Contrast between Surface Plasmon Polariton-Mediated Extraordinary Optical Transmission Behavior in Epitaxial and Polycrystalline Ag Films in the Mid- and Far-Infrared Regimes
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- 作者：Bo-Hong Li ; Charlotte E. Sanders ; James McIlhargey ; Fei Cheng ; Changzhi Gu ; Guanhua Zhang ; Kehui Wu ; Jisun Kim ; S. Hossein Mousavi ; Alexander B. Khanikaev ; Yu-Jung Lu ; Shangjr Gwo ; Gennady Shvets ; Chih-Kang Shih ; Xianggang Qiu
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：December 12, 2012
- 年：2012
- 卷：12
- 期：12
- 页码：6187-6191
- 全文大小：310K
- 年卷期：v.12,no.12(December 12, 2012)
- ISSN：1530-6992
文摘
In this Letter we report a comparative study, in the infrared regime, of surface plasmon polariton (SPP) propagation in epitaxially grown Ag films and in polycrystalline Ag films, all grown on Si substrates. Plasmonic resonance features are analyzed using extraordinary optical transmission (EOT) measurements, and SPP band structures for the two dielectric/metal interfaces are investigated for both types of film. At the Si/Ag interface, EOT spectra show almost identical features for epitaxial and polycrystalline Ag films and are characterized by sharp Fano resonances. On the contrary, at the air/Ag interface, dramatic differences are observed: while the epitaxial film continues to exhibit sharp Fano resonances, the polycrystalline film shows only broad spectral features and much lower transmission intensities. In corroboration with theoretical simulations, we find that surface roughness plays a critical role in SPP propagation for this wavelength range.