Patents by Inventor Tohru Takiguchi

Tohru Takiguchi 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).

  • Patent number: 9147997
    Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a light intensity lowering section located in each of the first optical waveguides and lower light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the respective semiconductor lasers; to decrease line width of the light output by the semiconductor lasers.
    Type: Grant
    Filed: April 23, 2015
    Date of Patent: September 29, 2015
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Takeshi Saito, Masakazu Takabayashi, Eitaro Ishimura, Tohru Takiguchi, Kazuhisa Takagi, Keisuke Matsumoto, Yoshifumi Sasahata
  • Publication number: 20150229407
    Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a light intensity lowering section located in each of the first optical waveguides and lower light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the respective semiconductor lasers; to decrease line width of the light output by the semiconductor lasers.
    Type: Application
    Filed: April 23, 2015
    Publication date: August 13, 2015
    Inventors: Takeshi Saito, Masakazu Takabayashi, Eitaro Ishimura, Tohru Takiguchi, Kazuhisa Takagi, Keisuke Matsumoto, Yoshifumi Sasahata
  • Patent number: 9042008
    Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.
    Type: Grant
    Filed: March 14, 2014
    Date of Patent: May 26, 2015
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Takeshi Saito, Masakazu Takabayashi, Eitaro Ishimura, Tohru Takiguchi, Kazuhisa Takagi, Keisuke Matsumoto, Yoshifumi Sasahata
  • Patent number: 8792756
    Abstract: An optical semiconductor device includes an optical semiconductor element and an optical waveguide butt-joined to the optical semiconductor element. The optical semiconductor element has a mesa structure including an active layer and a burying layer coating side faces of the active layer. The optical waveguide has a mesa structure including an optical waveguide layer having a layer structure different from the active layer, and a burying layer coating side faces of the optical waveguide layer. Mesa width of the optical waveguide is narrower than mesa width of the optical semiconductor element.
    Type: Grant
    Filed: August 13, 2012
    Date of Patent: July 29, 2014
    Assignee: Mitsubishi Electric Corporation
    Inventor: Tohru Takiguchi
  • Publication number: 20140198378
    Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.
    Type: Application
    Filed: March 14, 2014
    Publication date: July 17, 2014
    Applicant: Mitsubishi Electric Corporation
    Inventors: Takeshi Saito, Masakazu Takabayashi, Eitaro Ishimura, Tohru Takiguchi, Kazuhisa Takagi, Keisuke Matsumoto, Yoshifumi Sasahata
  • Publication number: 20140056556
    Abstract: An optical semiconductor device includes: semiconductor lasers separated into two groups; an optical coupler combining light output from the semiconductor lasers; an optical amplifier amplifying light output from the optical coupler; and waveguides respectively connecting the semiconductor lasers to the optical coupler. Each of the waveguides includes a respective bent waveguide. The bent waveguides have the same radius of curvature.
    Type: Application
    Filed: March 15, 2013
    Publication date: February 27, 2014
    Applicant: Mitsubishi Electric Corporation
    Inventors: Yoshifumi Sasahata, Tohru Takiguchi, Keisuke Matsumoto, Masakazu Takabayashi
  • Publication number: 20130136391
    Abstract: An optical semiconductor device includes an optical semiconductor element and an optical waveguide butt-joined to the optical semiconductor element. The optical semiconductor element has a mesa structure including an active layer and a burying layer coating side faces of the active layer. The optical waveguide has a mesa structure including an optical waveguide layer having a layer structure different from the active layer, and a burying layer coating side faces of the optical waveguide layer. Mesa width of the optical waveguide is narrower than mesa width of the optical semiconductor element.
    Type: Application
    Filed: August 13, 2012
    Publication date: May 30, 2013
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventor: Tohru TAKIGUCHI
  • Patent number: 8233515
    Abstract: An optical waveguide integrated semiconductor optical device includes a laser and an optical waveguide. The laser includes an active layer and a first cladding layer which are stacked on a second cladding layer. The optical waveguide includes an optical guiding layer and an undoped InP layer which are also stacked on the second cladding layer. A high resistance layer is located between the top surface of the optical guiding layer and a surface of the undoped InP layer and between a side of the first cladding layer and a side of the undoped InP layer.
    Type: Grant
    Filed: February 26, 2010
    Date of Patent: July 31, 2012
    Assignee: Mitsubishi Electric Corporation
    Inventor: Tohru Takiguchi
  • Publication number: 20110317731
    Abstract: A semiconductor laser includes a P-type InP substrate and a P-type InP cladding layer, an AlGaInAs strained quantum well active layer, an N-type InP cladding layer, a P-type InP buried layer, an N-type InP buried layer, a P-type InP buried layer, an N-type InP layer, an N-type InP contact layer, an SiO2 insulating film, an N-type electrode, and an electrode, all disposed on the P-type InP substrate. Further, the semiconductor laser includes an N-type InGaAsP layer.
    Type: Application
    Filed: January 28, 2011
    Publication date: December 29, 2011
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventor: Tohru Takiguchi
  • Publication number: 20110002352
    Abstract: An optical waveguide integrated semiconductor optical device includes a laser and an optical waveguide. The laser includes an active layer and a first cladding layer which are stacked on a second cladding layer. The optical waveguide includes an optical guiding layer and an undoped InP layer which are also stacked on the second cladding layer. A high resistance layer is located between the top surface of the optical guiding layer and a surface of the undoped InP layer and between a side of the first cladding layer and a side of the undoped InP layer.
    Type: Application
    Filed: February 26, 2010
    Publication date: January 6, 2011
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventor: Tohru Takiguchi
  • Patent number: 7835413
    Abstract: A semiconductor laser comprises: a ridge structure including a p-type cladding layer, an active layer, and an n-type cladding layer stacked on one another; and a burying layer burying sides of the ridge structure. The burying layer includes a p-type semiconductor layer and an n-type semiconductor layer that form a pn junction; and one of the p-type semiconductor layer and the n-type semiconductor layer has a carrier concentration of 5×1017 cm?3 or less near the pn junction.
    Type: Grant
    Filed: August 26, 2008
    Date of Patent: November 16, 2010
    Assignee: Mitsubishi Electric Corporation
    Inventors: Tohru Takiguchi, Yuichiro Okunuki, Go Sakaino
  • Patent number: 7720123
    Abstract: A buried type semiconductor laser 1 is made of a p-type InP substrate 2 and includes a ridge section 6 made up of a p type InP first clad layer 3, AlGaInAs distorted quantum well active layer 4 and n type InP second clad layer 5 laminated one atop another. On both sides of the ridge section 6, an buried current block layer 10 made up of a p-type InP first buried layer 7, n-type InP second buried layer 8 and semi-insulating Fe-doped InP third buried layer 9 laminated one atop another is formed. A top face of the third buried layer 9 is covered with an n-type InP semiconductor layer 11. The above structure can suppress the occurrence of a leakage current path on the top face of the third buried layer 9 and improve reliability of the buried type semiconductor laser.
    Type: Grant
    Filed: December 18, 2006
    Date of Patent: May 18, 2010
    Assignee: Mitsubishi Electric Corporation
    Inventors: Tohru Takiguchi, Chikara Watatani
  • Patent number: 7675954
    Abstract: A semiconductor laser device includes: an electrically insulating film on the top face of a laser chip; and a metal film, on the electrically insulating film. The electrically insulating film and/or the metal film has, in plan, a polygonal shape with five or more apexes, each of the apexes having an interior angle less than 180 degrees. Stress due to a change of temperature during operation is reduced, resulting in a semiconductor laser device having a longer life and higher reliability.
    Type: Grant
    Filed: June 6, 2005
    Date of Patent: March 9, 2010
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tomoko Kadowaki, Tohru Takiguchi, Toshio Tanaka, Yutaka Mihashi
  • Publication number: 20090290611
    Abstract: A semiconductor laser comprises: a ridge structure including a p-type cladding layer, an active layer, and an n-type cladding layer stacked on one another; and a burying layer burying sides of the ridge structure. The burying layer includes a p-type semiconductor layer and an n-type semiconductor layer that form a pn junction; and one of the p-type semiconductor layer and the n-type semiconductor layer has a carrier concentration of 5×1017 cm?3 or less near the pn junction.
    Type: Application
    Filed: August 26, 2008
    Publication date: November 26, 2009
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Tohru Takiguchi, Yuichiro Okunuki, Go Sakaino
  • Patent number: 7504664
    Abstract: A semiconductor optical device includes an active layer, a current blocking layer on both sides of the active layer, and a cladding layer on both the active layer and the current blocking layer. The current blocking layer includes a buried layer, at least one intermediate layer of Al(Ga)InAs and a cover blocking layer. The cover blocking layer is located between the cladding layer and the Al(Ga)InAs layers and has a higher oxidation resistance than the Al(Ga)InAs layer. The current blocking layer is grown such that each Al(Ga)InAs layer is not exposed at the surface of the current blocking layer.
    Type: Grant
    Filed: March 13, 2006
    Date of Patent: March 17, 2009
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Tohru Takiguchi
  • Publication number: 20080049805
    Abstract: A semiconductor laser includes a p-type InP substrate and a ridge section of a p type InP first cladding layer, an AlGaInAs strained quantum well active layer and a n type InP second cladding layer, laminated one atop the other. On both sides of the ridge section, a current blocking layer including a p-type InP first burying layer, an n-type InP second burying layer, and a semi-insulating Fe-doped InP third burying layer are laminated, one atop the other. A top face of the third burying layer is covered with an n-type InP semiconductor layer. This structure suppresses leakage current on the top face of the third burying layer and improves reliability of the semiconductor laser.
    Type: Application
    Filed: December 18, 2006
    Publication date: February 28, 2008
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Tohru TAKIGUCHI, Chikara WATATANI
  • Patent number: 7187701
    Abstract: A ridge waveguide semiconductor laser includes an active layer, semiconductor layers on the active layer and having a ridge-shaped waveguide, an insulating film on the semiconductor layer, a first electrode layer in contact with the semiconductor layer through an opening in the insulating film, and a second electrode layer on the first electrode layer having a stripe shape and extending along the waveguide. A distance from an end face of a resonator of the laser to an edge of the second electrode layer does not exceed 20 ?m.
    Type: Grant
    Filed: March 15, 2004
    Date of Patent: March 6, 2007
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yutaka Mihashi, Tohru Takiguchi, Toshio Tanaka, Tomoko Kadowaki, Yoshihiko Hanamaki, Nobuyuki Tomita
  • Publication number: 20070045633
    Abstract: A semiconductor optical device includes an active layer, a current blocking layer on both sides of the active layers and a cladding layer on both the active layer and the current blocking layer. The current blocking layer includes a buried layer, at least one intermediate layer of Al(Ga)InAs and a cover blocking layer. The cover blocking layer is located between the cladding layer and the Al(Ga)InAs layers and has a higher oxidation resistance than the Al(Ga)InAs layer. The current blocking layer is grown such that each Al(Ga)InAs layer is not exposed at the surface of the current blocking layer.
    Type: Application
    Filed: March 13, 2006
    Publication date: March 1, 2007
    Applicant: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Tohru Takiguchi
  • Publication number: 20060018358
    Abstract: A semiconductor laser device includes: an electrically insulating film, on the top face of a laser chip; and a metal film, on the electrically insulating film. The electrically insulating film and/or the metal film has, in plan, a polygonal shave with five or more apexes, each of the apexes having an interior angle less than 180 degrees. Stress due to a change of temperature during operation is reduced, resulting in a semiconductor laser device having a longer life and higher reliability.
    Type: Application
    Filed: June 6, 2005
    Publication date: January 26, 2006
    Applicant: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tomoko Kadowaki, Tohru Takiguchi, Toshio Tanaka, Yutaka Mihashi
  • Publication number: 20040218646
    Abstract: A ridge waveguide semiconductor laser includes an active layer, semiconductor layers on the active layer and having a ridge-shaped waveguide, an insulating film on the semiconductor layer, a first electrode layer in contact with the semiconductor layer through an opening in the insulating film, and a second electrode layer on the first electrode layer having a stripe shape and extending along the waveguide. A distance from an end face of a resonator of the laser to an edge of the second electrode layer does not exceed 20 &mgr;m.
    Type: Application
    Filed: March 15, 2004
    Publication date: November 4, 2004
    Applicant: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yutaka Mihashi, Tohru Takiguchi, Toshio Tanaka, Tomoko Kadowaki, Yoshihiko Hanamaki, Nobuyuki Tomita