Electrochemical restructuring of plasmonic metamaterials

Recent electrochemical experiments on gold-based photonic metamaterials have shown reversible optical modulation as well as an irreversible reduction in the plasmonic damping. Here, we systematically study the latter aspect as a possible means of postprocessing plasmonic gold nanoantennae arrays aiming at loss reduction. We characterize the samples by optical spectroscopy, electron microscopy, and atomic-force microscopy. For sub-10 nm gold thicknesses, the measured damping decreases by factors exceeding 3; for 20 nm thin structures, the obtained loss reduction still amounts to about 30%.