highly dispersive and highly nonlinear characteristics. The optical loop mirror construction splits an input pulse into two portions that propagate through the CDPF in opposite directions. The pulse portions are re-combined, and a compressed pulse with reduced noise is produced.Type: GrantFiled: January 24, 2002Date of Patent: July 19, 2005Assignee: The Furukawa Electric Company, Ltd.Inventors: Masateru Tadakuma, Osamu Aso, Shunichi Matsushita, Misao Sakano, Shu Namiki
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Patent number: 6892015Abstract: A waveform converter for altering the waveform and optical spectrum of an optical signal may comprise a nonlinear element having a nonlinear effect on optical pulses, a dispersion element having a dispersion effect on optical pulses, and a wavelength selecting element configured to select spectral components in a desired wavelength region.Type: GrantFiled: January 23, 2002Date of Patent: May 10, 2005Assignee: The Furukawa Electric Company, Ltd.Inventors: Masateru Tadakuma, Osamu Aso, Misao Sakano
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Publication number: 20050058417Abstract: 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: ApplicationFiled: April 27, 2004Publication date: March 17, 2005Inventors: Masateru Tadakuma, Yu Mimura, Misao Sakano, Osamu Aso, Takeshi Nakajima, Katsutoshi Takahashi
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Patent number: 6831775Abstract: A wavelength converting method and apparatus which converts wavelength division multiplexed (WDM) signal light, having a plurality of channels, by four-wave mixing the WDM signal light with at least one pump lightwave. Wavelength conversion of the WDM signal is accomplished without producing noise by FWM the WDM signal with a pump lightwave, wherein the pump lightwave frequency is separated from the WDM signal by an interval equal to or greater than the bandwidth of the WDM signal. Two pump lightwaves can be used instead of one, wherein one of the pump lightwaves has a frequency on one side of the bandwidth of the WDM signal, and the average frequency of the two pump lightwaves is on the other side of the WDM signal bandwidth.Type: GrantFiled: January 17, 2002Date of Patent: December 14, 2004Assignee: The Furukawa Electric Co., Ltd.Inventors: Shunichi Matsushita, Osamu Aso, Misao Sakano