A Numerical Study of Evanescent Fields in Backward-Wave Slabs

TL;DR

This paper uses FDTD simulations to analyze evanescent fields in backward-wave slabs, confirming surface mode excitation and evanescent mode amplification, which are crucial for superlensing applications.

Contribution

It provides a numerical verification of evanescent mode amplification in isotropic backward-wave slabs with epsilon=mu=-1, supporting superlens functionality.

Findings

Surface modes are excited at the slab interfaces.

Evanescent modes are amplified within the slab.

Numerical evidence supports superlensing capabilities.

Abstract

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.