American Institute of Physics Acta Medica Okayama 0003-6951 111 24 2017 Robust plasmonic hot-spots in a metamaterial lattice for enhanced sensitivity of infrared molecular detection 243106 EN Atsushi Ishikawa Department of Electrical and Electronic Engineering, Okayama University Shuhei Hara Department of Electrical and Electronic Engineering, Okayama University Takuo Tanaka Metamaterials Laboratory, RIKEN Xiang Zhan NSF Nanoscale Science and Engineering Center, University of California Kenji Tsuruta Department of Electrical and Electronic Engineering, Okayama University High-density and long-lived plasmonic hot-spots are an ideal system for high-sensitive surface-enhanced infrared absorption (SEIRA), but these conditions arc usually incompatible due to unwanted near-field coupling between the adjacent unit structures. Here, by fully controlling plasmonic interference in a metamaterial lattice, we experimentally demonstrate densely packed long-lived quadrupole plasmons for high-sensitive SEIRA. The metamaterial consists of a strongly coupled array of super-and sub-radiant plasmonic elements to exhibit an electromagnetic transparency mode at 1730 cm(-1), which spectrally overlaps with the C=O vibrational mode. In the SEIRA measurement, the C=O mode of poly(methyl methacrylate) molecules is clearly observed as a distinct dip within a transmission peak of the metamaterial. The corresponding numerical simulations reveal that constructive interference uniformly forms coherent quadrupole plasmons over the metamaterial lattice, leading to a stronger molecular signal from the system. Our metamaterial approach provides a robust way to construct ideal hot-spots over the sample, paving the way toward a reliable sensing platform of advanced infrared inspection technologies. Published by AIP Publishing. No potential conflict of interest relevant to this article was reported.