Localized and delocalized surface-plasmon-mediated light tunneling through monolayer hexagonal-close-packed metallic nanoshells

We studied theoretically light transmission through a monolayer of hexagonal-close-packed nanoparticles consisting of a metallic shell and a dielectric core. We found that light can transmit through the dense particle assemblies via excitation of a variety of surface-plasmons (SPs). Localized SPs confined within metal nanoshells can mediate a narrow-band dispersionless transmission resonance (TR). Wide-band TRs were also observed as a result of strong near-field interparticle SP couplings, forming hybrid modes that are either localized at the nanogaps between adjacent particles or confined in the lattice pores, or distributed across the structure, each with distinct dispersion characteristics. Optical tuning strategies of these TRs are also elucidated that can allow for observation of SP anticrossing effects.