(Color online) Two-dimensional conformal cloak proposed in Refs. 23 and 24: (a) Refractive index profile, with the boundary between superluminal (n < 1) and sub-luminal quadrants shown by solid curves (except the solid circle indicating the cloak boundary at r = a); the shading inside the circle (r = a) is cutoff at refractive index values n = 0 and n = 2, respectively; (b) refractive index as a function of the polar angle on the two sides of the discontinuity at r = a; (c) ray-tracing simulation showing trajectories and phase of the rays in the eikonal limit, assuming a plane wave incident along the x direction; (d) same as (c) with a plane wave propagating in the y direction.
(Color online) Two-dimensional conformal cloak proposed by Leonhardt et al. (Refs. 23 and 24). Full-wave simulations of the structure shown in Fig. 1. Angle of incidence: (a) 0, (b) π/8, (c) π/4, (d) π/2. TE polarization (E field out of plane) is assumed. Refractive index distribution is implemented using εz = n 2, with n given by Eqs. (2) and (3) and in-plane permeability μ = 1. Free-space wavelength λ 0 = a/5.
(Color online) Three-dimensional unidirectional acoustic cloak consisting of isotropic medium: (a) Pressure distribution on the cross-section of the cloak. Black lines show the streamlines of acoustic flux; acoustic wavelength at r a is λ 0 = a/2; (b) three-dimensional picture of the cloak with a finite exterior radius Rcut = 4a; wavelength in ambient medium (at r > Rcut ) λ 0 = a/2; the index transition is smoothed on a spatial scale ΔR = a/5. Acoustic wave impedance is assumed constant in both simulations; the speed of sound varies according to cs = c 0/n, where n is prescribed by the revolution of profile (2).
(Color online) Three-dimensional polarization-insensitive electromagnetic cloak made of isotropic non-magnetic medium: (a) Three-dimensional full-wave simulation with free-space wave-length λ 0 = 0.8a showing electric field component transverse to the propagation direction; simulation domain (excluding the PML) radius R = 4a; (b) 2.5-dimensional model with λ 0 = a/2 and cloak exterior radius Rcut = 6a; transition width ΔR = 0.3a.
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