Hybridized metal slit eigenmodes as an illustration of Babinet's principle.

Ögüt, Burcu; Vogelgesang, Ralf; Sigle, Wilfried; Talebi, Nahid; Koch, Christoph T; van Aken, Peter A · ACS Nano · 2011

basic_science · Level V

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Abstract

By energy-filtering transmission electron microscopy (EFTEM), we observe Fabry-Pérot-like surface plasmon resonances (SPRs) along the length of rectangular single and double slits drilled into free-standing thin silver films. These eigenmodes hybridize in closely situated slits. The nature of their lateral coupling is uncovered from finite-element simulations, which show that the symmetry and energy sequence of hybrid modes is governed by Babinet complementarity principles. Interestingly, the modes of a double slit system, being proto-self-complementary, may alternatively be explained by magnetic interactions between slit fields or by electrostatic interactions across the metallic bridge separating the slits.