Patents by Inventor Takaaki Ogata
Takaaki Ogata 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: 8917998Abstract: A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal is disclosed. The method comprises splitting data into two or more data streams, inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding, and multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output. Other methods, apparatuses, and systems also are disclosed.Type: GrantFiled: October 11, 2012Date of Patent: December 23, 2014Assignee: NEC Laboratories America, Inc.Inventors: Shaoliang Zhang, Lei Xu, Junqiang Hu, Fatih Yaman, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Patent number: 8873953Abstract: An inventive method for multi-symbol polarization switching for differential detection optical systems includes modulating a laser source by a DQPSK modulator, driving the DQPSK modulator with a data block configured for generating multi-symbol polarization-switched DQPSK differential-encoded signals, and polarizing the multi-symbol polarization-switched DQPSK signals with a polarizing modulator whose modulation speed is based on how often polarization states vary, wherein the data block provides a bits manipulation to provide the multi-symbol polarization switching thereby enabling differential detection for recovering correct original data by a receiver.Type: GrantFiled: June 14, 2012Date of Patent: October 28, 2014Assignee: NEC Laboratories America, Inc.Inventors: Shaoliang Zhang, Fatih Yaman, Lei Xu, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Patent number: 8787709Abstract: A method for optical chirp-free optical polarization modulation includes dividing a data modulated optical signal into a first optical path and a second optical path, using a Mach-Zehnder intensity modulator in the first optical path for imparting a ? phase difference between adjacent symbols of the data modulated optical signal in the first optical path, adjusting a delay and amplitude of symbols of the data modulated optical signal in the second path so that the symbols in the first path and the symbols in the second path are synchronized and have substantially equal power levels, and combining the first and second optical paths so that symbols from the first and second optical paths are in orthogonal polarizations.Type: GrantFiled: March 30, 2012Date of Patent: July 22, 2014Assignee: NEC Laboratories America, Inc.Inventors: Fatih Yaman, Shaoliang Zhang, Lei Xu, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Publication number: 20140178071Abstract: Methods, structures and systems for generating different polarization multiplexed signals wherein the drivers of the modulators are generic while a software-controlled manager allows the carrying of any standard 10 G/40 G/100 G data while—at the same time—being adaptively adjustable according to specific link requirements and users' requests in both dispersion-managed and uncompensated links.Type: ApplicationFiled: October 4, 2013Publication date: June 26, 2014Applicant: NEC LABORATORIES AMERICA, INC.Inventors: Shaoliang ZHANG, Fatih YAMAN, Ting WANG, Yoshihisa INADA, Takaaki OGATA, Yahuhiro AOKI
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Publication number: 20140099126Abstract: The invention is directed to a novel computer implemented method for finding a modulation format that has better receiver sensitivity than modulation formats that are currently being used, with a correlated symbol modulation in which neighboring symbols are coded and decoded together to increase receiver sensitivity.Type: ApplicationFiled: October 2, 2013Publication date: April 10, 2014Applicant: NEC LABORATORIES AMERICA, INC.Inventors: Fatih Ioanna Yaman, Shaoliang Zhang, Ting Wang, Takaaki Ogata, Yoshihisa Inada, Yasuhiro Aoki
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Publication number: 20120321303Abstract: An inventive method for multi-symbol polarization switching for differential detection optical systems includes modulating a laser source by a DQPSK modulator, driving the DQPSK modulator with a data block configured for generating multi-symbol polarization-switched DQPSK differential-encoded signals, and polarizing the multi-symbol polarization-switched DQPSK signals with a polarizing modulator whose modulation speed is based on how often polarization states vary, wherein the data block provides a bits manipulation to provide the multi-symbol polarization switching thereby enabling differential detection for recovering correct original data by a receiver.Type: ApplicationFiled: June 14, 2012Publication date: December 20, 2012Applicant: NEC LABORATORIES AMERICA, INC.Inventors: Shaoliang Zhang, Fatih Yaman, Lei Xu, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Publication number: 20120321311Abstract: An inventive method for coherent interleaved polarization-multiplexing PolMux optical communications with a single IQ modulator includes modulating a light source to generate a 50% return-to-zero RZ signal pulse at a frequency Rs, driving a single IQ modulator with inphase I and quadrature phase Q data at a bit rate of sais Rs to introduce phase modulation on said 50% RZ signal pulse to produce a QPSK pulse signal with all symbols being in a same polarization state without any time overlapping; and polarization modulating said QPSK signal to alternatively convert said QPSK signal into two orthogonal polarizations states enabling an interleaving PolMux signal with a symbol rate of Rs/2.Type: ApplicationFiled: June 14, 2012Publication date: December 20, 2012Applicant: NEC LABORATORIES AMERICA, INC.Inventors: Shaoliang Zhang, Fatih Yaman, Lei Xu, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Publication number: 20120251028Abstract: A method for optical chirp-free optical polarization modulation includes dividing a data modulated optical signal into a first optical path and a second optical path, using a Mach-Zehnder intensity modulator in the first optical path for imparting a ? phase difference between adjacent symbols of the data modulated optical signal in the first optical path, adjusting a delay and amplitude of symbols of the data modulated optical signal in the second path so that the symbols in the first path and the symbols in the second path are synchronized and have substantially equal power levels, and combining the first and second optical paths so that symbols from the first and second optical paths are in orthogonal polarizations.Type: ApplicationFiled: March 30, 2012Publication date: October 4, 2012Applicant: NEC LABORATORIES AMERICA, INC.Inventors: Fatih Yaman, Shaoliang Zhang, Lei Xu, Ting Wang, Yoshihisa Inada, Takaaki Ogata, Yasuhiro Aoki
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Patent number: 7123405Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: GrantFiled: February 18, 2004Date of Patent: October 17, 2006Assignee: NEC CorporationInventors: Ryu Yokoyama, Takaaki Ogata
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Patent number: 6868204Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: GrantFiled: March 18, 2002Date of Patent: March 15, 2005Assignee: NEC CorporationInventors: Ryu Yokoyama, Takaaki Ogata
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Patent number: 6845192Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: GrantFiled: February 18, 2004Date of Patent: January 18, 2005Assignee: NEC CorporationInventors: Ryu Yokoyama, Takaaki Ogata
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Publication number: 20040161244Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: ApplicationFiled: February 18, 2004Publication date: August 19, 2004Applicant: NEC CorporationInventors: Ryu Yokoyama, Takaaki Ogata
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Publication number: 20040161191Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: ApplicationFiled: February 18, 2004Publication date: August 19, 2004Applicant: NEC CorporationInventors: Ryu Yokoyama, Takaaki Ogata
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Patent number: 6539153Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: GrantFiled: March 26, 2001Date of Patent: March 25, 2003Assignee: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Publication number: 20020131696Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.Type: ApplicationFiled: March 18, 2002Publication date: September 19, 2002Inventors: Ryu Yokoyama, Takaaki Ogata
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Publication number: 20010012431Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: ApplicationFiled: March 26, 2001Publication date: August 9, 2001Applicant: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Kaoru Higuma, Junichiro Ichikawa
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Patent number: 6233385Abstract: The object of the present invention is to provide a light limiter which can control the generation of an optical surge, comprises few components, and has high reliability; in order to achieve the object, the light limiter of the present invention comprise a parametric amplification element parametrically amplifying an input signal light, and a wavelength selection element removing a wavelength component, excepting a specified wavelength, from among the signal light output from said parametric amplification element.Type: GrantFiled: January 28, 1999Date of Patent: May 15, 2001Assignee: NEC CorporationInventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Patent number: 6218658Abstract: The optical fuse of the present invention comprises: at least one light heatable portion for receiving an incident beam, and at least one thermally sensitive degradable portion with transparency and reflectivity, positioned in contact with the light heatable portion. The light heatable portion contains a light heatable material which generates heat depending on a specified light intensity of the incident beam. The thermally sensitive degradable portion contains a thermally sensitive degradable material which loses or reduces its transparency and reflectivity, depending on the heat generated by the light heatable portion when the light intensity of the incident beam exceeds a threshold value.Type: GrantFiled: March 17, 1999Date of Patent: April 17, 2001Assignees: NEC Corporation, Sumitomo Osaka Cement Co., Ltd.Inventors: Yasuhisa Taneda, Takaaki Ogata, Hirotoshi Nagata, Junichiro Ichikawa, Kaoru Higuma
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Patent number: 6134372Abstract: A light intensity attenuator and attenuating method is provided, by which a pulse-shaped optical surge can be attenuated and an optical signal component using desired light intensity can be output by using a simpler structural arrangement, and without using many optical components and circuits. In this method, an optical signal including a pulse-shaped optical surge component is received, and the optical signal is again output after the light intensity of the surge component is attenuated by a desired amount.Type: GrantFiled: June 1, 1999Date of Patent: October 17, 2000Assignees: Sumitomo Osaka Cement Co., Ltd., NEC CorporationInventors: Junichiro Ichikawa, Hirotoshi Nagata, Kaoru Higuma, Junichiro Minowa, Takaaki Ogata, Yasuhisa Taneda
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Patent number: 6064514Abstract: Optical surge preventing systems and methods for rare earth-doped optical fiber amplifiers are disclosed. The systems are so arranged as to cause any signal existing in a doped fiber section so as not to over excite the rare earth elements in the doped fiber section. In one embodiment, a background signal light with such a wavelength as to cause induced emission in the doped fiber section is always coupled into the doped fiber section regardless of whether a message signal light exists or not. The background signal light may be generated by any suitable light source or a light spontaneously emitted from either end of the doped fiber section. In another embodiment, a dummy signal light is coupled into the doped fiber section if the level of the message signal light becomes less than a predetermined value. Coupling of the background signal light or the dummy signal light into the doped fiber section may be done from either of the message signal input and output sides.Type: GrantFiled: October 29, 1996Date of Patent: May 16, 2000Assignee: NEC CorporationInventors: Yasuhiro Aoki, Takaaki Ogata, Kenichi Yoneyama, Yukio Michishita, Yoshiro Sato