Patents by Inventor Kazutaka Nara

Kazutaka Nara 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).

  • Publication number: 20160216451
    Abstract: The present invention provides a switch device for an optical signal which has high extendibility and which can suppress an increase of loss in extension. A switch device in one embodiment of the present invention includes, in a housing, four splitter portions, four switch portions, and extension splitter portions. The splitter portions are connected to path-side ports, the switch portions are connected to client-side ports, and the splitter portions and the switch portions are connected to one another via shuffle fiber arrays. One ends of the extension splitter portions are connected to path-side extension ports, and the other ends thereof are connected to client-side extension ports. The number of wavelengths processable by the switch device can be easily changed by changing a connection state of optical fibers to the path-side ports, the client-side ports, the path-side extension ports, and the client-side extension ports.
    Type: Application
    Filed: April 6, 2016
    Publication date: July 28, 2016
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi HASEGAWA, Kazutaka NARA
  • Patent number: 9354395
    Abstract: An optical waveguide element includes a cladding portion made of a silica-based glass, and an optical waveguide positioned in the cladding portion and made of a silica-based glass in which a ZrO2 particle is dispersed.
    Type: Grant
    Filed: February 25, 2014
    Date of Patent: May 31, 2016
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Yasuyoshi Uchida, Yuuki Taniguchi, Hiroshi Kawashima, Kazutaka Nara, Masanori Takahashi
  • Publication number: 20160085026
    Abstract: A spot-size-converting optical waveguide includes a core portion. A first core portion of the core portion has a first straight portion and a first tapered portion. The first straight portion extends in a direction, having width and height that are approximately constant in the direction, and the first tapered portion is continuous with the first straight portion and decreases in width and height toward a termination portion. A second core portion of the core portion has a straight-portion-coating portion, a tapered-portion-coating portion, and a second tapered portion, the straight-portion-coating portion covers the first straight portion, the tapered-portion-coating portion covers the first tapered portion continuously with the straight-portion-coating portion and decreases in width and height along the first tapered portion's shape, and the second tapered portion increases in width and height toward the direction. A refractive index of the second core portion is lower than that of the first core portion.
    Type: Application
    Filed: December 7, 2015
    Publication date: March 24, 2016
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Shintaro Yamasaki, Kazutaka Nara, Masanori Takahashi, Yasuyoshi Uchida
  • Publication number: 20160025930
    Abstract: An object of the present invention is to provide a switch unit for optical signals which is capable of reducing an area required for arrangement and reducing manufacturing costs, and a switch apparatus including the switch unit. A switch unit 30 according to one embodiment of the present invention includes two optical switch arrays 34a, 34b arranged to face in opposite directions and in parallel on a substrate. The two optical switch arrays extend along a surface of a chip, and each have four optical switches 31 arranged in parallel. Such a configuration makes it possible to reduce the size of the switch unit because in an excess region of one of the optical switch array, the other optical switch array is disposed.
    Type: Application
    Filed: October 7, 2015
    Publication date: January 28, 2016
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi HASEGAWA, Noritaka MATSUBARA, Kazutaka NARA
  • Publication number: 20150172794
    Abstract: An object of the invention is to provide a switch device, which achieves high expandability, high layout freedom, and low losses. A switch device of an embodiment includes a splitter unit, a first switch unit, a second switch unit, a fiber array which connects the splitter unit to the two switch units, and a control board. The fiber array includes multiple optical fibers bundled in an arrayed fashion. At an end of the fiber array on the splitter unit side, all the optical fibers are bundled into one and connected to the splitter unit. At an end of the fiber array on the switch unit side, the multiple optical fibers are divided into two groups and formed into two sub-fiber arrays, which are connected to the first switch unit and the second switch unit, respectively.
    Type: Application
    Filed: February 4, 2015
    Publication date: June 18, 2015
    Applicant: Furukawa Electric Co., Ltd.
    Inventors: Junichi HASEGAWA, Noritaka MATSUBARA, Kazutaka NARA
  • Patent number: 9054486
    Abstract: An optical amplifier device comprising an input/output section that inputs incident light and outputs emission light; a polarized light splitting section that causes a polarized light component of the incident light input from the input/output section to branch, and outputs first polarization mode light having a first polarization and second polarization mode light having a second polarization different from the first polarization; a polarization converting section that receives the first polarization mode light, converts the first polarization to the second polarization, and outputs first polarization converted light; and an optical amplifying section that amplifies the first polarization converted light input to one end of a waveguide, outputs the resulting amplified first polarization converted light from another end of the waveguide, amplifies the second polarization mode light input to the other end of the waveguide, and outputs the resulting amplified second polarization mode light from the one end of t
    Type: Grant
    Filed: November 25, 2013
    Date of Patent: June 9, 2015
    Assignee: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Hideaki Hasegawa, Masaki Funabashi, Kazuaki Kiyota, Takeshi Akutsu, Noriyuki Yokouchi, Kazutaka Nara
  • Patent number: 8837869
    Abstract: The invention of the present application provides an SOA-PLC hybrid integrated polarization diversity circuit including a PLC-PBS chip and an SOA-COS whose respective waveguides are coupled to each other. The PLC-PBS chip includes: first and second optical waveguides; a Mach-Zehnder interferometer circuit; and a half-wave plate placed in the first optical waveguide which TM mode light is split into. The SOA-COS includes: a third optical waveguide connected to the first optical waveguide; a fourth optical waveguide connected to the second optical waveguide; and an SOA formed in at least one of the third and fourth optical waveguides. One end of the third optical waveguide and one end of the fourth optical waveguide are connected to a U-turn optical waveguide, the one ends being not connected to the first optical waveguide and the second optical waveguide, respectively.
    Type: Grant
    Filed: January 7, 2013
    Date of Patent: September 16, 2014
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Takeshi Akutsu, Kazutaka Nara, Masaki Funabashi, Noriyuki Yokouchi, Hideaki Hasegawa
  • Publication number: 20140241683
    Abstract: An optical waveguide element includes a cladding portion made of a silica-based glass, and an optical waveguide positioned in the cladding portion and made of a silica-based glass in which a ZrO2 particle is dispersed.
    Type: Application
    Filed: February 25, 2014
    Publication date: August 28, 2014
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Yasuyoshi UCHIDA, Yuuki TANIGUCHI, Hiroshi KAWASHIMA, Kazutaka NARA, Masanori TAKAHASHI
  • Patent number: 8718423
    Abstract: An optical branching element includes: an input waveguide; a tapered waveguide connected to the input waveguide; two branched waveguides that are connected to the tapered waveguide and arranged so as to form a Y-shape with the input waveguide and the tapered waveguide; and a plurality of strip-like waveguides that are provided so as to connect between the two branched waveguides and not to protrude outside the two branched waveguides, and formed so as to decrease in width as becoming distant from the tapered waveguide.
    Type: Grant
    Filed: August 12, 2013
    Date of Patent: May 6, 2014
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Kazutaka Nara, Noritaka Matsubara
  • Publication number: 20140078580
    Abstract: An optical amplifier device comprising an input/output section that inputs incident light and outputs emission light; a polarized light splitting section that causes a polarized light component of the incident light input from the input/output section to branch, and outputs first polarization mode light having a first polarization and second polarization mode light having a second polarization different from the first polarization; a polarization converting section that receives the first polarization mode light, converts the first polarization to the second polarization, and outputs first polarization converted light; and an optical amplifying section that amplifies the first polarization converted light input to one end of a waveguide, outputs the resulting amplified first polarization converted light from another end of the waveguide, amplifies the second polarization mode light input to the other end of the waveguide, and outputs the resulting amplified second polarization mode light from the one end of t
    Type: Application
    Filed: November 25, 2013
    Publication date: March 20, 2014
    Applicant: FURUKAWA ELECTRIC CO., LTD
    Inventors: Hideaki HASEGAWA, Masaki FUNABASHI, Kazuaki KIYOTA, Takeshi AKUTSU, Noriyuki YOKOUCHI, Kazutaka NARA
  • Publication number: 20130330042
    Abstract: An optical branching element includes: an input waveguide; a tapered waveguide connected to the input waveguide; two branched waveguides that are connected to the tapered waveguide and arranged so as to form a Y-shape with the input waveguide and the tapered waveguide; and a plurality of strip-like waveguides that are provided so as to connect between the two branched waveguides and not to protrude outside the two branched waveguides, and formed so as to decrease in width as becoming distant from the tapered waveguide.
    Type: Application
    Filed: August 12, 2013
    Publication date: December 12, 2013
    Applicant: Furukawa Electric Co., Ltd.
    Inventors: Kazutaka NARA, Noritaka Matsubara
  • Publication number: 20130330041
    Abstract: The present invention aims to provide a low-wavelength-dependent optical coupler capable of concurrently achieving high process stability and low polarization dependence. An optical coupler 100 according to an embodiment includes a cladding layer 105 being formed on a substrate 104 and having two waveguides 101a, 101b inside. Three directional couplers 102a, 102b, 102c are each formed by bringing portions of the two waveguides close to each other in parallel, and the two delay paths 103a, 103b are each formed to give an optical path difference between the two waveguides. The delay path 103a is provided between the directional couplers 102a and 102b, and the delay path 103b is provided between the directional couplers 102b and 102c. The three directional couplers have the same coupling characteristic, and the two delay paths have different optical path differences from each other.
    Type: Application
    Filed: August 15, 2013
    Publication date: December 12, 2013
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Kazutaka NARA
  • Patent number: 8538213
    Abstract: There is provided a SSC chip whose yield may be improved and whose processing steps may be simplified as compare to those of a prior art PLC chip having a light waveguide circuit to which a spot-size converter (SSC) is added, a fiber array attached with the SSC chip, a PLC module attached with the SSC chip and a method for manufacturing the SSC chip. The SSC chip has four spot-size converters and is fabricated separately from a PLC chip. Each SSC has a straight waveguide having the same core width and height with an end of an input/output waveguide of the PLC chip, a horizontally tapered waveguide in which the core width is enlarged in a tapered shape in the horizontal direction from the core width of the straight waveguide, a vertically tapered waveguide in which the core height is enlarged in a tapered shape in the vertical direction from the core height of the horizontally tapered waveguide and a spot-size enlarged portion whose core width and core height are both enlarged.
    Type: Grant
    Filed: November 25, 2009
    Date of Patent: September 17, 2013
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Yasuyoshi Uchida, Kazutaka Nara
  • Publication number: 20130236136
    Abstract: An optical waveguide circuit includes a polarization beam splitter connecting to a first input optical waveguide; an optical interference element receiving one of orthogonally polarization-split lights of a first light from the polarization beam splitter, and one of orthogonally-polarized lights from a second light input to a second input optical waveguide, the optical interference element causing interference therebetween; a first connection optical waveguide connecting the polarization beam splitter and the optical interference element; and a second connection optical waveguide connecting the second input optical waveguide and the optical interference element. The first and the second input optical waveguides have a straight-line shape or an S-shape including a first bending portion and a second bending portion to cancel the polarization-rotation of light taking place in the first bending portion.
    Type: Application
    Filed: April 24, 2013
    Publication date: September 12, 2013
    Applicant: Furukawa Electric Co., Ltd.
    Inventors: Kazutaka NARA, Takashi Inoue, Noritaka Matsubara, Hiroshi Kawashima
  • Patent number: 8526102
    Abstract: The invention provides a PLC-type DP-QPSK demodulator that reduces connection loss between a polarization beam splitter and a 90-degree hybrid circuit and aims at reducing the manufacturing cost and an optical transmission system using the same. In an embodiment of the invention, a PLC-type DP-QPSK demodulator that receives a DP-QPSK signal includes one PLC chip having a planar lightwave circuit. Input ports and output ports of signal light are provided at an input end and at an output end of the PLC chip, respectively. Within the planar lightwave circuit, there are integrated a polarization beam splitter that splits the DP-QPSK signal into an X-polarization QPSK signal and a Y-polarization QPSK signal, and two 90-degree hybrid circuits that mix the X-polarization QPSK signal and local oscillation light and the Y-polarization QPSK signal and local oscillation light, respectively, split each QPSK signal into orthogonal components I, Q and output them.
    Type: Grant
    Filed: March 1, 2012
    Date of Patent: September 3, 2013
    Assignee: Furukawa Electronic Co., Ltd.
    Inventors: Takashi Inoue, Kazutaka Nara
  • Patent number: 8503843
    Abstract: The present invention provides a hybrid integrated optical module having a high coupling efficiency by suppressing a connection loss between waveguides. A hybrid integrated optical module according to an embodiment of the present invention is an optical module which integrates a semiconductor chip and a PLC chip. The semiconductor chip has a semiconductor waveguide and is mounted on a Si bench. The PLC chip includes a PLC substrate and an optical waveguide formed on the PLC substrate. An end face of the semiconductor chip protrudes from an end face of the Si bench toward the PLC chip side by a protrusion amount X. Gap adjustment (adjustment of a distance D) between the semiconductor waveguide and the optical waveguide becomes possible by setting a position where the end face of the semiconductor chip is brought into contact with an end face of the PLC chip to be a reference position (zero point).
    Type: Grant
    Filed: November 9, 2010
    Date of Patent: August 6, 2013
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Takeshi Akutsu, Junichi Hasegawa, Kazutaka Nara
  • Patent number: 8477409
    Abstract: Disclosed are a PLC-type delay demodulation circuit and a PLC-type optical interferometer capable of reducing the size of a PLC chip with respect to the arrangement of various kinds of light output waveguides. In a PLC-type delay demodulation circuit, arm waveguides of a first MZI and arm waveguides of a second MZI are formed so as to overlap each other in the same region of a planar lightwave circuit. The optical paths of the MZIs are arranged such that the propagation directions of two DQPSK signals branched by a Y-branch waveguide are opposite to each other.
    Type: Grant
    Filed: September 13, 2012
    Date of Patent: July 2, 2013
    Assignees: Furakawa Electric Co., Ltd., Fujitsu Optical Components Limited
    Inventors: Hiroshi Kawashima, Kazutaka Nara, Kohei Shibata
  • Patent number: 8457459
    Abstract: A multiplexer/demultiplexer includes: a waveguide chip including a first chip and a second chip that are divided by a plane and obtained by cutting, together with a substrate, in a direction crossing an optical axis, a first slab waveguide of an AWG including the first slab waveguide and a second slab waveguide that are formed on the substrate; a first base to which the first chip is fixed; a second base separated from the first base and to which the second chip is fixed; and a member that has one end fixed to the first base or chip and another end fixed to the second base or chip, in a state in which cut surfaces of the first and second chips face each other, and that is configured to move the first base and the second base relatively to each other along the plane by expanding/contracting when temperature changes.
    Type: Grant
    Filed: July 7, 2010
    Date of Patent: June 4, 2013
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Patent number: 8441717
    Abstract: The PLC-type delay demodulation circuit includes a planar lightwave circuit that is provided on one PLC chip and demodulates a DQPSK signal. The planar lightwave circuit includes a Y-branch waveguide that branches a DQPSK-modulated optical signal into two optical signals and first and second MZIs that delay the branched optical signals by one bit. A wave plate is provided in central portions of first and second arm waveguides of the first MZI and first and second arm waveguides of the second MZI in such a manner that the wave plate intersects all of the four arm waveguides, the four arm waveguides being close to one another in a portion where the wave plate is provided.
    Type: Grant
    Filed: December 23, 2011
    Date of Patent: May 14, 2013
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Hiroshi Kawashima, Kazutaka Nara
  • Publication number: 20130114929
    Abstract: An arrayed waveguide grating includes input waveguides, an input slab waveguide, n output waveguides, an output slab waveguide, and an arrayed waveguide. Gaps are formed in the output waveguides other than the output waveguides of both sides of an array of the output waveguides, respectively, such that loss increases toward the central side of the array. Sizes of the gaps in the output waveguides increase toward the central side of the array.
    Type: Application
    Filed: December 20, 2012
    Publication date: May 9, 2013
    Inventor: Kazutaka NARA