A two-dimensional square-rod-based tunable sonic crystal was constructed by $1.6\mathrm{mm}$-wide steel square rods in air with a lattice constant of $2.5\mathrm{mm}$ to operate in an ultrasonic regime. By means of simply rotating square rods, the scattering sections, corresponding to different geometric factors of the sonic crystal, have been changed to manipulate the refraction from positive to negative, and thus produce a tunable acoustic superlens. These results show an effective method to control wave propagations in not only sonic crystals, but also other periodic structures, such as light in photonic crystals and water propagation in periodic rods.

• Received 9 November 2005

DOI:https://doi.org/10.1103/PhysRevB.73.193101