  We investigate the influence of different metals on the electromagnetic
response of fishnet metamaterials in the optical regime.We found, instead of
using a Drude model, metals with a dielectric function from experimentally
measured data should be applied to correctly predict the behavior of optical
metamaterials. Through comparison of the performance for fishnet metamaterials
made with different metals (i.e., gold, copper, and silver), we found silver is
the best choice for the metallic parts compared to other metals, because silver
allows for the strongest negative-permeability resonance and, hence, for
optical fishnet metamaterials with a high figure-of-merit. Our study offers a
valuable reference in the designs for optical metamaterials with optimized
properties.
