title: Three-dimensional axisymmetric cloak based on the cancellation of acoustic scattering from a sphere.
abstract: This Letter presents the design, fabrication, and experimental characterization of a directional three-dimensional acoustic cloak for airborne sound. The cloak consists of 60 concentric acoustically rigid tori surrounding the cloaked object, a sphere of radius 4 cm. The major radii and positions of the tori along the symmetry axis are determined using the condition of complete cancellation of the acoustic field scattered from the sphere. They are obtained through an optimization technique that combines genetic algorithm and simulated annealing. The scattering cross section of the sphere with the cloak, which is the magnitude that is minimized, is calculated using the method of fundamental solutions. The low-loss fabricated cloak shows a reduction of the 90% of the sphere scattering cross section at the frequency of 8.55 kHz.
authors.affiliation: UMDO (Unidad Asociada al CSIC-IMM), Instituto de Ciencia de Materiales, Universidad de Valencia, P.O. Box 22085, 46071 Valencia, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Sanchis
authors.affiliation: Wave Phenomena Group, Universitat Politècnica de València, Camino de Vera s.n. (Edificio 7F), ES-46022 Valencia, Spain.
authors.forename: V M
authors.initials: VM
authors.lastname: García-Chocano
authors.affiliation: UMDO (Unidad Asociada al CSIC-IMM), Instituto de Ciencia de Materiales, Universidad de Valencia, P.O. Box 22085, 46071 Valencia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Llopis-Pontiveros
authors.affiliation: Wave Phenomena Group, Universitat Politècnica de València, Camino de Vera s.n. (Edificio 7F), ES-46022 Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Climente
authors.affiliation: UMDO (Unidad Asociada al CSIC-IMM), Instituto de Ciencia de Materiales, Universidad de Valencia, P.O. Box 22085, 46071 Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Martínez-Pastor
authors.affiliation: Wave Phenomena Group, Universitat Politècnica de València, Camino de Vera s.n. (Edificio 7F), ES-46022 Valencia, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Cervera
authors.affiliation: Wave Phenomena Group, Universitat Politècnica de València, Camino de Vera s.n. (Edificio 7F), ES-46022 Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sánchez-Dehesa