Patents by Inventor Takaaki Kakitsuka

Takaaki Kakitsuka 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: 20220320813
    Abstract: There are provided a first cladding layer formed on a Si substrate, a first core made of Si and formed on the first cladding layer, and a second cladding layer formed on the first cladding layer and covering the first core Additionally, this optical device includes a waveguide type laser formed over the second cladding layer, a second core made of InP and formed continuously to the laser, and a third cladding layer formed on the second cladding layer and covering the laser and the second core.
    Type: Application
    Filed: June 5, 2019
    Publication date: October 6, 2022
    Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220320831
    Abstract: An active region formed on a substrate, and a p-type region and an n-type region formed so as to sandwich the active region are provided. The p-type region and the n-type region are formed so as to sandwich the active region. Both edges of a first side being a side of the p-type region and facing a first side surface of the active region are rounded in a direction separating from the active region. Also, both edges of a second side being a side of the n-type region and facing a second side surface of the active region are rounded in a direction separating from the active region.
    Type: Application
    Filed: June 3, 2019
    Publication date: October 6, 2022
    Inventors: Takuma Tsurugaya, Takuro Fujii, Takaaki Kakitsuka, Shinji Matsuo
  • Patent number: 11418232
    Abstract: An inference processing apparatus includes an input data storage unit that stores pieces X of input data, a learned NN storage unit that stores a piece W of weight data of a neural network, a batch processing control unit that sets a batch size on the basis of information on the pieces X of input data, a memory control unit that reads out, from the input data storage unit, the pieces X of input data corresponding to the set batch size, and an inference operation unit that batch-processes operation in the neural network using, as input, the pieces X of input data corresponding to the batch size and the piece W of weight data and infers a feature of the pieces X of input data.
    Type: Grant
    Filed: November 6, 2019
    Date of Patent: August 16, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220231480
    Abstract: A device includes a first cladding layer, a waveguide laser, an absorption layer, and a second cladding layer. The absorption layer is constituted by an oversaturation absorption body such as graphene. Also, the absorption layer is provided between the active layer and the distributed Bragg reflection portion. The absorption layer is formed below a core forming an optical waveguide between the active layer and a distributed Bragg reflection portion.
    Type: Application
    Filed: June 10, 2019
    Publication date: July 21, 2022
    Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220216673
    Abstract: A length L1 of a first distributed Bragg reflector in a waveguide direction, a length L2 of a distributed feedback active region in the waveguide direction, a length L3 of a second distributed Bragg reflector in the waveguide direction, and a position xps of a phase shift portion are set to satisfy correlations of xps=L1+L2×?, L2(1??)+L3>xps, and 0.5<?<1. Further, the position xps is a position of the phase shift portion in the waveguide direction with an end portion thereof on the first distributed Bragg reflector side set as an origin.
    Type: Application
    Filed: May 16, 2019
    Publication date: July 7, 2022
    Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220085576
    Abstract: Provided is a tunable laser that prevents basic characteristics of the laser from deteriorating and enables a high-speed control of the oscillation wavelength. The tunable laser includes a semiconductor gain portion including a III-V compound semiconductor, an optical feedback portion configured to diffract light generated in the semiconductor gain portion and feed the diffracted light back to the semiconductor gain portion, and an optical modulation portion including an optical waveguide that contains doped indirect transition-type silicon. The semiconductor gain portion and the optical modulation portion are disposed so that optical modes thereof overlap each other, and the semiconductor gain portion includes an embedded active layer thin film of a type in which a current is injected in a lateral direction.
    Type: Application
    Filed: January 17, 2020
    Publication date: March 17, 2022
    Inventors: Takuma Aihara, Shinji Matsuo, Takaaki Kakitsuka, Tai Tsuchizawa, Tatsuro Hiraki
  • Patent number: 11276988
    Abstract: A semiconductor optical device that achieves both of heat dissipation and light confinement and permits efficient current injection or application of an electric field is implemented. The semiconductor optical device includes: a core layer including an active region (1) made of a compound semiconductor; two cladding layers (5, 6) injecting current into the core layer; and a third cladding layer (4) made of a material having a larger thermal conductivity, a smaller refractive index, and a larger band gap than a material for any of the core layer and the two cladding layers.
    Type: Grant
    Filed: May 15, 2018
    Date of Patent: March 15, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220045481
    Abstract: An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E12 mode, for example.
    Type: Application
    Filed: December 24, 2019
    Publication date: February 10, 2022
    Inventors: Takuma Aihara, Shinji Matsuo, Takaaki Kakitsuka, Tai Tsuchizawa, Tatsuro Hiraki
  • Publication number: 20220029385
    Abstract: A semiconductor laser includes an active region, a first distributed-Bragg-reflector region disposed contiguously with the active region, and a second distributed-Bragg-reflector region. The first distributed-Bragg-reflector region is formed contiguously with one side of the active region in a waveguide direction and includes a first diffraction grating. The second distributed-Bragg-reflector region is formed contiguously with to the other side of the active region in the waveguide direction and includes a second diffraction grating. The first diffraction grating includes recessed portions formed through a diffraction grating layer formed in the first distributed-Bragg-reflector region and convex portions adjacent to the recessed portions. The diffraction grating layer is made of a dielectric material.
    Type: Application
    Filed: December 2, 2019
    Publication date: January 27, 2022
    Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20220014231
    Abstract: An inference processing apparatus includes an input data storage unit that stores pieces X of input data, a learned NN storage unit that stores a piece W of weight data of a neural network, a batch processing control unit that sets a batch size on the basis of information on the pieces X of input data, a memory control unit that reads out, from the input data storage unit, the pieces X of input data corresponding to the set batch size, and an inference operation unit that batch-processes operation in the neural network using, as input, the pieces X of input data corresponding to the batch size and the piece W of weight data and infers a feature of the pieces X of input data.
    Type: Application
    Filed: November 6, 2019
    Publication date: January 13, 2022
    Inventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20210336412
    Abstract: A semiconductor optical device that achieves both of heat dissipation and light confinement and permits efficient current injection or application of an electric field is implemented. The semiconductor optical device includes: a core layer including an active region (1) made of a compound semiconductor; two cladding layers (5, 6) injecting current into the core layer; and a third cladding layer (4) made of a material having a larger thermal conductivity, a smaller refractive index, and a larger band gap than a material for any of the core layer and the two cladding layers.
    Type: Application
    Filed: May 15, 2018
    Publication date: October 28, 2021
    Inventors: Ryo NAKAO, Takaaki KAKITSUKA, Shinji MATSUO
  • Publication number: 20210203125
    Abstract: A semiconductor optical module includes a semiconductor laser element region having an active layer, a first cladding layer which is formed such that the active layer is embedded therein, a second cladding layer which is formed underneath the active layer and the first cladding layer, and a heater unit which produces a temperature change in a waveguide; an optical waveguide element region including a spot-size converter which converts a spot size of incident laser light, and an optical waveguide core layer which is formed such that the spot-size converter is embedded therein, the first cladding layer contains InP, the second cladding layer is made of a material lower in refractive index and higher in thermal conductivity than the first cladding layer, and a third cladding layer which is made of a material lower in refractive index and lower in thermal conductivity than the second cladding layer is formed underneath the spot-size converter and the heater unit.
    Type: Application
    Filed: March 15, 2019
    Publication date: July 1, 2021
    Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20210184421
    Abstract: A first conduction type first cladding layer and a second conduction type second cladding layer are arranged on the two sides in the vertical direction of a core portion having a multiple quantum-well structure, and a first conduction type third cladding layer and a second conduction type fourth cladding layer are arranged on the two sides in the horizontal direction of the core portion. A first electrode connected to the third cladding layer is formed. A second electrode connected to the fourth cladding layer is formed. A reverse bias is applied between the first and third cladding layers and the second and fourth cladding layers.
    Type: Application
    Filed: April 12, 2019
    Publication date: June 17, 2021
    Inventors: Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20210184427
    Abstract: A semiconductor laser is provided with: an active layer that excites a transverse electric (TE) mode and a transverse magnetic (TM) mode of light and constitutes at least a part of a resonator guiding the TE mode and the TM mode of light; and a diffraction grating as a frequency difference setting structure that sets the difference in oscillation frequency between the TE mode and the TM mode of light higher than a relaxation-oscillation frequency
    Type: Application
    Filed: May 28, 2019
    Publication date: June 17, 2021
    Inventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20210175685
    Abstract: A wavelength tunable laser formed on a substrate made of single-crystal silicon is provided. The wavelength tunable laser includes a light emitting portion made of a III-V compound semiconductor, and external resonators provided with an optical filter. Cores included in the external resonators are made of one of SiN, SiON, and SiOn (n is smaller than 2).
    Type: Application
    Filed: March 28, 2019
    Publication date: June 10, 2021
    Applicant: Nippon Telegraph and Telephone Corporation
    Inventors: Takuma AIHARA, Shinji MATSUO, Tai TSUCHIZAWA, Takaaki KAKITSUKA, Tatsurou HIRAKI
  • Publication number: 20210126430
    Abstract: A semiconductor laser includes a distributed feedback active region and two distribution Bragg reflecting mirror regions which are arranged to be continuous with the distributed feedback active region. The distributed feedback active region has an active layer which is composed of a compound semiconductor and a first diffraction grating. The first diffraction grating is composed of a recessed portion which is formed to extend through a diffraction grating layer formed on the active layer and a projection portion which is adjacent to the recessed portion.
    Type: Application
    Filed: May 9, 2019
    Publication date: April 29, 2021
    Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo
  • Publication number: 20200400977
    Abstract: To make it possible to more easily improve modulation efficiency in an optical modulator using a core made of an InP-based semiconductor. The optical modulator includes a lower cladding layer 102 formed on a substrate 101, a core 103 formed on the lower cladding layer 102, and an upper cladding layer 104 formed on the core 103. The core 103 is made of an InP-based semiconductor having a bandgap corresponding to a desired wavelength. Refractive indexes of the lower cladding layer 102 and upper cladding layer 104 are equal to or less than a refractive index of InP.
    Type: Application
    Filed: February 8, 2019
    Publication date: December 24, 2020
    Inventors: Tatsurou Hiraki, Takaaki Kakitsuka, Shinji Matsuo
  • Patent number: 8462827
    Abstract: The objective of the invention is to provide a photonic crystal device which enables efficient confinement of carriers while preventing the deterioration of device characteristics. Specifically a photonic crystal device has a photonic crystal in which media with different refractive indexes are regularly arranged, wherein an active region (11) includes an active layer (12) and carrier confinement layers (13, 14) provided on the top and bottom of the active layer (12) respectively for confining carriers. The photonic crystal is formed by a buried growth layer (15) with a larger bandgap than that of the active region (11).
    Type: Grant
    Filed: September 1, 2010
    Date of Patent: June 11, 2013
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Shinji Matsuo, Takaaki Kakitsuka, Masaya Notomi, Akihiko Shinya
  • Patent number: 8306433
    Abstract: There is provided an optical modulation signal generating device in which an operation speed is not limited by a relaxation oscillation frequency of a laser, and high-speed modulation and long-distance transmission can be performed. The optical modulation signal generating device converts a signal from a signal source into an optical signal and outputs the optical signal to a transmission medium having frequency dispersion. The optical modulation signal generating device includes an optical source (102) for performing frequency modulation by the signal from the signal source to generate an optical signal having only a frequency modulation component, and a frequency filter (103) for converting the frequency modulation component of the optical signal into an intensity modulation component and a frequency modulation component.
    Type: Grant
    Filed: June 25, 2008
    Date of Patent: November 6, 2012
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Takaaki Kakitsuka, Shinji Matsuo, Toru Segawa, Hiroyuki Suzuki
  • Publication number: 20120155502
    Abstract: The objective of the invention is to provide a photonic crystal device which enables efficient confinement of carriers while preventing the deterioration of device characteristics. Specifically a photonic crystal device has a photonic crystal in which media with different refractive indexes are regularly arranged, wherein an active region (11) includes an active layer (12) and carrier confinement layers (13, 14) provided on the top and bottom of the active layer (12) respectively for confining carriers. The photonic crystal is formed by a buried growth layer (15) with a larger bandgap than that of the active region (11).
    Type: Application
    Filed: September 1, 2010
    Publication date: June 21, 2012
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinji Matsuo, Takaaki Kakitsuka, Masaya Notomi, Akihiko Shinya