Sub-wavelength imaging and resolution by two linear chains of plasmonic particles

The idea of constructing a super-lens in optical region with two linear arrays of metal nano-spheres is introduced and simulated. Using linear arrays of resonating particles the distance between the source plane and the image plane can be increased compared to the structures using metal slab in the optical region. The frequency is close to the resonance of the metal nano-spheres, here, silver spheres are studied which resonate in the visible region. The sub-wavelength resolution lambda/6 with 0.384lambda separation between the source and image planes is obtained in numerical simulation for the optimized structure. The distance between the source and image, 0.384lambda, is rather good result and is large enough for practical applications. In many applications, like photolitography or near-field optical microscopy, it is necessary that this distance is as large as possible. However, the distance can not be too large because the image is formed by near fields. Effects due to the stochastic deviation in the radius and the period are also considered. It is found that for large enough number of spheres the moderate deviations do not destroy the sub-wavelength resolution, on the contrary, the effect is improved.