Imaging of Surface Plasmon Scattering by Lithographically Created Individual Surface Defects.

Abstract

A new technique for direct-write ablation on a 100 nm scale has been implemented in a photon scanning tunneling microscope setup. This combination allows us, for the first time, to study surface plasmon scattering by in situ created individual surface defects, while the sizes and shapes of the defects are varied. It is found that, within a certain range of size, a hill on an otherwise flat surface can be a source of a micrometer wide plasmon beam. Another new observation is that the effective cross section of a defect can be substantially larger than its visible geometrical size. These results suggest possible practical applications of surface plasmons in two-dimensional optical arrangements.