title: Observation of a coherent backscattering effect with a dipolar source for elastic waves: highlight of the role played by the source.
abstract: We report an experimental evidence of the role played by the source on the coherent backscattering effect (CBE) for elastic waves. The experiment is carried out in a chaotic cavity consisting of a silicon plate whose shape is a quarter stadium. With a monopolar source, it has already been shown that the time-integrated squared amplitude at the point source is twice as large as at the other points around the source. Here, by using a dipolar source, we show that we instead obtain two peaks with the same axis as the dipole one's. The shape of this "bicone" is well explained with a modal theory assuming that the source may be modeled by two sources with opposite phases. Then, the theory is generalized to any multipolar emitter and/or receiver. Particularly, we study CBE when emitter and receiver are reciprocal.
authors.affiliation: Laboratoire Ondes et Acoustique, ESPCI, Université Paris VII, UMR 7587, 10 rue Vauquelin, 75005 Paris, France. julien.derosy@espci.fr
authors.forename: J
authors.initials: J
authors.lastname: de Rosny
authors.forename: A
authors.initials: A
authors.lastname: Tourin
authors.forename: M
authors.initials: M
authors.lastname: Fink