Patents by Inventor Masatoshi Tokushima
Masatoshi Tokushima 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: 11137546Abstract: To provide an optical element that can be more easily aligned with an optical fiber, an optical element includes one grating coupler optically coupled to an optical fiber, a waveguide connected to the grating coupler, a multimode interferometer connected to the waveguide on the opposite side to the grating coupler, and a waveguide inserted between two input/output ports on the branched side of the multimode interferometer.Type: GrantFiled: February 12, 2020Date of Patent: October 5, 2021Assignees: NEC Corporation, Photonics Electronics Technology Research AssociationInventors: Masatoshi Tokushima, Jun Ushida
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Publication number: 20200264375Abstract: To provide an optical element that can be more easily aligned with an optical fiber, an optical element includes one grating coupler optically coupled to an optical fiber, a waveguide connected to the grating coupler, a multimode interferometer connected to the waveguide on the opposite side to the grating coupler, and a waveguide inserted between two input/output ports on the branched side of the multimode interferometer.Type: ApplicationFiled: February 12, 2020Publication date: August 20, 2020Applicants: NEC Corporation, Photonics Electronics Technology Research AssociationInventors: Masatoshi TOKUSHIMA, Jun USHIDA
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Patent number: 10535786Abstract: Provided is a light receiving element with high light receiving sensitivity. The light receiving element comprises: a light absorbing layer that absorbs light to generate a carrier; and a diffraction element that converts the optical path of first polarized light, which is obliquely incident on a plane formed by the light absorbing layer, so that the first polarized light propagates in a first direction along the light absorbing layer, and that converts the optical path of second polarized light incident from the same direction as the first polarized light so that the second polarized light propagates in a second direction, opposite the first direction, along the light absorbing layer.Type: GrantFiled: December 16, 2015Date of Patent: January 14, 2020Assignee: PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventors: Kenichiro Yashiki, Jun Ushida, Masatoshi Tokushima, Kazuhiko Kurata
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Patent number: 10088299Abstract: An alignment optical measurement element includes a grating coupler, and a reflector coupled to the grating coupler. The alignment optical measurement element is arranged so that: the grating coupler diffracts an incident light in a first direction into a first diffracted light to propagate the first diffracted light as a first propagating light in a second direction, the reflector reflects the first propagating light into a second propagating light in a third direction opposite to the second direction; and the grating coupler diffracts the second propagating light into a second diffracted light to emit the second diffracted light as an emitted light in a fourth direction opposite to the first direction.Type: GrantFiled: July 5, 2017Date of Patent: October 2, 2018Assignees: NEC CORPORATION, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventor: Masatoshi Tokushima
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Patent number: 10025031Abstract: A grating structure for a grating coupler is provided which has a high efficiency resulting from the operating principle, is easily manufactured, and simultaneously has little reflection loss. This grating structure is provided with a core layer having periodic recesses and protrusions formed on the upper surface, a first upper cladding layer in contact with the upper surface of the core layer, a second upper cladding layer in contact with the upper surface of the first upper cladding layer, and a first lower cladding layer in contact with the lower surface of the core layer. The recessed portions of said recesses and protrusions are filled with the same material as the first upper cladding layer. The refractive index of the material forming the core layer is greater than the refractive index of the materials forming the first upper cladding layer, the second upper cladding layer and the first lower cladding layer.Type: GrantFiled: March 7, 2016Date of Patent: July 17, 2018Assignee: PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventors: Masatoshi Tokushima, Jun Ushida
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Patent number: 9971099Abstract: A grating coupler includes a grating including a core and an anti-phase reflection coating provided on at least one part of the grating. The anti-phase reflection coating includes a high refractive index layer and a buffer layer. The high refractive index layer has at least one selected from a plurality of attributes characterizing the high refractive index layer. The at least one selected attribute gradually deceases along a propagation direction of light in the core of the grating.Type: GrantFiled: September 13, 2017Date of Patent: May 15, 2018Assignees: NEC CORPORATION, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventors: Masatoshi Tokushima, Jun Ushida
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Publication number: 20180128975Abstract: A grating structure for a grating coupler is provided which has a high efficiency resulting from the operating principle, is easily manufactured, and simultaneously has little reflection loss. This grating structure is provided with a core layer having periodic recesses and protrusions formed on the upper surface, a first upper cladding layer in contact with the upper surface of the core layer, a second upper cladding layer in contact with the upper surface of the first upper cladding layer, and a first lower cladding layer in contact with the lower surface of the core layer. The recessed portions of said recesses and protrusions are filled with the same material as the first upper cladding layer. The refractive index of the material forming the core layer is greater than the refractive index of the materials forming the first upper cladding layer, the second upper cladding layer and the first lower cladding layer.Type: ApplicationFiled: March 7, 2016Publication date: May 10, 2018Applicant: PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventors: Masatoshi Tokushima, Jun Ushida
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Publication number: 20180074264Abstract: A grating coupler includes a grating including a core and an anti-phase reflection coating provided on at least one part of the grating. The anti-phase reflection coating includes a high refractive index layer and a buffer layer. The high refractive index layer has at least one selected from a plurality of attributes characterizing the high refractive index layer. The at least one selected attribute gradually deceases along a propagation direction of light in the core of the grating.Type: ApplicationFiled: September 13, 2017Publication date: March 15, 2018Applicants: NEC CORPORATION, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIAT IONInventors: Masatoshi TOKUSHIMA, Jun USHIDA
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Publication number: 20180010906Abstract: An alignment optical measurement element includes a grating coupler, and a reflector coupled to the grating coupler. The alignment optical measurement element is arranged so that: the grating coupler diffracts an incident light in a first direction into a first diffracted light to propagate the first diffracted light as a first propagating light in a second direction, the reflector reflects the first propagating light into a second propagating light in a third direction opposite to the second direction; and the grating coupler diffracts the second propagating light into a second diffracted light to emit the second diffracted light as an emitted light in a fourth direction opposite to the first direction.Type: ApplicationFiled: July 5, 2017Publication date: January 11, 2018Applicants: NEC CORPORATION, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventor: Masatoshi TOKUSHIMA
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Publication number: 20170345952Abstract: Provided is a light receiving element with high light receiving sensitivity. The light receiving element comprises: a light absorbing layer that absorbs light to generate a carrier; and a diffraction element that converts the optical path of first polarized light, which is obliquely incident on a plane formed by the light absorbing layer, so that the first polarized light propagates in a first direction along the light absorbing layer, and that converts the optical path of second polarized light incident from the same direction as the first polarized light so that the second polarized light propagates in a second direction, opposite the first direction, along the light absorbing layer.Type: ApplicationFiled: December 16, 2015Publication date: November 30, 2017Applicant: Photonics Electronics Technology Research AssociationInventors: Kenichiro Yashiki, Jun Ushida, Masatoshi Tokushima, Kazuhiko Kurata
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Patent number: 9519115Abstract: An optical circuit, wherein the effects of reflected light generated by an optical component are reduced. The optical circuit (100) is provided with an optical branching (110) for branching light, an optical coupler (114) for coupling a first portion of branched light to an optical waveguide (118) for transmission, and an optical reflecting unit (116) for reflecting a second portion of the branched light, the phase difference between the reflected light from the optical coupler (114) and the reflected light from the optical reflecting unit (116) being (2m?1)? (where m is an integer) on an input side of the optical branching (110).Type: GrantFiled: March 19, 2014Date of Patent: December 13, 2016Assignee: PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATIONInventors: Kenichiro Yashiki, Masatoshi Tokushima
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Publication number: 20160054529Abstract: An optical circuit, wherein the effects of reflected light generated by an optical component are reduced. The optical circuit (100) is provided with an optical branching (110) for branching light, an optical coupler (114) for coupling a first portion of branched light to an optical waveguide (118) for transmission, and an optical reflecting unit (116) for reflecting a second portion of the branched light, the phase difference between the reflected light from the optical coupler (114) and the reflected light from the optical reflecting unit (116) being (2m?1)? (where m is an integer) on an input side of the optical branching (110).Type: ApplicationFiled: March 19, 2014Publication date: February 25, 2016Inventors: Kenichiro Yashiki, Masatoshi Tokushima
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Patent number: 8873906Abstract: Disclosed is an optical conversion element capable of highly efficient optical coupling between a silicon waveguide and a general single-mode optical fiber only by butt-coupling without requiring anti-reflective coating. One embodiment is an optical conversion element that includes a waveguide structure and converts a mode field of guided light and is characterized in that at least a dual core is included, an innermost core of the dual core is a silicon inverse tapered thin wire core, a first outer core is a forward tapered ridge core having a ridge structure formed of an oxide film with only width of the ridge core changing. The first outer core is positioned on a narrow width side of the innermost core.Type: GrantFiled: September 22, 2011Date of Patent: October 28, 2014Assignee: NEC CorporationInventors: Masatoshi Tokushima, Shigeru Nakamura
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Patent number: 8705920Abstract: A wavelength filter includes a first waveguide with a transmission band of a predetermined basic mode and a second waveguide, arranged in at least one location of the first waveguide, with a transmission band whose cutoff frequency corresponds to a finite value included in the transmission band of the basic mode. A pair of optical couplers constituting a Mach-Zehnder interferometer is connected to the opposite ends of a filter unit including the first waveguide and the second waveguide. When a plurality of wavelength filters is cascaded, the wavelength filters can be each varied in terms of the cutoff frequency of the second waveguide.Type: GrantFiled: December 25, 2009Date of Patent: April 22, 2014Assignee: NEC CorporationInventor: Masatoshi Tokushima
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Patent number: 8600204Abstract: Disclosed is an optical delay element that makes use of a line-defect waveguide of a photonic crystal, in which long optical delay time and small group speed dispersion are rendered compatible with each other and in which waveform distortion that might otherwise be produced in processing an ultra-high speed signal is eliminated. Two line-defect waveguides 5 and 11, having different pillar diameters and group velocity dispersions of opposite signs, are interconnected by a line-defect waveguide 8, the pillar diameters of which are gradually varied from one 5 of the line-defect waveguides to the other line-defect waveguide 11, such as to compensate for group speed dispersion as well as to maintain an optical delay effect.Type: GrantFiled: April 10, 2012Date of Patent: December 3, 2013Assignee: NEC CorporationInventor: Masatoshi Tokushima
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Patent number: 8554027Abstract: An optical switch is constituted of a wavelength filter and a control device. The wavelength filter includes a first waveguide exhibiting a transmission band of a predetermined basic mode and a second waveguide, arranged in at least one location of the first waveguide, exhibiting a transmission band with a cutoff frequency corresponding to a finite value included in the transmission band of the basic mode. A pair of optical couplers constituting a Mach-Zehnder interferometer is connected to opposite ends of a filter unit including the first waveguide and the second waveguide. When a plurality of wavelength filters is cascaded, these wavelength filters differ from each other in terms of the cutoff frequency of the second waveguide. The control device changes the cutoff frequency of the second waveguide within the transmission band of the first waveguide, thus adjusting the filtering band of the wavelength filter.Type: GrantFiled: December 25, 2009Date of Patent: October 8, 2013Assignee: NEC CorporationInventor: Masatoshi Tokushima
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Publication number: 20130188910Abstract: Disclosed is an optical conversion element capable of highly efficient optical coupling between a silicon waveguide and a general single-mode optical fiber only by butt-coupling without requiring anti-reflective coating. One embodiment is an optical conversion element that includes a waveguide structure and converts a mode field of guided light and is characterized in that at least a dual core is included, an innermost core of the dual core is a silicon inverse tapered thin wire core, a first outer core is a forward tapered ridge core having a ridge structure formed of an oxide film with only width of the ridge core changing. The first outer core is positioned on a narrow width side of the innermost core.Type: ApplicationFiled: September 22, 2011Publication date: July 25, 2013Applicant: NEC CorporationInventors: Masatoshi Tokushima, Shigeru Nakamura
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Patent number: 8478088Abstract: The object is to provide an optical switch capable of efficient operation and a manufacturing method thereof. The optical switch according to the present invention is a Mach-Zehnder interferometer type optical switch composed of a line defect waveguide of a photonic crystal. Further, the optical switch according to the present invention includes two directional couplers 20 and 23, and two paths of waveguides 30 and 32 therebetween. Furthermore, between the two paths, group velocity of guided light differs in the first path waveguide 20 and the second path waveguide 32.Type: GrantFiled: January 26, 2009Date of Patent: July 2, 2013Assignee: NEC CorporationInventor: Masatoshi Tokushima
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Patent number: 8355611Abstract: A waveguide stub is connected to a pillar-type square-lattice photonic crystal waveguide. Within the waveguide stub, the diameter of a defect is made larger than that of the original photonic crystal waveguide thereby reducing the group velocity of a guided light. The original waveguide and the waveguide stub are smoothly connected via a taper waveguide. Because of low group velocity of light in the waveguide stub, free spectral range (FSR) decreases thereby allowing the size of the waveguide stub to be reduced.Type: GrantFiled: November 25, 2008Date of Patent: January 15, 2013Assignee: NEC CorporationInventor: Masatoshi Tokushima
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Patent number: 8355614Abstract: In an exemplary embodiment, an optical waveguide (10) includes a first dielectric medium (11). In the first dielectric medium (11), line-defect rods (12) are arranged in one row and non-line-defect rods (13) are arranged along the row of line-defect rods (12) and on both sides of the row of the line-defect rods (12). The line-defect rods (12) and non-line-defect rods (13) form a two-dimensional square lattice. Of the rows of non-line-defect rods (13) arranged on the two sides of the row of line-defect rods (12), the number of rows of non-line-defect rods (13) on at least one side is at least one and no greater than five.Type: GrantFiled: January 26, 2009Date of Patent: January 15, 2013Assignee: NEC CorporationInventor: Masatoshi Tokushima