Optical characterization of epsilon-near-zero & epsilon-near-pole resonances of gold nanorod arrays

We report on the optical characterization of metallic nanowire (NW) metamaterials. In contrast to multilayer metamaterials, nanowire metamaterials exhibit an omnidirectional epsilon-near pole (ENP) and an angularly dependent epsilon-near-zero (ENZ), which are both highly absorptive resonances. We also demonstrate large tunability of the epsilon-near-zero resonance in the visible spectrum from 583 nm to 805 nm as the gold nanorod fill fraction changes from 26% to 10.5%. Energy dispersive x-ray (EDX) and X-ray Diffraction (XRD) analyses are used to ascertain the quality of electrochemically deposited Au nanowires prior to and after annealing.