Inter-slit Coupling in Gold Film Hole Arrays

TL;DR

This study investigates the strong inter-slit electromagnetic interactions in gold film hole arrays, revealing high coupling effects and their implications for extraordinary optical transmission mechanisms.

Contribution

It provides the first detailed analysis of inter-slit coupling in gold film hole arrays using electron energy loss spectroscopy, highlighting the dominance of short-range interactions.

Findings

Inter-slit coupling is about ten times stronger than intra-slit edge coupling.

Pronounced signal enhancements are observed due to high mode-localization.

Results suggest similar behavior between electron beam and optical transmission phenomena.

Abstract

Inter-slit interactions across one-dimensional arrays of sub-micro meter rectangular holes in gold films are explored. Using electron energy loss spectroscopy combined with scanning transmission electron microscopy, a series of cavity standing waves is resolved, indicating particularly high interslit interactions, about an order of magnitude larger than the intra-slit edge to edge coupling. Pronounced signal enhancements are thus induced, dominated by short-range interactions and high mode-localization, while yet, relatively long-range coherence is retained. The sub-nm electron beam, in spite of principal differences from broad-area probes, yields results similar to extraordinary optical transmission (EOT). Implications to EOT mechanisms, including its sub-wavelength, off-resonance limit, are pointed out.