Optical reconfiguration and polarization control in semicontinuous gold films close to the percolation threshold

摘要

In this work we have studied the intrinsic and reconfigured optical properties of semi-continuous gold films, fabricated via a simple metal evaporation technique. We have prepared three films of nominal thicknesses 5, 6, and 7nm. After fabrication the films are illuminated in areas by scanning a fs-pulsed laser over the films (Fig. 1). This results in permament morphological changes in the films observed in a scanning transmission electron microscope (STEM), see Fig. 2. The laser writing also introduces a polarized feature in the transmission spectra of the films. We have performed electron energy-loss spectroscopy (EELS) measurements and extensive finite-element simulations of our sample morphologies to better understand the origin of this polarization effect as well as the distribution of plasmonic resonances with and without laserwriting.