Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 31: Nano-optics of metallic and semiconducting nanostructures (theory)

O 31.5: Talk

Wednesday, March 25, 2009, 11:30–11:45, SCH A216

Poisson's Spot and Focusing of Surface Plasmon Polaritons — •Dominic Zerulla, Brian Ashall, and Brian Vohnsen — University College Dublin, School of Physics, Dublin 4, Ireland.

Surface plasmon polaritons (SPPs) are surface waves bound to the interface between a metal and a dielectric. Their wave characteristics make them ideal candidates for the study of 2d-wave propagation on the nanoscale. This was recently demonstrated in a study of Young's classical interference experiment realized with SPPs. Here we examine another classic of wave optics, namely Poisson's bright spot that appears in the shadow region behind an obstacle. Constructive interference produced by SPPs from opposing sides of a linear obstacle is expected to be less apparent than in the optical case where the field across the entire rim of a circular obstacle contributes. The finite propagation length of the SPPs limits the total propagation length and the outcome will therefore be an elongated spot in the shadow region. This can be considered as a first step towards realizing Fresnel lenses for SPPs. Focusing is required to fully explore the potential of SPPs in integrated optical components and sensors. Typically, mirror-like arrangements have been used to accomplish this. An alternative option, however, is dielectric loading to modify the phase of the SPP. Ultimately, a high numerical aperture is required and in such a case their vectorial nature must be taken into account. Here we examine the potential use of Poisson's spot for SPP confinement and the focusing of SPPs in more general terms. Our numerical predictions are compared with the outcome of preliminary experimental studies.