Patents by Inventor Jun-Ichi Umeda

Jun-Ichi Umeda 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: 5031172
    Abstract: An optical recording disc comprising a resin layer of resin material formed on a relatively rough surface of each transparent disc substrates, the resin material having approximately the same refractive index of light as the refractive index of the transparent disc substrate, and a recording layer formed on each of said resin layers. Accordingly, the optical recording disc enables a decrease in production costs and to write and read an information signal into and from the recording layer at an improved signal to noise ratio as compared to a conventional optical recording disc.
    Type: Grant
    Filed: December 28, 1988
    Date of Patent: July 9, 1991
    Assignees: Hitachi Maxell, Ltd., Hitachi, Ltd.
    Inventors: Jun-ichi Umeda, Kazuo Shigematsu
  • Patent number: 4509173
    Abstract: A semiconductor laser device is provided with a semiconductor substrate and at least a semiconductor assembly for optical confinement formed on the substrate which includes an active layer and cladding layers. A first electrode is disposed on the semiconductor assembly and a second electrode is disposed on the semiconductor substrate. To provide a phase-locked semiconductor laser device of high quality, a plurality of regions are provided in the semiconductor assembly which, in effect, cause a variation of a complex refractive index for a laser beam in a direction intersecting with a traveling direction of the laser beam. These regions can be discretely disposed over or under the active layer and give rise to a nonlinear interaction between adjacent laser emission regions formed by the plurality of regions.
    Type: Grant
    Filed: April 7, 1982
    Date of Patent: April 2, 1985
    Assignee: Hitachi, Ltd.
    Inventors: Jun-ichi Umeda, Hisao Nakashima, Takashi Kajimura, Takao Kuroda
  • Patent number: 4503540
    Abstract: A phase-locked semiconductor laser device comprising a laminated structure in which a plurality of first semiconductor layers having the substantially same composition are stacked in a manner to be sandwiched between second semiconductor layers having a band gap wider, and a refractive index lower, than those of said first semiconductor layers; a third semiconductor layer which is disposed in contact with at least one of side faces of said laminated structure parallel to a traveling direction of a laser beam, which is not narrower in the band gap and not higher in the refractive index than said first semiconductor layers and which does not have the same conductivity type as, at least, that of said first semiconductor layers; means to inject current into an interface between said first semiconductor layers and said third semiconductor layer disposed on the side face of said laminated structure; and means to act as an optical resonator for the laser beam.
    Type: Grant
    Filed: April 14, 1982
    Date of Patent: March 5, 1985
    Assignee: Hitachi, Ltd.
    Inventors: Hisao Nakashima, Jun-ichi Umeda, Takao Kuroda, Takashi Kajimura, Hiroshi Matsuda
  • Patent number: 4432091
    Abstract: In a semiconductor laser device having at least a first semiconductor layer, second and third semiconductor layers which are formed in a manner to sandwich the first semiconductor layer and which have a wider band gap and a lower refractive index than those of the first semiconductor layer, an optical resonator and carrier injection means; a semiconductor laser device characterized in that at least said first semiconductor layer has an angle of inclination (.theta.) relative to an axis which is perpendicular to optically flat faces constituting said optical resonator. The inclination angle .theta. (rad) should most preferably lie in a range of: ##EQU1## where .theta..sub.z denotes a reflection angle, .theta..sub.c a critical angle, W 1/2 of a thickness of a waveguide, and l a cavity length. The laser device is effective for preventing laser facets from breaking down, and can produce high power.
    Type: Grant
    Filed: January 25, 1982
    Date of Patent: February 14, 1984
    Assignee: Hitachi, Ltd.
    Inventors: Takao Kuroda, Takashi Kajimura, Yasutoshi Kashiwada, Naoki Chinone, Kunio Aiki, Jun-ichi Umeda
  • Patent number: 4426703
    Abstract: In a semiconductor laser device wherein a stripe-shaped impurity-diffused region is disposed in at least parts of semiconductor layers of from a surface semiconductor layer of a semiconductor layer assembly constituting the semiconductor laser device to a second semiconductor layer lying in contact with a first semiconductor layer having an active region, the impurity-diffused region having the same conductivity type as that of the second semiconductor layer and extending at least from the surface semiconductor layer to a depth vicinal to the first semiconductor layer, the impurity region serving as a current path; a semiconductor laser device characterized in that a third semiconductor layer in which the diffusion rate of an impurity for use in the formation of the impurity-diffused region is lower than in the second semiconductor layer is disposed between the surface semiconductor layer and the second semiconductor layer.
    Type: Grant
    Filed: June 9, 1981
    Date of Patent: January 17, 1984
    Assignee: Hitachi, Ltd.
    Inventors: Takao Kuroda, Takashi Kajimura, Jun-ichi Umeda, Katsutoshi Saito
  • Patent number: 4404678
    Abstract: A semiconductor laser device of this invention has a built-in passive guiding mechanism along the junction plane by growing planar double hetero (DH) layers on a grooved or projected substrate. It operates stably in the lowest transverse mode and provides light-output versus current characteristics free of either kinks or any anomalies.
    Type: Grant
    Filed: April 5, 1982
    Date of Patent: September 13, 1983
    Assignee: Hitachi, Ltd.
    Inventors: Kunio Aiki, Michiharu Nakamura, Jun-ichi Umeda
  • Patent number: 4369513
    Abstract: Disclosed is a semiconductor laser element having on a predetermined semiconductor substrate a stacked region for optical confinement including an active layer and clad layers, a first electrode disposed on the semiconductor substrate side and a second electrode disposed over the stacked region, and means for constructing an optical resonator, the semiconductor laser element comprising the fact that the means to inject current into the active layer is formed of a plurality of stripe conductive regions which are juxtaposed in traveling direction of a laser beam, and that laser radiations emitted in correspondence with the respective stripe conductive regions form a simply connected net and give rise to nonlinear interactions among them. As a typical example of the current injection means, the conductive regions have a strip-shaped pattern which includes a broader portion and a narrower portion.
    Type: Grant
    Filed: October 31, 1980
    Date of Patent: January 18, 1983
    Assignee: Hitachi, Ltd.
    Inventors: Jun-ichi Umeda, Takashi Kajimura
  • Patent number: 4337443
    Abstract: A semiconductor laser element is disclosed which includes a film of an amorphous material deposited on at least an optical output facet of the laser element and contains silicon and hydrogen as the indispensable components. The thickness of the amorphous film is preferably selected in the vicinity of (.lambda./4).multidot.m where .lambda. represents wavelength of laser light in the amorphous film and m represents an odd integer. A film of a transparent insulation material can be deposited over the amorphous film thereby to constitute a composite film. With the disclosed structure of the semiconductor laser element, increasement in a threshold current of the laser element can be suppressed to a minimum, while a maximum optical output power can be increased.
    Type: Grant
    Filed: February 25, 1980
    Date of Patent: June 29, 1982
    Assignee: Hitachi, Ltd.
    Inventors: Jun-ichi Umeda, Toshikazu Shimada, Michiharu Nakamura, Yoshifumi Katayama, Takashi Kajimura, Shigeo Yamashita
  • Patent number: 4326176
    Abstract: A semiconductor laser device of this invention has a built-in passive guiding mechanism along the junction plane by growing planar double hetero (DH) layers on a grooved or projected substrate. It operates stably in the lowest transverse mode and provides light-output versus current characteristics fee of either kinks or any anomalies.
    Type: Grant
    Filed: April 12, 1977
    Date of Patent: April 20, 1982
    Assignee: Hitachi, Ltd.
    Inventors: Kunio Aiki, Michiharu Nakamura, Jun-ichi Umeda
  • Patent number: 4288757
    Abstract: In certain applications, it is desirable to have a semiconductor laser device having shorter wave lengths of oscillation than are possible with conventional semiconductor lasers. To accomplish this, a semiconductor laser device is formed having a double-hetero structure, which comprises a semiconductor substrate composed of a GaAsP crystal, a first cladding layer formed on the substrate and composed of a GaAlAsP crystal of one conducting type, an active layer formed on the first cladding layer and composed of GaInAsP crystal, and a second cladding layer formed on the active layer and composed of a GaAlAsP crystal of the conducting type reverse to that of the first cladding layer. The cladding layers disposed on both sides of the active layer have a lower refractivity and a larger band gap than the active layer.
    Type: Grant
    Filed: July 10, 1979
    Date of Patent: September 8, 1981
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Kajimura, Motohisa Hirao, Michiharu Nakamura, Takao Kuroda, Shigeo Yamashita, Jun-Ichi Umeda
  • Patent number: 4257011
    Abstract: A semiconductor laser device has stabilized longitudinal and transverse modes without excess optical noise for a modulated signal generated by mode interaction. The fundamental construction of the semiconductor laser device comprises a structure wherein a first semiconductor layer is sandwiched between second and third semiconductor layers which have a greater band gap and lower index of refraction than the first semiconductor layer. That region of at least one of the second and third semiconductor layers which is remote from the first semiconductor layer corresponds substantially to a radiation region and serves as a light non-absorptive region in the shape of a stripe. A semiconductor layer has portions lying on both sides of the semiconductor layer remote from the first semiconductor layer and has an effective complex refractive-index for laser light discontinuous at both ends of the semiconductor layer remote from the first semiconductor layer.
    Type: Grant
    Filed: July 28, 1978
    Date of Patent: March 17, 1981
    Assignee: Hitachi, Ltd.
    Inventors: Michiharu Nakamura, Shigeo Yamashita, Takao Kuroda, Jun-ichi Umeda
  • Patent number: 4176325
    Abstract: A semiconductor laser device capable of emitting highly collimated beams, especially of a narrow beam divergence, is disclosed. A striped hetero-junction is formed on a predetermined semiconductor substrate by a first semiconductor layer (refractive index: n.sub.1, band gap: Eg.sub.1, thickness: d), a second semiconductor layer (n.sub.2) and a third semiconductor layer (n.sub.3), and the hetero-junction is sandwiched between portions of a fourth semiconductor layer (n.sub.4, Eg.sub.4) into a buried structure. At this time, the various materials are selected to follow the relations of d.ltoreq..lambda. (where .lambda. denotes the oscillation wavelength of the semiconductor laser), n.sub.2, n.sub.3 <n.sub.4 <n.sub.1, and Eg.sub.1 <Eg.sub.4, and the effective refractive index of the first semiconductor layer (n.sub.1eq) is made smaller than n.sub.4.
    Type: Grant
    Filed: October 19, 1977
    Date of Patent: November 27, 1979
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Kajimura, Kazutoshi Saito, Noriyuki Shige, Michiharu Nakamura, Jun-ichi Umeda, Masayoshi Kobayashi
  • Patent number: 4025939
    Abstract: A semiconductor laser device comprises an n-type GaAs layer, an n-type GaAlAs layer disposed on the n-type GaAs layer, an optical confinement region comprising a laser active region consisting of GaAs disposed on the n-type GaAlAs layer, a first p-type GaAlAs region whose aluminum content is less than that of the n-type GaAlAs layer, disposed on said laser active region and a second p-type GaAlAs region whose aluminum content is less than that of the first p-type GaAlAs region, the surface of which opposite that disposed on said first p-type GaAlAs region is a periodically corrugated surface, a p-type GaAlAs layer whose aluminum content is more than that of said first p-type GaAlAs region, disposed on the periodically corrugated surface of the second p-type GaAlAs region, a p-type GaAs layer disposed on said p-type GaAlAs layer, and electrodes disposed on the n-type and p-type GaAs layers, respectively, and which has a very low threshold value for laser oscillation and which is fabricated with a very high yie
    Type: Grant
    Filed: August 20, 1975
    Date of Patent: May 24, 1977
    Assignee: Hitachi, Ltd.
    Inventors: Kunio Aiki, Hitachi, Ltd., Michiharu Nakamura, Jun-Ichi Umeda