Metal and dielectric duality for an aligned Al nanorod array

In this letter, aluminum (Al) is used to make a narrow rod array (NRA) by oblique angle deposition method. The Al NRA film exhibits both metallic and dielectric optical characteristics. Like metal films, the Al NRA film only weakly disperses visible wavelength of normally incident light. However, strong interference causes the obliquely incident s -polarized and p -polarized lights to resonate in the Al NRA film. Even though the optical constant of the Al NRA film is dielectriclike, the surface plasmon wave excited and propagating on the surface of Al NRA is demonstrated to be responsible for the p -polarized resonance.