Controlling wave-matter interactions using plasmonic and photonicstructures : sensing, lensing and alternative materials.

Abstract

This thesis represents the culmination of research conducted as part of the EPSRC DTP PhD scheme (EP/R51309X/1) at Newcastle University. The research explored in this doctoral thesis was advised, supervised and directed by Dr Victor Pacheco-Peña from Newcastle University. The scope of this doctoral work spans a wide range of electromagnetic frequencies, from millimetre waves to optical frequencies, with a primary focus on advancing the control of electromagnetic waves, particularly within the domain of plasmonics. The following chapters explain the methodologies, findings, and implications of this research: Chapter 1 provides a comprehensive overview of traditional and modern methods for manipulating electromagnetic waves. First, traditional methods of manipulating electromagnetic waves will be discussed, such as the Babinet principle and the lens maker equation. Then, by classifying the properties of materials more modern methods will be expanded upon including a comprehensive exploration of plasmonics emphasising surface plasmon polaritons and localised surface plasmons. In Chapter 2, dual-dielectric structures are designed to produce a bent focus. Initially, the concept of photonic nanojets is introduced. This is then expanded upon to exploit the interference of two dielectric particles to generate a focus. The scattering and diffraction properties of the particles are then calculated to design asymmetry in the two particles to produce curved focal spots. Different configurations are explored with a demonstration of the experimental viability of the structures. Chapter 3 explores the use of a traditional technique to design lenses within the realm of surface plasmon polaritons. First, the effective media of surface plasmon polaritons is shown to determine the regions where surface plasmon polaritons will propagate and determine the desired geometries of the plasmonic lenses. The capabilities of plasmonic meniscus lenses and plasmonic convex-planar lenses are evaluated and contrasted in terms of power enhancement at the focus and their spatial resolution both along the propagation direction and transverse to it. The robustness of the plasmonic meniscus lenses is then explored introducing rotation and potential fabrication errors in the structures.