Figure 4
From: The Emergence of Dirac points in Photonic Crystals with Mirror Symmetry
Topological edge states induced by magneto-optical effect.
The projected band structure of the photonic crystal ribbon containing 33 layers with PEC boundary (the shaded area at both ends means the PEC boundary) at the end is shown for structural parameters {r1 = 0.2a, r = 0.2a} for (a) and {r1 = 0.1a, r = 0.2a} for (b). The inset on the right shows the electric field distribution of the two edge modes marked by circle arranged in the same order. In (b), the mirror symmetry breaking along the helical propagating direction strengthens the finite size effect and opens a gap in edge mode spectrum. In both cases ε = 5.4, μ = μ0 = 1 and μκ = 0.5 are taken. Here the periodicity of the ribbon is denoted by 
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