A Numerical Study of Evanescent Fields in Backward-Wave Slabs

Numerical study of evanescent fields in an isotropic backward-wave (BW) (double negative or "left-handed") slab is performed with the FDTD method. This system is expected to be able to restore all spatial Fourier components of the spectrum of a planar source, including evanescent fields, realizing a "superlens". The excitation of surface modes on the interfaces of the slab, which is the key process responsible for the sub-wavelength focusing, is numerically confirmed and the time-domain field behavior is studied. In particular, a numerical verification of the amplification of evanescent modes by an isotropic BW slab with epsilon=mu=-1 is provided.