Patents by Inventor Yuichi Takushima

Yuichi Takushima 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: 8509613
    Abstract: In optical communication systems, an optical signal which is modulated with a data signal is transmitted from an optical transmitter, and is launched into a fiber-optic transmission link. The present invention provides a method and an apparatus for the measurement of the distribution of the reflectivity along an optical transmission line implemented by using the signal processing based on the cross-correlation function between the data signal with which the optical transmitter is modulated and the back-reflected signal returned to the optical transmitter to provide the in-service monitoring of the fiber-optic transmission link.
    Type: Grant
    Filed: April 14, 2008
    Date of Patent: August 13, 2013
    Assignee: Korea Advanced Institute of Science and Technology
    Inventors: Yun Chur Chung, Yuichi Takushima
  • Publication number: 20090257743
    Abstract: In optical communication systems, an optical signal which is modulated with a data signal is transmitted from an optical transmitter, and is launched into a fiber-optic transmission link. The present invention provides a method and an apparatus for the measurement of the distribution of the reflectivity along an optical transmission line implemented by using the signal processing based on the cross-correlation function between the data signal with which the optical transmitter is modulated and the back-reflected signal returned to the optical transmitter to provide the in-service monitoring of the fiber-optic transmission link.
    Type: Application
    Filed: April 14, 2008
    Publication date: October 15, 2009
    Applicant: KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY
    Inventors: Yun Chur Chung, Yuichi Takushima
  • Patent number: 7450239
    Abstract: An optical pulse evaluation device and an in-service optical pulse evaluation device is disclosed which are capable of characteristics evaluation of an optical pulse itself or a sample launched therein in a relatively high bit-rate region. The optical pulse evaluation device evaluates a pulse waveform expressing an optical intensity of the optical pulse, an instantaneous frequency of the optical pulse, or a modulated light prepared by modulating the optical pulse in a light source end. The optical pulse evaluation device also observes a waveform change after a known optical pulse is passed through a device such as an optical fiber to evaluate a waveform deterioration or a compensation behavior caused by the device. The in-service optical pulse evaluation device is capable of measuring a wavelength dispersion in an optical communication.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: November 11, 2008
    Assignee: Santec Corporation
    Inventors: Noboru Uehara, Yuichi Takushima, Yasuyuki Ozeki, Yoichi Hirota
  • Patent number: 7388891
    Abstract: PROBLEM TO BE SOLVED: to realize a wide bandwidth light source capable of a stable operation providing a less spectrum variation. SOLUTION: Optical pulses 202 outputted by this optical pulse-generating device 201 are split by optical coupler 210. The one of split optical pulses is inputted in white light-emitting device 204 to emit the white light having the wide bandwidth. The other split is inputted in optical band pass filter 212 in operation-stabilizing circuit 207. Optical detector 213 detects a signal level of a specific wavelength and input in feedback circuit 215 to generate first and second feedback signals 205 and 206. Ring resonator fiber laser 208 uses any one of them and controls a rotation angle of the waveplate to realize stabilization of the output.
    Type: Grant
    Filed: March 9, 2005
    Date of Patent: June 17, 2008
    Assignee: Santec Corporation
    Inventors: Noboru Uehara, Yuichi Takushima, Kentaro Yasunaka
  • Publication number: 20070216993
    Abstract: A fiber laser includes in a resonator: a normal dispersion optical fiber; an anomalous dispersion optical fiber; a rare earth-doped optical fiber as a gain medium; and a mode locking mechanism, in which at least the rare earth-doped optical fiber is included as the normal dispersion optical fiber, and a length of the rare earth-doped optical fiber is set shorter than that of the anomalous dispersion optical fiber.
    Type: Application
    Filed: March 4, 2005
    Publication date: September 20, 2007
    Applicants: The Furukawa Electric Co., Ltd, Yuichi TAKUSHIMA
    Inventors: Keiichi Aiso, Masateru Tadakuma, Yuichi Takushima
  • Publication number: 20050219543
    Abstract: To obtain an optical pulse evaluation device and an in-service optical pulse evaluation device, which are capable of characteristics evaluation of an optical pulse itself or a sample launched therein, in a relatively high bit-rate region. Optical pulse 42 output repeatedly from an optical pulse light source 43 at a frequency fREP passes through sample 93 n sample stage 91 to be scanned by tunable wavelength optical band pass filter 47. A detection result by photodiode 51 is input in phase detection circuit 45 accompanying with the reference frequency fREP and the result is operated by operation unit 58C of personal computer 52 to know a spectral phase and a spectral intensity of the optical pulse passed through sample 93. Correcting this by applying the operation result in the state, where sample 93 has been removed enables to evaluate characteristics such as deterioration of optical pulse 42 by using sample 93. It is also possible to evaluate a waveform of optical pulse 42 as a light source.
    Type: Application
    Filed: March 31, 2005
    Publication date: October 6, 2005
    Inventors: Noboru Uehara, Yuichi Takushima, Yasuyuki Ozeki, Yoichi Hirota
  • Publication number: 20050201432
    Abstract: PROBLEM TO BE SOLVED: to realize a wide bandwidth light source capable of a stable operation providing a less spectrum variation. SOLUTION: Optical pulses 202 outputted by this optical pulse-generating device 201 are split by optical coupler 210. The one of split optical pulses is inputted in white light-emitting device 204 to emit the white light having the wide bandwidth. The other split is inputted in optical band pass filter 212 in operation-stabilizing circuit 207. Optical detector 213 detects a signal level of a specific wavelength and input in feedback circuit 215 to generate first and second feedback signals 205 and 206. Ring resonator fiber laser 208 uses any one of them and controls a rotation angle of the waveplate to realize stabilization of the output.
    Type: Application
    Filed: March 9, 2005
    Publication date: September 15, 2005
    Inventors: Noboru Uehara, Yuichi Takushima, Kentaro Yasunaka
  • Patent number: 6943951
    Abstract: An optical component of the present invention is compensated its optical dispersion, including third order dispersion, at low loss using optical dispersion compensating element comprising multi-layer film. In the optical component, an optical dispersion compensating element and a functional element are connected in series along an optical path.
    Type: Grant
    Filed: May 10, 2001
    Date of Patent: September 13, 2005
    Assignees: Oyokoden Lab Co., Ltd.
    Inventors: Kazuro Kikuchi, Yuichi Takushima, Mark Kenneth Jablonski, Yuichi Tanaka, Haruki Kataoka, Hironori Tokita, Kenji Furuki, Noboru Higashi, Kazunari Sato, Shiro Yamashita
  • Publication number: 20040032661
    Abstract: In the past, the occurrence of wavelength dispersion in signals transmitted through optical fibers caused considerable problems in terms of communications at a communications bit rate of 10 Gbps or more, and particularly optical communications at 20 Gbps or more. In order to solve the problems, though various proposals of dispersion compensation method and element have been made for its compensation, any of which did not solve it.
    Type: Application
    Filed: January 21, 2003
    Publication date: February 19, 2004
    Inventors: Kazuro Kikuchi, Yuichi Takushima, Mark K Jablonski, Yuichi Tanaka, Haruki Kataoka, Kenji Furuki, Noburo Higashi, Kazunori Sato, Shiro Yamashita
  • Publication number: 20030161045
    Abstract: An optical component of the present invention is compensated its optical dispersion, including third order dispersion, at low loss using optical dispersion compensating element comprising multi-layer film. In the optical component, an optical dispersion compensating element and a functional element are connected in series along an optical path.
    Type: Application
    Filed: April 16, 2003
    Publication date: August 28, 2003
    Inventors: Kazuro Kikuchi, Yuichi Takushima, Mark Kenneth Jablonski, Yuichi Tanaka, Haruki Kataoka, Hironori Tokita, Kenji Furuki, Noboru Higashi, Kazunari Sato, Shiro Yamashita
  • Publication number: 20020064334
    Abstract: A completely thin-film coupled three-cavity dispersion compensation element enables dispersion compensation over wider bandwidths then similar elements having fewer coupled cavities. By cascading these dispersion compensation elements even greater compensation bandwidths can be obtained, thereby further increasing the merit and usefulness of this device.
    Type: Application
    Filed: October 12, 2001
    Publication date: May 30, 2002
    Inventors: Mark Kenneth Jablonski, Kazuro Kikuchi, Yuichi Takushima, Yuichi Tanaka, Kenji Furuki
  • Publication number: 20020060865
    Abstract: This invention, a composite dispersion compensation structure, made up of at least two dispersion compensation elements in an opposing arrangement, and at least one reflection element, can provide low cost dispersion compensation over a wide bandwidth by utilizing multiple reflections.
    Type: Application
    Filed: October 12, 2001
    Publication date: May 23, 2002
    Inventors: Mark Kenneth Jablonskl, Kazuro Kikuchi, YUichi Takushima, Yuichi Tanaka, Kenji Furuki
  • Publication number: 20020044738
    Abstract: This invention, a composite dispersion compensation structure made up of at least two dispersion compensation elements in an opposing arrangement, can provide low cost dispersion compensation over a wide bandwidth by utilizing multiple reflections.
    Type: Application
    Filed: September 14, 2001
    Publication date: April 18, 2002
    Inventors: Mark Kenneth Jablonski, Kazuro Kikuchi, Yuichi Takushima, Yuichi Tanaka, Kenji Furuki