American Telephone & Telegraph Co., At&t Bell Laboratories

Bell Telephone Laboratories

Ernest G Burkhardt

Thomas J Bridges

Larry Allen Coldren

Thomas L Koch

Epitaxial regrowth by vapor phase epitaxy of controlled composition semiconductor material in and around undercut regions of a processed heterostructure wafer permits formation of a ridge waveguide capable of active or passive operation. Subsequent material selective and crystallographically preferential etching is employed to form mirror facets on each end of the ridge waveguide.

Buried undercut mesa-like waveguide and method of making same

Buried undercut mesa-like waveguide

The spectrophone, in which a gas containing an impurity in an absorption cell is illuminated by an optical beam that is modulated at an acoustic frequency, has an output pressure response at the acoustic frequency in accordance with the concentration of the impurity in the gas. This output is tuned by a magnetic (or electric) field applied to the absorption cell, while the optical wavelength is kept constant. The Zeeman (or Stark) effect of the impurity can thus be used to tune the absorption process of the impurity to a maximum response.

Growing community of inventors

Wall, NJ, United States of America

Ernest G Burkhardt