Browsing by Author "Sanghera, J. S."

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    Dynamics of the 5-EV optical-absorption in SIO2 glass
    Tsai, T. E.; Jewell, J. M.; Sanghera, J. S. (AIP Publishing, 1993-06-01)
    The optical absorption at 5 eV in SiO2 glass was observed, using laser calorimetry, to change reversibly depending on the intensity of UV light. The generation and bleaching of an absorption band at 5 eV by two- and one-photon absorption processes, respectively, can explain these reversible changes. This observation supports the structural model of unrelaxed oxygen deficiency center for the 5 eV absorption band in silica.
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    Effect Of Temperature on The Absorption Loss Of Chalcogenide Glass Fibers
    Nguyen, V. Q.; Sanghera, J. S.; Kung, F. H.; Aggarwal, I. D.; Lloyd, I. K. (Optical Society of America, 1999)
    The change in the absorption loss of IR-transmitting chalcogenide glass fibers in the temperature range? of -90 degrees C less than or equal to T less than or equal to 70 degrees C was investigated. For sulfur-based glass fibers the change in loss relative to room temperature was slightly affected by the temperature in the wavelength region of 1-5 mu m. For lambda greater than or equal to 6 mu m the change in loss was mainly due to multiphonon absorption. The change in loss for tellurium-based glass fibers increased significantly at T = 60 degrees C. The increase in the loss at short wavelengths (lambda less than or equal to 4.1 mu m) was due to electronic excitations in the tail states. Between 5 and 9 mu m there was noticeable free-carrier absorption. Beyond lambda greater than or equal to 9 mu m, multiphonon absorption dominated the loss spectrum. (C) 1999 Optical Society of America.
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    Infrared Evanescent-Absorption Spectroscopy with Chalcogenide Glass-Fibers
    Sanghera, J. S.; Kung, F. H.; Pureza, P. C.; Nguyen, V. Q.; Miklos, R. E.; Aggarwal, I. D. (Optical Society of America, 1994-01-01)
    We have used telluride glass fibers fabricated in house to measure the evanescent-absorption spectra of water, methanol, ethanol, isopropanol, acetone, ethanoic acid, hexane, and chloroform. Furthermore, detection limits of less than 2 vol. % solute were obtained for mixtures of water and methanol, ethanol, isopropanol, acetone, and ethanoic acid. Techniques to reduce the detection limits are discussed.