Phase transition and acoustic localization in arrays of air bubbles in water

Wave localization is a ubiquitous phenomenon. It refers to situations that transmitted waves in scattering media are trapped in space and remain confined in the vicinity of the initial site until dissipated. Here, we report a phase transition from acoustically extended to localized states in arrays of identical air-filled bubbles in water. It is shown that the acoustic localization in such media is coincident with the complete band gap of a corresponding lattice arrangement of the air bubbles. When the localization or the band gap occurs, a collective behavior of the bubbles appears, a unique feature differentiating the localization effect from the residual absorption effect. (C) 2001 American Institute of Physics.