Infrared optics of structured metal-insulator particulates

We show that rodlike particulates structured from interleaving layers of metal and insulator (or semiconductor) can exhibit novel infrared and far infrared characteristics that are tunable through the control of their geometric parameters. Results of scattering and absorption calculations are presented which demonstrate the validity of approximating the dielectric constant of the layered material by its effective medium value, thereby simplifying the prediction of the infrared properties. By clarifying the origin of the infrared absorption peaks, it is shown that the positions of the peaks are dependent on the transverse dimension of the particles as well as on the insulator dielectric constant and its relative fraction. The infrared characteristics of the structured particulates are contrasted with those of the metal, the insulator, and the semiconductor.