Slowing light in diatomic nanoshelled chains

Coupled plasmon modes have been studied theoretically in periodic chains of shelled and unshelled metal nanoparticles embedded alternatively in a dielectric host, thus forming a diatomic chain. We calculate the dispersion relation of the diatomic chains and show that we can tune the shelled particle band into the unshelled particle band by varying the permittivity contrast and/or the core–shell radius ratio. This offers a precise control of the group velocity of coupled plasmon modes. The experimental realization of such diatomic chains by surface plasmon enhanced binding will be discussed.