Patents by Inventor Shigefumi Yamasaki

Shigefumi Yamasaki 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: 7050672
    Abstract: A polarization-maintaining optical fiber component which suppresses coupling of propagating light to a high-order mode at the optical coupling section of the polarization-maintaining optical fiber component, caused by different refractive indexes between the stress applying sections and the cladding, thus reducing excess loss, is constructed by using a polarization-maintaining optical fiber having stress applying sections arranged symmetrically to each other with respect to a core in a cladding surrounding the core, wherein the largest one of those concentric circles of the core or the said cladding which do not reach the stress applying sections and do not include the stress applying sections within has a diameter of 20 ?m or greater.
    Type: Grant
    Filed: August 14, 2000
    Date of Patent: May 23, 2006
    Assignee: Fujikura Ltd.
    Inventors: Ryokichi Matsumoto, Hideki Sasaki, Kenji Nishide, Ryozo Yamauchi, Shigefumi Yamasaki
  • Patent number: 6463195
    Abstract: In a method of manufacturing a polarization-maintaining optical fiber coupler by heating lengthwise portions of two polarization-maintaining optical fibers extending side by side, and elongating the heated portions to thereby form a fused-elongated section, elongation is terminated when the cyclic changes in a coupling ratio of two polarized waves according to an elongation length at a wavelength in use are both within first two cycles, so that the coupling ratio of one of the polarized waves is equal to or less than 10% and the coupling ratio of the other one of the polarized waves is equal to or greater than 90%. This method can provide a polarization-maintaining optical fiber coupler whose coupling ratio has a large dependency on polarization with a short elongation length.
    Type: Grant
    Filed: May 25, 2000
    Date of Patent: October 8, 2002
    Assignee: Fujikura Ltd.
    Inventors: Hideki Sasaki, Ryozo Yamauchi, Hiroshi Hidaka, Kenji Nishide, Shigefumi Yamasaki, Ryokichi Matsumoto, Yoji Suzuki
  • Patent number: 6459829
    Abstract: The present invention provides a multiple wavelength excitation light source characterized in the provision of an optical multiplexing element that has a plurality of input terminals connected to lasers and functions to multiplex a plurality of lights that have different characteristics; and a reflecting element inserted near the output side of the output terminal of the optical multiplexing element, and functioning to reflect the light multiplexed at the optical multiplexing element at a low reflection coefficient. Accordingly, it becomes possible to provide high output excitation light in a stable manner.
    Type: Grant
    Filed: February 3, 2000
    Date of Patent: October 1, 2002
    Inventors: Ryozo Yamauchi, Akira Wada, Kenji Nishide, Shigefumi Yamasaki
  • Patent number: 6442313
    Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.
    Type: Grant
    Filed: February 5, 2001
    Date of Patent: August 27, 2002
    Assignee: Fujikura Ltd.
    Inventors: Ryozo Yamauchi, Akira Wada, Tetsuya Sakai, Nobuyuki Tanaka, Kensuke Shima, Kenji Nishide, Shigefumi Yamasaki
  • Patent number: 6298183
    Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.
    Type: Grant
    Filed: June 2, 1998
    Date of Patent: October 2, 2001
    Assignee: Fujikura Ltd.
    Inventors: Ryozo Yamauchi, Akira Wada, Tetsuya Sakai, Nobuyuki Tanaka, Kensuke Shima, Kenji Nishide, Shigefumi Yamasaki
  • Publication number: 20010019643
    Abstract: An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.
    Type: Application
    Filed: February 5, 2001
    Publication date: September 6, 2001
    Inventors: Ryozo Yamauchi, Akira Wada, Tetsuya Sakai, Nobuyuki Tanaka, Kensuke Shima, Kenji Nishide, Shigefumi Yamasaki
  • Patent number: 5848208
    Abstract: In an optical-fiber coupler formed by disposing two single-mode optical fibers 1 and 2 in parallel, and fusing and elongating the optical fibers at one position in the longitudinal extent of the optical fibers 1 and 2, variation of insertion loss dependent on the polarization can be eliminated in its manufacturing by imparting a twist to the optical coupling part 3' of the fused-elongated portion 3 so that with respect to the direction of a line on a plane orthogonally intersecting the longitudinal direction of the optical fibers 1 and 2, the line linking the centers of the two optical fibers 1 and 2, the direction of the line on a plane at one end of the optical coupling part 3' of the fused-elongated portion 3 makes an angle of 90 degrees with the direction of the line on a plane at the other end of the optical coupling part 3'.
    Type: Grant
    Filed: July 15, 1997
    Date of Patent: December 8, 1998
    Assignee: Fujikura Ltd.
    Inventors: Fumio Suzuki, Hideki Sasaki, Shigefumi Yamasaki, Tomio Abiru, Ryozo Yamauchi
  • Patent number: 5689578
    Abstract: The polarization-maintaining optical fiber 10 of the present invention is designed so that a plurality of core portions 12a,12b which have a high refractive index is provided in parallel along a single diameter direction in the cross section of the optical fiber, these core portions 12a,12b cooperating to propagate a single fundamental mode. In the production method for the polarization-maintaining optical fiber of the present invention, a plurality of holes 22 are formed longitudinally in parallel along a single diameter direction of a glass rod 21 having a low refractive index which forms the cladding, glass rods 23 for core use having a high refractive index which form the core portions are inserted into these holes 22, heating to form a unitary body is carried out, creating a preform which is then drawn.
    Type: Grant
    Filed: October 25, 1994
    Date of Patent: November 18, 1997
    Assignee: Fujikura ltd.
    Inventors: Ryozo Yamauchi, Kuniharu Himeno, Minoru Sawada, Fumio Suzuki, Kazuhiko Aikawa, Tetsuo Nozawa, Shigefumi Yamasaki