NSOM study of surface plasmon scattering by in-situ created individual defects

We have developed a direct-write lithography technique that allows us to create submicron size patterns on virtually any opaque surface. This technique implements a standard near-field scanning optical/shear force microscope described. The use of uncoated UV grade tapered fiber and nanosecond pulsed 248 nm excimer laser light allows us to deliver an estimated 200 GW/m/sup 2/ UV light power into a tip-sample region smaller than 200 x 200 nm/sup 2/ during a single laser pulse. This power is sufficient for local surface ablation of gold or silver and local melting of silicon without melting of the transparent UV fiber tip. The topographic changes caused by UV irradiation are immediately recorded by the shear force microscope. The developed technique is to some extent similar to STM lithography but is not restricted by the conductance of the sample surface. We have implemented our lithography technique to study the scattering of surface plasmons by single surface defects and to create some simple two-dimensional optical elements for SPs.