Patents by Inventor Shin Kamei
Shin Kamei 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: 9817186Abstract: Polarization rotators of conventional techniques require forming a silicon nitride layer, which is not employed in usual fabrication of a silicon waveguide circuit. In order to employ a polarization rotator function in an optical integrated circuit, a process of forming a silicon nitride layer is added just for that purpose. This increases the fabrication time and complicates the fabrication equipment. In a polarization rotator of the present invention, the waveguide width of a center core portion of a polarization converter is made small. Thus, the intensity of an optical wave does not concentrate only at the center core portion and is more influenced by structural asymmetry. With the configuration of the polarization rotator of the present invention, it is possible to efficiently cause polarization conversion with a structure including only a silicon waveguide and no silicon nitride layer or the like formed thereon.Type: GrantFiled: March 4, 2015Date of Patent: November 14, 2017Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Shin Kamei, Makoto Jizodo, Hiroshi Fukuda, Kiyofumi Kikuchi
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Publication number: 20170068048Abstract: Polarization rotators of conventional techniques require forming a silicon nitride layer, which is not employed in usual fabrication of a silicon waveguide circuit. In order to employ a polarization rotator function in an optical integrated circuit, a process of forming a silicon nitride layer is added just for that purpose. This increases the fabrication time and complicates the fabrication equipment. In a polarization rotator of the present invention, the waveguide width of a center core portion of a polarization converter is made small. Thus, the intensity of an optical wave does not concentrate only at the center core portion and is more influenced by structural asymmetry. With the configuration of the polarization rotator of the present invention, it is possible to efficiently cause polarization conversion with a structure including only a silicon waveguide and no silicon nitride layer or the like formed thereon.Type: ApplicationFiled: March 4, 2015Publication date: March 9, 2017Inventors: Shin Kamei, Makoto Jizodo, Hiroshi Fukuda, Kiyofumi Kikuchi
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Publication number: 20160087727Abstract: An optical modulator driver circuit (1) includes an amplifier (50, Q10, Q11, R10-R13), and a current amount adjustment circuit (51) capable of adjusting a current amount of the amplifier (50) in accordance with a desired operation mode. The current amount adjustment circuit (51) includes at least two current sources (IS10) that are individually ON/OFF-controllable in accordance with a binary control signal representing the desired operation mode.Type: ApplicationFiled: May 9, 2014Publication date: March 24, 2016Inventors: Munehiko Nagatani, Hideyuki Nosaka, Toshihiro Itoh, Koichi Murata, Hiroyuki Fukuyama, Takashi Saida, Shin Kamei, Hiroshi Yamazaki, Nobuhiro Kikuchi, Hiroshi Koizumi, Masafumi Nogawa, Hiroaki Katsurai, Hiroyuki Uzawa, Tomoyoshi Kataoka, Naoki Fujiwara, Hiroto Kawakami, Kengo Horikoshi, Yves Bouvier, Mikio Yoneyama, Shigeki Aisawa, Masahiro Suzuki
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Patent number: 8867873Abstract: An optical wavelength multi/demultiplexing circuit is provided in which temperature dependence at a transmission center wavelength remained in an athermalized AWG is compensated. An AWG according to an embodiment of the present invention is compensated for the main temperature dependence at the transmission center wavelength. The AWG comprises an optical splitter, a first and second arm waveguides, an optical mode combining coupler and a multimode waveguide between an input/output waveguide and a slab waveguide. The optical mode combining coupler couples fundamental mode light from the first arm waveguide as fundamental mode and the fundamental mode light from the second arm waveguide as first mode. The multimode waveguide is capable of propagating the fundamental and first mode light. This AWG is configured such that the temperature dependence remained in the arrayed waveguide grating is compensated by changing the optical path length difference between the first and second arm waveguides with temperature.Type: GrantFiled: June 30, 2009Date of Patent: October 21, 2014Assignee: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Yasuyuki Inoue, Mikitaka Itoh
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Patent number: 8787710Abstract: A interferometer type polarization beam combiner and splitter, which can combine or split polarized light over a wide band, is provided. The interferometer type polarization beam combiner and splitter includes: an optical splitter; an optical coupler; an optical path length difference imparting unit, which includes a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two input/output ports connected to the optical splitter; and two input/output ports connected to the optical coupler. A half-integer of a wavelength of ?c is set as a normalized phase difference, for the optical path length difference imparting unit, between two polarization states, and means for generating a difference in refractive index dispersion is provided between the optical waveguides of the optical path length difference imparting unit, so that the change rate of the transmittance with respect to wavelength is suppressed for the two polarization states.Type: GrantFiled: June 2, 2010Date of Patent: July 22, 2014Assignee: Nippon Telegraph and Telephone CorporationInventors: Takayuki Mizuno, Takashi Goh, Hiroshi Yamazaki, Shin Kamei, Tsutomu Kitoh
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Patent number: 8737779Abstract: An optical wavelength multi/demultiplexer having transmission characteristics with a higher rectangular degree than a conventional one includes an AWG and two-stage lattice circuit. An example of a two-stage lattice circuit according to the present invention includes an input waveguide, a third optical coupler, a third and fourth arm waveguides, a second optical coupler, a first and second arm waveguides, a first optical coupler, and output waveguides. The optical path length differences between the third and fourth arm waveguides and between the first and second arm waveguides are designed to be ?L. The path passing the third and first arm waveguides differs by 2·?L in optical length from that the fourth and second arm waveguides. The paths passing the third and second arm waveguides and passing the fourth and first arm waveguides differ by ?L from that passing the fourth and second arm waveguides.Type: GrantFiled: August 25, 2010Date of Patent: May 27, 2014Assignee: Nippon Telegraph and Telephone CorporationInventors: Tsutomu Kitoh, Shin Kamei, Toshikazu Hashimoto, Yohei Sakamaki, Hiroshi Takahashi, Manabu Oguma
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Patent number: 8483525Abstract: When a conventional synchronized AWG is employed to extend a transmission passband, an increase in loss near the optical center frequency can not be avoided. Because of passband width limit, a problem has existed in that the synchronized AWG could not be applied for a large, complicated communication system wherein a signal light passes a number of points. Therefore, an optical wavelength multiplexing/demultiplexing circuit of the present invention is a synchronized AWG, which includes an optical splitter arranged in an interference circuit that is connected on the side of one slab waveguide. The splitting ratio of the optical splitter varies, depending on the optical frequency, and the value becomes minimum near the optical center frequency of the synchronized AWG. The optical splitter is operated so that the splitting ratio is comparatively great at optical frequencies distant from the optical center frequency.Type: GrantFiled: January 8, 2010Date of Patent: July 9, 2013Assignee: Nippon Telegraph and Telephone CorporationInventors: Tsutomu Kitoh, Shin Kamei, Toshikazu Hashimoto, Yohei Sakamaki, Hiroshi Takahashi, Manabu Oguma
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Patent number: 8467642Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer according to the present invention including an input channel waveguide, an input slab waveguide, an arrayed waveguide, a polarization dependence eliminating means, an output slab waveguide, a temperature compensating means, and an output channel waveguide is characterized in that the temperature compensating means compensates for the temperature dependence of the optical path lengths in the channel waveguides of the arrayed waveguide, and the polarization dependence eliminating means eliminates the temperature dependence and the polarization dependence of the arrayed waveguide grating optical multiplexer/demultiplexer at the same time.Type: GrantFiled: February 19, 2009Date of Patent: June 18, 2013Assignees: NTT Electronics Corporation, Nippon Telegraph and Telephone CorporationInventors: Daisuke Ogawa, Takashi Saida, Yuji Moriya, Shigeo Nagashima, Yasuyuki Inoue, Shin Kamei
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Patent number: 8369666Abstract: An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.Type: GrantFiled: June 30, 2009Date of Patent: February 5, 2013Assignee: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Tsutomu Kitoh, Masaki Kohtoku, Tomohiro Shibata, Takuya Tanaka, Yasuyuki Inoue, Mikitaka Itoh
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Patent number: 8244133Abstract: A simple optical waveband multiplexer/demultiplexer operable to separate a wavelength-division multiplexed light beam WDM consisting of a plurality of wavebands WB each including a plurality of optical channels, into a predetermined plurality of wavebands WB, and output the separated plurality of wavebands WB from a plurality of output ports, wherein the wavelength-division multiplexed light beam WDM is transmitted through two array waveguides each capable of performing a demultiplexing function with a resolution corresponding to wavelengths of the optical channels, and a characteristic of sequentially shifting the output ports by one position with shifting of input ports by one position, whereby the wavelength-division multiplexed light beam WDM is separated into a plurality of wavebands WB each including the mutually different optical channels selected from the optical channels included in the wavelength-division multiplexed light beam WDM, and the separated wavebands WB are outputted from the plurality ofType: GrantFiled: April 18, 2007Date of Patent: August 14, 2012Assignees: National University Corporation, Nippon Telegraph and Telephone CorporationInventors: Ken-ichi Sato, Hiroshi Hasegawa, Shoji Kakehashi, Osamu Moriwaki, Shin Kamei, Kenya Suzuki, Yoshihisa Sakai, Kouichi Takiguchi
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Publication number: 20120170891Abstract: An optical wavelength multi/demultiplexer having transmission characteristics with a higher rectangular degree than a conventional one includes an AWG and two-stage lattice circuit. An example of a two-stage lattice circuit according to the present invention includes an input waveguide, a third optical coupler, a third and fourth arm waveguides, a second optical coupler, a first and second arm waveguides, a first optical coupler, and output waveguides. The optical path length differences between the third and fourth arm waveguides and between the first and second arm waveguides are designed to be ?L. The path passing the third and first arm waveguides differs by 2·?L in optical length from that the fourth and second arm waveguides. The paths passing the third and second arm waveguides and passing the fourth and first arm waveguides differ by ?L from that passing the fourth and second arm waveguides.Type: ApplicationFiled: August 25, 2010Publication date: July 5, 2012Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Tsutomu Kitoh, Shin Kamei, Toshikazu Hashimoto, Yohei Sakamaki, Hiroshi Takahashi, Manabu Oguma
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Publication number: 20120063716Abstract: A interferometer type polarization beam combiner and splitter, which can combine or split polarized light over a wide band, is provided. The interferometer type polarization beam combiner and splitter includes: an optical splitter; an optical coupler; an optical path length difference imparting unit, which includes a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two input/output ports connected to the optical splitter; and two input/output ports connected to the optical coupler. A half-integer of a wavelength of ?c is set as a normalized phase difference, for the optical path length difference imparting unit, between two polarization states, and means for generating a difference in refractive index dispersion is provided between the optical waveguides of the optical path length difference imparting unit, so that the change rate of the transmittance with respect to wavelength is suppressed for the two polarization states.Type: ApplicationFiled: June 2, 2010Publication date: March 15, 2012Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takayuki Mizuno, Takashi Goh, Hiroshi Yamazaki, Shin Kamei, Tsutomu Kitoh
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Publication number: 20110268447Abstract: When a conventional synchronized AWG is employed to extend a transmission passband, an increase in loss near the optical center frequency can not be avoided. Because of passband width limit, a problem has existed in that the synchronized AWG could not be applied for a large, complicated communication system wherein a signal light passes a number of points. Therefore, an optical wavelength multiplexing/demultiplexing circuit of the present invention is a synchronized AWG, which includes an optical splitter arranged in an interference circuit that is connected on the side of one slab waveguide. The splitting ratio of the optical splitter varies, depending on the optical frequency, and the value becomes minimum near the optical center frequency of the synchronized AWG. The optical splitter is operated so that the splitting ratio is comparatively great at optical frequencies distant from the optical center frequency.Type: ApplicationFiled: January 8, 2010Publication date: November 3, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Tsutomu Kitoh, Shin Kamei, Toshikazu Hashimoto, Yohei Sakamaki, Hiroshi Takahashi, Manabu Oguma
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Publication number: 20110116802Abstract: An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.Type: ApplicationFiled: June 30, 2009Publication date: May 19, 2011Applicant: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Tsutomu Kitoh, Masaki Kohtoku, Tomohiro Shibata, Takuya Tanaka, Yasuyuki Inoue, Mikitaka Itoh
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Publication number: 20110110624Abstract: An optical wavelength multi/demultiplexing circuit is provided in which temperature dependence at a transmission center wavelength remained in an athermalized AWG is compensated. An AWG according to an embodiment of the present invention is compensated for the main temperature dependence at the transmission center wavelength. The AWG comprises an optical splitter, a first and second arm waveguides, an optical mode combining coupler and a multimode waveguide between an input/output waveguide and a slab waveguide. The optical mode combining coupler couples fundamental mode light from the first arm waveguide as fundamental mode and the fundamental mode light from the second arm waveguide as first mode. The multimode waveguide is capable of propagating the fundamental and first mode light. This AWG is configured such that the temperature dependence remained in the arrayed waveguide grating is compensated by changing the optical path length difference between the first and second arm waveguides with temperature.Type: ApplicationFiled: June 30, 2009Publication date: May 12, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Shin Kamei, Yasuyuki Inoue, Mikitaka Itoh
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Publication number: 20100322556Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer according to the present invention including an input channel waveguide, an input slab waveguide, an arrayed waveguide, a polarization dependence eliminating means, an output slab waveguide, a temperature compensating means, and an output channel waveguide is characterized in that the temperature compensating means compensates for the temperature dependence of the optical path lengths in the channel waveguides of the arrayed waveguide, and the polarization dependence eliminating means eliminates the temperature dependence and the polarization dependence of the arrayed waveguide grating optical multiplexer/demultiplexer at the same time.Type: ApplicationFiled: February 19, 2009Publication date: December 23, 2010Inventors: Daisuke Ogawa, Takashi Saida, Yuji Moriya, Shigeo Nagashima, Yasuyuki Inoue, Shin Kamei
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Publication number: 20080226290Abstract: By reducing the number of PD arrays, and by simplifying the configuration of an optical power monitor in a WDM system, a miniaturized, cost reduced optical signal monitoring apparatus, optical system or optical signal monitoring method is provided. An optical power monitor 1 has an optical switch 30 having four input ports 31, a DMUX 2 having 48 output ports, and six CSP type PD array modules 50 each including an 8-channel PD array. The output port 32 of the optical switch 30 having four switchable input ports 31 is optically connected to the input port 21 of the AWG 20. The 48 output ports 22 of the AWG 20 are each optically connected to photosensitive surfaces 53 of the individual PDs included in the CSP type PD array modules 50. The CSP type PD array modules 50 are mounted on the end face of the AWG 20.Type: ApplicationFiled: March 5, 2008Publication date: September 18, 2008Applicants: Nippon Telegraph and Telephone Corporation, NTT Electronics CorporationInventors: Takaharu Ohyama, Takashi Goh, Shin Kamei, Shunichi Sohma, Mikitaka Itoh, Ikuo Ogawa, Akimasa Kaneko, Tomoyuki Yamada, Mitsuru Nagano, Yoshiyuki Doi, Takashi Saida
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Patent number: 7245793Abstract: An optical waveguide circuit includes a first loss component for causing a diffraction loss of light propagating through an optical waveguide, and a second loss component provided at least one of before and after the first loss component, for causing a diffraction loss less than the diffraction loss in the first loss component to the light propagating through the optical waveguide. This enables the beam spot size of the lightwave launched into the first loss component to be magnified seemingly, and to reduce the radiation angle of the lightwave at the first loss component, thereby making it possible to reduce the excess loss involved in the propagation of the light through the optical waveguide.Type: GrantFiled: November 17, 2003Date of Patent: July 17, 2007Assignee: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Yasuyuki Inoue, Takuya Tanaka, Toshikazu Hashimoto
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Publication number: 20070002429Abstract: There is achieved an optical channel monitor capable of preventing deviation of an image formation position due to variation in ambient temperature.Type: ApplicationFiled: May 15, 2006Publication date: January 4, 2007Applicant: YOKOGAWA ELECTRIC CORPORATIONInventors: Shin Kamei, Yasuyuki Suzuki
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Publication number: 20060290928Abstract: A photodiode array for entering incident light a spectroscope device equipped with a wavelength dispersion element and detecting light emanating from the spectroscope device. The arrangement of each of photodiode elements constituting the photodiode array is displaced.Type: ApplicationFiled: June 8, 2006Publication date: December 28, 2006Inventors: Tadashige Fujita, Yasuyuki Suzuki, Shin Kamei, Tsuyoshi Yakihara, Morio Wada, Akira Miura