Elliott Brown (Advisor), Jason Deibel (Committee Member), Doug Petkie (Committee Member), Peter Powers (Committee Member), Dave Tomich (Committee Member)
Doctor of Philosophy (PhD)
This dissertation is a study of the interaction of terahertz (THz) and long-wave infrared (LWIR) radiation with various periodic sub-wavelength metallic structures in free-space and on dielectric substrates. There are many new and useful applications for both THz and LWIR radiation. Unfortunately, heavy attenuation by the Earth's atmosphere and low output power from THz sources combine to make THz radiation weak and difficult to detect. LWIR is not as prone to atmospheric attenuation as THz radiation. Nevertheless, the detection of LWIR can be improved upon by strengthening the coupling between incoming radiation and LWIR detector systems.
Light passing through periodic sub-wavelength metallic structures can exhibit extraordinary optical transmission (EOT). When EOT occurs, the amount of light transmitted through such structures is enhanced to well beyond what would be predicted by geometric optics. In addition, exceedingly high electromagnetic (EM) fields develop in the apertures and along the conducting surfaces of EOT structures. These enhanced fields may be used to improve the performance of a THz or LWIR detector through a significant reduction in its size while maintaining good external radiation coupling.
Full-wave numerical simulations using the finite element method (FEM) were used to study the interaction of THz and LWIR radiation with one- and two-dimensional surface plasmonic EOT structures. This dissertation examines the numerical solutions to the Helmholtz wave equation for radiation interacting with plasmonic structures in both the THz and LWIR regions. The simulation results predict that both EOT and EM field enhancement will occur in both regions. In several cases, plasmonic structures designed from optimized FEM results have been fabricated and characterized. The experimental results confirm the simulation predictions qualitatively and quantitatively to within a few dB. Nevertheless, it must be noted that although detectors were a strong motivation for the research conducted here, the realization of detector improvement was not carried out.
Department or Program
Ph.D. in Engineering
Year Degree Awarded
Copyright 2014, some rights reserved. My ETD may be copied and distributed only for non-commercial purposes and may not be modified. All use must give me credit as the original author.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.