Cloaking and transparency for collections of particles with metamaterial and plasmonic covers

Following our recently developed idea of employing plasmonic covers to cloak an isolated conducting, plasmonic or insulating sphere through scattering cancellation, here we extend this concept by investigating the possibility of cloaking multiple objects placed in close proximity of each other, or even joined together to form a single object of large electrical size. We show how the coupling among the single particles, even when placed in the very near zone of each other, is drastically lowered by the presence of suitably designed covers, thus providing the possibility of making collections of objects transparent and "cloaked" to the impinging radiation even when the total physical size of the system is sensibly larger than the wavelength. Numerical simulations and animations validate these results and give further insights into the anomalous phenomenon of transparency and cloaking induced by plasmonic materials and metamaterials. (c) 2007 Optical Society of America.