Coupled plasmon-exciton induced transparency and slow light in plexcitonic metamaterials

Classical analogues of the well-known effect of electromagnetically induced transparency (EIT) in quantum optics have been the subject of considerable research in recent years from microwave to optical frequencies, because of their potential applications in slow light devices, studying nonlinear effects in low-loss nanostructures, and development of low-loss metamaterials.

A large variety of plasmonic structures has been proposed for producing classical EIT-like effects in different spectral ranges. The current approach for producing plasmon-induced transparency is usually based on precise design of plasmonic “molecules,” which can provide specific interacting dark and bright plasmonic modes with Fano-type resonance couplings.

In this paper, we show that classical interactions of coupled plasmonic and excitonic spherical nanoparticles (NPs) can result in much more effective transparency and slow light effects in metamaterials composed of such coupled NPs. To reveal more details of the wave-particle and particle-particle interactions, the electric field distribution and field lines of Poynting vector inside and around the NPs are calculated using the finite element method.

Finally, using extended Maxwell Garnett theory, we study the coupled-NP-induced transparency and slow light effects in a metamaterial comprising random mixture of silver and copper chloride (CuCl) NPs, and more effectively in a metamaterial consisting of random distribution of coated NPs with CuCl cores and aluminum shells in the UV region.