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(a) The scheme of the building block of an anisotropic NRIM and a NRW. (b) The transmission coefficients for the NRIM (red curve) and for the NRW (blue curve). The red curve demonstrates a transmission peak at 9.65 GHz, and it turns out to be a transmission dip for blue curve at 9.83 GHz, suggesting that the NRW indeed supports the slowing light effect. (c) The distribution of power flow within the tapered NRW at 9.83 GHz. The opposing signs (the red arrow for forward and the blue arrows for backward propagation) of the power flow in the core material and in the cladding materials suggest the occurrence of a huge negative Goos-Hänchen effect within the tapered NRW. The incident light is detoured around the interfaces between the anisotropic NRIM and air, and the energy is mainly trapped within the NRW.
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The measured magnitude (a) and the phase (b) of transmittance of the reduced NRW. Inset shows the image of the reduce NRW. The experimental results agree simulated results well in both the magnitude and the phase of transmittance with an offset in frequency due to mismatched constitutive parameters in simulation and in reality. Overall, the corresponding absorbance is equal to 0.90, suggesting a great energy confinement in the reduced NRW. Snapshots of the distributions of Ey field (c) and the Pz power flow (d) at 9.83 GHz in the reduced NRW. In (c), opposing signs of the Ey field between the core material and the cladding materials are an identifier for the fundamental degeneracy oscillatory mode in the RNW as suggested by the analytical solution shown in Ref. 10 . In (d), the huge negative Goos–Hänchen effect to equalize the forward and the backward propagating distances to achieve zero group velocity and the slowing light effect are observed.
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(a) The variation of the normalized power flow P = Ptot/(|P1| + |P2| + |P3|) and the effective refractive index with the reduced slab thickness for the reduced NRW. With the aids of half the critical thickness, free space k-vector, and retrieved n = −1.2 for the anisotropic NRIM, the index of the reduced NRW is derived. (b) The snapshot of distribution of E-field within the reduced NRW. An identical critical thickness is observed with the index set of (−1.2, 5, −1.2) for the upper cladding, the core, and the lower cladding materials, respectively. The distribution of E-field suggests the existence of the fundamental degeneracy oscillatory mode in the reduced NRW. (c) The snapshot of distribution of power flow within the reduced NRW. The opposite signs of the power flow at the critical thickness demonstrate the negative Goos–Hänchen effect and result in zero propagation distance and zero group velocity as well.
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