Masters Degrees (Physics)

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Browsing Masters Degrees (Physics) by Subject "Absorption coefficient"

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    Spectral characterization of materials using terahertz time domain spectroscopy (THz-TDS)
    (Stellenbosch : Stellenbosch University, 2014-12) Hissen, Huzifa Zain Alabdeen Abdarahman; Rohwer, Erich G.; Neethling, Pieter H.; Stellenbosch University. Faculty of Science. Dept. of Physics.
    ENGLISH ABSTRACT: Terahertz (THz) radiation is often used in many promising applications such as information and communication technology and airport security. Optimized and adapted terahertz fields hold huge promise for leading this technology further. This study is focused on terahertz time domain spectroscopy (THz-TDS). In THz-TDS the electric field is measured, therefore both amplitude and phase information of the THz pulse can be obtained. We used the pump-probe technique in order to measure a THz pulse from the photoconductive antenna. A pulsed fiber laser with FWHM of ' 100 fs was used for this. The frequency spectrum of the measured THz pulse was obtained via a fast Fourier transform. We studied the principles of the THz pulse generation as well as detection, with a photoconductive antenna as emitter and detector. In this study terahertz spectroscopy has been used to investigate the refractive index and absorption coefficient of different types of materials in the terahertz region. The last part of this study deals with a simple process for material parameter extraction of a polymer sample using commercial software called Teramat1.0. It uses the sample thickness, the reference THz pulse and the transmitted THz pulse to retrieve the complex refractive index of the sample.