Patents by Inventor Tetsuya Haruna

Tetsuya Haruna 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: 20190270662
    Abstract: The present invention relates to a method of manufacturing an optical fiber preform for obtaining an optical fiber with low transmission loss. A core preform included in the optical fiber preform comprises three or more core portions, which are each produced by a rod-in-collapse method, and in which both their alkali metal element concentration and chlorine concentration are independently controlled. In two or more manufacturing steps of the manufacturing steps for each of the three or more core portions, an alkali metal element is added. As a result, the mean alkali metal element concentration in the whole core preform is controlled to 7 atomic ppm or more and 70 atomic ppm or less.
    Type: Application
    Filed: May 20, 2019
    Publication date: September 5, 2019
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya HARUNA, Masaaki HIRANO, Yoshiaki TAMURA, Yuki KAWAGUCHI
  • Patent number: 10155687
    Abstract: An optical fiber preform of the present embodiment comprises a core portion and a cladding each comprised of silica glass. The core portion has a first dopant region including a central axis of the core portion and a second dopant region away from the central axis. The first dopant region contains a first dopant selected from among Na, K, and their compounds, and a concentration of the first dopant is 10 atomic ppm or more but 2,000 atomic ppm or less. The second dopant region contains a second dopant reducing viscosity of the silica glass. The second dopant has, as a characteristic at a temperature of 2,000° C. to 2,300° C., a diffusion coefficient of 1×10?12 cm2/s or higher but lower than that of the first dopant, and a concentration of the second dopant region is 10 atomic ppm or more.
    Type: Grant
    Filed: April 25, 2016
    Date of Patent: December 18, 2018
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Yuki Kawaguchi
  • Patent number: 10031285
    Abstract: The present embodiment relates to an MCF having a low transmission loss and having a structure for reducing a transmission loss and effectively suppressing an inter-core XT. The uncoupled MCF includes alkali metal having a predetermined concentration in which each of a plurality of cores contributes to reduction in the transmission loss, and a core pitch is set so that a sum h_total of power coupling coefficients of a specific core and the remaining all cores of the plurality of cores is 2.3×10?4/km or less.
    Type: Grant
    Filed: August 23, 2017
    Date of Patent: July 24, 2018
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya Nakanishi, Tetsuya Hayashi, Takashi Sasaki, Yoshiaki Tamura, Tetsuya Haruna
  • Patent number: 9932265
    Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.
    Type: Grant
    Filed: November 15, 2016
    Date of Patent: April 3, 2018
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya Haruna, Masaaki Hirano, Yoshiaki Tamura, Tetsuya Nakanishi
  • Patent number: 9910216
    Abstract: One of embodiments relates to an optical fiber in which an alkali metal element is efficiently doped to its core to suppress transmission loss from increasing. A mean concentration or a concentration distribution of the alkali metal element is adjusted such that 0.48 or less is obtained as an weighted value obtained by weighting a distribution of field intensity of guided light at a wavelength of 1550 nm, with respect to a radial direction distribution of a ratio ID2/I?3 of an intensity ID2 of Raman scattering light by a silica three-membered ring structure and an intensity I?3 of Raman scattering light by a Si—O stretching vibration, in a cross-sectional region having a diameter of 20 ?m.
    Type: Grant
    Filed: July 10, 2017
    Date of Patent: March 6, 2018
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya Haruna, Yoshiaki Tamura, Yoshihiro Tukuda
  • Publication number: 20170351022
    Abstract: The present embodiment relates to an MCF having a low transmission loss and having a structure for reducing a transmission loss and effectively suppressing an inter-core XT. The uncoupled MCF includes alkali metal having a predetermined concentration in which each of a plurality of cores contributes to reduction in the transmission loss, and a core pitch is set so that a sum h_total of power coupling coefficients of a specific core and the remaining all cores of the plurality of cores is 2.3×10?4/km or less.
    Type: Application
    Filed: August 23, 2017
    Publication date: December 7, 2017
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya NAKANISHI, Tetsuya HAYASHI, Takashi SASAKI, Yoshiaki TAMURA, Tetsuya HARUNA
  • Patent number: 9817184
    Abstract: An optical fiber having a reduced attenuation includes a silica glass core and a silica glass cladding. The silica glass core has substantially no germanium and includes a first core and a second core. The second core encloses the first core, the refractive index of the second core is larger than the refractive index of the first core, and the average value of halogen concentration of the second core is 5000 ppm or more. The silica glass cladding surrounds the second core and contains substantially no germanium. The refractive index of the cladding is smaller than the refractive index of the first core.
    Type: Grant
    Filed: October 11, 2016
    Date of Patent: November 14, 2017
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Masaaki Hirano, Hirotaka Sakuma
  • Publication number: 20170305781
    Abstract: One of embodiments relates to an optical fiber in which an alkali metal element is efficiently doped to its core to suppress transmission loss from increasing. A mean concentration or a concentration distribution of the alkali metal element is adjusted such that 0.48 or less is obtained as an weighted value obtained by weighting a distribution of field intensity of guided light at a wavelength of 1550 nm, with respect to a radial direction distribution of a ratio ID2/I?3 of an intensity ID2 of Raman scattering light by a silica three-membered ring structure and an intensity I?3 of Raman scattering light by a Si—O stretching vibration, in a cross-sectional region having a diameter of 20 ?m.
    Type: Application
    Filed: July 10, 2017
    Publication date: October 26, 2017
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya HARUNA, Yoshiaki TAMURA, Yoshihiro TUKUDA
  • Publication number: 20170108642
    Abstract: An optical fiber having a reduced attenuation includes a silica glass core and a silica glass cladding. The silica glass core has substantially no germanium and includes a first core and a second core. The second core encloses the first core, the refractive index of the second core is larger than the refractive index of the first core, and the average value of halogen concentration of the second core is 5000 ppm or more. The silica glass cladding surrounds the second core and contains substantially no gemianium. The refractive index of the cladding is smaller than the refractive index of the first core.
    Type: Application
    Filed: October 11, 2016
    Publication date: April 20, 2017
    Inventors: Yoshiaki TAMURA, Tetsuya HARUNA, Masaaki HIRANO, Hirotaka SAKUMA
  • Publication number: 20170101334
    Abstract: The present invention relates to a method of manufacturing an optical fiber preform for obtaining an optical fiber with low transmission loss. A core preform included in the optical fiber preform comprises three or more core portions, which are each produced by a rod-in-collapse method, and in which both their alkali metal element concentration and chlorine concentration are independently controlled. In two or more manufacturing steps of the manufacturing steps for each of the three or more core portions, an alkali metal element is added. As a result, the mean alkali metal element concentration in the whole core preform is controlled to 7 atomic ppm or more and 70 atomic ppm or less.
    Type: Application
    Filed: December 20, 2016
    Publication date: April 13, 2017
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya HARUNA, Masaaki HIRANO, Yoshiaki TAMURA, Yuki KAWAGUCHI
  • Patent number: 9588286
    Abstract: The optical fiber includes a core, the first cladding, and second cladding. The core is made of silica based glass containing Cl. The first cladding and the second cladding are made of silica based glass containing fluorine. The refractive index of the first cladding is lower than that of the core. The refractive index of the second cladding is lower than that of the core and higher than that of the first cladding. The second cladding is divided into an outer region having a uniform refractive index and an inner region having a refractive index higher than that of the outer region. The difference ?P between the maximum refractive index of the inner region and the refractive index of the outer region is 0.02% to 0.10% in terms of relative refractive index with respect to pure silica based glass. The radial thickness R of the inner region is 10 ?m to 25 ?m.
    Type: Grant
    Filed: June 6, 2014
    Date of Patent: March 7, 2017
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Tetsuya Haruna, Masaaki Hirano, Yoshiaki Tamura, Nobuhiro Hikichi
  • Publication number: 20170057867
    Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.
    Type: Application
    Filed: November 15, 2016
    Publication date: March 2, 2017
    Inventors: Tetsuya HARUNA, Masaaki HIRANO, Yoshiaki TAMURA, Tetsuya NAKANISHI
  • Patent number: 9575245
    Abstract: An optical fiber containing an alkali metal and capable of reducing Rayleigh scattering loss is provided. An optical fiber has a core and a cladding made of silica glass and enclosing the core. The cladding contains fluorine and has a refractive index lower than the refractive index of the core. The core contains first group dopants selected from the group of Na element, K element, or a compound thereof at an average concentration of 0.2 ppm or more and 10 ppm or less. The core also contains second group dopants for reducing the viscosity of silica glass and having a diffusion coefficient of 1×10?12 cm2/s or more and smaller than the diffusion coefficient of the first group dopants, by an average concentration of 0.2 ppm or more at a temperature of 2000° C. to 2300° C.
    Type: Grant
    Filed: November 17, 2015
    Date of Patent: February 21, 2017
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Yoshihiro Saito, Yuki Kawaguchi, Masaaki Hirano
  • Patent number: 9527765
    Abstract: There is provided a method for producing a low-loss alkali metal-doped silica core optical fiber having excellent hydrogen resistance. The method for producing the optical fiber according to the present invention includes a drawing step of drawing an optical fiber preform in a drawing furnace to produce a silica glass-based optical fiber including a core region containing an alkali metal with an average concentration of 0.5 atomic ppm or more and a cladding region that surrounds the core region and a heating step of heating the optical fiber in a heating furnace through which the optical fiber drawn from the drawing furnace passes.
    Type: Grant
    Filed: December 11, 2013
    Date of Patent: December 27, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya Haruna, Masaaki Hirano, Yoshiaki Tamura, Tetsuya Nakanishi
  • Patent number: 9512033
    Abstract: An optical fiber containing an alkali metal element and exhibiting low attenuation as well as excellent radiation resistance is provided. The optical fiber of the present invention has a core region and a cladding region enclosing the core region. The core region contains alkali metal elements by an average concentration of 0.2 atomic ppm or more. The attenuation at a wavelength of 1550 nm after irradiating with the radiation of 0.10 Gy or more of cumulative absorbed dose increases by 0.02 dB/km or less as compared with the attenuation exhibited prior to radiation exposure.
    Type: Grant
    Filed: April 1, 2016
    Date of Patent: December 6, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura
  • Publication number: 20160318793
    Abstract: An optical fiber preform of the present embodiment comprises a core portion and a cladding each comprised of silica glass. The core portion has a first dopant region including a central axis of the core portion and a second dopant region away from the central axis. The first dopant region contains a first dopant selected from among Na, K, and their compounds, and a concentration of the first dopant is 10 atomic ppm or more but 2,000 atomic ppm or less. The second dopant region contains a second dopant reducing viscosity of the silica glass. The second dopant has, as a characteristic at a temperature of 2,000° C. to 2,300° C., a diffusion coefficient of 1×10?12 cm2/s or higher but lower than that of the first dopant, and a concentration of the second dopant region is 10 atomic ppm or more.
    Type: Application
    Filed: April 25, 2016
    Publication date: November 3, 2016
    Inventors: Yoshiaki TAMURA, Tetsuya HARUNA, Yuki KAWAGUCHI
  • Patent number: 9411095
    Abstract: An optical fiber preform which can be drawn into a low attenuation optical fiber is provided with a core portion and a cladding portion surrounding the core portion. The core portion includes a first core portion and a second core portion surrounding the first core portion. The cladding portion includes a first cladding portion surrounding the second core portion and a second cladding portion surrounding the first cladding portion. The first core portion contains an alkali metal element, the concentration of oxygen molecules contained in glass is 30 mol ppb or more and 200 mol ppb or less in a part of or entire region having an alkali metal atom concentration of 100 atomic ppm or more, and the concentration of oxygen molecules contained in glass is 10 mol ppb or less in a region having an alkali metal atom concentration of 50 atomic ppm or less.
    Type: Grant
    Filed: January 28, 2014
    Date of Patent: August 9, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Masaaki Hirano
  • Publication number: 20160214886
    Abstract: An optical fiber containing an alkali metal element and exhibiting low attenuation as well as excellent radiation resistance is provided. The optical fiber of the present invention has a core region and a cladding region enclosing the core region. The core region contains alkali metal elements by an average concentration of 0.2 atomic ppm or more. The attenuation at a wavelength of 1550 nm after irradiating with the radiation of 0.10 Gy or more of cumulative absorbed dose increases by 0.02 dB/km or less as compared with the attenuation exhibited prior to radiation exposure.
    Type: Application
    Filed: April 1, 2016
    Publication date: July 28, 2016
    Inventors: Masaaki HIRANO, Tetsuya HARUNA, Yoshiaki TAMURA
  • Publication number: 20160147010
    Abstract: An optical fiber containing an alkali metal and capable of reducing Rayleigh scattering loss is provided. An optical fiber has a core and a cladding made of silica glass and enclosing the core. The cladding contains fluorine and has a refractive index lower than the refractive index of the core. The core contains first group dopants selected from the group of Na element, K element, or a compound thereof at an average concentration of 0.2 ppm or more and 10 ppm or less. The core also contains second group dopants for reducing the viscosity of silica glass and having a diffusion coefficient of 1×10?12 cm2/s or more and smaller than the diffusion coefficient of the first group dopants, by an average concentration of 0.2 ppm or more at a temperature of 2000° C. to 2300° C.
    Type: Application
    Filed: November 17, 2015
    Publication date: May 26, 2016
    Inventors: Yoshiaki TAMURA, Tetsuya HARUNA, Yoshihiro SAITO, Yuki KAWAGUCHI, Masaaki HIRANO
  • Patent number: 9340444
    Abstract: A method includes (1) a thermal diffusion process for using an alkali metal salt raw material having an average particle size of 1 mm or less in diameter, supplying a vapor of the alkali metal salt produced by heating the alkali metal salt raw material together with a carrier gas to the inside of a silica-based glass pipe from one end side of the glass pipe, and heating the glass pipe using a heat source which relatively moves in a longitudinal direction of the glass pipe to cause an oxidation reaction of an alkali metal and thermally diffuse the alkali metal into an inner side of the glass pipe, (2) a collapsing process for collapsing the glass pipe after the thermal diffusion process to prepare a core rod; and (3) a cladding portion addition process for adding a cladding portion around the core rod prepared in the collapsing process.
    Type: Grant
    Filed: December 13, 2012
    Date of Patent: May 17, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura