Patents by Inventor Naoto Jikutani

Naoto Jikutani 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: 7720125
    Abstract: A surface-emission laser device comprises an active layer, cavity spacer layers provided at both sides of the active layer, reflection layers provided at respective sides of the cavity spacer layers, the reflection layers reflecting an oscillation light oscillated in the active layer and a selective oxidation layer. The selective oxidation layer is provided between a location in the reflection layer corresponding to a fourth period node of the standing wave distribution of the electric field of the oscillating light and a location in the reflection layer adjacent to the foregoing fourth period node in the direction away from the active layer and corresponding to an anti-node of the standing wave distribution of the electric field of the oscillation light.
    Type: Grant
    Filed: November 27, 2006
    Date of Patent: May 18, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Naoto Jikutani, Shunichi Sato
  • Publication number: 20100118907
    Abstract: A surface-emission laser diode comprises a cavity region over a semiconductor substrate and includes an active layer containing at least one quantum well active layer producing a laser light and a barrier layer, a spacer layer is provided in the vicinity of the active layer and formed of at least one material, an upper and lower reflectors are provided at a top part and a bottom part of the cavity region, the cavity region and the upper and lower reflectors form a mesa structure over the semiconductor substrate, the upper and lower reflectors being formed of a semiconductor distributed Bragg reflector having a periodic change of refractive index and reflecting incident light by interference of optical waves, at least a part of the semiconductor distributed Bragg reflector is formed of a layer of small refractive index of AlxGa1-xAs (0<x?1) and a layer of large refractive index of AlyGa1-yAs (0?y<x?1), the lower reflector is formed of a first lower reflector having a low-refractive index layer of AlAs an
    Type: Application
    Filed: January 21, 2010
    Publication date: May 13, 2010
    Applicant: RICOH COMPANY, LTD.
    Inventors: Shunichi Sato, Akihiro Itoh, Naoto Jikutani
  • Patent number: 7693204
    Abstract: A surface-emitting laser device is disclosed that includes a substrate connected to a heat sink; a first reflective layer formed of a semiconductor distributed Bragg reflector on the substrate; a first cavity spacer layer formed in contact with the first reflective layer; an active layer formed in contact with the first cavity spacer layer; a second cavity spacer layer formed in contact with the active layer; and a second reflective layer formed of a semiconductor distributed Bragg reflector in contact with the second cavity spacer layer. The first cavity spacer layer includes a semiconductor material having a thermal conductivity greater than the thermal conductivity of a semiconductor material forming the second cavity spacer layer.
    Type: Grant
    Filed: August 9, 2007
    Date of Patent: April 6, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Shunichi Sato, Kei Hara, Naoto Jikutani
  • Patent number: 7684456
    Abstract: A laser diode includes a substrate having a lattice constant of GaAs or between GaAs and GaP, a first cladding layer of AlGaInP formed on the substrate, an active layer of GaInAsP formed on the first cladding layer, an etching stopper layer of GaInP formed on the active layer, a pair of current-blocking regions of AlGaInP formed on the etching stopper layer so as to define a strip region therebetween, an optical waveguide layer of AlGaInP formed on the pair of current-blocking regions so as to cover the etching stopper layer in the stripe region, and a second cladding layer of AlGaInP formed on the optical waveguide layer, wherein the current-blocking regions having an Al content substantially identical with an Al content of the second cladding layer.
    Type: Grant
    Filed: October 16, 2006
    Date of Patent: March 23, 2010
    Assignee: Ricoh Company, Ltd.
    Inventor: Naoto Jikutani
  • Patent number: 7684458
    Abstract: A surface-emission laser diode comprises a cavity region over a semiconductor substrate and includes an active layer containing at least one quantum well active layer producing a laser light and a barrier layer, a spacer layer is provided in the vicinity of the active layer and formed of at least one material, an upper and lower reflectors are provided at a top part and a bottom part of the cavity region, the cavity region and the upper and lower reflectors form a mesa structure over the semiconductor substrate, the upper and lower reflectors being formed of a semiconductor distributed Bragg reflector having a periodic change of refractive index and reflecting incident light by interference of optical waves, at least a part of the semiconductor distributed Bragg reflector is formed of a layer of small refractive index of AlxGa1-xAs (0<x?1) and a layer of large refractive index of AlyGa1-yAs (0?y<x?1), the lower reflector is formed of a first lower reflector having a low-refractive index layer of AlAs an
    Type: Grant
    Filed: June 8, 2005
    Date of Patent: March 23, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Shunichi Sato, Akihiro Itoh, Naoto Jikutani
  • Publication number: 20090286342
    Abstract: A semiconductor light-emitting device has a semiconductor layer containing Al between a substrate and an active layer containing nitrogen, wherein Al and oxygen are removed from a growth chamber before growing said active layer and a concentration of oxygen incorporated into said active layer together with Al is set to a level such that said semiconductor light-emitting device can perform a continuous laser oscillation at room temperature.
    Type: Application
    Filed: March 20, 2009
    Publication date: November 19, 2009
    Inventors: Takashi Takahashi, Morimasa Kaminishi, Shunichi Sato, Akihiro Itoh, Naoto Jikutani
  • Publication number: 20090285252
    Abstract: A disclosed surface-emitting laser includes a substrate and multiple semiconductor layers stacked on the substrate. A normal of the principal plane of the substrate is inclined with respect to one of crystal orientations <1 0 0> toward one of crystal orientations <1 1 1>. The semiconductor layers include a resonator structure including an active layer; and a semiconductor multilayer mirror stacked on the resonator structure. The semiconductor multilayer mirror includes a confined structure where a current passage area is surrounded by an oxidized area including at least an oxide generated by oxidation of a part of a selective oxidation layer containing aluminum. A strain field caused by the oxidation is present at least in a part of the vicinity of the oxidized area. In the strain field, the amount of strain in a first axis direction is different from the amount of strain in a second axis direction.
    Type: Application
    Filed: May 12, 2009
    Publication date: November 19, 2009
    Applicant: RICOH COMPANY, LTD.
    Inventors: TOSHIHIRO ISHII, KENGO MAKITA, NAOTO JIKUTANI, KAZUHIRO HARASAKA, SHUNICHI SATO, SATORU SUGAWARA
  • Publication number: 20090285602
    Abstract: In a surface emitting laser element, on a substrate whose normal direction of a principal surface is inclined, a resonator structural body including an active layer, and a lower semiconductor DBR and an upper semiconductor DBR sandwiching the resonator structural body are stacked. A shape of a current passing through region in an oxide confinement structure of the upper semiconductor DBR is symmetrical to an axis passing through a center of the current passing through region parallel to an X axis and symmetrical to an axis passing through the center of the current passing through region parallel to a Y axis, and a length of the current passing through region is greater in the Y axis direction than in the X axis direction. A thickness of an oxidized layer surrounding the current passing through region is greater in the ?Y direction than in the +X and ?X directions.
    Type: Application
    Filed: April 30, 2009
    Publication date: November 19, 2009
    Applicant: RICOH COMPANY, LTD
    Inventors: Kazuhiro Harasaka, Shunichi Sato, Naoto Jikutani, Toshihiro Ishii
  • Publication number: 20090268769
    Abstract: A surface-emission laser diode includes an active layer, a pair of cavity spacer layers formed at both sides of the active layer, a current confinement structure defining a current injection region into the active layer, and a pair of distributed Bragg reflectors opposing with each other across a structure formed of the active layer and the cavity spacer layers, the current confinement structure being formed by a selective oxidation process of a semiconductor layer, the pair of distributed Bragg reflectors being formed of semiconductor materials, wherein there is provided a region containing an oxide of Al and having a relatively low refractive index as compared with a surrounding region in any of the semiconductor distributed Bragg reflector or the cavity spacer layer in correspondence to a part spatially overlapping with the current injection region in a laser cavity direction.
    Type: Application
    Filed: April 24, 2009
    Publication date: October 29, 2009
    Inventor: Naoto Jikutani
  • Patent number: 7590159
    Abstract: A surface-emission laser diode includes a distributed Bragg reflector tuned to wavelength of 1.1 ?m or longer, wherein the distributed Bragg reflector includes an alternate repetition of a low-refractive index layer and a high-refractive index layer, with a heterospike buffer layer having an intermediate refractive index interposed therebetween with a thickness in the range of 5-50 nm.
    Type: Grant
    Filed: June 7, 2007
    Date of Patent: September 15, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Naoto Jikutani, Shunichi Sato, Takashi Takahashi, Akihiro Itoh, Takuro Sekiya, Akira Sakurai, Masayoshi Katoh, Teruyuki Furuta, Kazuya Miyagaki, Ken Kanai, Atsuyuki Watada, Koei Suzuki, Satoru Sugawara, Shinji Satoh, Shuuichi Hikichi
  • Publication number: 20090168828
    Abstract: A vertical-cavity, surface-emission-type laser diode includes an optical cavity formed of an active region sandwiched by upper and lower reflectors, wherein the lower reflector is formed of a distributed Bragg reflector and a non-optical recombination elimination layer is provided between an active layer in the active region and the lower reflector.
    Type: Application
    Filed: February 26, 2009
    Publication date: July 2, 2009
    Applicant: RICOH COMPANY, LTD.,
    Inventors: Shunichi Sato, Takashi Takahashi, Naoto Jikutani, Morimasa Kaminishi, Akihiro Itoh
  • Publication number: 20090155944
    Abstract: A surface emitting laser device is disclosed that is able to selectively add a sufficiently large loss to a high order transverse mode so as to efficiently suppress a high order transverse mode oscillation and to oscillate at high output in a single fundamental transverse mode. The surface emitting laser device includes a first resonance region that includes an active layer and spacer layers, two distributed Bragg reflectors that sandwich the resonance region, and a current confinement structure that defines a current injection region for the active layer. At least one of the distributed Bragg reflectors includes a second resonance region arranged in the current injection region excluding a predetermined region surrounding a center of the current injection region.
    Type: Application
    Filed: November 12, 2008
    Publication date: June 18, 2009
    Inventor: Naoto Jikutani
  • Patent number: 7542499
    Abstract: A surface-emission laser diode includes an active layer, a pair of cavity spacer layers formed at both sides of the active layer, a current confinement structure defining a current injection region into the active layer, and a pair of distributed Bragg reflectors opposing with each other across a structure formed of the active layer and the cavity spacer layers, the current confinement structure being formed by a selective oxidation process of a semiconductor layer, the pair of distributed Bragg reflectors being formed of semiconductor materials, wherein there is provided a region containing an oxide of Al and having a relatively low refractive index as compared with a surrounding region in any of the semiconductor distributed Bragg reflector or the cavity spacer layer in correspondence to a part spatially overlapping with the current injection region in a laser cavity direction.
    Type: Grant
    Filed: November 24, 2004
    Date of Patent: June 2, 2009
    Assignee: Ricoh Company, Ltd.
    Inventor: Naoto Jikutani
  • Patent number: 7519095
    Abstract: A vertical-cavity, surface-emission-type laser diode includes an optical cavity formed of an active region sandwiched by upper and lower reflectors, wherein the lower reflector is formed of a distributed Bragg reflector and a non-optical recombination elimination layer is provided between an active layer in the active region and the lower reflector.
    Type: Grant
    Filed: July 13, 2007
    Date of Patent: April 14, 2009
    Assignee: Ricoh Company, Ltd
    Inventors: Shunichi Sato, Takashi Takahashi, Naoto Jikutani, Morimasa Kaminishi, Akihiro Itoh
  • Publication number: 20090022199
    Abstract: A surface-emission laser device comprises an active layer, cavity spacer layers provided at both sides of the active layer, reflection layers provided at respective sides of the cavity spacer layers, the reflection layers reflecting an oscillation light oscillated in the active layer and a selective oxidation layer. The selective oxidation layer is provided between a location in the reflection layer corresponding to a fourth period node of the standing wave distribution of the electric field of the oscillating light and a location in the reflection layer adjacent to the foregoing fourth period node in the direction away from the active layer and corresponding to an anti-node of the standing wave distribution of the electric field of the oscillation light.
    Type: Application
    Filed: November 27, 2006
    Publication date: January 22, 2009
    Inventors: Naoto Jikutani, Shunichi Sato
  • Patent number: 7466738
    Abstract: A surface emitting laser device is disclosed that is able to selectively add a sufficiently large loss to a high order transverse mode so as to efficiently suppress a high order transverse mode oscillation and to oscillate at high output in a single fundamental transverse mode. The surface emitting laser device includes a first resonance region that includes an active layer and spacer layers, two distributed Bragg reflectors that sandwich the resonance region, and a current confinement structure that defines a current injection region for the active layer. At least one of the distributed Bragg reflectors includes a second resonance region arranged in the current injection region excluding a predetermined region surrounding a center of the current injection region.
    Type: Grant
    Filed: October 12, 2005
    Date of Patent: December 16, 2008
    Assignee: Ricoh Company, Ltd.
    Inventor: Naoto Jikutani
  • Patent number: 7453096
    Abstract: A semiconductor light-emitting device has a semiconductor layer containing Al between a substrate and an active layer containing nitrogen, wherein Al and oxygen are removed from a growth chamber before growing said active layer and a concentration of oxygen incorporated into said active layer together with Al is set to a level such that said semiconductor light-emitting device can perform a continuous laser oscillation at room temperature.
    Type: Grant
    Filed: April 17, 2006
    Date of Patent: November 18, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Takashi Takahashi, Morimasa Kaminishi, Shunichi Sato, Akihiro Itoh, Naoto Jikutani
  • Publication number: 20080233017
    Abstract: A semiconductor oxidation apparatus is provided with a sealable oxidation chamber defined by walls, a base provided within the oxidation chamber and configured to support a semiconductor sample, a supply part configured to supply water vapor into the oxidation chamber to oxidize a specific portion of the semiconductor sample, a monitoring window provided in one of the walls of the oxidation chamber and disposed at a position capable of confronting the semiconductor sample supported on the base, a monitoring part provided outside the oxidation chamber and capable of confronting the semiconductor sample supported on the base via the monitoring window, and an adjusting part configured to adjust a distance between the base and the monitoring part.
    Type: Application
    Filed: February 13, 2006
    Publication date: September 25, 2008
    Inventors: Shunichi Sato, Naoto Jikutani, Akihiro Itoh, Shinya Umemoto, Yoshiaki Zenno, Takatoshi Yamamoto
  • Publication number: 20080212636
    Abstract: A surface-emission laser diode comprises a cavity region over a semiconductor substrate and includes an active layer containing at least one quantum well active layer producing a laser light and a barrier layer, a spacer layer is provided in the vicinity of the active layer and formed of at least one material, an upper and lower reflectors are provided at a top part and a bottom part of the cavity region, the cavity region and the upper and lower reflectors form a mesa structure over the semiconductor substrate, the upper and lower reflectors being formed of a semiconductor distributed Bragg reflector having a periodic change of refractive index and reflecting incident light by interference of optical waves, at least a part of the semiconductor distributed Bragg reflector is formed of a layer of small refractive index of AlxGa1-xAs (0<x?1) and a layer of large refractive index of AlyGa1-yAs (0?y<x?1), the lower reflector is formed of a first lower reflector having a low-refractive index layer of AlAs an
    Type: Application
    Filed: June 8, 2005
    Publication date: September 4, 2008
    Applicant: RICOH COMPANY, LTD.
    Inventors: Shunichi Sato, Akihiro Itoh, Naoto Jikutani
  • Patent number: 7384479
    Abstract: An optical semiconductor device operable in a 0.6 ?m band includes an active layer of GaInNP sandwiched by a pair of GaInP layer with a thickness of about 2 molecular layers or less.
    Type: Grant
    Filed: March 16, 2005
    Date of Patent: June 10, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Naoto Jikutani, Shunichi Sato, Takashi Takahashi