Browsing by Subject "Electromagnetic field enhancement"

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Open Access
Universal infrared absorption spectroscopy using uniform electromagnetic enhancement
(American Chemical Society, 2016) Ayas S.; Bakan, G.; Ozgur E.; Celebi, K.; Dana, A.
Infrared absorption spectroscopy has greatly benefited from the electromagnetic field enhancement offered by plasmonic surfaces. However, because of the localized nature of plasmonic fields, such field enhancements are limited to nanometer-scale volumes. Here, we demonstrate that a relatively small, but spatially uniform field enhancement can yield a superior infrared detection performance compared to the plasmonic field enhancement exhibited by optimized infrared nanoantennas. A specifically designed CaF2/Al thin film surface is shown to enable observation of stronger vibrational signals from the probe material, with wider bandwidth and a deeper spatial extent of the field enhancement as compared to such plasmonic surfaces. It is demonstrated that the surface structure presented here can enable chemically specific and label-free detection of organic monolayers using surface-enhanced infrared spectroscopy, indicating a great potential in highly sensitive yet cost-effective biomolecular sensing applications.
Open Access
Validation of electromagnetic field enhancement in near-infrared through Sierpinski fractal nanoantennas
(Optical Society of American (OSA), 2014) Cakmakyapan, S.; Cinel, N.A.; Cakmak, A.O.; Özbay, Ekmel
We introduced fractal geometry to the conventional bowtie antennas. We experimentally and numerically showed that the resonance of the bowtie antennas goes to longer wavelengths, after each fractalization step, which is considered a tool to miniaturize the main bowtie structure. We also showed that the fractal geometry provides multiple hot spots on the surface, and it can be used as an efficient SERS substrate. © 2014 Optical Society of America.