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 $\sim \lambda$ 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.