Patents by Inventor Shinya Sasaki
Shinya Sasaki 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: 5995278Abstract: An optical transmission system in which influences of worsening of the waveform by SPM are canceled by setting an amount of compensation of a dispersion compensator at about 50% of a total amount of dispersion of an optical fiber transmission line so that received waveform is almost not varied, even if light intensity is varied. In the case where a plurality of dispersion compensators are used, the number of compensators is optimized by setting arrangement interval in the neighborhood of a receiving end at a small value. Further, in a transmission line, in which amounts of dispersion of optical fibers have positive and negative fluctuations, the smallest transmission distance of a transmission system is increased by effecting dispersion compensation so that an expected value of the total amount of dispersion of the transmission line is abnormal dispersion.Type: GrantFiled: July 10, 1998Date of Patent: November 30, 1999Assignee: Hitachi, Ltd.Inventors: Nobuhiko Kikuchi, Shinya Sasaki
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Patent number: 5880876Abstract: An optical transmission system in which influences of worsening of the waveform by SPM are cancelled by setting an amount of compensation of a dispersion compensator at about 50% of a total amount of dispersion of an optical fiber transmission line so that received waveform is almost not varied, even if light intensity is varied. In the case where a plurality of dispersion compensators are used, the number of compensators is optimized by setting arrangement interval in the neighborhood of a receiving end at a small value. Further, in a transmission line, in which amounts of dispersion of optical fibers have positive and negative fluctuations, the smallest transmission distance of a transmission system is increased by effecting dispersion compensation so that an expected value of the total amount of dispersion of the transmission line is abnormal dispersion.Type: GrantFiled: October 17, 1996Date of Patent: March 9, 1999Assignee: Hitachi, Ltd.Inventors: Nobuhiko Kikuchi, Shinya Sasaki
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Patent number: 5875046Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: November 5, 1996Date of Patent: February 23, 1999Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5861972Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: November 6, 1996Date of Patent: January 19, 1999Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5812289Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: August 29, 1996Date of Patent: September 22, 1998Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5739932Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: June 20, 1996Date of Patent: April 14, 1998Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5671074Abstract: An optical transmission system accomplishes optical transmission over a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission over a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: June 20, 1996Date of Patent: September 23, 1997Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Kyoji Takeyari, Hiroyuki Nakano
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Patent number: 5606445Abstract: In an optical transmission system, SPM influences on the degradation of wave forms are canceled by setting an amount of compensation of a dispersion compensator at about 50% of the total amount of dispersion of an optical fiber transmission line so that a received wave form is substantially not varied, even if light intensity is varied. When a plurality of dispersion compensator are used, the number of compensators is optimized by setting the arrangement interval in the vicinity of the receiving end to a small value. Further, in a transmission line, in which amounts of dispersion of optical fibers have positive and negative fluctuations, the smallest transmission distance of a transmission system is increased by effecting dispersion compensation so that an expected value of the total amount of dispersion of the transmission line is abnormal dispersion.Type: GrantFiled: August 30, 1994Date of Patent: February 25, 1997Assignee: Hitachi, Ltd.Inventors: Nobuhiko Kikuchi, Shinya Sasaki
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Patent number: 5555477Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.Type: GrantFiled: April 7, 1993Date of Patent: September 10, 1996Assignee: Hitachi, Ltd.Inventors: Keiji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Ashi, Hironari Matsuda, Satoshi Aoki, Yukio Nakano, Masahiro Takatori, Toru Kazawa, Shinya Sasaki, Ryoji Takeyari, Hiroyuki Nakano
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Patent number: 5515196Abstract: An optical transmitter apparatus comprises a light source for optical signal transmission, an intensity modulator, a transmit signal generator and a signal generator. A transmit signal to be transmitted is supplied from the transmit signal generator to the intensity modulator, while a signal generated by the signal generator is supplied to the phase modulator. A light beam emitted from the light source passes through the intensity modulator and the phase modulator to be subsequently sent out as an optical signal for transmission with intensity thereof being modulated upon passing through the intensity modulator while spectrum thereof being spread by phase modulation which the optical signal undergoes upon passing through the phase modulator.Type: GrantFiled: April 2, 1993Date of Patent: May 7, 1996Assignee: Hitachi, Ltd.Inventors: Shigeki Kitajima, Hirohisa Sano, Katsuhiko Kuboki, Shinya Sasaki
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Patent number: 5500756Abstract: An optical repeater for realizing transmission of supervisory information of an optical fiber transmission system without the output power of an optical fiber amplifier being reduced, wherein a supervisory optical transmitter and optical receiver with a wavelength which is similar to the wavelength of the pumping light source of the optical fiber amplifier are mounted, and on the input side of the optical repeater, pumping light is multiplexed in the forward direction and a supervisory optical signal, which is multiplexed in wavelength and transmitted, is demultiplexed simultaneously by the first wavelength multi- and demultiplexer and they are received by the supervisory optical receiver, and on the output side of the optical repeater, pumping light is muitiplexed in the reverse direction and a supervisory optical signal outputted from the supervisory optical transmitter is multiplexed by the second wavelength multi- and demultiplexer.Type: GrantFiled: February 26, 1993Date of Patent: March 19, 1996Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Shinya Sasaki, Yukio Nakano, Hiroyuki Nakano, Ryoji Tateyari, Hironari Matsuda, Kenji Tomooka, Naohiro Sakakida, Shin Nishimura, Yoshihiro Yano, Youichi Igarashi, Satoshi Aoki, Masahiro Takatori, Tohru Kazawa, Yoshihiro Ashi
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Patent number: 5408349Abstract: An optical frequency division multiplexing transmission system for sending a large volume of information by a single optical fiber is disclosed. Each of an optical frequency division multiplexing transmitter equipment and an optical frequency division multiplexing receiver equipment has an optical filter having a periodic optical transmission characteristic therein. Each optical filter is stabilized with an absolutely-stabilized standard optical frequency. Each optical signal frequency is stabilized to a periodic transmission characteristic of the optical filter arranged in the optical frequency division multiplexing transmitter equipment, and each local frequency to a periodic transmission characteristic of the optical filter arranged in the optical frequency division multiplexing receiver equipment.Type: GrantFiled: July 1, 1992Date of Patent: April 18, 1995Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Shinya Sasaki, Katsuhiko Kuboki
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Patent number: 5396361Abstract: A system for stabilizing a frequency separation between two coherent light sources includes first and second current sources driving first and second semiconductor laser devices with first and second frequencies, respectively. Light from the semiconductor laser devices is combined in a multiplexer, and a portion the combined light is diverted to an optical-to-electrical transducer. Output current from the transducer is combined with an output of a local oscillator driven at a selected frequency. A combined signal is then filtered, and used to form a control signal of one of the semiconductor laser devices.Type: GrantFiled: June 19, 1992Date of Patent: March 7, 1995Assignee: Hitachi, Ltd.Inventors: Shinya Sasaki, Hideaki Tsushima, Minoru Maeda
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Patent number: 5323258Abstract: A homodyne optical receiver includes a polarization beam splitter for dividing an optical signal into an optical signal with horizontal polarization and an optical signal with vertical polarization. Optical couplers combine two optical signals of the two polarized components with two optical local signals, which signals are almost matched therewith in polarization, and in a state where they are matched with each other in phase. Detectors homodyne-detect respective output optical signals of the optical couplers and two weighting circuits assign output signals of the detectors weights which are approximately proportional to amplitudes thereof, respectively. An adder adds output signals of the weighting circuits.Type: GrantFiled: October 4, 1991Date of Patent: June 21, 1994Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Ryoji Takeyari, Shinya Sasaki, Shigeki Kitajima, Katsuhiko Kuboki
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Patent number: 5305134Abstract: An optical frequency division multiplexing transmitter is disclosed, which comprises a plurality of optical transmitters having different optical frequencies; an optical combiner multiplexing optical signals outputted by the different optical transmitters; and an optical filter having passbands, the frequency of each of which is approximately in accordance with the frequency of each of the signals, in which the signal thus multiplexed is inputted.Type: GrantFiled: August 29, 1990Date of Patent: April 19, 1994Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Shinya Sasaki, Shigeki Kitajima, Kiichi Yamashita
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Patent number: 5274490Abstract: A unipolar original electrical signal is encoded by alternate mark inversion and combined with a DC bias current for injection of a semiconductor laser to produce a bipolar FSK optical signal that is transmitted to a receiver. At the receiver, the received signal is coupled with optical local power and fed to an optical/electrical transducer, preferably a semiconductor, to produce an electrical signal that is demodulated to produce the original unipolar signal. The demodulator may be of different types, for example employing delaying part of the amplified electrical signal and mixing the delayed part with the original signal for passage of the combined signal through a low pass filter; with proper selection of the delay, an AMI decoder is not needed. The demodulator may also be of the type that has one or more band pass filters to respectively separate the positive mark, space and negative mark signals that may thereafter be added.Type: GrantFiled: April 30, 1991Date of Patent: December 28, 1993Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Shinya Sasaki
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Patent number: 5271890Abstract: A coating film of a carbon allotrope is formed on a substrate by continuously supplying a fine carbon powder onto the substrate and simultaneously irradiating the fine carbon powder with a laser beam of a high output level thereby inducing sublimation of the fine carbon powder, and quenching the sublimated fine carbon powder to cause deposition thereof on the substrate.Type: GrantFiled: October 30, 1992Date of Patent: December 21, 1993Assignee: Agency of Industrial Science & Technology, Ministry of International Trade & IndustryInventors: Hirofumi Shimura, Shinya Sasaki, Yuji Enomoto
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Patent number: 5144467Abstract: An optical tuning device including a channel designator and an intermediate frequency stabilizer for stabilizing the frequency of a difference signal corresponding to the frequency difference between a transmitted optical signal and a local oscillation optical signal. The channel designator includes a bias control circuit for continuously changing the optical frequency of a local oscillation light source up to a frequency corresponding to a target channel, a channel detection circuit for detecting channel passage on the basis of the difference signal, and a channel counting circuit for storing therein the selected channel and the target channel, detecting the direction of the target channel, counting the number of channel passage times, and detecting arrival at the target channel.Type: GrantFiled: July 25, 1990Date of Patent: September 1, 1992Assignee: Hitachi, Ltd.Inventors: Shigeki Kitajima, Kiichi Yamashita, Shinya Sasaki, Hideaki Tsushima
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Patent number: 5142402Abstract: A polarization diversity optical receiving apparatus comprises at least one frequency converter for performing frequency conversion upon an IF signal, an adder for adding two IF signals together, and a demodulator for converting a signal outputted from the adder to a baseband signal.Type: GrantFiled: December 14, 1989Date of Patent: August 25, 1992Assignee: Hitachi, Ltd.Inventors: Hideaki Tsushima, Shinya Sasaki, Ryoji Takeyari
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Patent number: 5113524Abstract: An optical receiver includes a squeezer for changing the quantum state of a signal lightwave to a squeezed state, a slave laser put in an injection locking state by the signal lightwave outputted from the squeezer, and an optical homodyne detector for carrying out optical homodyne detection for the signal lightwave outputted from the slave laser.Type: GrantFiled: September 27, 1989Date of Patent: May 12, 1992Assignees: Hitachi, Ltd., Osamu HirotaInventors: Osamu Hirota, Hideaki Tsushima, Shinya Sasaki, Yoshitaka Takasaki, Minoru Maeda