Composite acoustic medium with simultaneously negative density and modulus

Phys Rev Lett. 2010 Feb 5;104(5):054301. doi: 10.1103/PhysRevLett.104.054301. Epub 2010 Feb 5.


We fabricated an acoustic composite structure consisting of a periodic array of interspaced membranes and side holes. Experimental data on the transmission, effective density, and phase velocity are presented. The system exhibits two critical frequencies, omega{SH} and omega{c}. Our metamaterial is double negative and transparent for frequencies lower than omega{SH}. For the frequencies omega{SH}<omega<omega{c}, the medium is opaque and only the density is negative. For the frequencies above omega{c}, the system is double positive and transparent. The present medium exhibits a very wide double negative spectral range that opens the possibility of the application of metamaterials for "white lights."