Metamaterial Absorbers for Infrared Detection of Molecular Self-Assembled Monolayers

• DOI: 10.1038/srep12570
• Publication Date: 2015-07-31T09:14:27Z
• Authors: Atsushi Ishikawa; Takuo Tanaka
• Keywords: Fano resonance; Fano plane

The emerging field of plasmonic metamaterials has introduced new degree freedom to manipulate optical from nano macroscopic scale, offering an attractive platform for sensing applications. So far, metamaterial sensor concepts, however, have focused on hot-spot engineering improve the near-field enhancement, rather than fully exploiting tailored material properties. Here, we present a novel spectroscopic technique based infrared (IR) absorber allowing low-background detection scheme as well significant enhancement. Specifically, experimentally demonstrate resonant coupling modes and IR vibrational molecular self-assembled monolayer. consisting array Au/MgF2/Au structures exhibits anomalous absorption at ~ 3000 cm(-1), which spectrally overlaps with C-H stretching modes. Symmetric/asymmetric 16-Mercaptohexadecanoic acid monolayer are clearly observed Fano-like anti-resonance peaks within broad metamaterial. Spectral analysis using Fano line-shape fitting reveals underlying interference in plasmon-molecular coupled systems. Our approach achieves attomole sensitivity large signal-to-noise ratio far-field measurement, thus may open up avenues realizing ultrasensitive inspection technologies.