Virtual singular scattering of electromagnetic waves in transformation media concept

Abstract

A phenomenon of virtual singular scattering with multiplicative effect has been revealed while studying electromagnetic wave multiple scattering on a dielectric scatterer embedded into a flat left handed material slab (Veselago’s lens) by the usual scattering operator (Tmatrix) technique. If both a scatterer and an observation point (receiver) approach the so-called near field zone of a source of electromagnetic waves, the scattering process becomes a singular one which is mathematically attributed to the spatial singularity of the free space Green function at the origin. Virtual singular scattering means that a scatterer is only virtually situated in the near field zone of a source, being, in fact, positioned in the far field zone. Such a situation is realized if the inner focus of Veselago’s lens approaches the position of a scatterer. Veselago’s lens transfers the singularity of the free space Green function by implementing the coordinate transformation which results in the formation of virtual sources inside and behind the slab and virtual scatterers (as a source of secondary waves) on both slab sides. Considering a line-like dielectric scatterer, we demonstrate that the scattering efficiency is proportional to the product of singular quasistatic parts of two empty space Green functions, which means a multiplicative quasistatic singularity of the Green function for a slab of inhomogeneous Veselago medium. The appearance of virtual scatterers outside the slab involves both the inside and outside lens focuses. This circumstance physically distinguishes the multiplicative effect from the well known superlensing effect utilizing only the outer lens focus. We show that small inhomogeneity contributes significantly into the scattered field in the regime similar to the well known Mie resonance scattering.