Siday, Thomas;
(2020)
Efficient probes for terahertz near-field microscopy and spectroscopy.
Doctoral thesis (Ph.D), UCL (University College London).
Preview |
Text
Thesis_20200317.pdf - Accepted Version Download (44MB) | Preview |
Abstract
This thesis focuses on improving the sensitivity and spatial resolution of two near-field microscopy techniques at terahertz (THz) frequencies: direct detection in the near-field using a collection-mode aperture probe, and using the apex of a metallic tip to scatter a near-field interaction into the far-field. The first technique is limited in spatial resolution primarily due to strong attenuation of THz fields transmitted through the subwavelength aperture. By integrating a terahertz detector with an optical metasurface it is possible to make nanoscale terahertz detectors, which can efficiently detect non-propagating THz fields close to the rear of the aperture, increasing probe sensitivity and spatial resolution. The scattering technique suffers from high background signals and weak scattering from the tip apex. By designing a scattering probe to act as a resonant dipole antenna, the efficiency of the scattering process can be improved, and by efficiently coupling THz radiation to the probe using a radially polarized THz source, interference from background signals can be reduced. These improvements can enable imaging of a variety of fascinating systems, including polaritons in monolayers and heterostructures of 2D materials, biological systems and topological insulators.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Efficient probes for terahertz near-field microscopy and spectroscopy |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10093610 |
Archive Staff Only
 |
View Item |
