Omnidirectional phononic reflection and selective transmission in one-dimensional acoustic layered structures

We report the theoretical evidence for the occurrence of omnidirectional reflection in one-dimensional phononic crystal structures, namely, a layered periodic structure that may exhibit total reflection of waves for all incident angles and polarizations in a given frequency range “the omnidirectional band gap”. By introducing a defect layer in the finite-size layered structure, selective waves falling within this omnidirectional band gap may be transmitted through the structure. Such acoustic materials could be used for designing high-quality acoustic mirrors and filters in many frequency ranges of interest.