Patents by Inventor Munefumi Tsurusawa
Munefumi Tsurusawa 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: 6728019Abstract: An optical gate according to the invention comprises a polarization divider to divide an optical signal into two orthogonal polarization components and to output them as a first polarization component which precedes in the time base and a second polarization component which follows the first one in the time base; a semiconductor optical amplifier to modulate the phase of the second polarization component output from the polarization divider according to a control light; an assist light supplier to supply to the semiconductor optical amplifier an assist light to help the recovery of the refractive index variation of the semiconductor optical amplifier caused by the control light; a polarization combiner to combine the first and second polarization components of the optical signal transmitting on the semiconductor optical amplifier so as to adjust them in the same time location; and a polarization extractor to extract a predetermined polarization direction component from the output from the polarization combineType: GrantFiled: July 2, 2001Date of Patent: April 27, 2004Assignee: KDD Submarine Cable Systems Inc.Inventors: Masashi Usami, Kosuke Nishimura, Munefumi Tsurusawa
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Patent number: 6377388Abstract: An optical signal processor is disclosed comprising a first optical path having a first electroabsorption optical modulator to be applied with a constant voltage and to absorb light of a signal wavelength, a second optical path having a fixed phase relation with the first optical path relative to a probe wavelength, a probe light introducer for dividing probe light of the probe wavelength into two portions and feeding them respectively into the first and second optical paths, an original signal light introducer for introducing original signal light of the signal wavelength into the first electroabsorption optical modulator, and a combiner for combining both light of the probe wavelength passed through the first and second paths.Type: GrantFiled: November 20, 2000Date of Patent: April 23, 2002Assignees: DDI Corporation, KDD Submarine Cable Systems Inc.Inventors: Haruhisa Sakata, Kosuke Nishimura, Masashi Usami, Munefumi Tsurusawa
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Publication number: 20020003650Abstract: An optical gate according to the invention comprises a polarization divider to divide an optical signal into two orthogonal polarization components and to output them as a first polarization component which precedes in the time base and a second polarization component which follows the first one in the time base; a semiconductor optical amplifier to modulate the phase of the second polarization component output from the polarization divider according to a control light; an assist light supplier to supply to the semiconductor optical amplifier an assist light to help the recovery of the refractive index variation of the semiconductor optical amplifier caused by the control light; a polarization combiner to combine the first and second polarization components of the optical signal transmitting on the semiconductor optical amplifier so as to adjust them in the same time location; and a polarization extractor to extract a predetermined polarization direction component from the output from the polarization combineType: ApplicationFiled: July 2, 2001Publication date: January 10, 2002Inventors: Masashi Usami, Kosuke Nishimura, Munefumi Tsurusawa
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Publication number: 20010012430Abstract: A nonlinear optical element is disclosed for reducing intensity noise of both mark level and space level, and being stable, miniaturized and low-priced. Signal light enters a semiconductor waveguide layer (14). The semiconductor waveguide layer (14) has a band gap wavelength shorter than a wavelength of the signal light. A diffraction grating (12), having a Bragg wavelength close to the wavelength of the signal light, is disposed adjacent to the semiconductor waveguide layer (14). DC voltage is applied to the semiconductor waveguide layer (14).Type: ApplicationFiled: February 5, 2001Publication date: August 9, 2001Inventors: Masashi Usami, Hideaki Tanaka, Kosuke Nishimura, Munefumi Tsurusawa, Haruhisa Sakata
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Patent number: 6091536Abstract: An optical processor comprising, a semiconductor saturable absorber; a current source for injecting a current to the semiconductor saturable absorber; a signal light introducer for introducing a signal light to the saturable absorber; a control light introducer for introducing a control light having a wavelength not longer than the wavelength of the signal light into the semiconductor saturable absorber; an assist light introducer for introducing an assist light having a wavelength longer than the wavelength of the signal light into the semiconductor saturable absorber; and a signal light extractor for extracting the signal light after treatment by the semiconductor saturable absorber.Type: GrantFiled: December 16, 1998Date of Patent: July 18, 2000Assignee: KDD CorporationInventors: Masashi Usami, Munefumi Tsurusawa, Yuichi Matsushima
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Patent number: 5912911Abstract: An optical short pulse reshaping device capable of effectively eliminating noise from or reshaping of input optical short pulses of a pulse width of picosecond order shorter than a carrier life time. The device comprises: a semiconductor laser element, means for injecting an electric current to the semiconductor laser element for obtaining an oscillation state of the semiconductor laser element, means for injecting into the semiconductor laser element input optical short pulses of a wavelength shorter than that of the oscillation light of said semiconductor laser element, and means for taking out optical short pulses emitted from the semiconductor laser element in distinction from its oscillation output light.Type: GrantFiled: May 28, 1997Date of Patent: June 15, 1999Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Masashi Usami, Munefumi Tsurusawa, Yuichi Matsushima
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Patent number: 5805327Abstract: There is disclosed a reshaping device for optical short pulses to effectively perform reshaping of and eliminate noise from an optical short pulse of a pulse width of pico second order less than a carrier life time. Input optical short pulses are applied to a saturable absorption element, while an assist light of a wavelength longer than that of the input optical signal pulses is also applied to the saturable absorption element to accelerate, by stimulated emission, recombination of excited electrons and holes produced in the saturable absorption element in response to the input optical signal pulses, so that the input optical signal pulses reshaped are derived from the saturable absorption element.Type: GrantFiled: May 21, 1996Date of Patent: September 8, 1998Assignee: Kokusai Denshin Denwa Kabushiki KaishaInventors: Masashi Usami, Yuichi Matsushima, Munefumi Tsurusawa