Patents by Inventor Mikitaka Itoh
Mikitaka Itoh 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: 10333280Abstract: A configuration of a DFB laser-based wavelength tunable laser is well known, but long resonators have difficulty in forming uniform resonators due to production variations, thereby inducing limitation in narrowing the spectral linewidth in the DFB laser-based wavelength tunable laser as well. In the semiconductor laser device of the present invention, a semiconductor laser that oscillates in a single mode and a low-loss lightwave circuit using SiO2 glass are arranged on the common substrate. The lightwave circuit is configured such that part of output light from the semiconductor laser propagates through a certain length of an optical path, and then is reflected by a reflector and is fed back to the semiconductor laser. Output light from the semiconductor laser and an input waveguide of the lightwave circuit can also be configured to be optically connected directly to each other. The present invention can provide a compact laser device with a narrowed spectral linewidth and stable wavelength controllability.Type: GrantFiled: September 29, 2016Date of Patent: June 25, 2019Assignees: Nippon Telegraph and Telephone Corporation, Tohoku UniversityInventors: Hiroyuki Ishii, Naoki Fujiwara, Kei Watanabe, Mikitaka Itoh, Keisuke Kasai, Masataka Nakazawa
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Patent number: 10126502Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: GrantFiled: January 26, 2017Date of Patent: November 13, 2018Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takanori Ishikawa, Tomoyo Shibazaki, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Publication number: 20180269659Abstract: A configuration of a DFB laser-based wavelength tunable laser is well known, but long resonators have difficulty in forming uniform resonators due to production variations, thereby inducing limitation in narrowing the spectral linewidth in the DFB laser-based wavelength tunable laser as well. In the semiconductor laser device of the present invention, a semiconductor laser that oscillates in a single mode and a low-loss lightwave circuit using SiO2 glass are arranged on the common substrate. The lightwave circuit is configured such that part of output light from the semiconductor laser propagates through a certain length of an optical path, and then is reflected by a reflector and is fed back to the semiconductor laser. Output light from the semiconductor laser and an input waveguide of the lightwave circuit can also be configured to be optically connected directly to each other. The present invention can provide a compact laser device with a narrowed spectral linewidth and stable wavelength controllability.Type: ApplicationFiled: September 29, 2016Publication date: September 20, 2018Inventors: Hiroyuki Ishii, Naoki Fujiwara, Kei Watanabe, Mikitaka Itoh, Keisuke Kasai, Masataka Nakazawa
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Patent number: 10050717Abstract: A multi-stage interferometer circuit of the present invention includes: a multiplexing port; (N?1) stages of lattice type two-beam interferometers, wherein each stage includes a two-beam delay circuit having a path length difference of an integral multiple of M·? L/2, and wherein the two-beam delay circuit of the lattice type two-beam interferometer of the first stage is connected to the multiplexing port; an M-beam interferometer including: two sets of 1×(M/2) optical couplers connected to the first optical coupler of the lattice type two-beam interferometer at the final stage; an M-array delay circuit, each delay circuit of which has a delay length different from each other by ?L; and M×M optical couplers; and M demultiplexing ports, wherein one or more transversal filters are arranged inside the multi-stage interferometer circuit so that the light guided between the demultiplexing port and the multiplexing ports passes therethrough at least once.Type: GrantFiled: February 19, 2016Date of Patent: August 14, 2018Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takashi Goh, Mikitaka Itoh, Kiyofumi Kikuchi
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Publication number: 20180034555Abstract: A multi-stage interferometer circuit of the present invention includes: a multiplexing port; (N-1) stages of lattice type two-beam interferometers, wherein each stage includes a two-beam delay circuit having a path length difference of an integral multiple of M·? L/2, and wherein the two-beam delay circuit of the lattice type two-beam interferometer of the first stage is connected to the multiplexing port; an M-beam interferometer including: two sets of 1×(M/2) optical couplers connected to the first optical coupler of the lattice type two-beam interferometer at the final stage; an M-array delay circuit, each delay circuit of which has a delay length different from each other by ?L; and M×M optical couplers; and M demultiplexing ports, wherein one or more transversal filters are arranged inside the multi-stage interferometer circuit so that the light guided between the demultiplexing port and the multiplexing ports passes therethrough at least once.Type: ApplicationFiled: February 19, 2016Publication date: February 1, 2018Inventors: Takashi Goh, Mikitaka Itoh, Kiyofumi Kikuchi
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Patent number: 9684129Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: GrantFiled: March 26, 2015Date of Patent: June 20, 2017Assignees: NTT Electronics Corporation, Nippon Telegraph and Telephone CorporationInventors: Takanori Ishikawa, Tomoyo Shibazaki, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Publication number: 20170146742Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: ApplicationFiled: January 26, 2017Publication date: May 25, 2017Inventors: Takanori Ishikawa, Tomoyo Shibazaki, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Patent number: 9116305Abstract: An arrayed waveguide grating provided with a first slab waveguide formed on a substrate; a second slab waveguide formed on the substrate; a first input/output waveguide connected to the first slab waveguide; a second input/output waveguide connected to the second slab waveguide; two or more channel waveguide groups connecting the first and second slab waveguides, each of the channel waveguide groups formed of an aggregate of a plurality of channel waveguides having path lengths sequentially becoming longer by a predetermined path length difference; and an optical filter arranged in at least one of the first and second slab waveguides.Type: GrantFiled: December 28, 2012Date of Patent: August 25, 2015Assignee: Nippon Telegraph and Telephone CorporationInventors: Hirotaka Nakamura, Shinya Tamaki, Shunji Kimura, Takayuki Mizuno, Hiroshi Takahashi, Mikitaka Itoh, Tsutomu Kitoh
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Publication number: 20150205043Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: ApplicationFiled: March 26, 2015Publication date: July 23, 2015Inventors: Takanori Ishikawa, Tomoyo Shibazkai, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Patent number: 9020307Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: GrantFiled: November 26, 2010Date of Patent: April 28, 2015Assignees: NTT Electronics Corporation, Nippon Telegraph and Telephone CorporationInventors: Takanori Ishikawa, Tomoyo Shibazaki, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Publication number: 20140376861Abstract: An arrayed waveguide grating provided with a first slab waveguide formed on a substrate; a second slab waveguide formed on the substrate; a first input/output waveguide connected to the first slab waveguide; a second input/output waveguide connected to the second slab waveguide; two or more channel waveguide groups connecting the first and second slab waveguides, each of the channel waveguide groups formed of an aggregate of a plurality of channel waveguides having path lengths sequentially becoming longer by a predetermined path length difference; and an optical filter arranged in at least one of the first and second slab waveguides.Type: ApplicationFiled: December 28, 2012Publication date: December 25, 2014Inventors: Hirotaka Nakamura, Shinya Tamaki, Shunji Kimura, Takayuki Mizuno, Hiroshi Takahashi, Mikitaka Itoh, Tsutomu Kitoh
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Patent number: 8867873Abstract: An optical wavelength multi/demultiplexing circuit is provided in which temperature dependence at a transmission center wavelength remained in an athermalized AWG is compensated. An AWG according to an embodiment of the present invention is compensated for the main temperature dependence at the transmission center wavelength. The AWG comprises an optical splitter, a first and second arm waveguides, an optical mode combining coupler and a multimode waveguide between an input/output waveguide and a slab waveguide. The optical mode combining coupler couples fundamental mode light from the first arm waveguide as fundamental mode and the fundamental mode light from the second arm waveguide as first mode. The multimode waveguide is capable of propagating the fundamental and first mode light. This AWG is configured such that the temperature dependence remained in the arrayed waveguide grating is compensated by changing the optical path length difference between the first and second arm waveguides with temperature.Type: GrantFiled: June 30, 2009Date of Patent: October 21, 2014Assignee: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Yasuyuki Inoue, Mikitaka Itoh
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Patent number: 8369666Abstract: An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.Type: GrantFiled: June 30, 2009Date of Patent: February 5, 2013Assignee: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Tsutomu Kitoh, Masaki Kohtoku, Tomohiro Shibata, Takuya Tanaka, Yasuyuki Inoue, Mikitaka Itoh
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Publication number: 20120251041Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.Type: ApplicationFiled: November 26, 2010Publication date: October 4, 2012Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, NTT ELECTRONICS CORPORATIONInventors: Takanori Ishikawa, Tomoyo Shibazaki, Mitsuru Nagano, Masahiro Yanagisawa, Hiroshi Terui, Mikitaka Itoh
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Publication number: 20110116802Abstract: An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.Type: ApplicationFiled: June 30, 2009Publication date: May 19, 2011Applicant: Nippon Telegraph and Telephone CorporationInventors: Shin Kamei, Tsutomu Kitoh, Masaki Kohtoku, Tomohiro Shibata, Takuya Tanaka, Yasuyuki Inoue, Mikitaka Itoh
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Publication number: 20110110624Abstract: An optical wavelength multi/demultiplexing circuit is provided in which temperature dependence at a transmission center wavelength remained in an athermalized AWG is compensated. An AWG according to an embodiment of the present invention is compensated for the main temperature dependence at the transmission center wavelength. The AWG comprises an optical splitter, a first and second arm waveguides, an optical mode combining coupler and a multimode waveguide between an input/output waveguide and a slab waveguide. The optical mode combining coupler couples fundamental mode light from the first arm waveguide as fundamental mode and the fundamental mode light from the second arm waveguide as first mode. The multimode waveguide is capable of propagating the fundamental and first mode light. This AWG is configured such that the temperature dependence remained in the arrayed waveguide grating is compensated by changing the optical path length difference between the first and second arm waveguides with temperature.Type: ApplicationFiled: June 30, 2009Publication date: May 12, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Shin Kamei, Yasuyuki Inoue, Mikitaka Itoh
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Publication number: 20080226290Abstract: By reducing the number of PD arrays, and by simplifying the configuration of an optical power monitor in a WDM system, a miniaturized, cost reduced optical signal monitoring apparatus, optical system or optical signal monitoring method is provided. An optical power monitor 1 has an optical switch 30 having four input ports 31, a DMUX 2 having 48 output ports, and six CSP type PD array modules 50 each including an 8-channel PD array. The output port 32 of the optical switch 30 having four switchable input ports 31 is optically connected to the input port 21 of the AWG 20. The 48 output ports 22 of the AWG 20 are each optically connected to photosensitive surfaces 53 of the individual PDs included in the CSP type PD array modules 50. The CSP type PD array modules 50 are mounted on the end face of the AWG 20.Type: ApplicationFiled: March 5, 2008Publication date: September 18, 2008Applicants: Nippon Telegraph and Telephone Corporation, NTT Electronics CorporationInventors: Takaharu Ohyama, Takashi Goh, Shin Kamei, Shunichi Sohma, Mikitaka Itoh, Ikuo Ogawa, Akimasa Kaneko, Tomoyuki Yamada, Mitsuru Nagano, Yoshiyuki Doi, Takashi Saida
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Patent number: 6937797Abstract: A planar lightwave circuit is provided. The planar lightwave circuit includes a waveguide and a spotsize converter which is a part of the waveguide, wherein a core is embedded in a cladding in the waveguide, and the spotsize converter is located near an end face of a substrate on which the planar lightwave circuit is formed, the spotsize converter including: a core width fine-tuning part in an end face side of the substrate; and a core width converting part which follows the core width fine-tuning part; wherein core width of the spotsize converter is minimum at an end face of the substrate, a mean taper angle ?1 of the core width fine-tuning part is larger than 0° and smaller than a mean taper angle ?2 of the core width converting part.Type: GrantFiled: September 13, 2001Date of Patent: August 30, 2005Assignee: Nippon Telegraph and Telephone CorporationInventors: Takayuki Mizuno, Tsutomu Kitoh, Yasuyuki Inoue, Yoshinori Hibino, Mikitaka Itoh, Takashi Saida, Yasuhiro Hida
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Patent number: 6775454Abstract: A silica-based optical waveguide circuit serves to reduce the time required to production while allowing a spot size converting function to work sufficiently. In a silica-based optical waveguide circuit comprising an input/output waveguide core formed to be thicker than an waveguide core and a tapered portion for connecting the input/output waveguide core and the waveguide core, wherein the waveguide circuit further has a core layer at each side of the input/output waveguide core, a thickness T of the core layer at the side of the input/output waveguide core is smaller than the thickness H of the input/output waveguide core.Type: GrantFiled: May 9, 2002Date of Patent: August 10, 2004Assignee: Nippon Telegraph and Telephone CorporationInventors: Mikitaka Itoh, Takashi Saida, Yasuhiro Hida, Yasuyuki Inoue
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Patent number: 6625370Abstract: An optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without degradation of the optical characteristics and reliability are disclosed, and a fabricating method of an optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without increasing the fabricating burden and the cost are disclosed. The optical waveguide comprises a planar substrate; a lower cladding which is provided on the planar substrate, where the lower cladding has a ridge; a core, provided on the ridge of the lower cladding, for transmitting light; and an upper cladding provided in a manner such that the core is covered with the upper cladding. The ridge has a shape predetermined so as to decrease polarization dependence of the optical waveguide to a required low level.Type: GrantFiled: August 16, 2001Date of Patent: September 23, 2003Assignee: Nippon Telegraph and Telephone CorporationInventors: Mikitaka Itoh, Ryoichi Kasahara, Takashi Saida, Yasuhiro Hida