Theoretical studies of plasmon resonances in one-dimensional nanoparticle chains: narrowlineshapes with tunable widths

Abstract

In this paper we describe a new configuration for producing narrow extinction lineshapesfor light scattering from one-dimensional arrays of silver nanoparticles. In thisconfiguration, which is specifically concerned with an array with a finite number ofrelatively large (radius greater than around 30 nm) nanoparticles, the wavevector of thelight is chosen to be parallel to the array axis, while the polarization direction isperpendicular to the array axis. This leads to narrow plasmon/photonic lineshapes whenthe particle spacing is half the incident wavelength. This effect stands in contrast to thenarrow lines previously found for wavevector and polarization vector perpendicular to thearray axis, where the optimum spacing is close to the wavelength. The results arerationalized using a semi-analytical evaluation of the coupled dipole interaction, and it isdemonstrated that the parallel and perpendicular chains have very different dependence onthe number of particles in the chain. Results as a function of chain orientation relativeto the wavevector are also considered, as is the possibility of sensing using anarray configuration that combines the parallel and perpendicular chain directions.