Simultaneously photonic and phononic metamaterials

Metamaterials have been primarily studied in electromagnetics and acoustics to date. In the fields of photonic and phononic crystals, structures simultaneously exhibiting both optical and acoustic---so-called phoXonic\textemdash properties---have been proposed, but this has not been done for metamaterials. Here we propose the concept of a phoxonic metamaterial, and demonstrate a working design in the GHz electromagnetic and kHz acoustic range that can simultaneously exhibit negative electromagnetic refraction at the same time as negative acoustic refraction