Patents by Inventor Kouji Nakahara
Kouji Nakahara 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: 20170123172Abstract: Provided is a semiconductor optical device, an arrayed semiconductor optical device, an optical module having a structure to reduce the parasitic capacitance as well as a high design degree of freedom and having a multilayer structure in which a semi-insulating substrate, a first semiconductor layer having one conductive type, an active layer having light emission function, a second semiconductor layer having the other conductive type, an insulating layer, and a conductive layer are stacked in order from the bottom. The multilayer structure includes a light emitting structure, a first electrode structure, and a second electrode structure. In the semi-insulating substrate and the first semiconductor layer, a first grove which separates the second electrode structure from a remaining portion and approaches the second electrode structure with a non-linear shape rather than a linear shape in its entirety is formed.Type: ApplicationFiled: October 26, 2016Publication date: May 4, 2017Inventors: Koichiro ADACHI, Kouji NAKAHARA
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Patent number: 9263852Abstract: In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 ? to equal to or less than 0.9 ?, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.Type: GrantFiled: January 5, 2015Date of Patent: February 16, 2016Assignee: OCLARO JAPAN, INC.Inventors: Kouji Nakahara, Yuki Wakayama
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Publication number: 20150155687Abstract: In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 ? to equal to or less than 0.9 ?, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.Type: ApplicationFiled: January 5, 2015Publication date: June 4, 2015Inventors: Kouji NAKAHARA, Yuki WAKAYAMA
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Patent number: 8958451Abstract: In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 ? to equal to or less than 0.9 ?, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.Type: GrantFiled: January 29, 2014Date of Patent: February 17, 2015Assignee: Oclaro Japan, Inc.Inventors: Kouji Nakahara, Yuki Wakayama
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Patent number: 8891570Abstract: In a BH laser which uses InGaAlAs-MQW in an active layer, Al-based semiconductor multi-layer films including an InP buffer layer and an InGaAlAs-MQW layer, and an InGaAsP etching stop layer are formed in a mesa shape, and a p type InP burial layer is buried in side walls of the mesa shape. An air ridge mesa-stripe of a lateral center that is substantially the same as that of the mesa shape is formed on the mesa shape. According to the present structure, a leakage current can be considerably reduced, the light confinement coefficient can be made to be larger than in a BH laser in the related art, and thereby it is possible to implement a semiconductor laser with a low leakage current and a high relaxation oscillation frequency.Type: GrantFiled: February 7, 2013Date of Patent: November 18, 2014Assignee: Oclaro Japan, Inc.Inventors: Kouji Nakahara, Yuki Wakayama, Takeshi Kitatani, Kazunori Shinoda
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Publication number: 20140211823Abstract: In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 ? to equal to or less than 0.9 ?, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.Type: ApplicationFiled: January 29, 2014Publication date: July 31, 2014Applicant: Oclaro Japan, Inc.Inventors: Kouji NAKAHARA, Yuki WAKAYAMA
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Patent number: 8569727Abstract: The object of the invention included in the present application is to automatically prevent the deterioration of the image even when the image quality of the projected image is deteriorated due to the replacement of the light source or the like. The following light beam scanning image projection apparatus is one means for achieving the object.Type: GrantFiled: June 11, 2009Date of Patent: October 29, 2013Assignee: Hitachi, Ltd.Inventors: Etsuko Nomoto, Shigehisa Tanaka, Hitoshi Nakamura, Toshiki Sugawara, Kouji Nakahara
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Patent number: 8124432Abstract: In an InGaN-based nitride semiconductor optical device having a long wavelength (440 nm or more) equal to or more than that of blue, the increase of a wavelength is realized while suppressing In (Indium) segregation and deterioration of crystallinity. In the manufacture of an InGaN-based nitride semiconductor optical device having an InGaN-based quantum well active layer including an InGaN well layer and an InGaN barrier layer, a step of growing the InGaN barrier layer includes: a first step of adding hydrogen at 1% or more to a gas atmosphere composed of nitrogen and ammonia and growing a GaN layer in the gas atmosphere; and a second step of growing the InGaN barrier layer in a gas atmosphere composed of nitrogen and ammonia.Type: GrantFiled: December 3, 2009Date of Patent: February 28, 2012Assignee: Opnext Japan, Inc.Inventors: Tomonobu Tsuchiya, Shigehisa Tanaka, Akihisa Terano, Kouji Nakahara
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Publication number: 20110096383Abstract: The object of the invention included in the present application is to automatically prevent the deterioration of the image even when the image quality of the projected image is deteriorated due to the replacement of the light source or the like. The following light beam scanning image projection apparatus is one means for achieving the object.Type: ApplicationFiled: June 11, 2009Publication date: April 28, 2011Inventors: Etsuko Nomoto, Shigehisa Tanaka, Hitoshi Nakamura, Toshiki Sugawara, Kouji Nakahara
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Publication number: 20100150194Abstract: In an InGaN-based nitride semiconductor optical device having a long wavelength (440 nm or more) equal to or more than that of blue, the increase of a wavelength is realized while suppressing In (Indium) segregation and deterioration of crystallinity. In the manufacture of an InGaN-based nitride semiconductor optical device having an InGaN-based quantum well active layer including an InGaN well layer and an InGaN barrier layer, a step of growing the InGaN barrier layer includes: a first step of adding hydrogen at 1% or more to a gas atmosphere composed of nitrogen and ammonia and growing a GaN layer in the gas atmosphere; and a second step of growing the InGaN barrier layer in a gas atmosphere composed of nitrogen and ammonia.Type: ApplicationFiled: December 3, 2009Publication date: June 17, 2010Applicant: OPNEXT JAPAN, INC.Inventors: Tomonobu TSUCHIYA, Shigehisa TANAKA, Akihisa TERANO, Kouji NAKAHARA
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Patent number: 7583714Abstract: The relationship between the reflectivity characteristic of a DBR layer(s), in which an InP layer and an InGaAlAs layer are laminated alternatively, and the optical absorption characteristic of the InGaAlAs layer, is a trade-off in a vertical cavity surface emitting laser on an InP substrate. The present invention applies a semiconductor DBR layer(s), in which an InP layer and an InGaAlAs-MQW (multi-quantum-wells) layer are laminated alternatively, in order to dissolve the above trade-off. The InGaAlAs-MQW layer is composed of InGaAlAs-wells and barriers. The InP layer is doped uniformly and the InGaAlAs-MQW layer has a structure in which at least a part thereof is doped.Type: GrantFiled: February 27, 2007Date of Patent: September 1, 2009Assignee: Opnext Japan, Inc.Inventors: Kouji Nakahara, Koichiro Adachi, Takashi Shiota, Tomonobu Tsuchiya, Kazunori Shinoda
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Publication number: 20080144683Abstract: The relationship between the reflectivity characteristic of a DBR layer(s), in which an InP layer and an InGaAlAs layer are laminated alternatively, and the optical absorption characteristic of the InGaAlAs layer, is a trade-off in a vertical cavity surface emitting laser on an InP substrate. The present invention applies a semiconductor DBR layer(s), in which an InP layer and an InGaAlAs-MQW (multi-quantum-wells) layer are laminated alternatively, in order to dissolve the above trade-off. The InGaAlAs-MQW layer is composed of InGaAlAs-wells and barriers. The InP layer is doped uniformly and the InGaAlAs-MQW layer has a structure in which at least a part thereof is doped.Type: ApplicationFiled: February 27, 2007Publication date: June 19, 2008Inventors: Kouji NAKAHARA, Koichiro Adachi, Takashi Shiota, Tomonobu Tsuchiya, Kazunori Shinoda
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Publication number: 20070241344Abstract: For a semiconductor light emitting device using GaInNAs as an active layer, since GaInNAs includes N, the critical thickness is reduced and it is difficult to lengthen the wavelength of a laser beam. A semiconductor light emitting device is prepared, which has an active layer comprising a quantum well layer formed by successively stacking a GaInNAs layer and a GaInAs layer and GaAs barrier layers stacked on both sides of the quantum well layer. The quantum level of the conduction band is present above the conduction band edge of the GaInAs layer.Type: ApplicationFiled: April 10, 2007Publication date: October 18, 2007Inventors: Koichiro Adachi, Kouji Nakahara, Jun-ichi Kasai, Takeshi Kitatani
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Patent number: 7223993Abstract: In the semiconductor laser or electro-absorption optical modulator that includes strained quantum well layers as active layers, making laser characteristics or modulator characteristics adequate has seen the respective limits since band structures, especially, ?Ec and ?Ev, have been unable to be adjusted independently. This invention is constructed by stacking an n-type InGaAlAs-GRIN-SCH layer 3, an MQW layer 4, a p-type InGaAlAs-GRIN-SCH layer 5, a p-type InAlAs electron-stopping layer 6, and others, in that order, on an n-type InP wafer 1; wherein the MQW layer 4 includes InGaAlAs-strained quantum well layers and InGaAlAsSb-formed barrier layers each having strain of an opposite sign to the strain applied to the quantum well layers.Type: GrantFiled: August 25, 2005Date of Patent: May 29, 2007Assignee: Hitachi, Ltd.Inventors: Kouji Nakahara, Makoto Kudo, Shigehisa Tanaka, Masataka Shirai
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Publication number: 20070051939Abstract: In the semiconductor laser or electro-absorption optical modulator that includes strained quantum well layers as active layers, making laser characteristics or modulator characteristics adequate has seen the respective limits since band structures, especially, ?Ec and ?Ev, have been unable to be adjusted independently. This invention is constructed by stacking an n-type InGaAlAs-GRIN-SCH layer 3, an MQW layer 4, a p-type InGaAlAs-GRIN-SCH layer 5, a p-type InAlAs electron-stopping layer 6, and others, in that order, on an n-type InP wafer 1; wherein the MQW layer 4 includes InGaAlAs-strained quantum well layers and InGaAlAsSb-formed barrier layers each having strain of an opposite sign to the strain applied to the quantum well layers.Type: ApplicationFiled: August 25, 2005Publication date: March 8, 2007Inventors: Kouji Nakahara, Makoto Kudo, Shigehisa Tanaka, Masataka Shirai
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Patent number: 6989550Abstract: The prior art distributed feedback laser having an InGaAlAs active layer involves a problem that its laser characteristics are deteriorated at high temperature due to the high device resistance. According to the present invention, a ridge type laser is fabricated by: forming an InGaAlAs-MQW layer 104 on a n-type InP substrate 101; growing a p-type InGaAlAs-GRIN-SCH layer 105, a p-type InAlAs electron stopping layer 106 and a p-type grating layer 107 in this order on the InGaAlAs-MQW layer 104; forming a grating; and regrowing a p-type InP cladding layer 108 and a p-type InGaAs contact layer in this order. The concave depth of the grating is smaller than the thickness of the p-type grating layer 107.Type: GrantFiled: June 27, 2003Date of Patent: January 24, 2006Assignees: Hitachi, Ltd., Opnext Japan, Inc.Inventors: Kouji Nakahara, Tomonobu Tsuchiya, Akira Taike, Kazunori Shinoda
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Patent number: 6990133Abstract: Laser diodes containing aluminum at high concentration in an active layer have been usually suffered from remarkable facet deterioration along with laser driving operation and it has been difficult for the laser diodes to attain high reliability. An aluminum oxide film lacking in oxygen is formed adjacent to the semiconductor on an optical resonator facet, by which facet deterioration can be minimized and, accordingly, the laser diode can be operated with no facet deterioration at high temperature for long time and a laser diode of high reliability can be manufactured at a reduced cost.Type: GrantFiled: February 6, 2004Date of Patent: January 24, 2006Assignees: Hitachi, Ltd., Opnext Japan, Inc.Inventors: Takeshi Kikawa, Kouji Nakahara, Etsuko Nomoto
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Patent number: 6985505Abstract: The present invention provides a highly reliable ridge-waveguide semiconductor laser diode and an optical module. The p-side electrode of the ridge-waveguide laser diode has a first conductor layer region and a second conductor layer region formed on the first conductor layer region. At least one of facets of the second conductor layer region is recessed inward from a reflection facet. Thus, the ridge-waveguide semiconductor laser diode has a structure in which strain which is caused by the electrode stress to be applied on the diode facet is reduced and the saturable absorption does not occur. The ridge-waveguide semiconductor laser diode thus obtained is highly reliable, and the optical module using the same is remarkably high in reliability.Type: GrantFiled: May 17, 2005Date of Patent: January 10, 2006Assignee: Opnext Japan, Inc.Inventors: Etsuko Nomoto, Kouji Nakahara, Shinji Tsuji, Makoto Shimaoka
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Patent number: 6958831Abstract: At a conventional image scanning method, it takes long time to transfer an image data of whole image, consequently it takes long time to display the whole image on a display. Therefore, an image scanning method and an apparatus thereof, with which a user can recognize mistakes at reading a document at earlier time, are provided. By one time scanning, an image data whose resolution is lower than fundamental resolution is read. The image data of lower resolution is obtained by that the image data are thinned out. And this image data having lower resolution is displayed on a display as a preview image. By rescanning, an image whose resolution is higher than the preview image is read and displayed. This preview image can be displayed in short time, therefore the user can recognize a mistake at earlier time.Type: GrantFiled: September 17, 1999Date of Patent: October 25, 2005Assignee: NEC CorporationInventor: Kouji Nakahara
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Publication number: 20050207463Abstract: The present invention provides a highly reliable ridge-waveguide semiconductor laser diode and an optical module. The p-side electrode of the ridge-waveguide laser diode has a first conductor layer region and a second conductor layer region formed on the first conductor layer region. At least one of facets of the second conductor layer region is recessed inward from a reflection facet. Thus, the ridge-waveguide semiconductor laser diode has a structure in which strain which is caused by the electrode stress to be applied on the diode facet is reduced and the saturable absorption does not occur. The ridge-waveguide semiconductor laser diode thus obtained is highly reliable, and the optical module using the same is remarkably high in reliability.Type: ApplicationFiled: May 17, 2005Publication date: September 22, 2005Inventors: Etsuko Nomoto, Kouji Nakahara, Shinji Tsuji, Makoto Shimaoka