Patents by Inventor Yasuhiko Arakawa

Yasuhiko Arakawa 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).

  • Publication number: 20210296517
    Abstract: Provided is an infrared detector capable of achieving high sensitivity with little noise. An infrared detector includes: contact layers; a photoelectric conversion layer; a barrier layer; and an insertion layer. Each of the contact layers is doped with a dopant. The photoelectric conversion layer is placed between the contact layers, and includes a quantum layer (quantum dots) and an intermediate layer. The barrier layer is placed between the photoelectric conversion layer and one of the contact layers. The insertion layer is placed between, and in contact with, the photoelectric conversion layer and the one contact layer.
    Type: Application
    Filed: March 11, 2021
    Publication date: September 23, 2021
    Inventors: HIROFUMI YOSHIKAWA, YASUHIKO ARAKAWA
  • Patent number: 10866143
    Abstract: An infrared photodetection system is provided that is capable of measuring infrared light up to high-temperature regions while improving a temperature resolution for low-temperature regions without increasing image-acquisition time even if the measuring temperature range varies. The infrared photodetection system is set up to exhibit sensitivity spectrum SSP1 for high sensitivity (for low temperature use) and sensitivity spectrum SSP2 for low sensitivity (for high temperature use) in the transmission band of the bandpass filter when different voltages are applied to a quantum-dot infrared photodetector. The infrared photodetection system then integrates temperature data for the infrared light detected using sensitivity spectrum SSP1 and temperature data for the infrared light detected using sensitivity spectrum SSP2, in order to output a temperature distribution in a measurement region.
    Type: Grant
    Filed: March 28, 2019
    Date of Patent: December 15, 2020
    Assignees: SHARP KABUSHIKI KAISHA, THE UNIVERSITY OF TOKYO
    Inventors: Takahiro Doe, Hirofumi Yoshikawa, Tazuko Kitazawa, Yasuhiko Arakawa
  • Publication number: 20200378833
    Abstract: Provided is an infrared detection apparatus without a bandpass filter and capable of reducing an error produced when a temperature of an object is calculated. A detection unit has a quantum-dot stacked structure. A first voltage and a second voltage are respectively provided for setting a first responsivity peak wavelength and a second responsivity peak wavelength to be used for detecting an infrared ray in the detection unit. The second responsivity peak wavelength is different from the first responsivity peak wavelength. A detector detects (i) a first photocurrent to be output from the detection unit when the first voltage is applied to the photoelectric conversion layer, and (ii) a second photocurrent to be output from the detection unit when the second voltage is applied to the photoelectric conversion layer. A calculator calculates a temperature of an object based on the first photocurrent and the second photocurrent detected by the detector.
    Type: Application
    Filed: June 1, 2020
    Publication date: December 3, 2020
    Inventors: HIROFUMI YOSHIKAWA, TAKAHIRO DOE, YASUHIKO ARAKAWA
  • Patent number: 10811554
    Abstract: A high detectivity infrared photodetector is provided. An infrared photodetector 10 includes n-type semiconductor layers 3 and 5 and a photoelectric conversion layer 4. The photoelectric conversion layer 4 includes quantum dots 411, a barrier layer 42, and a single-sided barrier layer 43. The single-sided barrier layer 43 is inserted between the barrier layer 42 and the n-type semiconductor layer 5 and has a wider band gap than does the barrier layer 42. Letting y be an energy level difference between the bottom of the conduction band of the single-sided barrier layer 43 and the bottom of the conduction band of the n-type semiconductor layer 5, z be a voltage in volts applied to the photoelectric conversion layer 4, and d be a thickness in nanometers of the photoelectric conversion layer 4, the infrared photodetector 10 satisfies y?27×exp(0.64×z/(d×10000)).
    Type: Grant
    Filed: June 14, 2019
    Date of Patent: October 20, 2020
    Assignees: SHARP KABUSHIKI KAISHA, THE UNIVERSITY OF TOKYO
    Inventors: Hirofumi Yoshikawa, Takahiro Doe, Yasuhiko Arakawa
  • Publication number: 20200173848
    Abstract: A detector includes an active layer containing a quantum well or quantum dots and the detector can shift a detection wavelength by applying a voltage to the active layer. The detector has a reference wavelength to be referred to as a criterion for calibration or correction of the detection wavelength within a range in which the detection wavelength is shifted. A method of calibrating or correcting with the detector, a detection wavelength with the reference wavelength being defined as the criterion is provided.
    Type: Application
    Filed: February 10, 2020
    Publication date: June 4, 2020
    Inventors: Teruhisa KOTANI, Hirofumi YOSHIKAWA, Tazuko KITAZAWA, Yasuhiko ARAKAWA, Jinkwan KWOEN
  • Patent number: 10659743
    Abstract: An image projection device includes: a first mirror oscillating to scan an image light beam forming an image projected onto a retina of a user; a light source emitting the image light beam and a detection light beam to the first mirror at different timings; a second mirror having a first region reflecting the image light beam reflected by the first mirror to the retina and a second region reflecting the detection light beam reflected by the first mirror in a direction different from a direction in which the image light beam is reflected, and scanning neither the image light beam nor the detection light beam reflected by the first mirror; a detector detecting the detection light beam reflected by the second region; and a controller adjusting oscillation of the first mirror and an emission timing of the image light beam based on a detection result by the detector.
    Type: Grant
    Filed: April 26, 2016
    Date of Patent: May 19, 2020
    Assignees: QD LASER, INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko Arakawa, Mitsuru Sugawara, Makoto Suzuki, Shuichi Tojo
  • Patent number: 10636833
    Abstract: A quantum dot infrared detector includes a quantum dot-stacked structure in which quantum dot layers each containing quantum dots stacked on top of one another and intermediate layers. The quantum dots are sandwiched between the intermediate layers in the height direction of the quantum dots. The quantum dots have conduction band quantum confinement levels that include a conduction band ground level, a conduction band first excitation level at a higher energy position than the conduction band ground level, and a conduction band second excitation level at a higher energy position than the conduction band ground level. An energy gap between the conduction band first excitation level and the conduction band bottom of the intermediate layer and an energy gap between the conduction band second excitation level and the conduction band bottom of the intermediate layer are each smaller than twice thermal energy.
    Type: Grant
    Filed: September 4, 2018
    Date of Patent: April 28, 2020
    Assignees: SHARP KABUSHIKI KAISHA, The University of Tokyo
    Inventors: Hirofumi Yoshikawa, Yasuhiko Arakawa
  • Patent number: 10627631
    Abstract: The present invention is an image projection device that includes: a light source 12 that emits a laser beam 34; a scanning mirror 14 that two-dimensionally scans the laser beam 34 emitted from the light source 12; and a projection mirror 24 that projects scanned light onto a retina 26 of an eyeball 22 of a user to project an image onto the retina 26, the scanned light being composed of the laser beam 34 that has been scanned by the scanning mirror 14, wherein the laser beam 34 emitted from the light source 12 is scanned by using a part of an operating range of the scanning mirror 14.
    Type: Grant
    Filed: August 28, 2018
    Date of Patent: April 21, 2020
    Assignees: QD LASER, INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko Arakawa, Mitsuru Sugawara, Makoto Suzuki
  • Publication number: 20190393373
    Abstract: A high detectivity infrared photodetector is provided. An infrared photodetector 10 includes n-type semiconductor layers 3 and 5 and a photoelectric conversion layer 4. The photoelectric conversion layer 4 includes quantum dots 411, a barrier layer 42, and a single-sided barrier layer 43. The single-sided barrier layer 43 is inserted between the barrier layer 42 and the n-type semiconductor layer 5 and has a wider band gap than does the barrier layer 42. Letting y be an energy level difference between the bottom of the conduction band of the single-sided barrier layer 43 and the bottom of the conduction band of the n-type semiconductor layer 5, z be a voltage in volts applied to the photoelectric conversion layer 4, and d be a thickness in nanometers of the photoelectric conversion layer 4, the infrared photodetector 10 satisfies y?27×exp(0.64×z/(d×10000)).
    Type: Application
    Filed: June 14, 2019
    Publication date: December 26, 2019
    Inventors: Hirofumi YOSHIKAWA, Takahiro DOE, Yasuhiko ARAKAWA
  • Patent number: 10444519
    Abstract: An image projection device includes: one light source unit emitting an image light beam, which forms an image, of visible light and a checking light beam of visible light; an optical system projecting the image light beam emitted from emitted from the one light source unit onto a first surface region of an eye of a user to project the image light beam onto a retina of the user, and projecting the checking light beam emitted from the one light source unit onto a second surface region, which is distant from the first surface region, of the eye of the user; a light detector detecting a reflected light that is the checking light beam reflected by the eye of the user; and a controller controlling at least one of the one light source unit and the optical stem based on a detection result of the reflected light by the light detector.
    Type: Grant
    Filed: April 26, 2016
    Date of Patent: October 15, 2019
    Assignees: QD LASER, INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko Arakawa, Mitsuru Sugawara, Makoto Suzuki, Michio Arai
  • Publication number: 20190301944
    Abstract: An infrared photodetection system is provided that is capable of measuring infrared light up to high-temperature regions while improving a temperature resolution for low-temperature regions without increasing image-acquisition time even if the measuring temperature range varies. The infrared photodetection system is set up to exhibit sensitivity spectrum SSP1 for high sensitivity (for low temperature use) and sensitivity spectrum SSP2 for low sensitivity (for high temperature use) in the transmission band of the bandpass filter when different voltages are applied to a quantum-dot infrared photodetector. The infrared photodetection system then integrates temperature data for the infrared light detected using sensitivity spectrum SSP1 and temperature data for the infrared light detected using sensitivity spectrum SSP2, in order to output a temperature distribution in a measurement region.
    Type: Application
    Filed: March 28, 2019
    Publication date: October 3, 2019
    Inventors: Takahiro DOE, Hirofumi YOSHIKAWA, Tazuko KITAZAWA, Yasuhiko ARAKAWA
  • Patent number: 10340663
    Abstract: A quantum cascade laser includes a semiconductor substrate and an active layer having a cascade structure, in which unit layered bodies, each composed of a quantum well light emitting layer and an injection layer, are stacked, wherein the unit layered body has a subband level structure having an upper laser level, a lower laser level, and a relaxation miniband composed of at least two energy levels with an energy spacing smaller than the energy difference (EUL) between the upper laser level and the lower laser level, the energy width of the relaxation miniband is smaller than the energy (ELO?EUL) obtained by subtracting the energy difference (EUL) from the energy (ELO) of longitudinal optical phonons, and electrons subjected to the intersubband transition are relaxed in the relaxation miniband and are injected into a quantum well light emitting layer in a subsequent unit layered body.
    Type: Grant
    Filed: May 19, 2017
    Date of Patent: July 2, 2019
    Assignees: SHARP KABUSHIKI KAISHA, THE UNIVERSITY OF TOKYO
    Inventors: Teruhisa Kotani, Yasuhiko Arakawa
  • Patent number: 10340662
    Abstract: A QCL (10) includes a first electrode (15), a first contact layer (11) that is in contact with the first electrode (15) and is made of a first compound semiconductor, a second electrode (14) having a polarity opposite to that of the first electrode (15), a second contact layer (13) that is in contact with the second electrode (14) and is made of a second compound semiconductor, and an active layer (12) disposed between the first contact layer (11) and the second contact layer (13) and including two or more active layer units. Each of the active layer units includes one or more quantum well layers made of a third compound semiconductor and one or more barrier layers made of a fourth compound semiconductor, and each of the quantum well layers and each of the barrier layers are alternately stacked.
    Type: Grant
    Filed: May 7, 2015
    Date of Patent: July 2, 2019
    Assignees: Sharp Kabushiki Kaisha, The University of Tokyo
    Inventors: Teruhisa Kotani, Yasuhiko Arakawa
  • Publication number: 20190074320
    Abstract: A quantum dot infrared detector includes a quantum dot-stacked structure in which quantum dot layers each containing quantum dots stacked on top of one another and intermediate layers. The quantum dots are sandwiched between the intermediate layers in the height direction of the quantum dots. The quantum dots have conduction band quantum confinement levels that include a conduction band ground level, a conduction band first excitation level at a higher energy position than the conduction band ground level, and a conduction band second excitation level at a higher energy position than the conduction band ground level. An energy gap between the conduction band first excitation level and the conduction band bottom of the intermediate layer and an energy gap between the conduction band second excitation level and the conduction band bottom of the intermediate layer are each smaller than twice thermal energy.
    Type: Application
    Filed: September 4, 2018
    Publication date: March 7, 2019
    Inventors: HIROFUMI YOSHIKAWA, YASUHIKO ARAKAWA
  • Patent number: 10181539
    Abstract: A photoelectric conversion element includes a buffer layer, a BSF layer, a base layer, a photoelectric conversion layer, an emitter layer, a window layer, a contact layer, and a p-type electrode sequentially on one surface of a substrate, and includes an n-type electrode on the other surface of the substrate. The photoelectric conversion layer has at least one quantum dot layer. The at least one quantum dot layer includes a quantum dot and a barrier layer. A photoelectric conversion member including the buffer layer, the BSF layer, the base layer, the photoelectric conversion layer, the emitter layer, the window layer, and the contact layer has an edge of incidence that receives light in an oblique direction relative to the growth direction of the quantum dot. A concentrator concentrates sunlight and causes the concentrated sunlight to enter the photoelectric conversion member from the edge of incidence.
    Type: Grant
    Filed: June 26, 2017
    Date of Patent: January 15, 2019
    Assignees: SHARP KABUSHIKI KAISHA, THE UNIVERSITY OF TOKYO
    Inventors: Hirofumi Yoshikawa, Makoto Izumi, Yasuhiko Arakawa, Takeo Kageyama
  • Publication number: 20180364489
    Abstract: The present invention is an image projection device that includes: a light source 12 that emits a laser beam 34; a scanning mirror 14 that two-dimensionally scans the laser beam 34 emitted from the light source 12; and a projection mirror 24 that projects scanned light onto a retina 26 of an eyeball 22 of a user to project an image onto the retina 26, the scanned light being composed of the laser beam 34 that has been scanned by the scanning mirror 14, wherein the laser beam 34 emitted from the light source 12 is scanned by using a part of an operating range of the scanning mirror 14.
    Type: Application
    Filed: August 28, 2018
    Publication date: December 20, 2018
    Applicants: QD LASER INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko ARAKAWA, Mitsuru SUGAWARA, Makoto SUZUKI
  • Publication number: 20180331240
    Abstract: A quantum dot infrared detector includes a photoelectric conversion layer. The photoelectric conversion layer includes a quantum dot stacked structure in which quantum dot layers are stacked, each quantum dot layer including at least quantum dots, a underlayer for the quantum dots, and a partial cap layer at least partially covering the quantum dots. The underlayer is AlxGa1-xAs (0?x<1), and the partial cap layer is AlyGa1-yAs (0?y<1). When the lower of x and y is represented by z and a size of the quantum dots in a direction perpendicular to a stacking direction of the quantum dot stacked structure is represented by R (nm), z satisfies z?0.14×R?1.6, and the size of the quantum dots in the stacking direction is less than or equal to 0.5R.
    Type: Application
    Filed: May 10, 2018
    Publication date: November 15, 2018
    Inventors: HIROFUMI YOSHIKAWA, Makoto Izumi, TAZUKO KITAZAWA, TERUHISA KOTANI, YASUHIKO ARAKAWA
  • Patent number: 10088682
    Abstract: The present invention is an image projection device that includes: a light source 12 that emits a laser beam 34; a scanning mirror 14 that two-dimensionally scans the laser beam 34 emitted from the light source 12; and a projection mirror 24 that projects scanned light onto a retina 26 of an eyeball 22 of a user to project an image onto the retina 26, the scanned light being composed of the laser beam 34 that has been scanned by the scanning mirror 14, wherein the laser beam 34 emitted from the light source 12 is scanned by using a part of an operating range of the scanning mirror 14.
    Type: Grant
    Filed: April 25, 2014
    Date of Patent: October 2, 2018
    Assignees: QD LASER, INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko Arakawa, Mitsuru Sugawara, Makoto Suzuki
  • Patent number: 10038306
    Abstract: A nitride semiconductor device includes a GaN substrate in which an angle between a principal surface and an m-plane of GaN is ?5° or more and +5° or less, a first intermediate layer disposed on the principal surface of the substrate and made of AlzGa(1?z)N, 0?z?1, and a second intermediate layer disposed on a principal surface of the first intermediate layer, having an Al content different from that of the first intermediate layer, and made of Alx1Iny1Ga(1?x1?y1)N, 0?x1?1, 0?y1?1. A quantum cascade laser includes the nitride semiconductor device.
    Type: Grant
    Filed: December 14, 2016
    Date of Patent: July 31, 2018
    Assignees: Sharp Kabushiki Kaisha, THE UNIVERSITY OF TOKYO
    Inventors: Teruhisa Kotani, Yasuhiko Arakawa
  • Publication number: 20180184059
    Abstract: An image projection device includes: a first mirror oscillating to scan an image light beam forming an image projected onto a retina of a user; a light source emitting the image light beam and a detection light beam to the first mirror at different timings; a second mirror having a first region reflecting-the image light beam reflected by the first mirror to the retina and a second region reflecting the detection light beam reflected by the first mirror in a direction different from a direction in which the image light beam is reflected, and scanning neither the image light beam nor the detection light beam reflected by the first mirror; a detector detecting the detection light beam reflected by the second region; and a controller adjusting oscillation of the first mirror and an emission timing of the image light beam based on a detection result by the detector.
    Type: Application
    Filed: April 26, 2016
    Publication date: June 28, 2018
    Applicants: QD LASER, INC., THE UNIVERSITY OF TOKYO
    Inventors: Yasuhiko ARAKAWA, Mitsuru SUGAWARA, Makoto SUZUKI, Shuichi TOJO