Patents by Inventor Lap-Tak A. Cheng

Lap-Tak A. Cheng 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).

  • Increasing the birefringence of KTP and its isomorphs for type II phase matching
    Patent number: 5311352
    Abstract: Method and device for wavelength conversion using type II phase matching are characterized by employing a crystal consisting essentially of doped MTiOXO.sub.4 (wherein M is K, Rb and/or Tl and X is P and/or As) containing Fe, Nb and/or Ta dopant in an amount, totalling at least about 100 ppm, effective to increase the n.sub.z -n.sub.x optical birefringence of the doped crystal at least about 0.001 compared to a crystal without the dopant. Generation of output waves of an optical birefringence higher than the highest corresponding optical birefringence of a crystal without the dopant is disclosed. Among the useful crystals are crystals consisting essentially of doped MTiOXO.sub.4 containing at least about 100 ppm Ta.
    Type: Grant
    Filed: December 23, 1992
    Date of Patent: May 10, 1994
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: John D. Bierlein, Lap K. Cheng, Lap-Tak A. Cheng
  • Polymeric compositions for nonlinear optics
    Patent number: 5272218
    Abstract: Disclosed are polymers which contain NLO dye moieties based upon a barbituric acid group, a thiobarbituric acid group or a 1,3-bis(dicyanomethylene)indan-2-ylidene group. These polymers, after poling, are useful in NLO elements in devices employing nonlinear optics. Also disclosed are various intermediates used in making such polymers.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: December 21, 1993
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Lap-Tak A. Cheng, Wilson Tam