Accurate modeling of left-handed media using finite-difference time-domain method and finite-size effects of a left-handed medium slab on the image quality revisited

TL;DR

This paper highlights the importance of correct FDTD implementation for modeling left-handed media, showing that proper spatial averaging improves accuracy and revises previous conclusions about sub-wavelength imaging and finite-size effects.

Contribution

It demonstrates that conventional FDTD methods can be inaccurate for LHM modeling and proposes a correction technique, leading to revised understanding of imaging and size effects.

Findings

Conventional FDTD can misrepresent evanescent waves in LHM.

Proper spatial averaging corrects FDTD inaccuracies.

Finite-size LHM slabs do not significantly affect sub-wavelength imaging.

Abstract

The letter contains an important message regarding the numerical modeling of left-handed media (LHM) using the finite-difference time-domain (FDTD) method which remains at the moment one of the main techniques used in studies of these exotic materials. It is shown that conventional implementation of the dispersive FDTD method leads to inaccurate description of evanescent waves in the LHM. This defect can be corrected using the spatial averaging at the interfaces. However, a number of results obtained using conventional FDTD method has to be reconsidered. For instance, the accurate simulation of sub-wavelength imaging by the finite-sized slabs of left-handed media does not reveal the cavity effect reported in [Phys. Rev. Lett. 92, 107404 (2004)]. Hence the finite transverse dimension of LHM slabs does not have significant effects on the sub-wavelength image quality, in contrary to previous assertions.