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: 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
  • Publication number: 20160131832
    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: Application
    Filed: June 6, 2014
    Publication date: May 12, 2016
    Inventors: Tetsuya HARUNA, Masaaki HIRANO, Yoshiaki TAMURA, Nobuhiro HIKICHI
  • Patent number: 9335465
    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: January 15, 2013
    Date of Patent: May 10, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura
  • Patent number: 9322990
    Abstract: An optical fiber preform has a core portion having a first core portion including a central axis, a second core portion disposed around the first core portion, and a third core portion disposed around the second core portion. The first core portion contains 10 atomic ppm or more of an alkali metal and 10 to 600 atomic ppm of chlorine, the second core portion contains 10 atomic ppm or less of the alkali metal and 10 to 600 atomic ppm of chlorine, and the third core portion contains 10 atomic ppm or less of the alkali metal and 2,000 atomic ppm or more of chlorine. An optical fiber has a core region doped with an alkali metal and chlorine, wherein the minimum concentration of chlorine in the core region is 1,000 atomic ppm or more, and the average concentration of the alkali metal therein is 0.2 atomic ppm or more.
    Type: Grant
    Filed: June 18, 2015
    Date of Patent: April 26, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura
  • Patent number: 9229160
    Abstract: An easily producible optical fiber preform which is drawn to an optical fiber having a core containing a sufficient concentration of alkali metal is provided. An optical fiber preform 10 is composed of silica-based glass and includes a core portion 20 and a cladding portion 30. The core portion 20 includes a first core portion 21 including a central axis and a second core portion 22 disposed on the perimeter of the first core portion 21. The cladding portion 30 includes a first cladding portion 31 disposed on the perimeter of the second core portion 22 and a second cladding portion 32 disposed on the perimeter of the first cladding portion 31. The core portion 20 contains an alkali metal at an average concentration of 5 atomic ppm or more. The concentration of the OH group in the perimeter portion of the first cladding portion 31 is 200 mol ppm or more.
    Type: Grant
    Filed: December 15, 2014
    Date of Patent: January 5, 2016
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Masaaki Hirano
  • Publication number: 20150370008
    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: Application
    Filed: January 28, 2014
    Publication date: December 24, 2015
    Inventors: Yoshiaki TAMURA, Tetsuya HARUNA, Masaaki HIRANO
  • Patent number: 9199877
    Abstract: A method for making a high quality optical fiber preform includes: thermally defusing the alkali metal element into the inner side of a silica glass pipe by heating the glass pipe from the outside by a heat source while vapors of alkali metal salt generated by heating an alkali metal salt is supplied to the inside of the glass pipe from an end thereof; collapsing the glass pipe for forming a core rod; and adding a cladding part around the circumference of the core rod. At the start of the thermal diffusion, the alkali metal salt is heated at a temperature for making the vapor pressure of the alkali metal salt to be 0.1 kPa or less, and thereafter the alkali metal salt is heated up to a temperature for making the vapor pressure of the alkali metal salt to be larger than 0.1 kPa.
    Type: Grant
    Filed: December 28, 2012
    Date of Patent: December 1, 2015
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tetsuya Haruna, Masaaki Hirano, Yoshiaki Tamura
  • Publication number: 20150329405
    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: December 11, 2013
    Publication date: November 19, 2015
    Inventors: Tetsuya HARUNA, Masaaki HIRANO, Yoshiaki TAMURA, Tetsuya NAKANISHI
  • Publication number: 20150299022
    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: Application
    Filed: December 13, 2012
    Publication date: October 22, 2015
    Inventors: Masaaki HIRANO, Tetsuya HARUNA, Yoshiaki TAMURA
  • Publication number: 20150285992
    Abstract: An optical fiber preform has a core portion having a first core portion including a central axis, a second core portion disposed around the first core portion, and a third core portion disposed around the second core portion. The first core portion contains 10 atomic ppm or more of an alkali metal and 10 to 600 atomic ppm of chlorine, the second core portion contains 10 atomic ppm or less of the alkali metal and 10 to 600 atomic ppm of chlorine, and the third core portion contains 10 atomic ppm or less of the alkali metal and 2,000 atomic ppm or more of chlorine. An optical fiber has a core region doped with an alkali metal and chlorine, wherein the minimum concentration of chlorine in the core region is 1,000 atomic ppm or more, and the average concentration of the alkali metal therein is 0.2 atomic ppm or more.
    Type: Application
    Filed: June 18, 2015
    Publication date: October 8, 2015
    Inventors: Masaaki HIRANO, Tetsuya HARUNA, Yoshiaki TAMURA
  • Patent number: 9139466
    Abstract: An optical fiber preform includes a core portion, in which the core portion includes an alkali-metal-doped core glass portion doped with an alkali metal, the maximum concentration of oxygen molecules in the core portion is 30 mol ppb or more, and the average concentration of the alkali metal in the core portion is 5 atomic ppm or more. A method of manufacturing an optical fiber preform includes an alkali-metal-doping step of doping a pipe composed of silica-based glass with an alkali metal, an oxygen-molecule-doping step of doping the glass pipe with oxygen molecules, and a collapsing step of collapsing the glass pipe by heating the glass pipe, in which the optical fiber preform is manufactured.
    Type: Grant
    Filed: January 18, 2012
    Date of Patent: September 22, 2015
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura
  • Publication number: 20150260912
    Abstract: An alkali-metal-doped core optical fiber having high hydrogen resistance and a method for manufacturing such an optical fiber are provided. A method for manufacturing a deuterium-treated optical fiber according to the present invention includes a preform-forming step of forming a silica glass optical fiber preform having a core doped with an alkali metal element, a drawing step of drawing the optical fiber preform to form an optical fiber, and an exposing step of exposing the optical fiber to a deuterium gas atmosphere. Alkali-metal-doped core optical fibers can be manufactured by using this method. In the exposing step, the optical fiber is exposed to an atmosphere containing deuterium gas at a temperature of 20° C. or more under conditions where (deuterium gas partial pressure)×(exposure time) is 50 kPa·hour or more.
    Type: Application
    Filed: August 23, 2013
    Publication date: September 17, 2015
    Inventors: Tetsuya Haruna, Masaaki Hirano, Yoshiaki Tamura
  • Publication number: 20150241629
    Abstract: An optical fiber having a central axis includes a core extending along the central axis and containing an alkali metal element, and a cladding having a lower refractive index than the core, wherein a radial distance with respect to the central axis is defined as r, a power of light propagating through the core at the radial distance r is defined as P(r), and a fictive temperature at a radial distance rmax at which rP(r) becomes maximum is at least 50° C. lower than a fictive temperature on the central axis.
    Type: Application
    Filed: February 20, 2015
    Publication date: August 27, 2015
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Masaaki Hirano
  • Publication number: 20150226914
    Abstract: Provided is an optical fiber that is suitable for high-density packing and long-haul transmission. An optical fiber according to the present invention includes a core and a cladding. At a wavelength of 1550 nm, an effective area Aeff is 100 ?m2 or less and a chromatic dispersion Disp is 19.0 ps/nm/km or more and 22 ps/nm/km or less, and, when an effective length is denoted by Leff and an attenuation is denoted by cc, a figure of merit FOM represented by an expression “FOM=5 log{|Disp|·Leff}?10 log {Leff/Aeff}?100?” is 3.2 dB or more.
    Type: Application
    Filed: September 2, 2013
    Publication date: August 13, 2015
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura, Yoshinori Yamamoto
  • Patent number: 9097834
    Abstract: An optical fiber preform has a core portion having a first core portion including a central axis, a second core portion disposed around the first core portion, and a third core portion disposed around the second core portion. The first core portion contains 10 atomic ppm or more of an alkali metal and 10 to 600 atomic ppm of chlorine, the second core portion contains 10 atomic ppm or less of the alkali metal and 10 to 600 atomic ppm of chlorine, and the third core portion contains 10 atomic ppm or less of the alkali metal and 2,000 atomic ppm or more of chlorine. An optical fiber has a core region doped with an alkali metal and chlorine, wherein the minimum concentration of chlorine in the core region is 1,000 atomic ppm or more, and the average concentration of the alkali metal therein is 0.2 atomic ppm or more.
    Type: Grant
    Filed: April 9, 2012
    Date of Patent: August 4, 2015
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaaki Hirano, Tetsuya Haruna, Yoshiaki Tamura
  • Patent number: 9036972
    Abstract: An easily producible optical fiber preform which is drawn to an optical fiber having a core containing a sufficient concentration of alkali metal is provided. An optical fiber preform 10 is composed of silica-based glass and includes a core portion 20 and a cladding portion 30. The core portion 20 includes a first core portion 21 including a central axis and a second core portion 22 disposed on the perimeter of the first core portion 21. The cladding portion 30 includes a first cladding portion 31 disposed on the perimeter of the second core portion 22 and a second cladding portion 32 disposed on the perimeter of the first cladding portion 31. The core portion 20 contains an alkali metal at an average concentration of 5 atomic ppm or more. The concentration of the OH group in the perimeter portion of the first cladding portion 31 is 200 mol ppm or more.
    Type: Grant
    Filed: November 16, 2012
    Date of Patent: May 19, 2015
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshiaki Tamura, Tetsuya Haruna, Masaaki Hirano