Twisted arrays of resonant particles

In this paper we simulate and analyze a twisted array of gold ellipsoidal nanoparticies operating at optical wavelengths. The particles, shown in Fig. 1, are oriented along the z axis with spacing d and are sequentially rotated about the z axis by a constant angle φο. In response to an external field E(r) each nanoparticle is assumed to behave as a point dipole with dipole moment p = α E, where α is the ellipsoid polarizability tensor. Although our analysis is restricted to nanoparticle arrays, the general results are expected to be valid for all classes of twisted resonant arrays and all frequency ranges. Using Green´s function methods, we first analyze an infinite twisted array to find the traveling wave modes and their properties. We then simulate a finite twisted array to confirm the predicted behavior.