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

We report the theoretical evidence for the occurrence of onmidirectional re flection in one-dimensional phononic crystal structures, namely, a layered periodic structure that may exhibit total deflection of waves for all incid ent angles and polarizations in a given frequency range "the omnidirectiona l band gap". By introducing a defect layer in the finite-size layered struc ture, selective waves falling within this omnidirectional band gap may be t ransmitted through the structure. Such acoustic materials could be used for designing high-quality acoustic mirrors and filters in many frequency rang es of interest. (C) 2001 Elsevier Science B.V. All rights reserved.