Diffraction of obliquely incident light by single nanoholes in thin noble-metal films

摘要

The diffraction of obliquely incident light by single nanoholes in thin gold and silver films is studied using dark-field microspectroscopy. The single-hole spectra show a dominant transmission peak in the near infrared. It is considerably red shifted with respect to calculations that assume perfect conduction in the metal and lies at essentially the same spectral position for gold and silver. The diffracted intensity at the transmission peak shows a pronounced dependence on light polarization, being significantly higher for p-polarized than s-polarized light. This difference is in qualitative agreement with the results of the calculations. Surprisingly, we find no such difference at wavelengths immediately below that of the transmission peak.