Patents by Inventor Masuo Suyama
Masuo Suyama 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: 7092149Abstract: An input monitoring system is provided in an optical amplifying repeater to monitor a level of an optical input signal. A monitored level of the optical input signal is used to detect a fault on an optical transmission path or to control a bias current for a laser diode which emits and supplies an exciting signal for exciting an optical fiber amplifier. To accurately monitor a level of the optical input signal, the input monitoring system comprises an input terminal supplied with the optical input signal, an optical fiber amplifier for amplifying the optical input signal, a first photo diode for detecting and outputting an electric signal corresponding a level of the optical input signal, and an optical switch operatively connected to the input terminal, the optical fiber amplifier and first photo diode for switching the optical input signal alternatively into the optical fiber amplifier and the first photo diode.Type: GrantFiled: May 21, 1998Date of Patent: August 15, 2006Assignee: Fujitsu LimitedInventors: Shinichirou Harasawa, Hiroyuki Deguchi, Masuo Suyama
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Patent number: 6480658Abstract: An optical transmission system for transmitting an optical signal through an optical fiber transmission line includes a first optical fiber transmitting the optical signal and having a first zero-dispersion wavelength shorter than a wavelength of the optical signal, and a second optical fiber transmitting the optical signal from the first optical fiber and having a second zero-dispersion wavelength longer than the wavelength of the optical signal. A first nonlinear effective cross-sectional area of the first optical fiber is larger than a second nonlinear effective cross-sectional area of the second optical fiber.Type: GrantFiled: October 13, 2000Date of Patent: November 12, 2002Assignee: Fujitsu LimitedInventors: Takao Naito, Masuo Suyama, José Chesnoy, Olivier Gautheron
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Patent number: 6204945Abstract: The invention provides a signal light outputting apparatus for use for optical communication by wavelength multiplex transmission and an optical transmission system with the same wherein control of powers and/or wavelengths of signal lights to be transmitted can be performed with certainty and the signal lights can be transmitted and received accurately while making transmission characteristics of the signal lights equal to each other.Type: GrantFiled: April 15, 1997Date of Patent: March 20, 2001Assignee: Fujitsu LimitedInventors: Hiroyuki Iwata, Masuo Suyama
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Patent number: 5838476Abstract: An input monitoring system is provided in an optical amplifying repeater to monitor a level of an optical input signal. A monitored level of the optical input signal is used to detect a fault on an optical transmission path or to control a bias current for a laser diode which emits and supplies an exciting signal for exciting an optical fiber amplifier. To accurately monitor a level of the optical input signal, the input monitoring system comprises an input terminal supplied with the optical input signal, an optical fiber amplifier for amplifying the optical input signal, a first photo diode for detecting and outputting an electric signal corresponding a level of the optical input signal, and an optical switch operatively connected to the input terminal, the optical fiber amplifier and first photo diode for switching the optical input signal alternatively into the optical fiber amplifier and the first photo diode.Type: GrantFiled: October 10, 1995Date of Patent: November 17, 1998Assignee: Fujitsu LimitedInventors: Shinichirou Harasawa, Hiroyuki Deguchi, Masuo Suyama
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Patent number: 5729372Abstract: The invention provides an optical transmission method and apparatus suitable for use with a terminal station apparatus for an optical communication system for a very long distance of up to several thousands kilometers across an ocean as well as an optical amplification method and apparatus suitable for use with a repeater for an optical communication system. The methods and apparatus are improved in that the excessive loss in an optical amplifier and the variation of the branching ratio are suppressed to suppress the variation of the gain to suppress the polarization dependency of the loss or the gain on a transmission line of the optical communication system. The optical transmission apparatus comprises a depolarized light source for outputting depolarized light, and an external modulator for modulating light from the depolarized light source.Type: GrantFiled: September 12, 1996Date of Patent: March 17, 1998Assignee: Fujitsu LimitedInventors: Takafumi Terahara, Terumi Chikama, Masuo Suyama, Takao Naito
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Patent number: 5546213Abstract: An optical communication system transmits information with a pumping light beam acting as the carrier, and with a signal light beam. This optical communication system includes an optical fiber amplifier adapted to amplify the signal light beam by having the signal light beam and the pumping light beam propagate through a rare-earth-doped fiber doped with a rare-earth element. A modulating circuit modulates the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state. When the signal light beam and the pumping light beam are propagated in the same direction through the rare-earth-doped fiber, the transmission of information with the pumping light beam acting as the carrier, can provide transmission of a supervisory signal for an optical repeater.Type: GrantFiled: February 1, 1994Date of Patent: August 13, 1996Assignee: Fujitsu LimitedInventor: Masuo Suyama
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Patent number: 5539566Abstract: The invention provides an optical transmission method and apparatus suitable for use with a terminal station apparatus for an optical communication system for a very long distance of up to several thousands kilometers across an ocean as well as an optical amplification method and apparatus suitable for use with a repeater for an optical communication system. The methods and apparatus are improved in that the excessive loss in an optical amplifier and the variation of the branching ratio are suppressed to suppress the variation of the gain to suppress the polarization dependency of the loss or the gain on a transmission line of the optical communication system. The optical transmission apparatus comprises a depolarized light source for outputting depolarized light, and an external modulator for modulating light from the depolarized light source.Type: GrantFiled: April 20, 1995Date of Patent: July 23, 1996Assignee: Fujitsu LimitedInventors: Takafumi Terahara, Terumi Chikama, Masuo Suyama, Takao Naito
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Patent number: 5535050Abstract: An optical transmission system transmits an optical signal. The optical transmission system may include an optical amplifier. The optical amplifier amplifies a received optical signal. A pumping light source outputs a pumping light beam and monitor information or supervisory information. This optical amplifier is adapted to amplify the received optical signal by propagating the received optical signal. An optical fiber which may be doped with a rare-earth element. An optical coupler couples the received optical signal and a first pumping light beam to the input of the optical fiber. Through propagation of the signal through the optical fiber, the received optical signal is amplified.Type: GrantFiled: March 8, 1995Date of Patent: July 9, 1996Assignee: Fujitsu LimitedInventor: Masuo Suyama
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Patent number: 5526163Abstract: An optical communication system in which transmission of information with a pumping light beam acting as the carrier, in addition to transmission of information with a signal light beam, is made possible is disclosed. This optical communication system includes an optical fiber amplifier adapted to amplify a signal light beam by having the signal light beam and a pumping light beam propagated through its rare-earth-doped fiber doped with a rare earth element and a modulating circuit for modulating the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state.Type: GrantFiled: March 8, 1995Date of Patent: June 11, 1996Assignee: Fujitsu LimitedInventor: Masuo Suyama
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Patent number: 5521737Abstract: An optical communication system transmits information with a pumping light beam acting as the carrier, and with a signal light beam. This optical communication system includes an optical fiber amplifier adapted to amplify the signal light beam by having the signal light beam and the pumping light beam propagate through a rare-earth-doped fiber doped with a rare-earth element. A modulating circuit modulates the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state. When the signal light beam and the pumping light beam are propagated in the same direction through the rare-earth-doped fiber, the transmission of information with the pumping light beam acting as the carrier, can provide transmission of a supervisory signal for an optical repeater.Type: GrantFiled: March 8, 1995Date of Patent: May 28, 1996Assignee: Fujitsu LimitedInventor: Masuo Suyama
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Patent number: 5510931Abstract: An optical communication system transmits information with a pumping light beam acting as the carrier, and with a signal light beam. This optical communication system includes an optical fiber amplifier adapted to amplify the signal light beam by having the signal light beam and the pumping light beam propagate through a rare-earth-doped fiber doped with a rare-earth element. A modulating circuit modulates the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state. When the signal light beam and the pumping light beam are propagated in the same direction through the rare-earth-doped fiber, the transmission of information with the pumping light beam acting as the carrier, can provide transmission of a supervisory signal for an optical repeater.Type: GrantFiled: March 8, 1995Date of Patent: April 23, 1996Assignee: Fujitsu LimitedInventor: Masuo Suyama
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Patent number: 5299048Abstract: An optical communication system for obtaining transmission of information with a pumping light beam acting as carrier, in addition to transmission of information with a signal light beam. This optical communication system includes an optical fiber amplifier amplifying a signal light beam by having the signal light beam and a pumping light beam propagated through a rare-earth-doped fiber, and a modulating circuit for modulating the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state.Type: GrantFiled: December 8, 1992Date of Patent: March 29, 1994Assignee: Fujitsu LimitedInventor: Masuo Suyama