| Free electrons in metals can strongly interact with light to form Surface-Plasmon-Polaritons (SPPs). The resulting electromagnetic waves are confined within sub-wavelength dimensions and can propagate along the metal interface. These waves can potentially be used in many areas such as sensing, imaging, energy and optoelectronics. To efficiently utilize SPP propagation, their relatively short propagation length has to be enhanced. Also, methods of SPP modulation have to be devised. Efficient optical modulation of SPPs will pave the way for great advances in all-optical switching and miniaturization of on-chip circuits. It will also unlock the tremendous potential of nano-scale propagation of SPPs for the possibility to make efficient sensors to be applied in fields such as medicine and drug delivery. The aim of this thesis is to survey the existing methods for SPP modulation and to investigate novel engineering approaches to achieve efficient SPP modulation. The theoretical approach used in the investigations is based on a numerical model recently developed using Finite Difference Time Domain (FDTD) method. Various prototypes that can modulate SPP have been simulated through the use of Chalcogenide (ChG) glass and noble metals. It was found that the designed prototypes when pumped with varying input intensity signals were capable of modulating SPPs by activating the nonlinear behaviour of ChG glass, thus paving the way for fabrication of active devices. |
