摘要

Transformation optics (TO), based on the formally invariant property of Maxwell's equations, has provided a powerful strategy to design anisotropic or nearly-isotropic devices, in both time-varied and static fields. In this paper, we present and investigate the negative refraction or reflection phenomena by positive-index anisotropic materials based on transformation-optics design. First, we propose and design an inhomogeneous transformed planar lens, in which we will show the negative-refraction-like properties of transformation media. Secondly, we present a homogeneous transformed lens based on linear spatial transformation, in which we will reveal the negative-reflection properties of positive transformation media. Both transformed lenses have unusual properties which are different from those in natural materials.