APS/Wenshan Cai

Figure 1: (Top) Light-bending behaviors in materials with positive, near-zero, and negative indices of refraction. In the index-near-zero medium, the electromagnetic fields become homogeneous with a uniform phase distribution. (Bottom) The dispersion relations of a dielectric strip waveguide with an air cladding (green) and a plasmonic waveguide with a dielectric core surrounded by a metallic cladding (red). The black circles indicate the cutoff conditions. The two straight lines correspond to the light lines of vacuum ($ω/k=c$) and glass ($ω/k=c/n$), respectively, and the dashed line represents the dispersion curve of surface plasmons. The inset shows the electric field (arrows) and magnetic field (color map) of the zero-index mode at the cutoff frequency.