Browsing by Author "Wang, Shunxi"

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    A tunable laser-based mid-infrared source for use in trace gas detection
    (1997) Wang, Shunxi; Tittel, Frank K.
    A new widely tunable mid-infrared (IR) source based on difference-frequency generation (DFG) in Gallium Selenide (GaSe) for use in high-resolution spectroscopy and trace gas detection is described. The characteristics of type-I phasematching in GaSe are studied. Preliminary results on the improvement of the dispersion relations for GaSe are presented. Spectroscopic feasibility experiments are reported that involve the spectroscopy of ethylene $\rm (C\sb2H\sb4)$ at low pressures near 950 $\rm cm\sp{-1}.$ Two near-IR Ti:Sapphire lasers served as convenient pump sources, which can be eventually replaced by two high power near-IR diode lasers. Design issues (including optimum elliptical focusing conditions), potential improvements and new directions are also discussed.
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    Lithium niobate thin films on diamond substrates for SAW devices
    (2001) Wang, Shunxi; Rabson, Thomas A.
    Lithium niobate thin films have been grown on diamond/silicon substrates by metallo-organic decomposition and radio frequency (R. F.) magnetron sputtering. The surface acoustic wave (SAW) characterizations of the multilayer lithium niobate/diamond/silicon are calculated. The lithium niobate thin films as well as the diamond/silicon substrates are structurally analyzed using techniques such as Bragg X-ray diffraction, scanning electron microscopy, atomic force microscopy, electron microprobe, and Raman spectroscopy to determine their crystal structure, surface morphology and composition distribution. With the use of a lift-off photolithography planar process, surface acoustic wave filter devices on substrates such as lithium niobate single crystal plates, zinc oxide/diamond/silicon, and lithium niobate/diamond/silicon, are fabricated. Microwave characterizations, such as the frequency response, of these filters are measured, and their impulse response in the time domain are obtained by fast Fourier transformation. SAW activities for LiNbO3/diamond/silicon structure are observed. Discussions about the results and further improvements are presented.