Optically saturated and unsaturated collective resonances of flat metallic nanoantenna arrays

We study collective optical properties of arrays of flat gold nanoantennas, demonstrating they can support optically saturated and unsaturated plasmonic lattice modes when the incident light is polarized along their short axes. The saturated mode is nearly immune to the variation of the refractive i...

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Veröffentlicht in:Journal of applied physics 2017-08, Vol.122 (6)
Hauptverfasser: Sadeghi, Seyed M., Wing, Waylin J., Gutha, Rithvik R., Sharp, Christina, Hatef, Ali
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Sprache:eng
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Zusammenfassung:We study collective optical properties of arrays of flat gold nanoantennas, demonstrating they can support optically saturated and unsaturated plasmonic lattice modes when the incident light is polarized along their short axes. The saturated mode is nearly immune to the variation of the refractive index of the environment, while the unsaturated mode undergoes a large red shift without degradation as the refractive index increases. Our results show that when the incident light becomes polarized along the long axes of the nanoantennas, an increase of the refractive index of the superstrate leads to the formation of secondary plasmon peaks. These peaks are spectrally narrow and can detect variations of the ambient refractive index with a sensitivity of up to 620 nm/RIU (refractive index unit). The results suggest that the periodic arrays of flat metallic nanostructures can support hybridization of their multipolar plasmonic resonances with diffraction orders with distinct similarities and differences compared to those seen in cases of arrays of metallic nanorods.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4998182