Patents by Inventor Tomoyuki Akiyama

Tomoyuki Akiyama 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: 10911148
    Abstract: An optical transmission apparatus includes first and second optical waveguides to transmit light of multiple wavelengths; optical couplers on the waveguides, to couple the lights transmitted through the waveguides, so as to output the coupled light to the waveguides; phase shifters provided at preceding stages of part of the optical couplers, to change a phase shift amount of the light transmitted through the first and/or second optical waveguides, wherein the number of optical couplers in the part is greater than or equal to the number of the types of wavelengths; a monitor to monitor the intensity of the light output to the second optical waveguide via the optical coupler at the last stage; and a controller to control the phase shifters by changing the phase shift amount for each of the phase shifters in a direction in which the output of the monitor decreases.
    Type: Grant
    Filed: October 17, 2019
    Date of Patent: February 2, 2021
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Publication number: 20200389247
    Abstract: An optical add-drop device includes optical circuits. Each of the optical circuits includes first to third sub optical circuits. Each sub optical circuit includes an input coupler, output coupler, and a phase shifter. In each of the optical circuit, two ports of the output coupler in the first sub optical circuit are respectively coupled to the input coupler in the second sub optical circuit and the input coupler in the third sub optical circuit. The output coupler in the second sub optical circuit in each of the optical circuits is coupled to a drop port or the input coupler in the first sub optical circuit in the adjacent optical circuit. The input coupler in the third sub optical circuit in each of the optical circuits is coupled to an add port or the output coupler in the third sub optical circuit in the adjacent optical circuit.
    Type: Application
    Filed: May 28, 2020
    Publication date: December 10, 2020
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Publication number: 20200379181
    Abstract: An optical demultiplexer is disclosed that separates light including a plurality of wavelengths into light of respective wavelengths. Unit circuits are cascaded in a tree structure. In optical demultiplexer components having the same structure, a combination of arm length differences in waveguide pairs is the same with respect to the N?1 Asymmetric Mach-Zehnder interferometers in which the phase shifters are arranged, where N equals number of 2×2 couplers. In three of the optical demultiplexer components in at least one of the unit circuits, N is three or more. Each of control circuits controls the phase shifters arranged in a corresponding optical demultiplexer component of a corresponding unit circuit in order to increase or decrease a value of a function having, as an argument, a power value acquired by a monitor from among monitors arranged at four optical waveguides at an output side of the corresponding unit circuit.
    Type: Application
    Filed: May 27, 2020
    Publication date: December 3, 2020
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Publication number: 20200136729
    Abstract: An optical transmission apparatus includes first and second optical waveguides to transmit light of multiple wavelengths; optical couplers on the waveguides, to couple the lights transmitted through the waveguides, so as to output the coupled light to the waveguides; phase shifters provided at preceding stages of part of the optical couplers, to change a phase shift amount of the light transmitted through the first and/or second optical waveguides, wherein the number of optical couplers in the part is greater than or equal to the number of the types of wavelengths; a monitor to monitor the intensity of the light output to the second optical waveguide via the optical coupler at the last stage; and a controller to control the phase shifters by changing the phase shift amount for each of the phase shifters in a direction in which the output of the monitor decreases.
    Type: Application
    Filed: October 17, 2019
    Publication date: April 30, 2020
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki AKIYAMA
  • Patent number: 10547406
    Abstract: An optical element includes a gain chip, a ring modulator, which is a band-pass filter, a first optical waveguide and a second optical waveguide that are optically connected to the ring modulator, and a heater, wherein the first optical waveguide and the second optical waveguide are formed to be equal in optical path length (have no difference in optical path length) between a first light coupling point and a second light coupling point and equal in shape and length between the first light coupling point and the second light coupling point (to be symmetrical with the ring modulator interposed therebetween (with respect to the ring modulator)).
    Type: Grant
    Filed: July 6, 2017
    Date of Patent: January 28, 2020
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Patent number: 10488596
    Abstract: The invention relates to an optical fiber mounted photonic integrated circuit device, wherein the tolerance for positioning in terms of the coupling between the single mode optical fibers and the optical waveguides provided on the photonic integrated circuit device is increased. An optical waveguide core group is provided in such a manner where a plurality of optical waveguide cores having a portion that is tapered in the direction of the width within a plane are aligned parallel to each other at intervals that allow for mutual directional coupling and that are narrower than the width of the core of the single mode optical fiber, and the inclined connection end surface of the single mode optical fiber and the upper surface of an end portion of the optical waveguide cores face each other for coupling.
    Type: Grant
    Filed: August 28, 2017
    Date of Patent: November 26, 2019
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Patent number: 10491321
    Abstract: An optical demultiplexer has at least one unit circuit formed by three AMZs having a same arm length difference and cascaded in a tree structure in which two output ports of the 1st AMZ are connected to the 2nd AMZ and the 3rd AMZ, respectively, wherein the unit circuit has first and second monitors connected to the first and second output ports of the 2nd AMZ, and third and fourth monitors connected to the first and second output ports of the 3rd AMZ, a first control circuit controlling the transmissivity of the 1st AMZ so as to increase the monitoring result of the second and fourth monitors, a second control circuit controlling the transmissivity of the 2nd AMZ to decrease the monitoring result of the first monitor, and a third control circuit controlling the transmissivity of the 3rd AMZ to decrease the monitoring result of the third monitor.
    Type: Grant
    Filed: January 23, 2019
    Date of Patent: November 26, 2019
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Patent number: 10439729
    Abstract: A demultiplexing unit that is provided in an optical device and performs demultiplexing into a plurality of optical signals having wavelengths different from each other includes a plurality of optical filters that are coupled in multiple stages and in which a period of a peak wavelength of a transmission spectrum differs among different stages, a monitoring optical filter coupled to one of the plurality of optical filters, a monitoring photodetector coupled to the output side of the monitoring optical filter, and a plurality of wavelength adjustment units that are provided individually for the plurality of optical filters and the monitoring optical filter and cause wavelength shifts of an equal amount in a same direction.
    Type: Grant
    Filed: August 30, 2018
    Date of Patent: October 8, 2019
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Patent number: 10389083
    Abstract: A modulated light source includes a reflective semiconductor optical amplifier including a mirror at a first end of the reflective semiconductor optical amplifier, a modulator configured to modulate a central wavelength, a first mirror configured to reflect light transmitted by the modulator, an optical filter disposed between a second end of the reflective semiconductor optical amplifier and the modulator, and a second mirror configured to reflect part of incoming light and to transmit the other part of the incoming light. The reflective semiconductor optical amplifier, the optical filter, and the second mirror configure a Fabry-Perot laser. The first mirror is configured to feed light emitted from the Fabry-Perot laser back to the Fabry-Perot laser, and the modulated light source is configured to select light corresponding to one of longitudinal modes oscillated by the Fabry-Perot laser, to modulate the selected light, and to output the modulated light.
    Type: Grant
    Filed: September 21, 2018
    Date of Patent: August 20, 2019
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Publication number: 20190245642
    Abstract: An optical demultiplexer has at least one unit circuit formed by three AMZs having a same arm length difference and cascaded in a tree structure in which two output ports of the 1st AMZ are connected to the 2nd AMZ and the 3rd AMZ, respectively, wherein the unit circuit has first and second monitors connected to the first and second output ports of the 2nd AMZ, and third and fourth monitors connected to the first and second output ports of the 3rd AMZ, a first control circuit controlling the transmissivity of the 1st AMZ so as to increase the monitoring result of the second and fourth monitors, a second control circuit controlling the transmissivity of the 2nd AMZ to decrease the monitoring result of the first monitor, and a third control circuit controlling the transmissivity of the 3rd AMZ to decrease the monitoring result of the third monitor.
    Type: Application
    Filed: January 23, 2019
    Publication date: August 8, 2019
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki AKIYAMA
  • Publication number: 20190097383
    Abstract: A modulated light source includes a reflective semiconductor optical amplifier including a mirror at a first end of the reflective semiconductor optical amplifier, a modulator configured to modulate a central wavelength, a first mirror configured to reflect light transmitted by the modulator, an optical filter disposed between a second end of the reflective semiconductor optical amplifier and the modulator, and a second mirror configured to reflect part of incoming light and to transmit the other part of the incoming light. The reflective semiconductor optical amplifier, the optical filter, and the second mirror configure a Fabry-Perot laser. The first mirror is configured to feed light emitted from the Fabry-Perot laser back to the Fabry-Perot laser, and the modulated light source is configured to select light corresponding to one of longitudinal modes oscillated by the Fabry-Perot laser, to modulate the selected light, and to output the modulated light.
    Type: Application
    Filed: September 21, 2018
    Publication date: March 28, 2019
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Publication number: 20190097732
    Abstract: A demultiplexing unit that is provided in an optical device and performs demultiplexing into a plurality of optical signals having wavelengths different from each other includes a plurality of optical filters that are coupled in multiple stages and in which a period of a peak wavelength of a transmission spectrum differs among different stages, a monitoring optical filter coupled to one of the plurality of optical filters, a monitoring photodetector coupled to the output side of the monitoring optical filter, and a plurality of wavelength adjustment units that are provided individually for the plurality of optical filters and the monitoring optical filter and cause wavelength shifts of an equal amount in a same direction.
    Type: Application
    Filed: August 30, 2018
    Publication date: March 28, 2019
    Applicants: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIAT ION
    Inventor: Tomoyuki Akiyama
  • Publication number: 20180067265
    Abstract: The invention relates to an optical fiber mounted photonic integrated circuit device, wherein the tolerance for positioning in terms of the coupling between the single mode optical fibers and the optical waveguides provided on the photonic integrated circuit device is increased. An optical waveguide core group is provided in such a manner where a plurality of optical waveguide cores having a portion that is tapered in the direction of the width within a plane are aligned parallel to each other at intervals that allow for mutual directional coupling and that are narrower than the width of the core of the single mode optical fiber, and the inclined connection end surface of the single mode optical fiber and the upper surface of an end portion of the optical waveguide cores face each other for coupling.
    Type: Application
    Filed: August 28, 2017
    Publication date: March 8, 2018
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Patent number: 9897761
    Abstract: The invention relates to an optical fiber mounted photonic integrated circuit device where the tolerance in the positioning of the coupling between a single mode optical fiber and an optical waveguide provided in the photonic integrated circuit device is increased. A second optical waveguide of which the cross-section of the core is in the form of a slab having a width that is greater than the mode diameter of the single mode optical fiber, and which is tapered in such a manner that the thickness of the core is reduced as the location is closer to the connection portion with the single mode optical fiber, is provided on the input/output end side of the first optical waveguide through which light propagates in such a manner that the inclined connection end surface of the single mode optical fiber is coupled to the upper surface of the second optical waveguide.
    Type: Grant
    Filed: February 28, 2017
    Date of Patent: February 20, 2018
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventors: Tomoyuki Akiyama, Tsuyoshi Aoki
  • Publication number: 20180013512
    Abstract: An optical element includes a gain chip, a ring modulator, which is a band-pass filter, a first optical waveguide and a second optical waveguide that are optically connected to the ring modulator, and a heater, wherein the first optical waveguide and the second optical waveguide are formed to be equal in optical path length (have no difference in optical path length) between a first light coupling point and a second light coupling point and equal in shape and length between the first light coupling point and the second light coupling point (to be symmetrical with the ring modulator interposed therebetween (with respect to the ring modulator)).
    Type: Application
    Filed: July 6, 2017
    Publication date: January 11, 2018
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Publication number: 20170276879
    Abstract: The invention relates to an optical fiber mounted photonic integrated circuit device where the tolerance in the positioning of the coupling between a single mode optical fiber and an optical waveguide provided in the photonic integrated circuit device is increased. A second optical waveguide of which the cross-section of the core is in the form of a slab having a width that is greater than the mode diameter of the single mode optical fiber, and which is tapered in such a manner that the thickness of the core is reduced as the location is closer to the connection portion with the single mode optical fiber, is provided on the input/output end side of the first optical waveguide through which light propagates in such a manner that the inclined connection end surface of the single mode optical fiber is coupled to the upper surface of the second optical waveguide.
    Type: Application
    Filed: February 28, 2017
    Publication date: September 28, 2017
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventors: Tomoyuki Akiyama, Tsuyoshi Aoki
  • Patent number: 9636916
    Abstract: An ink temperature adjustment device and an inkjet printer include an ink temperature adjustment path connected to a midway point on an ink supply path for supplying ink to an inkjet head configured to form an image by ejecting the ink. The ink temperature adjustment path is for adjusting a temperature of the ink supplied to the inkjet head. The ink temperature adjustment path includes an upflow path for the ink to flow upward and a downflow path for the ink to flow downward. A total cross-sectional area of the upflow path is larger than a total cross-sectional area of the downflow path.
    Type: Grant
    Filed: August 14, 2015
    Date of Patent: May 2, 2017
    Assignee: RISO KAGAKU CORPORATION
    Inventors: Tomoyuki Akiyama, Asayo Shimoda, Hiroshi Sugitani, Akira Nishiyama
  • Publication number: 20170005454
    Abstract: A modulated light source includes a ring modulator, a first optical waveguide and a second optical waveguide that are optically connected to the ring modulator, and a third optical waveguide that optically connects an end of the first optical waveguide and an end of the second optical waveguide. At least part of the third optical waveguide has optical gain, and an optical waveguide loop including the ring modulator, the first optical waveguide, the second optical waveguide, and the third optical waveguide is used as a resonator to cause laser oscillation.
    Type: Application
    Filed: May 4, 2016
    Publication date: January 5, 2017
    Applicants: FUJITSU LIMITED, Photonics Electronics Technology Research Association
    Inventor: Tomoyuki Akiyama
  • Patent number: 9537289
    Abstract: A modulated light source includes a ring modulator, a first optical waveguide and a second optical waveguide that are optically connected to the ring modulator, and a third optical waveguide that optically connects an end of the first optical waveguide and an end of the second optical waveguide. At least part of the third optical waveguide has optical gain, and an optical waveguide loop including the ring modulator, the first optical waveguide, the second optical waveguide, and the third optical waveguide is used as a resonator to cause laser oscillation.
    Type: Grant
    Filed: May 4, 2016
    Date of Patent: January 3, 2017
    Assignees: FUJITSU LIMITED, PHOTONICS ELECTRONICS TECHNOLOGY RESEARCH ASSOCIATION
    Inventor: Tomoyuki Akiyama
  • Publication number: 20160370607
    Abstract: An optical semiconductor element includes a ring modulator, and a light absorbing material provided at a position apart from a path for a modulated light which is guided by the ring modulator, the light absorbing material absorbing a light leaked out of a ring waveguide of the ring modulator, and increasing a temperature of the ring waveguide.
    Type: Application
    Filed: September 1, 2016
    Publication date: December 22, 2016
    Applicant: FUJITSU LIMITED
    Inventor: Tomoyuki AKIYAMA