Plasmonic Oscillations in Au Nano-rods Fabricated by Electron Beam Lithography

Localized Surface Plasmon Resonances (LSPR) in rod-shaped Gold (Au) nanoparticles patterned with Electron Beam Lithography (EBL) technique are observed via reflectance measurements. Resonance peaks corresponding to the principal axes of the nano-rods are shown to be affected by each other. Excitation of one of the peaks is found to result in a decrease in the peak intensity of the resonance through the other axis. Arrays of Au nanoparticles with constant width and thickness but increasing length are examined for further understanding of the effect. As the particle length increased from 70 nm to 300 nm, resonance peak wavelength shifted from 650 nm to 1200 nm. Total reflectance intensities of samples with varying principal axis dimensions obtained through the spectral region of interest are also examined to see the relation between contributing electrons and total amount of reflected intensity. Results corresponding to both polarized and unpolarized illumination of samples are presented together to gain better understanding of lowered reflectance peak intensities obtained from the latter case. Based on the results obtained so far, nano-sized metal rods are promising tools for optically switched intensity modulation in the visible and near-IR region.