Optical response of periodically modulated nanostructures near the interband transition threshold of noble metals.
We investigate the influence of the core d-electrons on the spectral optical response of arrays of sub-wavelength holes near the transition from the d-band to the Fermi level of noble metals (d?E(F)). Our model shows that, due to the dispersion of the metal dielectric function near d?E(F), the first order peaks in the enhanced spectral transmission shift nonlinearly as a function of the period of the nanostructure. In addition, we outline in that spectral region an apparent large resonance which does not depend on the geometrical parameters of the nanostructure. It is shown to correspond to the transparency window resulting from the spectral superposition of the large absorption associated to the core d-electrons and high reflectivity due to the conduction electrons. The analysis is performed for gold, copper and silver nanostructures.
Halté
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V
Benabbas
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Bigot
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