Near-Field Imaging of a Silver Nanowire Using a Thin Silver Film

This work deals with the near-field, sub-wavelength imaging of nanoscale objects using a thin silver film (near-field lens, NFL). As an example object, we consider a thin circular nanowire illuminated by a ppolarized plane wave. The simulation considers the coupling between the object and the lens and is based on the addition theorems of cylindrical and plane waves. We compare the realistic imaging regime with objectimage coupling versus an artificial regime with no coupling effect. In addition, the localized field enhancement transfer is also investigated with realistic loss in the film. The simulation results show that a shadow image of the wire can be obtained at the imaging plane. The results also demonstrate that the field enhancement resulting from the localized surface plasmon resonance at the wire surface can be transferred to the other side of the lens. The coupling between the wire and the lens acts to decrease the overall enhancement transferred to the imaging side of the lens.