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Topic

Experimental Validation of On-chip Terahertz Spoof Surface Plasmon Polariton Structures Integrated to Coplanar Strip Waveguide

Department of Electrical and Computer Engineering

Date & location

• Wednesday, April 9, 2025

• 9:00 A.M.

• Engineering Office Wing

Reviewers

Supervisory Committee

• Dr. Levi Smith, Department of Electrical and Computer Engineering, University of Victoria (Co-Supervisor)

• Dr. Thomas Darcie, Department of Electrical and Computer Engineering, UVic (Co-Supervisor)

• Dr. Andrew MacRae, Department of Physics, UVic (Outside Member) 

External Examiner

• Dr. Christopher Collier, Faculty of Applied Science, University of British Columbia 

Chair of Oral Examination

• Dr. Sardar Malek, Department of Civil Engineering, UVic

   

Abstract

This dissertation addresses the gap in experimental validation of Spoof Surface  Plasmon Polaritons (SSPP) at Terahertz (THz) frequencies (0.3- 3 THz), a domain  extensively explored through theoretical and simulation-based research but still lacking broadband experimental validation at THz range. The SSPP structures, which mimic the behavior of optical surface plasmon polaritons at lower frequencies (e.g.  microwave and THz), have unique electromagnetic properties such as strong subwavelength field confinement, flexible characteristics based on geometry, the potential for miniaturization, and ease of on-chip integration, that is beneficial for a variety of applications including, sensing, imaging, and communications.

 In this work, we present the first experimental verification of SSPP characteristics at THz frequencies (beyond 300 GHz) using guided wave systems with CoPlanar Strip (CPS) feedlines. We also design and demonstrate several CPS-based SSPP structures, including two SSPP-based Low Pass Filter (LPF)s that can also be used as sensors, and two novel THz Band Pass Filter (BPF)s, all of which have potential for applications in filtering, sensing, and communication technologies. These works serve as proof of concept for filtering and also experimental validation of SSPP at THz frequencies.

 Further, we investigate the use of these THz waveguides for sensing applications.  For this purpose, we selected glucose, a material with a distinct absorption signature beyond 1 THz, to showcase the sensing capabilities of the waveguides. The interaction between glucose and the evanescent electromagnetic field of the waveguide is demonstrated, where CPS waveguides are preliminary used to capture the mate rial’s absorption over a broad spectral range. To enhance the sensor’s sensitivity, we tune the SSPP structures to match the absorption frequency of glucose. This tuning leverages the strong field confinement properties of SSPP, as well as their band-edge sensitivity to changes in surrounding permittivity, resulting in significant improvements in sensor performance. The experimental results presented in this dissertation not only validate the practical application of SSPP structures at THz frequencies but also introduce novel designs and techniques that enhance their capabilities in sensing applications. This work contributes to the growing field of SSPP research, providing valuable insights for the development of advanced THz technologies, including sensors, filters, and communication systems.