Design, Construction, and Applications of a High-Resolution Terahertz Time-Domain Spectrometer

Citation

Holland, Daniel Brian (2014) Design, Construction, and Applications of a High-Resolution Terahertz Time-Domain Spectrometer. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z91J97QR. https://resolver.caltech.edu/CaltechTHESIS:04222014-120506633

Abstract

This thesis reports on the design, construction, and initial applications of a high-resolution terahertz time-domain ASOPS spectrometer. The instrument employs asynchronous optical sampling (ASOPS) between two Ti:sapphire ultrafast lasers operating at a repetition rate of approximately 80 MHz, and we thus demonstrate a THz frequency resolution approaching the limit of that repetition rate. This is an order of magnitude improvement in resolution over typical THz time-domain spectrometers. The improved resolution is important for our primary effort of collecting THz spectra for far-infrared astronomy. We report on various spectroscopic applications including the THz rotational spectrum of water, where we achieve a mean frequency error, relative to established line centers, of 27.0 MHz. We also demonstrate application of the THz system to the long-duration observation of a coherent magnon mode in a anti-ferromagnetic yttrium iron oxide (YFeO3) crystal. Furthermore, we apply the all-optical virtual delay line of ASOPS to a transient thermoreflectance experiment for quickly measuring the thermal conductivity of semiconductors.

Thesis Files