Patents by Inventor Hirofumi Shimomura
Hirofumi Shimomura 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: 7280470Abstract: Multiple working paths are established on each working rings and multiple protection paths are established on each of multiple protection rings. A working path on a first working ring spans across first and second nodes for signal transmission in a first direction of the ring, and a working path on a second working ring spans across the first and second nodes for signal transmission in a second, opposite direction of the ring. A protection path on a first protection ring spans across the first and second nodes for signal transmission in said second direction, and a protection path on a second protection ring spans across the first and second nodes for signal transmission in said first direction. The first and second nodes normally use the working paths, respectively. When one of the working paths fails, the first and second nodes use a corresponding protection path.Type: GrantFiled: September 3, 2003Date of Patent: October 9, 2007Assignee: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura
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Patent number: 7197246Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.Type: GrantFiled: August 27, 2002Date of Patent: March 27, 2007Assignee: NEC CorporationInventors: Hirofumi Shimomura, Seigo Takahashi, Naoya Henmi
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Patent number: 6895183Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.Type: GrantFiled: April 30, 2002Date of Patent: May 17, 2005Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi, Hitoshi Takeshita
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Patent number: 6809846Abstract: Disclosed is an optical switch for transmitting or shutting down an input light signal in accordance with a set switching state. The optical switch comprises first and second optical amplifiers connected in cascade. When an optical fiber amplifier comprising EDFs (11 and 12) and pumping sources (31 and 32) is used as the first and second optical amplifiers, the switching is accomplished by switching on or off the pumping sources (31 and 32) in accordance with control signals supplied from a control circuit (300). One input light signal can be dropped through a first optical branch (51) located on the input side of the optical switch, while another input light signal can be added through a second optical branch (53).Type: GrantFiled: November 26, 2003Date of Patent: October 26, 2004Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi
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Publication number: 20040114933Abstract: Disclosed is an optical switch for transmitting or shutting down an input light signal in accordance with a set switching state. The optical switch comprises first and second optical amplifiers connected in cascade. When an optical fiber amplifier comprising EDFs (11 and 12) and pumping sources (31 and 32) is used as the first and second optical amplifiers, the switching is accomplished by switching on or off the pumping sources (31 and 32) in accordance with control signals supplied from a control circuit (300). One input light signal can be dropped through a first optical branch (51) located on the input side of the optical switch, while another input light signal can be added through a second optical branch (53).Type: ApplicationFiled: November 26, 2003Publication date: June 17, 2004Applicant: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi
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Publication number: 20040057375Abstract: In a ring topology network, a number of nodes interconnect transmission links to form first and second working rings and first and second optical protection rings in a ring topology. Multiple working paths are established on each working ring and multiple protection paths are established on each protection ring corresponding to the working paths. A first working path spans across first and second nodes for transmission of a signal in a first direction of the ring topology, and a second working path of the second working ring spans across the first and second nodes for transmission of a signal in a second direction of the ring topology opposite to the first direction. A first protection path on the first protection ring spans across the first and second nodes for transmission of a signal in the second direction of the ring topology, and a second protection path of the second protection ring spans across the first and second nodes for transmission of a signal in the first direction of the ring topology.Type: ApplicationFiled: September 3, 2003Publication date: March 25, 2004Applicant: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura
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Patent number: 6657952Abstract: In a ring topology network, a number of nodes interconnect transmission links to form first and second working rings and first and second optical protection rings in a ring topology. Multiple working paths are established on each working ring and multiple protection paths are established on each protection ring corresponding to the working paths. A first working path spans across first and second nodes for transmission of a signal in a first direction of the ring topology, and a second working path of the second working rings spans across the first and second nodes for transmission of a signal in a second direction of the ring topology opposite to the first direction. A first protection path on the first protection ring spans across the first and second nodes for transmission of a signal in the second direction of the ring topology, and a second protection path of the second protection ring spans across the first and second nodes for transmission of a signal in the first direction of the ring topology.Type: GrantFiled: November 27, 1998Date of Patent: December 2, 2003Assignee: NEC CorporationInventors: Tatsuya Shiragaki, Naoya Henmi, Makoto Nishio, Hitoshi Takeshita, Hirofumi Shimomura
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Patent number: 6538779Abstract: A signal quality monitoring method with reliability is disclosed. After extracting a clock signal from the light signal, a decision region is set for each bit of the light signal. The decision region is defined by a plurality of threshold amplitudes corresponding respectively to threshold phases which are produced with respect to the clock signal. The quality of the light signal is monitored depending on whether an amplitude of the light signal falls into the decision region at timings of the N threshold phases.Type: GrantFiled: June 14, 1999Date of Patent: March 25, 2003Assignee: NEC CorporationInventors: Hitoshi Takeshita, Hirofumi Shimomura, Tatsuya Shiragaki, Naoya Henmi
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Publication number: 20030048507Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.Type: ApplicationFiled: August 27, 2002Publication date: March 13, 2003Applicant: NEC CORPORATIONInventors: Hirofumi Shimomura, Seigo Takahashi, Naoya Henmi
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Patent number: 6466344Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmission of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.Type: GrantFiled: August 28, 2001Date of Patent: October 15, 2002Assignee: NEC CorporationInventors: Hirofumi Shimomura, Seigo Takahashi, Naoya Henmi
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Publication number: 20020131116Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=I˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.Type: ApplicationFiled: April 30, 2002Publication date: September 19, 2002Applicant: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi, Hitoshi Takeshita
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Publication number: 20020126372Abstract: Disclosed is an optical signal repeating and amplifying device which has: an optical amplifier which amplifies an optical signal to be input thereto and then outputs it; and an optical filter means through which only one wavelength light of the optical signal to be output from the optical amplifier is passed. Also disclosed is an optical level adjusting device which has: an optical demultiplexer which demultiplexes a wavelength-multiplexed optical signal into a plurality of wavelength lights; a plurality of optical attenuators which attenuate separately the demultiplexed plurality of wavelength lights to be output from the optical demultiplexer; and an optical multiplexer which multiplexes the attenuated wavelength lights to be output from the plurality of optical attenuators into a wavelength-multiplexed optical signal and output it.Type: ApplicationFiled: April 22, 2002Publication date: September 12, 2002Inventors: Hirofumi Shimomura, Naoya Henmi
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Patent number: 6424440Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have a least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.Type: GrantFiled: October 28, 1998Date of Patent: July 23, 2002Assignee: NEC CorporationInventors: Hirofumi Shimomura, Seigo Takahashi, Naoya Henmi
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Patent number: 6404525Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.Type: GrantFiled: July 28, 1998Date of Patent: June 11, 2002Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi, Hitoshi Takeshita
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Patent number: 6400498Abstract: Disclosed is an optical signal repeating and amplifying device which has: an optical amplifier which amplifies an optical signal to be input thereto and then outputs it; and an optical filter means through which only one wavelength light of the optical signal to be output from the optical amplifier is passed. Also disclosed is an optical level adjusting device which has: an optical demultiplexer which demultiplexes a wavelength-multiplexed optical signal into a plurality of wavelength lights; a plurality of optical attenuators which attenuate separately the demultiplexed plurality of wavelength lights to be output from the optical demultiplexer; and an optical multiplexer which multiplexes the attenuated wavelength lights to be output from the plurality of optical attenuators into a wavelength-multiplexed optical signal and output it.Type: GrantFiled: May 29, 1998Date of Patent: June 4, 2002Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi
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Patent number: 6347168Abstract: There is disclosed an array type space optical switch 10 of the present invention, in which each one end of optical fibers 101a to 104a, 101b to 104b is fixed to support members 105a, 105b. The optical fibers 101a and 101b form one pair, and have end surfaces opposite to each other, and the optical fibers 102a and 102b form one pair, and have end surfaces opposite to each other. Moreover, the optical fibers 103a and 103b form one pair, and have end surfaces opposite to each other, and the optical fibers 104a and 104b form one pair, and have end surfaces opposite to each other. A space propagation part 200 is formed between the end surfaces of the optical fibers 101a to 104a and 101b to 104b. An interrupting plate is inserted to or extracted from the space propagation part 200.Type: GrantFiled: January 28, 2000Date of Patent: February 12, 2002Assignee: NEC CorporationInventors: Hirofumi Shimomura, Naoya Henmi
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Publication number: 20020003644Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.Type: ApplicationFiled: August 28, 2001Publication date: January 10, 2002Applicant: NEC CorporationInventors: Hirofumi Shimomura, Seigo Takahashi, Naoya Henmi