Figure 5
From: Dirac directional emission in anisotropic zero refractive index photonic crystals
Seven-beam Dirac directional emission in photonic crystals with 51.4° rhombic lattice.
(a) Semi-X Dirac dispersion when the radius is r = 0.173a and the permittivity is ε = 12.5.(a1)–(a2) The corresponding iso-frequency contours to show the multi-mode near Dirac frequency. (b) Ez fields of the heptagonal device to show the absence of zero-refractive-index feature. (c) Semi-Y Dirac dispersion when the radius is fixed at a slight difference value of r = 0.178a. (c1) Elliptical iso-frequency contours above Dirac frequency and (c2) Hyperbolic iso-frequency contours below Dirac frequency. (d) Ez fields of seven-beam directional emitter when zero-refractive-index is present.
