Patents by Inventor Junichiro Ichikawa
Junichiro Ichikawa 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: 20070053625Abstract: An optical modulator using a thin plate capable of improving an S/N ratio of an output light is provided. The optical modulator including a thin plate 1 having an electrooptic effect and having a thickness of 20 ?m or less, an optical waveguide 4 formed on a top or bottom surface of the thin plate, and a modulation electrode formed on the top surface of the thin plate to modulate light passing through the optical waveguide, wherein a stray light removing member 10 is disposed within the thin plate or in a vicinity of the thin plate.Type: ApplicationFiled: March 27, 2006Publication date: March 8, 2007Applicant: Sumitomo Osaka Cement Co., Ltd.Inventors: Masayuki Ichioka, Katsutoshi Kondou, Yasuhiro Ishikawa, Takashi Shinriki, Satoshi Oikawa, Junichiro Ichikawa
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Patent number: 7174059Abstract: The present invention provides a highly-integrated and compact optical element and further provides an optical element having various functions such as lower driving voltage, chirping suppression and polarization-independency. The optical element comprising a substrate 1 consisting of a material having an electrooptic effect, top optical waveguides 2-1 an 2-2 formed on the top face of said substrate, bottom optical waveguides formed on the bottom face of said substrate, a top modulating electrode for controlling the phase of a light wave being propagated through said top optical waveguide, and a bottom modulating electrode for controlling the phase of a light wave being propagated through said bottom optical waveguide, is characterized in that at least one side edge of said substrate comprises output and input of said optical waveguides formed on said top and bottom faces, and a turnback element is located adjacent to said one side edge to guide the light wave from said output to said input.Type: GrantFiled: March 25, 2005Date of Patent: February 6, 2007Assignees: Sumitomo Osaka Cement Co., Ltd., National Institute for Materials ScienceInventors: Satoshi Oikawa, Junichiro Ichikawa, Futoshi Yamamoto, Sunao Kurimura, Kenji Kitamura
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Publication number: 20070019968Abstract: A method and device for adequately controlling the DC bias of each of the optical modulating sections of an optical modulator even while the optical modulator is operating in normal mode and even with a simple structure.Type: ApplicationFiled: March 26, 2004Publication date: January 25, 2007Inventors: Yoshihiro Hashimoto, Junichiro Ichikawa, Kaoru Higuma, Takahisa Fujita
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Publication number: 20070014014Abstract: An object of the present invention is to provide an optical device having high quality, excellent productivity and optical characteristics, and capable of suppressing a refractive index of a substrate surface from increasing when a dopant is thermally diffused into, or a heat treatment is performed in order to compensate of process distortion in stoichiometric lithium niobate crystal or a crystal substrate in which Mg is doped into the crystal, and a method of manufacturing the same. According to the present invention, there is provided a method of manufacturing an optical device including the steps of: forming a dopant layer on a substantial stoichiometric lithium niobate single crystal substrate; and diffusing a dopant in the dopant layer into at least a portion of the substantial stoichiometric lithium niobate single crystal substrate, wherein, in the diffusing step, a heat treatment is performed at a diffusion temperature of 1000° C. to 1200° C.Type: ApplicationFiled: March 3, 2006Publication date: January 18, 2007Applicants: Sumitomo Osaka Cement Co., Ltd., National Institute For Materials ScienceInventors: Futoshi Yamamoto, Katsutoshi Kondou, Junichiro Ichikawa, Masaru Nakamura, Sunao Kurimura, Shunji Takekawa, Kenji Kitamura
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Publication number: 20060269184Abstract: The present invention provides a highly-integrated and compact optical element and further provides an optical element having various functions such as lower driving voltage, chirping suppression and polarization-independency. The optical element has a substrate 1 formed of a material having an electrooptic effect, a plurality of optical waveguides formed on the substrate, and a modulating electrode for applying electric field into the optical waveguides, and is characterized in that the modulating electrode has at least two branching and confluence lines on the same line for applying the same modulating signal into different optical waveguides.Type: ApplicationFiled: August 7, 2006Publication date: November 30, 2006Applicants: Sumitomo Osaka Cement Co., Ltd., National Institute for Materials ScienceInventors: Masayuki Ichioka, Junichiro Ichikawa, Sunao Kurimura, Kenji Kitamura
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Publication number: 20060110089Abstract: An optical modulator restricted in a photorefractive phenomenon caused by a stray light in an optical modulator, and improved in the quenching ratio characteristics of a signal light. The optical modulator comprises a substrate consisting of a material having an electro-optic effect, an optical waveguide formed on the substrate, and a modulating electrode for allowing an electric field to work on the optical waveguide and changing the phase of light passing through the optical waveguide, characterized in that stray light removing means are provided on the surface of the substrate.Type: ApplicationFiled: August 29, 2003Publication date: May 25, 2006Inventors: Junichiro Ichikawa, Masayuki Ichioka, Tokutaka Hara, Yuji Yamane
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Publication number: 20060079006Abstract: The present invention provides a method for forming a ferroelectric spontaneous polarization reversal capable of forming a ferroelectric spontaneous polarization reversal condition homogeneously within the ferroelectric spontaneous polarization reversal region even across a large region of 50 ?m and over in width of a ferroelectric spontaneous polarization reversal. Also, it provides a method for forming a ferroelectric spontaneous polarization reversal where a ferroelectric substrate has convexo-concave structure, such as ridge structure and the like, on its surface and the polarity of the region including one portion of said convex part is reversed with accuracy.Type: ApplicationFiled: March 18, 2005Publication date: April 13, 2006Applicants: Sumitomo Osaka Cement Co., Ltd., National Institute for Materials ScienceInventors: Futoshi Yamamoto, Junichiro Ichikawa, Satoshi Oikawa, Sunao Kurimura, Kenji Kitamura
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Patent number: 7009758Abstract: The present invention intends to control DC drift phenomenon in a light control element having ridge structure, and to provide a light control element with high drive stability in a large area. The present invention has character that, in a light control element being equipped with a base plate that has an electrooptic effect, an optical guide and an electrode for modulation that are formed on said base plate, which has ridge structure, an anti-DC drift layer is installed on the surface of the above mentioned base plate where the optical guide is formed, and annealing treatment is performed after ridge processing.Type: GrantFiled: March 25, 2004Date of Patent: March 7, 2006Assignee: Sumitomo Osaka Cement Co., Ltd.Inventors: Junichiro Ichikawa, Futoshi Yamamoto, Takashi Shinriki, Yoshihiro Hashimoto
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Publication number: 20050271313Abstract: The present invention provides a highly-integrated and compact optical element and further provides an optical element having various functions such as lower driving voltage, chirping suppression and polarization-independency. The optical element comprising a substrate 1 consisting of a material having an electrooptic effect, top optical waveguides 2-1 an 2-2 formed on the top face of said substrate, bottom optical waveguides formed on the bottom face of said substrate, a top modulating electrode for controlling the phase of a light wave being propagated through said top optical waveguide, and a bottom modulating electrode for controlling the phase of a light wave being propagated through said bottom optical waveguide, is characterized in that at least one side edge of said substrate comprises output and input of said optical waveguides formed on said top and bottom faces, and a turnback element is located adjacent to said one side edge to guide the light wave from said output to said input.Type: ApplicationFiled: March 25, 2005Publication date: December 8, 2005Applicants: Sumitomo Osaka Cement Co., Ltd., National Institute for Materials ScienceInventors: Satoshi Oikawa, Masayuki Ichioka, Junichiro Ichikawa, Futoshi Yamamoto, Sunao Kurimura, Kenji Kitamura
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Publication number: 20040264827Abstract: Present invention offers an optical modulator capable of efficiently transmitting electric signals to an acting portion of a signal electrode with acting on an optical waveguide even when the electric signals are in high frequency zone, and capable of performing high frequency broad band operation. The optic modulator comprises a substrate 1 formed of a material having electro-optical effect, an optical waveguide formed on the substrate, and an electrode 3 for modulating the light passing through the optical waveguide. The optical modulator is characterized in that an electric signal connection pad unit 6 is provided on a part of the electrode, and in that the thickness of the substrate which is located at least on a lower part of the electric signal connection pad unit 6 and directly or indirectly continuous to the electric signal connection pad unit 6 is thinner than the thickness of other parts of the substrate.Type: ApplicationFiled: August 6, 2004Publication date: December 30, 2004Inventors: Junichiro Ichikawa, Takahisa Fujita, Yuji Yamane, Norikazu Miyazaki, Mitsuru Sakuma
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Publication number: 20040252365Abstract: The present invention intends to control DC drift phenomenon in a light control element having ridge structure, and to provide a light control element with high drive stability in a large area. The present invention has character that, in a light control element being equipped with a base plate that has an electrooptic effect, an optical guide and an electrode for modulation that are formed on said base plate, which has ridge structure, an anti-DC drift layer is installed on the surface of the above mentioned base plate where the optical guide is formed, and annealing treatment is performed after ridge processing.Type: ApplicationFiled: March 25, 2004Publication date: December 16, 2004Applicant: SUMITOMO OSAKA CEMENT CO., Ltd.Inventors: Junichiro Ichikawa, Futoshi Yamamoto, Takashi Shinriki, Yoshihiro Hashimoto
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Publication number: 20040033021Abstract: A wavelength stabilization module which can restrain light reflected by the fiber grating from returning to a light source, and a stable wavelength laser beam generating device. A wavelength stabilization module of the invention comprises an optical splitter 122 for splitting light lead from a light source 110 through a fiber 143 into first and second lights, a fiber grating 210 which has light of a specific wavelength in the first light pass therethrough and reflects light of the other wavelengths in the first light, and a light quantity change operating unit 311 for detecting a change in quantity of light passing through the fiber grating using the second light as reference light, and is configured to direct light, reflected by the fiber grating 210, to the outside of the fiber, and is configured to feed back the detected change in light quantity to the light source 110.Type: ApplicationFiled: June 27, 2003Publication date: February 19, 2004Inventors: Hitoshi Oguri, Junichiro Ichikawa, Masayuki Ichioka, Takeshi Sakai, Tokutaka Hara, Taizo Nakajima, Kenichi Kubodera
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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: 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: 5526448Abstract: An optical waveguide device usable as an optical wave-modulator and having a reduced DC drift includes a LiNbO.sub.3 substrate, an optical waveguide formed in a front surface portion of the substrate, a dielectric layer covering the front surface of the substrate and the optical waveguide surface, and an electrode system arranged on the dielectric layer, the dielectric layer comprising a matrix component consisting of an amorphous SiO.sub.2 and a doping element component consisting of Li and/or Nb; and having a refractive index lower than that of the amorphous SiO.sub.2 matrix free from the doping element component.Type: GrantFiled: September 30, 1994Date of Patent: June 11, 1996Assignee: Sumitomo Cement Company, Ltd.Inventors: Hirotoshi Nagata, Junichiro Minowa, Manabu Yamada, Junichiro Ichikawa, Jamshid Nayyer, Shinichi Shimotsu, Junichi Ogiwara, Masanobu Kobayashi, Hideki Honda, Kazumasa Kiuchi, Takashi Shinriki, Toshihiro Sakamoto