Acoustic total transmission and total reflection in zero-index metamaterials with defects

The acoustic wave propagation is investigated in the zero-index metamaterial (ZIM) waveguide embedded with defects. Two types of ZIMs, the index-near-zero metamaterials with matched impedance and the density-near-zero metamaterials with mismatched impedance, are examined. Theoretical derivations and numerical simulations show that the total transmission or total reflection can be achieved by properly tailoring the parameters of the defects even in deep-subwavelength scale. Moreover, the transmission is sensitive to the parameters of the defects, suggesting the active control of acoustic transmission by using particular defects with tunable parameters such as porous materials. (C) 2013 AIP Publishing LLC.