Patents by Inventor Junichi Kumasako
Junichi Kumasako 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: 7936993Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: GrantFiled: December 30, 2009Date of Patent: May 3, 2011Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Patent number: 7751706Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: GrantFiled: November 10, 2008Date of Patent: July 6, 2010Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Publication number: 20100135664Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: ApplicationFiled: December 30, 2009Publication date: June 3, 2010Applicant: FUJITSU LIMITEDInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Publication number: 20090080894Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: ApplicationFiled: November 10, 2008Publication date: March 26, 2009Applicant: FUJITSU LIMITEDInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Patent number: 7466920Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: GrantFiled: February 12, 2003Date of Patent: December 16, 2008Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Publication number: 20080260331Abstract: A lens 39 is molded in one of the surfaces of a support plate 33, and a lens is molded in one of the surfaces of a support plate 35. The support plate 33 is integrated with the support plate 35 with a filter 34 sandwiched between the other surfaces of the support plates 33 and 35. In the support plates 33 and 35, seal portions 38 and 40 are formed to have a height larger than a lens thickness, so as to surround lenses 39 and 41. A spacer 31 is bonded to the seal portion 38 of the support plate 33 with an adhesive agent, and a spacer 37 is bonded to the seal portion 40 of the support plate 35 with an adhesive agent. To both end faces of the optical multiplexer/demultiplexer 301 thus formed, fiber arrays 42 and 43 are coupled respectively to form an optical multiplexing/demultiplexing module 401.Type: ApplicationFiled: January 20, 2006Publication date: October 23, 2008Applicant: OMRON CorporationInventors: Homare Takeda, Koichi Furusawa, Junichi Kumasako, Xiangquan Zhang
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Patent number: 7372622Abstract: In a WDM transmission system employing a plurality of short wavelength bands having great attenuation due to optical fiber transmission, an optical repeater is constructed of a first multiplexing section and a second multiplexing section. The first multiplexing section is used for wavelength-multiplexing both the excitation light from a first Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The second multiplexing section is used for wavelength-multiplexing both the excitation light from a second Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The first and second multiplexing sections are provided between the optical fibers disposed between end offices. Thus an equal and satisfactory optical SN ratio even at any band are obtained.Type: GrantFiled: March 27, 2006Date of Patent: May 13, 2008Assignee: Fujitsu LimitedInventors: Kentaro Nakamura, Takafumi Terahara, Rainer Hainberger, Junichi Kumasako
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Publication number: 20080074733Abstract: The present invention relates to a Raman amplifier where flexibility in device design considering both of Raman amplification and dispersion compensation is high. In the Raman amplifier, the Raman amplification optical fiber included in the optical amplification section and the dispersion compensating optical fiber included in the dispersion compensation section are arranged while being optically connected to each other. Since the optical amplification section and the dispersion compensation section are provided as independent optical devices, one device can be designed without being restricted to the design conditions of the other device.Type: ApplicationFiled: November 7, 2007Publication date: March 27, 2008Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.Inventors: Tetsufumi Tsuzaki, Motoki Kakui, Takafumi Terahara, Junichi Kumasako
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Patent number: 7307782Abstract: The present invention relates to a Raman amplifier where flexibility in device design considering both of Raman amplification and dispersion compensation is high. In the Raman amplifier, the Raman amplification optical fiber included in the optical amplification section and the dispersion compensating optical fiber included in the dispersion compensation section are arranged while being optically connected to each other. Since the optical amplification section and the dispersion compensation section are provided as independent optical devices, one device can be designed without being restricted to the design conditions of the other device.Type: GrantFiled: July 31, 2002Date of Patent: December 11, 2007Assignees: Sumitomo Electric Industries, Ltd., Fujitu LimitedInventors: Tetsufumi Tsuzaki, Motoki Kakui, Takafumi Terahara, Junichi Kumasako
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Publication number: 20060176545Abstract: In a WDM transmission system employing a plurality of short wavelength bands having great attenuation due to optical fiber transmission, an optical repeater is constructed of a first multiplexing section and a second multiplexing section. The first multiplexing section is used for wavelength-multiplexing both the excitation light from a first Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The second multiplexing section is used for wavelength-multiplexing both the excitation light from a second Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The first and second multiplexing sections are provided between the optical fibers disposed between end offices. Thus an equal and satisfactory optical SN ratio even at any band are obtained.Type: ApplicationFiled: March 27, 2006Publication date: August 10, 2006Applicant: FUJITSU LIMITEDInventors: Kentaro Nakamura, Takafumi Terahara, Rainer Hainberger, Junichi Kumasako
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Patent number: 7075709Abstract: In a WDM transmission system employing a plurality of short wavelength bands having great attenuation due to optical fiber transmission, an optical repeater is constructed of a first multiplexing section and a second multiplexing section. The first multiplexing section is used for wavelength-multiplexing both the excitation light from a first Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The second multiplexing section is used for wavelength-multiplexing both the excitation light from a second Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The first and second multiplexing sections are provided between the optical fibers disposed between end offices. Thus an equal and satisfactory optical SN ratio even at any band are obtained.Type: GrantFiled: March 25, 2002Date of Patent: July 11, 2006Assignee: Fujitsu LimitedInventors: Kentaro Nakamura, Takafumi Terahara, Rainer Hainberger, Junichi Kumasako
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Patent number: 6941074Abstract: Different bands (C-band and L-band) are allotted respectively to an upstream optical signal and a downstream optical signal. In a transmission-path optical fiber for Raman amplification, the C-band optical signal is amplified by pumping light from a C-band pumping light source, and the L-band optical signal is amplified by pumping light from an L-band pumping light source. As a result of this configuration, the optical signals are Raman-amplified through backward pumping in both upstream and downstream directions, whereby negative effects, which could be exerted on the optical signals by forward pumping, can be avoided.Type: GrantFiled: March 8, 2001Date of Patent: September 6, 2005Assignee: Fujitsu LimitedInventors: Kentaro Nakamura, Takafumi Terahara, Junichi Kumasako, Rainer Hainberger
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Patent number: 6741389Abstract: The present invention aims at providing an optical transmission system for improving transmission characteristics, taking account of the nonlinear optical effect to be caused not only in an optical fiber transmission path wherein the distributed Raman amplification is performed but also in an amplifying medium wherein the discrete Raman amplification is performed, within an optical transmission device.Type: GrantFiled: March 11, 2002Date of Patent: May 25, 2004Assignee: Fujitsu LimitedInventors: Junichi Kumasako, Takafumi Terahara
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Publication number: 20030185568Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: ApplicationFiled: February 12, 2003Publication date: October 2, 2003Applicant: Fujitsu LimitedInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Publication number: 20030117693Abstract: In a WDM transmission system employing a plurality of short wavelength bands having great attenuation due to optical fiber transmission, an optical repeater is constructed of a first multiplexing section and a second multiplexing section. The first multiplexing section is used for wavelength-multiplexing both the excitation light from a first Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The second multiplexing section is used for wavelength-multiplexing both the excitation light from a second Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The first and second multiplexing sections are provided between the optical fibers disposed between end offices. Thus an equal and satisfactory optical SN ratio even at any band are obtained.Type: ApplicationFiled: March 25, 2002Publication date: June 26, 2003Applicant: FUJITSU LIMITEDInventors: Kentaro Nakamura, Takafumi Terahara, Rainer Hainberger, Junichi Kumasako
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Publication number: 20030099030Abstract: The present invention aims at providing an optical transmission system for improving transmission characteristics, taking account of the nonlinear optical effect to be caused not only in an optical fiber transmission path wherein the distributed Raman amplification is performed but also in an amplifying medium wherein the discrete Raman amplification is performed, within an optical transmission device.Type: ApplicationFiled: March 11, 2002Publication date: May 29, 2003Inventors: Junichi Kumasako, Takafumi Terahara
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Publication number: 20030063371Abstract: The present invention relates to a Raman amplifier where flexibility in device design considering both of Raman amplification and dispersion compensation is high. In the Raman amplifier, the Raman amplification optical fiber included in the optical amplification section and the dispersion compensating optical fiber included in the dispersion compensation section are arranged while being optically connected to each other. Since the optical amplification section and the dispersion compensation section are provided as independent optical devices, one device can be designed without being restricted to the design conditions of the other device.Type: ApplicationFiled: July 31, 2002Publication date: April 3, 2003Inventors: Tetsufumi Tsuzaki, Motoki Kakui, Takafumi Terahara, Junichi Kumasako
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Publication number: 20020051267Abstract: Different bands (C-band and L-band) are allotted respectively to an upstream optical signal and a downstream optical signal. In a transmission-path optical fiber for Raman amplification, the C-band optical signal is amplified by pumping light from a C-band pumping light source, and the L-band optical signal is amplified by pumping light from an L-band pumping light source. As a result of this configuration, the optical signals are Raman-amplified through backward pumping in both upstream and downstream directions, whereby negative effects, which could be exerted on the optical signals by forward pumping, can be avoided.Type: ApplicationFiled: March 8, 2001Publication date: May 2, 2002Inventors: Kentaro Nakamura, Takafumi Terahara, Junichi Kumasako, Rainer Hainberger