Download original image
Diagrams identifying the sign of the refractive index according to the signs of the real and imaginary parts of the constitutive parameters. Blue (dark) areas refer to positive-index dissipative media (n′ > 0 and n″ > 0) supporting forward waves, while pink (light) areas refer to negative-index dissipative media (n′ < 0 and n″ > 0) supporting backward waves. White areas refer to amplifying media (n″ < 0) that are not considered here . (a) Diagram for acoustic metamaterials with complex-valued bulk modulus κ (= κ′ + iκ″) and mass density ρ (= ρ′ + iρ″). (b) Diagram for electromagnetic metamaterials with complex-valued relative permittivity ε (= ε′ + iε″) and relative permeability μ (= μ′ + iμ″).
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.