Broadband TeraHertz time domain spectroscopy for rapid material characterization
This work revolves around the design and construction of a broadband terahertz time domain spectrometer using nonlinear optics for the generation and detection of THz light. Methods for signal collection and processing are discussed, including the removal of spurious reflections using window functions. Furthermore, attenuated total reflection is optimized for THz light as a means to circumvent critical issues faced when working with polar solvents or highly absorbing samples. The discussion then turns to the calibration and analysis of performance of the spectrometer with measurements of the THz power and peak THz electric field generated by the spectrometer as well as evaluation of the signal-to-noise and dynamic range of the instrument. Issues involving humid air are introduced and re-framed as a way of using a slight contamination of water vapour as an internal standard. Finally, it is shown how THz-TDS can be used to characterize low energy phenomena in two uniquely different classes of materials, namely that of magnetic metal oxides and organic chiral species. The former analyzes materials that may find use in the development of new computational devices, while the latter forms the basis for quick way to differentiate between isomeric species present in liquid and solid phases.
THz-TDS, spectroscopy, material characterization, terhertz radiation, nonlinear optics, ATR, attenuated total reflection