Figure 5
Schematic diagram for the variation of effective refraction index (a) and normalized power flow (b) with the reduced slab thickness at three different frequencies. The refractive indices of the core materials at three different frequencies are −6.04, −6.16 and −6.5, respectively. The cladding materials are air for the three frequencies. From (a), the effective refraction index of the NRW, smaller than the one of the components of the all dielectric taper suggests the mechanism of the slowing light effect stemming from the negative Goos-Hänchen effect instead of large group refraction index. From (b), the reduced slab thicknesses where the effective group velocities are zero at the three frequencies are 0.363, 0.357, and 0.329, respectively.
