Plasmon-polariton transport in metal-nanoparticle chains embedded in a gain medium

Plasmon-polariton transport on chains of noncontacting noble-metal nanoparticles suffers from severe attenuation. A possible way of countering the attenuation by embedding the nanoparticle chain in an optical-gain medium is considered. It is found that short-wavelength surface polaritons can acquire exponential growth that can counter nonradiative loss. This is most pronounced for modes polarized transverse to the chain axis immediately outside the light line; this growth factor is likely to be sufficient to counterbalance losses and so lead to low-attenuation propagation of plasmon polaritons in nanoparticle chains.