SCANNING NEAR-FIELD OPTICAL PROBE WITH ULTRASMALL SPOT SIZE

A novel Light-emitting probe for scanning near-field optical microscop y is investigated theoretically. The three-dimensional vectorial Helmh oltz equation is solved for the new probe geometry by using the multip le multipole method. The novel probe consists of a dielectric tip that is entirely metal coated. It provides a single near-field spot that c an be smaller than 20 nm (FWHM). The dependence on tip radius, taper a ngle, and metal thickness in front of the tip is investigated for the power transmission through the probe as well as for the spot size.