Electromagnetic properties of a left-handed medium slab excited by three-dimensional electric dipoles

We have studied the physical properties of electromagnetic (EM) waves in a lossy left-handed medium (LHM) slab under the excitation of three-dimensional (3D) electric dipoles. We first investigate the well-known imaging property of the LHM slab by a 3D dipole. We show that the propagating part of EM fields emitted by the 3D dipole can be well refocused at the image points, while the evanescent part can be partly recovered which helps to achieve the super-resolution, just like the case of two-dimensional 2D point source. We also show that strong surface waves are excited on the slab interfaces by the 3D dipole, where the surface modes look like cylindrical waves. This is quite different from the 2D case. Second, we have realized the energy localization using the LHM slab and two opposite-direction electric dipoles. The relations between the imaging resolution and the localization ability of the LHM slab have been investigated theoretically and numerically, which will be helpful in the future design of energy-localization devices. (c) 2005 Elsevier B.V. All rights reserved.