Electromagnetic waves focused by a negative-index planar lens

Abstract

We demonstrate that negative refraction occurs for both cw and pulsed electromagnetic waves when traversing from a "right-handed" (index > 0) to a "left-handed" (index < 0) material (LHM) which has causal dispersive intrinsic properties. We also demonstrate that a divergent line source spaced a distance H in front of a planar LHM slab and excited by either an impulse cw or a Gaussian frequency pulse is imaged at a distance H away, inside the LHM, and at H to the other side of the slab. The image size is approximately lambda consistent with limitations dictated by wave optics. We find no evidence of evanescent mode amplification. The studies were performed using numerical experiments with finite difference time domain solutions and incorporating a causal Lorentzian form for the frequency-dependent material properties.