Figure 3

Effective parameters for three-layer effective medium model and perfect absorption conditions. Real (red) and Imaginary (blue) parts of (a) effective permittivity (\({{\epsilon }}_{{\rm{eff}}}\)) and (b) effective permeability (\({\mu }_{{\rm{eff}}}\)). (c) \(|{r}_{12}|\,\)(red) and \(|\alpha \cdot {r}_{23}|\) (blue): terms used in the amplitude condition (Eq. 2). Inset depicts various transmission and reflection coefficients of MPA structure. (d) \(\theta \) (red), \(\gamma \) (blue), \(2\beta \) (green), \(\varphi ({r}_{21})\) (black) and \(\varphi ({r}_{23})\) (orange): terms used in the phase condition (Eqs 3, 4). Two perfect absorption regions at 5.94 μm and 1.79 μm are highlighted in green.