Plasmonic dynamics and propagation in photonic materials

This thesis focuses on new methods and materials that are relevant to optical excitation, manipulation, and propagation in nano-scale structures. Scanning tunneling microscopy is used to establish the mechanism of light radiation induced by electron tunneling to single metal nano-particles. Ultrashort pulse optical interferometry studies are utilized to elucidate the dynamics of individual metal nano-particles and spatially designed collections thereof.; This thesis also presents a novel time-domain experimental approach to study the dynamics of wave propagation in a surface plasmon-based photonic crystal. The surface plasmon field is launched and propagated into a thin Ag film decorated with a monolayer of self-assembled polystyrene beads. The polystyrene/Ag interface serves to perturb the propagating plasmon field. The dielectric lattice was shown to create photonic structures for surface plasmons. The dynamics of the plasmon field propagating in the photonic structure is directly observed by interferometric cross correlation measurements. The broad bandwidth of the ultrashort pulses makes it possible to identify plasmon bandgaps and to construct dispersion curves around these bandgaps from a single interferometric measurement. The results of numerical simulations for a one-dimensional lattice that matches the experimental wavevector and dielectric media boundary conditions are in very good agreement with experiments. The optical phase-maintaining measurement also allows direct construction of the Wigner-Ville transform to visualize the time-frequency evolution of the complex field. The possibility of extracting the refractive index profile of the photonic crystal from the time-frequency distribution as well as the outlook for plasmon-based wave propagation in nano-photonic structures is discussed.; These investigations demonstrate novel routes to “nano-optics” that may form the basis of future optical sensing and optical computing devices. The thesis concludes with a discussion of these possibilities.