Patents by Inventor Kazuo Yamane
Kazuo Yamane 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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Publication number: 20020039226Abstract: An optical amplifying apparatus of the present invention comprises a correction part for correcting a predetermined fixed value of an output optical level by a correction amount according to an optical power of amplified spontaneous emission (ASE). The correction amount is, for example, computed by predetermined formulas. According to the present invention, when a WDM optical signal is optically amplified, the output is fixedly amplified for each channel by the correction amount which is a value obtained with the ASE levels taken into consideration, so that a fluctuation in the level of the average optical power of the channels is suppressed even if an optical signal is dropped/added therefrom/thereto during repeated transmissions.Type: ApplicationFiled: October 3, 2001Publication date: April 4, 2002Applicant: FUJITSU LIMITEDInventors: Makoto Murakami, Motoyoshi Sekiya, Hideto Saito, Hiroaki Tomofuji, Takeshi Sakamoto, Kazuo Yamane
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Publication number: 20010050792Abstract: The invention provides a wavelength multiplexing transmission apparatus includes a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other, and a wavelength multiplexing section for wavelength multiplexing the optical signals outputted from the optical signal outputting sections and sending out a resulting optical signal. Each of the optical signal outputting sections includes a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength, and a wavelength filter capable of passing therethrough and sending out only an optical signal of the predetermined wavelength to be outputted from the transmission light source to prevent a wavelength drift of the optical signal outputted from the transmission light source.Type: ApplicationFiled: August 7, 2001Publication date: December 13, 2001Applicant: Fujitsu LimitedInventors: Kazuo Yamane, Takashi Tsuda, Yumiko Kawasaki, Satoru Okano
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Patent number: 6295147Abstract: The invention provides a wavelength multiplexing transmission apparatus includes a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other, and a wavelength multiplexing section for wavelength multiplexing the optical signals outputted from the optical signal outputting sections and sending out a resulting optical signal. Each of the optical signal outputting sections includes a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength, and a wavelength filter capable of passing therethrough and sending out only an optical signal of the predetermined wavelength to be outputted from the transmission light source to prevent a wavelength drift of the optical signal outputted from the transmission light source.Type: GrantFiled: July 15, 1998Date of Patent: September 25, 2001Assignee: Fujitsu LimitedInventors: Kazuo Yamane, Takashi Tsuda, Yumiko Kawasaki, Satoru Okano
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Patent number: 6288836Abstract: The present invention relates to an optical amplifier and an optical communication system applied to WDM (wavelength division multiplexing). The optical amplifier includes an optical amplifying medium to which WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths is supplied, a pumping unit for pumping the optical amplifying medium such that the medium gives a gain to the WDM signal light, a feedback loop for controlling the pumping unit so that the gain is maintained constant, and an optical attenuator for giving a variable attenuation to the WDM signal light. Through the structure of the present invention, it becomes possible to provide an optical amplifier which can maintain constant the optical output level per channel of WDM and can maintain the gain characteristic constant.Type: GrantFiled: March 18, 1998Date of Patent: September 11, 2001Assignee: Fujitsu LimitedInventors: Yumiko Kawasaki, Satoru Okano, Kazuo Yamane, Hiroshi Nishimoto, Takashi Tsuda
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Patent number: 6282214Abstract: In a wavelength multiplexing light source used in an optical wavelength division multiplexing (WDM) transmission system and the like, at least three semiconductor lasers of single longitudinal mode have oscillation frequencies outside of their pull-in range at a normal injection locking without a modulation side band, an output light of a first semiconductor laser is injected in one way into a second semiconductor laser having an oscillation frequency adjacent to that of the first o semiconductor laser through a first one-way optical injection means to generate a modulation side band. The output light of the second semiconductor laser is then injected in one way into a third semiconductor laser having an oscillation frequency adjacent to that of the second semiconductor laser through a second one-way optical injection means to generate the modulation side band for an injection locking.Type: GrantFiled: March 4, 1999Date of Patent: August 28, 2001Assignees: Fujitsu Limited, Nagoya UniversityInventors: Ryosuke Goto, Kazuo Yamane, Toshio Goto, Masakazu Mori
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Publication number: 20010015843Abstract: In an optical transmission system comprising a transmitter, a receiver, and a transmission line that connects the transmitter and the receiver, a dispersion compensator is disposed in the receiver. The transmitter comprises an E/O (electro-optical signal converter) and a post-amplifier. An optical signal that has been RZ-coded is supplied to the E/O. The transmitter pre-chirps the optical signal. The pre-chirp is performed by red-chirp of which the value of the chirping parameter &agr; is positive. When the pre-chirp is performed, the non-linear effect of the optical signal on the transmission line can be canceled. In addition, with the RZ coded signal, the inter-symbol interference can be alleviated. Thus, the total dispersion amount of the dispersion compensator can be suppressed. In addition, the power of the optical output can be increased.Type: ApplicationFiled: December 28, 2000Publication date: August 23, 2001Inventors: Akira Miyauchi, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Publication number: 20010007605Abstract: Both wavelength dispersion and a dispersion slope of a line fiber are simultaneously compensated for by combining two types of dispersion compensators having different characteristics.Type: ApplicationFiled: January 4, 2001Publication date: July 12, 2001Inventors: Shinya Inagaki, Hisashi Takamatsu, Kazuo Yamane, Takashi Tsuda
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Patent number: 6061173Abstract: An optical amplifier amplifies a wavelength-division-multiplexed optical input signal composed of optical signals having different wavelengths such that the output level of each of the optical signal is always optimized and such that the difference between the gains of the amplifier on the optical signals is minimized when the number of optical signals is two. The output level of the amplifier is controlled according to the number of the optical signals, to optimize the output level of each of the optical signals.Type: GrantFiled: December 7, 1998Date of Patent: May 9, 2000Assignee: Fujitsu LimitedInventors: Kazuo Yamane, Michikazu Shima, Yumiko Kawasaki, Kenji Tagawa, Shinya Inagaki, Norifumi Shukunami
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Patent number: 6038063Abstract: An optical amplifier relates to WDM (wavelength division multiplexing). The optical amplifier includes an optical amplifying unit, an ALC (automatic output level control) circuit for controlling the unit based on the output level thereof, and AGC (automatic gain control) circuit for controlling the unit based on the input and output levels thereof. A selecting circuit alternatively selects and operates the ALC and AGC circuits in accordance with a predetermined rule. Accordingly, the inconvenience occurring in the case of performing only one of ALC and AGC can be eliminated.Type: GrantFiled: March 18, 1998Date of Patent: March 14, 2000Assignee: Fujitsu LimitedInventors: Takashi Tsuda, Hiroshi Nishimoto, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Patent number: 5977020Abstract: A thermosensitive reversible recording material capable of forming and holding clear colored images with a high contrast and capable of being repeatedly color-developed and color-erased many times, has a thermosensitive recording layer formed on substrate sheet and including (A) at least one reversibly color-developing and -erasing compound selected from those of the formulae (I), (II) and (III), and (B) at least one dye precursor compound of the formula (IV). ##STR1## R.sup.1 =naphyl or lower alkoxy-substituted phenyl group Y.sup.1, Y.sup.2 =--NHCO--, --SCONH--, --CONHCO--, etc., n, m, p=10 to 29, R.sup.2, R.sup.3, R.sup.4, R.sup.5 =C.sub.1 -C.sub.9 alkyl, C.sub.3 -C.sub.6 cycloalkyl or substituted or non-substituted phenyl group, R.sup.6, R.sup.7 =C.sub.1 -C.sub.6 alkyl or phenyl group.Type: GrantFiled: July 13, 1998Date of Patent: November 2, 1999Assignee: Oji Paper Co., Ltd.Inventors: Makoto Nishioka, Kazuo Yamane
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Patent number: 5928988Abstract: A thermosensitive reversible recording material having a thermosensitive recording layer formed on a substrate sheet and including a substantially colorless dye precursor and a color developing agent capable of reversibly color-developing and erasing the dye-precursor, in which the color developing agent comprises an aromatic compound of the general formula (1) and optionally an overcoat layer preferably containing an electron-beam or ultraviolet-ray cured polymer is formed on the thermosensitive recording layer general formula (1): ##STR1## ?R=naphthyl or lower alkoxy-substituted phenol group, Y=--NHCO--, --SCONH--, --CONHCO--, --NHCONH--, --OCO--, --NHCOO--, --NHCOS--, --S--, --NHCONHSO.sub.2 --, --O--, --OCSNH--, --CONHNH--, --OCONHSO.sub.2 --, --CO--, --SCSNH--, --NHSO.sub.2 --, --CONHSO.sub.2 --, --OSO.sub.Type: GrantFiled: December 3, 1997Date of Patent: July 27, 1999Assignee: OJI Paper Co., Ltd.Inventors: Kazuo Yamane, Makoto Nishioka
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Patent number: 5877881Abstract: A chirping parameter .alpha. in a transmitter is set to a positive value with respect to an SMF that has a positive dispersion value with respect to signal light. A dispersion compensator is provided not only at the receiving end but also at the transmitting end. This achieves a reduction in the number of types of dispersion compensators that should be prepared in advance to optimize transmission characteristics despite the variety in the lengths of transmission fibers.Type: GrantFiled: November 20, 1996Date of Patent: March 2, 1999Assignee: Fujitsu Ltd.Inventors: Akira Miyauchi, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Patent number: 5870217Abstract: The invention provides a multi-wavelength optical batch amplification apparatus wherein, upon batch amplification of a multi-wavelength input optical signal, the powers of optical signals on the input and output sides of an optical amplifier are monitored totally or individually to control the powers of optical signals of the output optical signal of the optical amplifier so that they may be fixed equally.Type: GrantFiled: February 13, 1997Date of Patent: February 9, 1999Assignee: Fujitsu LimitedInventors: Hiroyuki Itou, Kazuo Yamane, Michikazu Shima
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Patent number: 5841558Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.Type: GrantFiled: January 22, 1997Date of Patent: November 24, 1998Assignee: Fujitsu LimitedInventors: Yuji Tamura, Hiroyuki Itou, Tsukasa Takahashi, Michikazu Shima, Yumiko Kawasaki, Kazuo Yamane
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Patent number: 5798857Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.Type: GrantFiled: January 22, 1997Date of Patent: August 25, 1998Assignee: Fujitsu LimitedInventors: Yuji Tamura, Hiroyuki Itou, Tsukasa Takahashi, Michikazu Shima, Yumiko Kawasaki, Kazuo Yamane
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Patent number: 5764404Abstract: An optical amplifier amplifies a wavelength division-multiplexed optical input signal composed of optical signals having different wavelengths such that the output level of each of the optical signal is always optimized and such that the difference between the gains of the amplifier on the optical signals is minimized when the number of optical signals is two. The output level of the amplifier is controlled according to the number of the optical signals, to optimize the output level of each of the optical signals.Type: GrantFiled: July 28, 1995Date of Patent: June 9, 1998Assignee: Fujitsu LimitedInventors: Kazuo Yamane, Michikazu Shima, Yumiko Kawasaki, Kenji Tagawa, Shinya Inagaki, Norifumi Shukunami
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Patent number: 5702850Abstract: A thermosensitive reversible color-developing and disappearing agent includes an aromatic compound having at least one group of the formula, --SO.sub.2 NHCXNH--, wherein X.dbd.O or S atom, and at least one straight chain alkyl group with 11 or more carbon atoms, and is reactive with a dye precursor in a thermosensitive recording material to thereby record colored images on the recording material upon heating imagewise, and make the colored images disappear upon heating to a temperature lower than the colored image-forming temperature.Type: GrantFiled: September 13, 1995Date of Patent: December 30, 1997Assignee: New Oji Paper Co., Ltd.Inventors: Makoto Nishioka, Kazuo Yamane, Masaki Nishimura, Yoshiyuki Takahashi
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Patent number: 5680246Abstract: The optical amplifier includes a doped fiber doped with a rare earth element, a pumping light source, means for introducing signal light and pumping light into the doped fiber, detection means for detecting whether or not amplified signal light is included in light outputted from the doped fiber, and means for decreasing the intensity of the pumping light when it is detected that amplified signal light is not included. It can be possible to eliminate an influence of an optical surge arising from a characteristic of the doped fiber.Type: GrantFiled: March 28, 1995Date of Patent: October 21, 1997Assignee: Fujitsu LimitedInventors: Tsukasa Takahashi, Hiroyuki Itou, Yuji Tamura, Michikazu Shima, Kazuo Yamane, Yumiko Kawasaki, Keisuke Imai, Yoshinori Ohkuma, Kazuhiro Suzuki, Yasunori Nagakubo, Takashi Tsuda, Yuji Miyaki
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Patent number: 5625481Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.Type: GrantFiled: February 14, 1995Date of Patent: April 29, 1997Assignee: Fujitsu LimitedInventors: Yuji Tamura, Hiroyuki Itou, Tsukasa Takahashi, Michikazu Shima, Yumiko Kawasaki, Kazuo Yamane
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Patent number: 5434691Abstract: A communications system includes a plurality of optical transmission lines in an active system and an optical transmission line in a protection system, and transmitter/receiver devices connected to respective ends of the optical transmission lines. The transmitter/receiver devices respectively include a first interface unit for establishing a first interface with signal transmission lines, a second interface unit for establishing a second interface with one of the optical transmission lines, a first multiplexer/demultiplexer unit for executing a first multiplexing and demultiplexing operation, and a second multiplexer/demultiplexer unit for executing a second multiplexing and demultiplexing operation.Type: GrantFiled: November 16, 1994Date of Patent: July 18, 1995Assignee: Fujitsu LimitedInventor: Kazuo Yamane