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).
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Patent number: 11855410Abstract: 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: GrantFiled: May 15, 2019Date of Patent: December 26, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
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Patent number: 11747659Abstract: The optical modulator includes a lower cladding layer formed on a substrate, a core formed on the lower cladding layer, and an upper cladding layer formed on the core. The core is made of an InP-based semiconductor having a bandgap corresponding to a desired wavelength. Refractive indexes of the lower cladding layer and upper cladding layer are equal to or less than a refractive index of InP.Type: GrantFiled: February 8, 2019Date of Patent: September 5, 2023Assignee: Nippon Telegraph and Telephone CorporationInventors: Tatsurou Hiraki, Takaaki Kakitsuka, Shinji Matsuo
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Patent number: 11705693Abstract: 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: GrantFiled: December 24, 2019Date of Patent: July 18, 2023Assignee: Nippon Telegraph and Telephone CorporationInventors: Takuma Aihara, Shinji Matsuo, Takaaki Kakitsuka, Tai Tsuchizawa, Tatsuro Hiraki
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Patent number: 11557876Abstract: 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: GrantFiled: May 28, 2019Date of Patent: January 17, 2023Assignee: Nippon Telegraph and Telephone CorporationInventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220320813Abstract: 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: ApplicationFiled: June 5, 2019Publication date: October 6, 2022Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220320831Abstract: 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: ApplicationFiled: June 3, 2019Publication date: October 6, 2022Inventors: Takuma Tsurugaya, Takuro Fujii, Takaaki Kakitsuka, Shinji Matsuo
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Patent number: 11418232Abstract: 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: GrantFiled: November 6, 2019Date of Patent: August 16, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220231480Abstract: 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: ApplicationFiled: June 10, 2019Publication date: July 21, 2022Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220216673Abstract: 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: ApplicationFiled: May 16, 2019Publication date: July 7, 2022Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220085576Abstract: 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: ApplicationFiled: January 17, 2020Publication date: March 17, 2022Inventors: Takuma Aihara, Shinji Matsuo, Takaaki Kakitsuka, Tai Tsuchizawa, Tatsuro Hiraki
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Patent number: 11276988Abstract: 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: GrantFiled: May 15, 2018Date of Patent: March 15, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220045481Abstract: 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: ApplicationFiled: December 24, 2019Publication date: February 10, 2022Inventors: Takuma Aihara, Shinji Matsuo, Takaaki Kakitsuka, Tai Tsuchizawa, Tatsuro Hiraki
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Publication number: 20220029385Abstract: 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: ApplicationFiled: December 2, 2019Publication date: January 27, 2022Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20220014231Abstract: 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: ApplicationFiled: November 6, 2019Publication date: January 13, 2022Inventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20210336412Abstract: 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: ApplicationFiled: May 15, 2018Publication date: October 28, 2021Inventors: Ryo NAKAO, Takaaki KAKITSUKA, Shinji MATSUO
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Publication number: 20210203125Abstract: 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: ApplicationFiled: March 15, 2019Publication date: July 1, 2021Inventors: Suguru Yamaoka, Ryo Nakao, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20210184421Abstract: 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: ApplicationFiled: April 12, 2019Publication date: June 17, 2021Inventors: Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20210184427Abstract: 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 frequencyType: ApplicationFiled: May 28, 2019Publication date: June 17, 2021Inventors: Nikolaos-Panteleimon Diamantopoulos, Takaaki Kakitsuka, Shinji Matsuo
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Publication number: 20210175685Abstract: 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: ApplicationFiled: March 28, 2019Publication date: June 10, 2021Applicant: Nippon Telegraph and Telephone CorporationInventors: Takuma AIHARA, Shinji MATSUO, Tai TSUCHIZAWA, Takaaki KAKITSUKA, Tatsurou HIRAKI
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Publication number: 20210126430Abstract: 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: ApplicationFiled: May 9, 2019Publication date: April 29, 2021Inventors: Erina Kanno, Koji Takeda, Takaaki Kakitsuka, Shinji Matsuo