Figure 2. Performance of the designed non-blind invisibility cloak.

(a) Acoustic field distribution of the bare circular scatterer without cloak. (b–e) Acoustic field distributions of the circular scatterer with optimized two-layer cloaks of material properties in case (a) (ρ₁ < 0, κ₁ > 0, ρ₂ < 0, κ₂ < 0), case (b) (ρ₁ > 0, κ₁ < 0, ρ₂ < 0, κ₂ > 0), case (c) (ρ₁ < 0, κ₁ > 0, ρ₂ < 0, κ₂ > 0) and case (d) (ρ₁ > 0, κ₁ < 0, ρ₂ > 0, κ₂ < 0), subject to plane wave incidence. (f) Total scattering cross sections of the circular scatterer for three different cases: the bare circular scatterer, and the same scatterer protected by the dual layers cloak in cases (a,b).