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Mitchell, Michael Eric

University of British Columbia

Terahertz radiation, given its unique location in the electromagnetic spectrum between radio-frequency and infrared radiation, has been highly regarded for its potential of non-invasive spectroscopy. The long wavelengths and low photon energies of terahertz radiation allow for the measurement of the rotational and vibrational modes of cellular tissue without damaging the cells themselves. However, the long wavelengths inherent to THz radiation restrict the focal spot sizes and therefore limit the size of samples that can be analyzed with THz spectroscopy systems. Spatial resolution has been a long-standing issue for THz spectroscopy systems, especially for the long wavelengths of the low frequency (0.3-to-0.7) THz band, being the focus of this thesis. The thesis highlights the validity, through theoretical and experimental testing, of using dielectric spheres to focus THz radiation to a scale that improves the spatial resolution of conventional THz spectroscopy systems. The dielectric spheres focus the THz radiation into so-called “THz microjets”, which can achieve subwavelength focusing over a broad-bandwidth. A complete optimization of the dielectric sphere, both in terms of size and material parameters, is undertaken. Optimal dielectric spheres are then manufactured out of custom THz microcomposite materials and experimentally characterized in terms of the focusing performance. Finally, the dielectric spheres are demonstrated in a spectroscopic application to show the improvement in resolution.

Text

2022-08-18

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82415

Electrical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/