Tunable optical properties of nanoporous gold leaf metamaterials

We report on the optical properties of nanoporous gold leaf (NPGL) metamaterials consisting of single and multiple-fold layers, and having different pore and ligament sizes. Due to their complex structure, such metamaterials have a unique optical property, which distinguishes them from homogeneous gold films. Thus, the transmission spectra of NPGLs feature two characteristic peaks positioned at ~ 490 nm and ~560 nm to 605 nm. The most notable result of this study is that the optical properties of NPGLs can be tuned by changing the dielectric environment and by applying voltage in an electrochemical cell.