Optical properties of Ag and Au nanowire gratings

The optical response of regularly arranged noble metal wires with nanoscopi c cross sections (nanowire gratings) strongly depends on the polarization d irection of the incident light. We use silver and gold nanowire gratings pr oduced by electron beam lithography to study this effect by optical extinct ion spectroscopy. For a polarization direction perpendicular to the wire ax is, the excitation of a dipolar plasmon mode dominates the extinction spect rum. The spectral position of the plasmon resonance can be tuned by an appr opriate choice of nanowire geometry and material. For a polarization direct ion parallel to the wire axis, the profile of the extinction spectrum varie s mainly as a function of the grating constant. In particular, a transmissi on maximum for small grating constants is found. By combining the surface p lasmon excitation and grating effect for orthogonal polarization directions , a spectrally selective polarizer with an extinction ratio of 26 is demons trated. (C) 2001 American Institute of physics.