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: 20110123153
    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: January 27, 2011
    Publication date: May 26, 2011
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventor: Kazutaka NARA
  • Publication number: 20110110622
    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: Application
    Filed: November 9, 2010
    Publication date: May 12, 2011
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Takeshi AKUTSU, Junichi Hasegawa, Kazutaka Nara
  • Publication number: 20110097035
    Abstract: Two Mach-Zehnder optical interferometer circuits 13a and 13b are accurately point-symmetrically connected to each other to form a first point-symmetrically connected optical interferometer circuit 5 constituting a light input side circuit 1. Optical signals having a plurality of wavelengths are input to a light input terminal 17. A second point-symmetrically connected optical interferometer circuit 7 having the same functional structure as the first point-symmetrically connected optical interferometer circuit 5 is connected to a through port 18, which is an output terminal of the light input side circuit 1, as a first light output side circuit 2. A cross port 19, which is the other output terminal of the light input side circuit 1, is connected to a second light output side circuit 3 having at least one of Mach-Zehnder optical interferometer circuits 13c and 13d whose transmittance characteristics are different from those of the Mach-Zehnder optical interferometer circuits 13a and 13b.
    Type: Application
    Filed: January 3, 2011
    Publication date: April 28, 2011
    Applicant: The FURUKAWA ELECTRIC CO., LTD.
    Inventors: Kazutaka NARA, Haruki Urabe, Tsunetoshi Saitoh, Masahito Morimoto
  • Publication number: 20110085761
    Abstract: An arrayed waveguide grating includes: at least one first waveguide; a first slab waveguide connected to the at least one first waveguide; a plurality of second waveguides; a second slab waveguide connected to the plurality of second waveguides; and an arrayed waveguide. The arrayed waveguide includes: M channel waveguides connected between the first slab waveguide and the second slab waveguide, wherein M is a natural number; and a phase correcting portion configured to provide a predetermined phase to at least a part of the M channel waveguides by one or both of a width and a length of the at least the part of the M channel waveguides being changed.
    Type: Application
    Filed: December 20, 2010
    Publication date: April 14, 2011
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Kazutaka NARA, Yasuyoshi Uchida, Noritaka Matsubara
  • Patent number: 7885493
    Abstract: Two Mach-Zehnder optical interferometer circuits 13a and 13b are accurately point-symmetrically connected to each other to form a first point-symmetrically connected optical interferometer circuit 5 constituting a light input side circuit 1. Optical signals having a plurality of wavelengths are input to a light input terminal 17. A second point-symmetrically connected optical interferometer circuit 7 having the same functional structure as the first point-symmetrically connected optical interferometer circuit 5 is connected to a through port 18, which is an output terminal of the light input side circuit 1, as a first light output side circuit 2. A cross port 19, which is the other output terminal of the light input side circuit 1, is connected to a second light output side circuit 3 having at least one of Mach-Zehnder optical interferometer circuits 13c and 13d whose transmittance characteristics are different from those of the Mach-Zehnder optical interferometer circuits 13a and 13b.
    Type: Grant
    Filed: November 26, 2008
    Date of Patent: February 8, 2011
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Kazutaka Nara, Haruki Urabe, Tsunetoshi Saitoh, Masahito Morimoto
  • Patent number: 7884996
    Abstract: A delay-line demodulator for demodulating a differential quadrature phase shift keying (DQPSK) signal is provided. The demodulator includes two Mach-Zehnder interferometers individually comprising two waveguides having different lengths therebetween and through which a light signal branched from the DQPSK signal propagates, respectively. A phase of the light signal propagating at one of the waveguides is delayed as compared to a phase of the light signal propagating at another one of the waveguides, wherein a divergence amount of polarization is adjusted by driving sets of heaters that are facing each other and sandwiching a half wavelength plate therebetween.
    Type: Grant
    Filed: December 2, 2009
    Date of Patent: February 8, 2011
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Publication number: 20110008002
    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: Application
    Filed: July 7, 2010
    Publication date: January 13, 2011
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi HASEGAWA, Kazutaka Nara
  • Publication number: 20100303410
    Abstract: An arrayed waveguide grating includes: at least one input waveguide; an input slab waveguide connected to the input waveguide; a plurality of output waveguides; an output slab waveguide connected to the output waveguides; and an arrayed waveguide. The arrayed waveguide includes: M channel waveguides connected between the input slab waveguide and the output slab waveguide; and a phase correcting portion configured to provide a predetermined phase to at least a part of the M channel waveguides by a form of the at least the part of the M channel waveguides being changed.
    Type: Application
    Filed: May 25, 2010
    Publication date: December 2, 2010
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Kazutaka Nara, Noritaka Matsubara
  • Publication number: 20100278483
    Abstract: An athermal AWG module 10 comprises: an AWG 11 having waveguides partially divided to separate a chip, separated chips being connected by a compensation plate 33 to achieve temperature-independence; an athermal AWG chip 12 having a substrate and the AWG 11 formed on the substrate; a package 13 having an opening 14 and accommodating the athermal AWG chip 12; and a cover for blocking the opening 14. The athermal AWG chip 12 is fully covered with a gelled refractive index matching agent 16 that is matched in refractive index to the waveguides of the AWG 11. As the gelled refractive index matching agent 16 is excellent in water resistance and hardly passes water, the adhesive agent for fixing the compensation plate 33 to the surfaces of the separated two chips is prevented from being deteriorated due to ingress of water, thereby enhancing the reliability.
    Type: Application
    Filed: December 23, 2009
    Publication date: November 4, 2010
    Applicant: FURUKAWA ELECTRIC CO., LTD
    Inventors: Junichi HASEGAWA, Kazutaka Nara
  • Patent number: 7813032
    Abstract: The present invention provides methods to control phase shift of delay demodulation devices to reduce Polarization Dependent wavelength (PD?) to be less than, for example, 0.5 GHz (i.e. 0.004 nm).
    Type: Grant
    Filed: March 27, 2009
    Date of Patent: October 12, 2010
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Publication number: 20100142900
    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: Application
    Filed: November 25, 2009
    Publication date: June 10, 2010
    Applicant: FURUKAWA ELECTRIC CO., LTD.
    Inventors: Yasuyoshi Uchida, Kazutaka Nara
  • Publication number: 20100111468
    Abstract: An optical integrated circuit includes a planar lightwave circuit, and a semiconductor element, which are fixed at one contact surface. A semiconductor optical amplifier (SOA) and a turnaround waveguide having a turnaround portion are formed on a semiconductor substrate. The turnaround waveguide is turned around on the second substrate and is connected to an output port of the SOA. An input port and an output port of the turnaround waveguide are optically coupled at the contact surface with an input port and an output port of the optical waveguides respectively.
    Type: Application
    Filed: June 10, 2009
    Publication date: May 6, 2010
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Masaki FUNABASHI, Junichi Hasegawa, Takeshi Akutsu, Kazutaka Nara, Noriyuki Yokouchi
  • Publication number: 20100073760
    Abstract: A delay-line demodulator for demodulating a differential quadrature phase shift keying (DQPSK) signal is provided. The demodulator includes two Mach-Zehnder interferometers individually comprising two waveguides having different lengths therebetween and through which a light signal branched from the DQPSK signal propagates, respectively. A phase of the light signal propagating at one of the waveguides is delayed as compared to a phase of the light signal propagating at another one of the waveguides, wherein a divergence amount of polarization is adjusted by driving sets of heaters that are facing each other and sandwiching a half wavelength plate therebetween.
    Type: Application
    Filed: December 2, 2009
    Publication date: March 25, 2010
    Applicant: FURUKAWA ELECTRIC CO., LTD
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Publication number: 20100067098
    Abstract: The present invention provides methods to control phase shift of delay demodulation devices to reduce Polarization Dependent wavelength (PD?) to be less than, for example, 0.5 GHz (i.e. 0.004 nm).
    Type: Application
    Filed: March 27, 2009
    Publication date: March 18, 2010
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi HASEGAWA, Kazutaka NARA
  • Publication number: 20100053731
    Abstract: Delay demodulation devices with optimized temperature and pressure distribution on a Planar Lightwave Circuit (PLC) are provided. The delay demodulation device 1 comprises: an input waveguide 2, which receives DQPSK signals; a Y-shape waveguide 3, which splits the light waveguide 2; a first Mach-Zehnder interferometer 4; and a second Mach-Zehnder interferometer 5. Both ends of arm waveguides 8, 9 on Mach-Zehnder interferometer 4 and the both ends of arm waveguides 12, 13 on Mach-Zehnder interferometer 5 are bent toward the center portion of the PLC. Because of the angle, the lengths of these arm waveguides 8, 9 are shortened in the Z-direction, and input couplers 6, 10 and output couplers 7, 11 of the Mach-Zehnder interferometers are shortened as well in the Z-direction. Therefore, the area covered by the Mach-Zehnder interferometers 4, 5 is reduced.
    Type: Application
    Filed: March 27, 2009
    Publication date: March 4, 2010
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi HASEGAWA, Kazutaka Nara
  • Publication number: 20100046064
    Abstract: A delay demodulation device, which reduces chip size and polarization dependent frequency (PDf), is provided. The delay demodulation device comprises: an input waveguide, which receives DQPSK signals; a Y-shape waveguide, which splits the input waveguide; a first Mach-Zehnder interferometer; and a second Mach-Zehnder interferometer. Both end of two arm waveguides of first Mach-Zehnder interferometer and both ends of two arm waveguides of second Mach-Zehnder interferometer are angled toward the center portion of a Planar Lightwave Circuit (PLC). Because of the angle, the length of the two arm waveguides of the first Mach-Zehnder interferometer and the length of the two arm waveguides of the second Mach-Zehnder interferometer in Z-direction can be shortened, and input couplers and output couplers of the Mach-Zehnder interferometers in Z-direction can be shortened as well. The area occupied by the Mach-Zehnder interferometers is also reduced.
    Type: Application
    Filed: March 31, 2009
    Publication date: February 25, 2010
    Applicant: THE FURUKAWA ELECTRIC CO., LTD.
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Patent number: 7649678
    Abstract: A delay-line demodulator for demodulating a differential quadrature phase shift keying (DQPSK) signal is provided. The demodulator includes two Mach-Zehnder interferometers individually comprising two waveguides having different lengths therebetween and through which a light signal branched from the DQPSK signal propagates, respectively. A phase of the light signal propagating at one of the waveguides is delayed as compared to a phase of the light signal propagating at another one of the waveguides, wherein a divergence amount of polarization is adjusted by driving sets of heaters that are facing each other and sandwiching a half wavelength plate therebetween.
    Type: Grant
    Filed: October 9, 2008
    Date of Patent: January 19, 2010
    Assignee: Furukawa Electric Co., Ltd.
    Inventors: Junichi Hasegawa, Kazutaka Nara
  • Patent number: 7561765
    Abstract: An optical integrated circuit 1 according to the present invention includes a planar lightwave circuit 2, and a semiconductor element 3, which are fixed at one contact surface 12. A semiconductor optical amplifier (SOA) 9 is formed on a semiconductor substrate 8. A semiconductor waveguide 10 and a semiconductor waveguide 11 are formed on an input side and an output side of SOA 9, respectively. The semiconductor waveguide 11 has a turnaround portion 11a turned around on the semiconductor substrate 8. Respective ends of the optical waveguides 5 and 6 on a PLC platform 4 and respective ends of semiconductor waveguides 10 and 11 are optically coupled with each other at the contact surface 12.
    Type: Grant
    Filed: March 10, 2008
    Date of Patent: July 14, 2009
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Masaki Funabashi, Junichi Hasegawa, Takeshi Akutsu, Kazutaka Nara, Noriyuki Yokouchi
  • Patent number: 7555175
    Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer 10 of the present invention 10 comprises one arrayed waveguide grating (AWG) 20 having two input waveguides 21, 22 and two output waveguide-groups 23, 24, and a Mach Zehnder Interferometer-type interleaver 30 integrated with the AWG 20. Each of the input waveguides 21, 22 is formed by a Mach Zehnder Interferometer having the same free spectral range as the frequency spacing of the AWG. The Interferometer includes a 3 dB coupler 51 connected to the 3 dB coupler 32, a 100% coupler 52, a waveguide delay line 53 with an optical path length difference ?L of 4.1 mm formed between the couplers 51, 52, and a phase shifter 54 of ? formed between the 100% coupler 52 and a 3 dB coupler 55 connected to the first slab waveguide 25.
    Type: Grant
    Filed: August 24, 2007
    Date of Patent: June 30, 2009
    Assignee: The Furukawa Electric Co., Ltd
    Inventor: Kazutaka Nara
  • Patent number: 7542640
    Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer includes an arrayed waveguide grating formed on a substrate. The arrayed waveguide grating includes two slab waveguides, one arrayed waveguide, first input/output waveguides respectively connected to each end facet of slab waveguides, and second input/output waveguide-groups respectively connected to the end facets. The first input/output waveguides are provided for inputting or outputting a plurality of lights (?1˜?n) each of which has a different wavelength and multiplexed. The second input/output waveguides are provided for individually inputting or outputting a plurality of lights (?1˜?n). One arrayed waveguide 23 can be used to carry out simultaneously multiplexing and demultiplexing. It is able to carry out simultaneously multiplexing and demultiplexing with one arrayed waveguide grating.
    Type: Grant
    Filed: March 27, 2008
    Date of Patent: June 2, 2009
    Assignee: The Furukawa Electric Co., Ltd.
    Inventor: Kazutaka Nara