Patents by Inventor Yasuaki Hashizume

Yasuaki Hashizume 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).

  • Patent number: 12169347
    Abstract: A semiconductor Mach-Zehnder optical modulator includes input-side lead-out lines, phase modulation electrode lines, and electrodes that apply modulation signals propagating through the phase modulation electrode lines to waveguides, respectively. The semiconductor Mach-Zehnder optical modulator further includes a conductive layer between a substrate and the waveguides, a plurality of first wiring layers connected to the conductive layer, and a second wiring layer that connects an electrode pad and the plurality of first wiring layers.
    Type: Grant
    Filed: September 12, 2019
    Date of Patent: December 17, 2024
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Josuke Ozaki, Yoshihiro Ogiso, Yasuaki Hashizume
  • Patent number: 11994783
    Abstract: Provided is an IQ optical modulator including a nest-type MZ optical waveguide having optical modulation regions of I channel and Q channel End portions of an input optical waveguide and an output optical waveguide of the IQ optical modulator are located on a same edge face of a chip of the IQ optical modulator, an optical cross waveguide is included in which an optical waveguide between a first optical combiner and a second optical combiner of the nest-type MZ optical waveguide and the input optical waveguide cross each other, a first optical divider is provided between the I-channel optical modulation region and the Q-channel optical modulation region, and a light propagation direction in the first optical divider and a light propagation direction in the optical modulation regions are opposite to each other.
    Type: Grant
    Filed: September 13, 2019
    Date of Patent: May 28, 2024
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yoshihiro Ogiso, Josuke Ozaki, Yasuaki Hashizume, Mitsuteru Ishikawa, Nobuhiro Nunoya
  • Patent number: 11971590
    Abstract: In the adjustment method of optical coupling for an optical integrated circuit according to the present disclosure, the optimal adjustment position of optical coupling is determined on the basis of, for example, a sum of a plurality of photocurrents at electrodes on arm waveguides respectively formed on the plurality of MZIs in the polarization-multiplexing IQ modulator. According to the maximum value of the sum of the plurality of photocurrents, the light condensing spot position is adjusted to the center position of the end face core of the optical waveguide of the integrated chip. Typically, the light condensing spot position is adjusted to the center of the end face core by displacing the two input lenses.
    Type: Grant
    Filed: October 29, 2019
    Date of Patent: April 30, 2024
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yasuaki Hashizume, Yoshihiro Ogiso, Josuke Ozaki
  • Publication number: 20240128716
    Abstract: To detect deterioration of an SOA and perform feedback control to keep light intensity of output light constant in a configuration in which a DFB laser, an EA modulator, and the SOA are monolithically integrated. A semiconductor optical integrated element includes: a DFB laser that outputs continuous light; an EA modulator that modulates the continuous light; a first multimode interference coupler that inputs the modulated light from a first input port, divides the modulated light, and outputs the divided modulated light from two or more output ports; semiconductor optical amplifiers that are connected to respective output ports of the first multimode interference coupler and amplify each of the divided modulated light; a second multimode interference coupler that has input ports connected to respective outputs of the semiconductor optical amplifiers, multiplexes the amplified modulated light, and outputs the multiplexed modulated light from a first output port; and a monitoring waveguide.
    Type: Application
    Filed: March 23, 2021
    Publication date: April 18, 2024
    Inventors: Yasuhiko Nakanishi, Takahiko Shindo, Shigeru Kanazawa, Meishin Chin, Yasuaki Hashizume
  • Publication number: 20230350133
    Abstract: In the adjustment method of optical coupling for an optical integrated circuit according to the present disclosure, the optimal adjustment position of optical coupling is determined on the basis of, for example, a sum of a plurality of photocurrents at electrodes on arm waveguides respectively formed on the plurality of MZIs in the polarization-multiplexing IQ modulator. According to the maximum value of the sum of the plurality of photocurrents, the light condensing spot position is adjusted to the center position of the end face core of the optical waveguide of the integrated chip. Typically, the light condensing spot position is adjusted to the center of the end face core by displacing the two input lenses.
    Type: Application
    Filed: October 29, 2019
    Publication date: November 2, 2023
    Inventors: Yasuaki Hashizume, Yoshihiro Ogiso, Josuke Ozaki
  • Publication number: 20230288737
    Abstract: An optical module includes: a polarization controller that includes a main body including a polarization multiplexer and demultiplexer portion that, upon input of two kinds of light that are in perpendicularly-polarized states, performs polarization multiplexing on the two kinds of light and output polarization-multiplexed light, and upon input of light, performs polarization demultiplexing on the light and outputs two kinds of light that are in perpendicularly-polarized states, a first polarizer, a first input portion, a second input portion, a third input portion, a first output portion, and a second output portion; and an optical device configured to receive input of light via the polarization controller and output light via the polarization controller.
    Type: Application
    Filed: May 17, 2023
    Publication date: September 14, 2023
    Applicants: FURUKAWA ELECTRIC CO., LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazuya NAGASHIMA, Yozo ISHIKAWA, Josuke OZAKI, Yasuaki HASHIZUME
  • Publication number: 20230273497
    Abstract: A semiconductor IQ optical modulator in which a phase modulation unit is configured by a differential capacitively loaded traveling-wave electrode structure based on an SS line configuration, phase modulation units of adjacent channels are spaced apart from each other by 400 ?m or more, a distance between main signal lines of the capacitance loading type structure is 60 ?m or less, a DC phase adjustment electrode and a PAD are provided between an I side phase modulation unit and a Q side phase modulation unit, the DC phase adjustment electrode is spaced apart by at least 80 ?m or more from a signal line of the phase adjustment unit, and a crosstalk characteristic between the adjacent channels is ?30 dB or less in a required frequency band.
    Type: Application
    Filed: August 3, 2020
    Publication date: August 31, 2023
    Inventors: Josuke Ozaki, Yoshihiro Ogiso, Yasuaki Hashizume, Hiromasa Tanobe, Mitsuteru Ishikawa
  • Publication number: 20220326587
    Abstract: A semiconductor Mach-Zehnder optical modulator includes input-side lead-out lines, phase modulation electrode lines, and electrodes that apply modulation signals propagating through the phase modulation electrode lines to waveguides, respectively. The semiconductor Mach-Zehnder optical modulator further includes a conductive layer between a substrate and the waveguides, a plurality of first wiring layers connected to the conductive layer, and a second wiring layer that connects an electrode pad and the plurality of first wiring layers.
    Type: Application
    Filed: September 12, 2019
    Publication date: October 13, 2022
    Inventors: Josuke Ozaki, Yoshihiro Ogiso, Yasuaki Hashizume
  • Publication number: 20220326585
    Abstract: Provided is an IQ optical modulator including a nest-type MZ optical waveguide having optical modulation regions of I channel and Q channel End portions of an input optical waveguide and an output optical waveguide of the IQ optical modulator are located on a same edge face of a chip of the IQ optical modulator, an optical cross waveguide is included in which an optical waveguide between a first optical combiner and a second optical combiner of the nest-type MZ optical waveguide and the input optical waveguide cross each other, a first optical divider is provided between the I-channel optical modulation region and the Q-channel optical modulation region, and a light propagation direction in the first optical divider and a light propagation direction in the optical modulation regions are opposite to each other.
    Type: Application
    Filed: September 13, 2019
    Publication date: October 13, 2022
    Inventors: Yoshihiro Ogiso, Josuke Ozaki, Yasuaki Hashizume, Mitsuteru Ishikawa, Nobuhiro Nunoya
  • Patent number: 8625943
    Abstract: Excess optical power in a waveguide device is appropriately terminated. According to one embodiment of the present invention, the waveguide device comprises a termination structure filled with a light blocking material for terminating light from the end section of a waveguide. This termination structure can be formed by forming a groove on an optical waveguide by removing the clad and core, and filling the inside of that groove with a material attenuating the intensity of the light (light blocking material). In this manner, light that enters into the termination structure is attenuated by the light blocking material, and influence on other optical devices as a crosstalk component can be suppressed. With such termination structure, not only the influence on optical devices integrated on the same substrate, but also the influence on other optical devices directly connected to that substrate can be suppressed.
    Type: Grant
    Filed: May 26, 2009
    Date of Patent: January 7, 2014
    Assignees: Nippon Telegraph and Telephone Corporation, NTT Electronics Corporation
    Inventors: Shunichi Soma, Takashi Goh, Yasuaki Hashizume, Masahiro Yanagisawa, Takanori Ishikawa, Mitsuru Nagano, Atsushi Murasawa, Masayuki Okuno
  • Patent number: 8346030
    Abstract: A Mach-Zehnder interferometer circuit (700) is provided with two couplers (722, 724) and two arm waveguides (706, 708) connecting the couplers with each other, each fabricated on a substrate, in which a polarization rotation device (732) is disposed in a groove dividing each of the two arm waveguides into two, the polarization rotation device (732) for converting vertically polarized light into horizontally polarized light, and birefringence is adjusted by performing laser irradiation or the like partially into at least one of the two arm waveguides such that a difference between birefringence values divided by an optical wavelength to be used is within a range of 2 m-0.2 to 2 m+0.2 (m is an integer including zero), the birefringence values being those integrated linearly along the respective two arm waveguides in an optical signal travelling direction.
    Type: Grant
    Filed: August 24, 2007
    Date of Patent: January 1, 2013
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yasuaki Hashizume, Manabu Oguma, Takashi Saida, Masaki Kotoku, Takayuki Mizuno
  • Patent number: 8150219
    Abstract: In an optical interferometer, polarization dependence attributable to the optical path difference has conventionally been eliminated by inserting a half-wave plate at the center of the interferometer. However, light induced by polarization coupling produced in directional couplers used in the optical interferometer causes interference having different interference conditions from those of the normal light. Polarization rotators that effect any one of 90° rotation and ?90° rotation of all states of polarization of incoming light are inserted in the optical interferometer, and thereby the interference conditions of light induced by polarization coupling are made the same as those of the normal light. Each of the polarization rotators is implemented by using two half-wave plates and by varying an angle of combination of these half-wave plates. Alternatively, each of the polarization rotators is implemented through a combination of one half-wave plate and a waveguide having birefringence properties.
    Type: Grant
    Filed: December 27, 2007
    Date of Patent: April 3, 2012
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yusuke Nasu, Manabu Oguma, Yasuaki Hashizume, Yasuyuki Inoue, Hiroshi Takahashi, Kuninori Hattori, Toshikazu Hashimoto, Yohei Sakamaki
  • Publication number: 20110103736
    Abstract: A Mach-Zehnder interferometer circuit (700) is provided with two couplers (722, 724) and two arm waveguides (706, 708) connecting the couplers with each other, each fabricated on a substrate, in which a polarization rotation device (732) is disposed in a groove dividing each of the two arm waveguides into two, the polarization rotation device (732) for converting vertically polarized light into horizontally polarized light, and birefringence is adjusted by performing laser irradiation or the like partially into at least one of the two arm waveguides such that a difference between birefringence values divided by an optical wavelength to be used is within a range of 2m?0.2 to 2m+0.2 (m is an integer including zero), the birefringence values being those integrated linearly along the respective two arm waveguides in an optical signal travelling direction.
    Type: Application
    Filed: August 24, 2007
    Publication date: May 5, 2011
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yasuaki Hashizume, Manabu Oguma, Takashi Saida, Masaki Kotoku, Takayuki Mizuno
  • Publication number: 20110064355
    Abstract: Excess optical power in a waveguide device is appropriately terminated. According to one embodiment of the present invention, the waveguide device comprises a termination structure filled with a light blocking material for terminating light from the end section of a waveguide. This termination structure can be formed by forming a groove on an optical waveguide by removing the clad and core, and filling the inside of that groove with a material attenuating the intensity of the light (light blocking material). In this manner, light that enters into the termination structure is attenuated by the light blocking material, and influence on other optical devices as a crosstalk component can be suppressed. With such termination structure, not only the influence on optical devices integrated on the same substrate, but also the influence on other optical devices directly connected to that substrate can be suppressed.
    Type: Application
    Filed: May 26, 2009
    Publication date: March 17, 2011
    Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, NTT ELECTRONICS CORPORATION
    Inventors: Shunichi Soma, Takashi Goh, Yasuaki Hashizume, Masahiro Yanagisawa, Takanori Ishikawa, Mitsuru Nagano, Atsushi Murasawa, Masayuki Okuno
  • Publication number: 20100104237
    Abstract: In an optical interferometer, polarization dependence attributable to the optical path difference has conventionally been eliminated by inserting a half-wave plate at the center of the interferometer. However, light induced by polarization coupling produced in directional couplers used in the optical interferometer causes interference having different interference conditions from those of the normal light. Polarization rotators that effect any one of 90° rotation and ?90° rotation of all states of polarization of incoming light are inserted in the optical interferometer, and thereby the interference conditions of light induced by polarization coupling are made the same as those of the normal light. Each of the polarization rotators is implemented by using two half-wave plates and by varying an angle of combination of these half-wave plates. Alternatively, each of the polarization rotators is implemented through a combination of one half-wave plate and a waveguide having birefringence properties.
    Type: Application
    Filed: December 27, 2007
    Publication date: April 29, 2010
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yusuke Nasu, Manabu Oguma, Yasuaki Hashizume, Yasuyuki Inoue, Hiroshi Takahashi, Kuninori Hattori, Toshikazu Hashimoto, Yohei Sakamaki
  • Patent number: 7389033
    Abstract: A planar lightwave circuit type variable optical attenuator with a small polarization dependent loss is provided. By setting the waveguide birefringence (absolute value) in first and second optical coupler sections equal to or greater than 3.5×10?4, the polarization mode coupling is made equal to or less than ?25 dB, and the effect of the polarization dependence caused by the polarization mode coupling at the cross port of the first and second optical couplers is suppressed. In addition to or independently of this, the arm waveguide length can be designed to be equal to an integer multiple of the optical beat length obtained by dividing a used optical wavelength by the waveguide birefringence.
    Type: Grant
    Filed: January 13, 2006
    Date of Patent: June 17, 2008
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Yasuaki Hashizume, Yasuyuki Inoue, Takashi Saida, Akio Sugita
  • Publication number: 20070212012
    Abstract: A planar lightwave circuit type variable optical attenuator with a small polarization dependent loss is provided. By setting the waveguide birefringence (absolute value) in first and second optical coupler sections equal to or greater than 3.5×10?4, the polarization mode coupling is made equal to or less than ?25 dB, and the effect of the polarization dependence caused by the polarization mode coupling at the cross port of the first and second optical couplers is suppressed. In addition to or independently of this, the arm waveguide length can be designed to be equal to an integer multiple of the optical beat length obtained by dividing a used optical wavelength by the waveguide birefringence.
    Type: Application
    Filed: January 13, 2006
    Publication date: September 13, 2007
    Applicant: Nippon Telegraph and Telephone Corporation
    Inventors: Yasuaki Hashizume, Yasuyuki Inoue, Takashi Saida, Akio Sugita
  • Patent number: 6757454
    Abstract: A low-cost, high-reliability polarization-independent optical waveguide interferometer is proposed which does not bring about any additional job involved in the insertion of a half-wave plate or excess loss of light. In an optical multi/demultiplexer utilizing optical interference of light waves passing through a plurality of optical waveguides with different lengths, such as an AWG and a Mach-Zehnder interferometer, longitudinal integral values of birefringence values of the individual waveguides, which values are variable or invariable along the waveguides, are made equal for all waveguides 201 and 202. Thus, simply varying the waveguide width can implement polarization-independent operation, or on the contrary implement a polarization beam splitter.
    Type: Grant
    Filed: January 29, 2002
    Date of Patent: June 29, 2004
    Assignees: Nippon Telegraph and Telephone Corporation, NTT Advanced Technology Corporation
    Inventors: Yasuyuki Inoue, Yasuaki Hashizume, Yoshinori Hibino, Akio Sugita, Yasuhiro Hida, Hiroshi Takahashi
  • Publication number: 20020181870
    Abstract: A low-cost, high-reliability polarization-independent optical waveguide interferometer is proposed which does not bring about any additional job involved in the insertion of a half-wave plate or excess loss of light. In an optical multi/demultiplexer utilizing optical interference of light waves passing through a plurality of optical waveguides with different lengths, such as an AWG and a Mach-Zehnder interferometer, longitudinal integral values of birefringence values of the individual waveguides, which values are variable or invariable along the waveguides, are made equal for all waveguides 201 and 202. Thus, simply varying the waveguide width can implement polarization-independent operation, or on the contrary implement a polarization beam splitter.
    Type: Application
    Filed: January 29, 2002
    Publication date: December 5, 2002
    Inventors: Yasuyuki Inoue, Yasuaki Hashizume, Yoshinori Hibino, Akio Sugita, Yasuhiro Hida, Hiroshi Takahashi