Controlling light confinement by excitation of localized surface plasmons

Localized surface plasmons can be used to control near-field optical phenom ena in the subwavelength range. Specifically, this chaper reviews recent re sults which show that localized surface plasmons can confine the optical in tensity down to nanoscopic dimensions. The discussion first considers how a collection-mode near-field optical microscope can observe the squeezing of the plasmon field of metallic nanostructures deposited on a flat surface. Numerical simulations then provide illustrations of the confined fields ass ociated with nanostructures which are feasible using current microfabricati on techniques. Finally, we present arguments which explain how localized su rface plasmons can deliver a significant amount of power to the very end of a tetrahedral tip used as the light source of an illumination-mode near-fi eld optical microscope.