IMAGING OF SURFACE-PLASMON SCATTERING BY LITHOGRAPHICALLY CREATED INDIVIDUAL SURFACE-DEFECTS

A new technique for direct-write ablation on a 100 nm scale has been i mplemented in a photon scanning tunneling microscope setup. This combi nation allows us, for the first time, to study surface plasmon scatter ing 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 ef fective cross section of a defect can be substantially larger than its visible geometrical size. These results suggest possible practical ap plications of surface plasmons in two-dimensional optical arrangements .