Patents by Inventor Miki Takeda
Miki Takeda 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: 8699126Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: October 25, 2012Date of Patent: April 15, 2014Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 8320040Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: July 6, 2011Date of Patent: November 27, 2012Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20110262140Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: July 6, 2011Publication date: October 27, 2011Applicant: Fujitsu LimitedInventors: Yasushi SUGAYA, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 8004752Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: March 24, 2009Date of Patent: August 23, 2011Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20090225403Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: March 24, 2009Publication date: September 10, 2009Inventors: Yasushi SUGAYA, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 7474459Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first-light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: September 6, 2002Date of Patent: January 6, 2009Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20070165299Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level.Type: ApplicationFiled: March 29, 2007Publication date: July 19, 2007Applicant: Fujitsu LimitedInventors: Yasushi SUGAYA, Miki TAKEDA, Susumu KINOSHITA, Terumi CHIKAMA
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Patent number: 7224517Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: March 4, 2002Date of Patent: May 29, 2007Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20030002140Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first-light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: September 6, 2002Publication date: January 2, 2003Applicant: FUJITSU LIMITEDInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 6480329Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: December 28, 2000Date of Patent: November 12, 2002Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20020093726Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: March 4, 2002Publication date: July 18, 2002Applicant: FUJITSU LIMITEDInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 6400499Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: January 18, 2001Date of Patent: June 4, 2002Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 6369938Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: June 24, 1999Date of Patent: April 9, 2002Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20010046084Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: March 5, 2001Publication date: November 29, 2001Inventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Publication number: 20010026395Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: ApplicationFiled: March 5, 2001Publication date: October 4, 2001Inventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama
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Patent number: 6172801Abstract: There is disclosed a technique regarding an optical amplifier in an optical communications system. In order to effectively suppress optical surges during amplification of signal light, through a simple structure, there is provided an amplifying medium which amplifies input light and outputs the amplified light, and reflecting members are connected to the input and output sides of the amplifying medium. The reflecting members can reflect light with a predetermined optical wavelength different from a signal light wavelength contained in the input light.Type: GrantFiled: September 9, 1997Date of Patent: January 9, 2001Assignee: Fujitsu LimitedInventors: Miki Takeda, Susumu Kinoshita
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Patent number: 6151158Abstract: A device comprising an optical amplifier including an optical amplifying medium, and first and second optical filters operatively connected to the optical amplifier to suppress the wavelength dependence of gain. The medium has an input end and an output end for an optical signal. The medium is pumped so that it provides a gain band. The gain band includes a first band giving a relatively high gain and noise figure to the optical signal and a second band giving a relatively low gain and noise figure to the optical signal. The first optical filter is connected to the input end of the medium and has characteristics such that the first optical filter suppresses the wavelength dependence of gain in the second band. The second optical filter is connected to the output end of the medium and has characteristics such that the second optical filter suppresses the wavelength dependence of gain in the first band.Type: GrantFiled: December 30, 1997Date of Patent: November 21, 2000Assignee: Fujitsu LimitedInventors: Miki Takeda, Susumu Kinoshita, Hiroshi Onaka
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Patent number: 6134046Abstract: An optical amplifying fiber including a core doped with a rare earth element and having a first refractive index, a cladding surrounding the core and having a second refractive index smaller than the first refractive index, and a fiber grating formed in the core for transmitting signal light having a first wavelength and pump light having a second wavelength and removing amplified spontaneous emission. The fiber grating is preferably positioned upstream of a middle point of the entire length of the optical amplifying fiber in terms of a propagation direction of signal light.Type: GrantFiled: March 16, 1998Date of Patent: October 17, 2000Assignee: Fujitsu LimitedInventors: Norifumi Shukunami, Shinya Inagaki, Miki Takeda
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Patent number: 6055092Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second-stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.Type: GrantFiled: May 28, 1996Date of Patent: April 25, 2000Assignee: Fujitsu LimitedInventors: Yasushi Sugaya, Miki Takeda, Susumu Kinoshita, Terumi Chikama