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The enhanced optical transmission through the annular aluminum metal with different number of concentric rings arranged in a long-range periodic structure on the silicon substrate is investigated. The measured transmission spectra demonstrate that the surface plasmon modes depend sensitively on the structural parameters of the metallic rings. The degenerate (1,0), (1,1), and (2,1) Al/Si surface plasmon modes are determined by the long periodicity of the structure. The localized modes in cavities with different length can be observed in this structure as well. These phenomena suggest that both surface plasmons and localized cavity modes are excited within super unit cell. [ABSTRACT FROM AUTHOR]

This paper reports the optical properties of Al/Si structure and trilayer Ag/SiO2/Ag plasmonic thermal emitter with different concentric metal rings on top metal film. It is found that when the metal width is smaller than 40% of the period (=gap+metal width), the (1,0) Al/Si surface plasmon leads to a maximum in the transmission spectra; otherwise, the opposite is observed. The dispersion relations and emission spectra of the plasmonic thermal emitters were investigated. The emission peaks are independent of the gap width and redshift as annular metal width increases. This phenomenon suggests the excitation of Fabry-Pérot type resonance within cavity of Ag/SiO2/Ag structure. No (1,0) Ag/SiO2 surface plasmon was observed. [ABSTRACT FROM AUTHOR]