Patents by Inventor Kai H. Chang

Kai H. Chang 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: 7546750
    Abstract: Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.
    Type: Grant
    Filed: July 15, 2003
    Date of Patent: June 16, 2009
    Assignee: Fitel USA Corp.
    Inventors: Kai H. Chang, David Kalish, Thomas John Miller
  • Patent number: 6865327
    Abstract: Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.
    Type: Grant
    Filed: September 19, 2002
    Date of Patent: March 8, 2005
    Assignee: Fitel USA Corp.
    Inventors: Robert M. Atkins, Alice W. Liu, Poul Kristensen, Morten Østergaard Pedersen, Stig Nissen Knudsen, Jan Levin Nielsen, Jake Bromage, Kai H. Chang
  • Patent number: 6776012
    Abstract: Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. The method includes the steps of dehydrating an optical fiber glass core rod in a first environment including oxygen and at least one of chlorine-containing gases, fluorine-containing gases and carbon monoxide; and adjusting the oxygen stoichiometry of the first environment so that it is neither oxygen-rich nor oxygen-deficient. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss.
    Type: Grant
    Filed: June 26, 2001
    Date of Patent: August 17, 2004
    Assignee: Fitel USA Corp.
    Inventors: Kai H Chang, David Kalish, Thomas John Miller
  • Publication number: 20040139766
    Abstract: Systems and methods for treating spools of fiber using recycled gas. Spools of fiber are placed in chambers which can be sealed for exposure to the treatment gas. When a chamber is closed and sealed the treatment gas is pumped into the chamber to a specified pressure temperature and pressure to react with the fiber. Upon completion of the reaction the gas is pumped from the chamber in order to facilitate the removal of the treated fiber. The gas can be evacuated with a vacuum pump and compressed to be stored in a pressure vessel for reuse. At this time the gas may be analyzed. If the concentration of a component is too low, the gas may be vented or it may be enriched so that it may be recycled; otherwise it is compressed for storage and the process is repeated.
    Type: Application
    Filed: January 17, 2003
    Publication date: July 22, 2004
    Inventors: Gene K. Weeks, Junjun Wu, Ramdane Assas, Kai H. Chang, Siu-Ping Hong
  • Publication number: 20040042746
    Abstract: Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.
    Type: Application
    Filed: September 19, 2002
    Publication date: March 4, 2004
    Inventors: Robert M. Atkins, Alice W. Liu, Poul Kristensen, Morten Ostergaard Pedersen, Stig Nissen Knudsen, Jan Levin Nielsen, Jake Bromage, Kai H. Chang
  • Publication number: 20040011081
    Abstract: Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.
    Type: Application
    Filed: July 15, 2003
    Publication date: January 22, 2004
    Inventors: Kai H. Chang, David Kalish, Thomas John Miller
  • Publication number: 20020197005
    Abstract: Embodiments of the invention include a method for making optical fibers that have reduced aging loss, hydrogen aging and other losses over the life of the fiber, and optical systems including such optical fibers. Improved conditions in fiber manufacturing environments are provided to reduce the likelihood of generating defects in optical fiber preforms that, in optical fiber drawn therefrom, attract and bond with hydrogen atoms to form molecules that increase transmission loss in the fiber. The improved conditions include the establishment and adjustment of the oxygen stoichiometry in one or more of the environments in which optical fiber manufacturing process steps occur. Optical fiber made by methods according to embodiments of the invention have improved transmission characteristics, e.g., transmission loss at 1385 nanometers that is less than 0.33 dB/km and the change in transmission loss thereafter is less than 0.05 dB/km.
    Type: Application
    Filed: June 26, 2001
    Publication date: December 26, 2002
    Inventors: Kai H. Chang, David Kalish, Thomas John Miller
  • Publication number: 20020194877
    Abstract: Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.
    Type: Application
    Filed: June 26, 2001
    Publication date: December 26, 2002
    Inventors: Kai H. Chang, David Kalish, Thomas John Miller